# "Cooper's Tom Thumb loco"



## Grimm (Oct 5, 2009)

I have been just lurking here, soaking up as much knowledge as I can before I begin my first foray into live steam.  I have decided which engine I'm going to make after I have finished my snow plow, it's the so-called "Tom Thumb" engine made by Peter Cooper in 1830.  The engine was made as an experiment to convince the B&O directors to use steam power instead of horse power on the railroad.  The engine was fairly simple and only had a small boiler and a single piston.  I thought that this would be a much better first engine to build.  I thought at first I might make a grasshopper or a coal crab type engines but I think that at my level of experience I would just be getting into trouble.    There are no plans known that depict the engine from the time period, even in the B&O report they state, "This engine being too small for advantageous use, no further description of it is deemed necessary."    So I'm working off of just the eye witness accounts, Peter Cooper's recollections, and a drawing done by B. H. Latrobe in 1869.  The drawing doesn't have many of the features that the origonal engine had and Ross Winans appears to have not fully endorsed the drawing, so it's an iffy resource.  
 
On to my question -  Peter Cooper in an interview with the Boston Herald on July 9, 1882 states "But I couldn't find any iron pipes. The fact is that there were none for sale in this country. So I took two muskets and broke off the wood part, and used the barrels for tubing to the boiler, laying one on one side and the other on the other."  

 
My  question is why would he have needed two musket barrels?  The two possibilities I thought of were that the barrels were too small and he needed two to get enough steam from the boiler to work the piston.  The other possibility I was thinking of was that one of the barrels was to supply steam to the piston, the other one was to empty all of the steam from the boiler so it could be filled with water.   In Ross Winans report to the company about the engines performance he states, "Seventh mile travelled in five minutes and thirty seconds; the engine stopped at the middle depot for fifteen minutes to receive a supply of water.", and later continues, "Sixth mile traveled in four minutes five seconds. (Four minutes occupied in taking in a supply of water.)"   In Little Journeys to the homes of great business men: PETER COOPER by Elbert Hubbard, 1894 states, "Peter experimented and found that the water in the boiler would last one hour; then the fire would have to be drawn, and the boiler cooled and refilled."  This doesn't seem correct because according to Winans' report the second time the engine took on water it only took 4 minutes, not nearly enough time to cool the boiler.  The only way that this could be accomplished would be to drain the steam and pressure and then fill the boiler with more water.  Which sounds like the more likely possibility?   Also does anyone know of the formula to calculate the amount of steam needed to run a piston that is 3.5 inches in diameter and has a 14 inch stroke?  I was thinking that a formula might make it easier to decide between the two.  Thanks so much.

 
Jason


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## Semper Vaporo (Jan 2, 2008)

*RE: Steam pipe question*

I was always under the impression that the rifle barrels were used as flue tubes in the boiler, so your comments are a big surprise. Now I have looked a bit using Google and from what (very) small amount of additional reading I have just done, I am wondering if his boiler was a water tube type and the gun barrels were the tubes where the water was flashed to steam.

If it was a water tube boiler, then replenishing the water could be done rather quickly. Pressure could be released and water added to the main reservoir without much trouble.

The replicas of the Tom Thumb show a vertical boiler that could be either a flue tube or water tube type (though my impression is that it is a vertical flue tube type), but all the descriptions of it say it is NOT an accurate replica at all. It is larger, heavier and has a much larger boiler... MUCH LARGER.

According to John Latrobe (lawyer for the B&O Railroad from its inception):

"The boiler of Mr. Cooper's engine was not as large as the kitchen boiler attached to many a range in modern mansions. It was of about the same diameter, but not much more than half as high. It stood upright in the car, and was filled, above the furnace, which occupied the lower section, with vertical tubes."

This description still leaves me wondering if it was flue tube or water tube since I understand that many of these "kitchen boilers" were of the water tube type, being used to supply hot water (not cooking in it)... (not unlike the modern "point of supply hot water heaters").



I'll have to go hunting for the formulae for sizing the boiler and cylinder sizes. I know there are some. Are you planing on making a full sized replica or a model of one. Your bore and stroke are from the original.


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## Grimm (Oct 5, 2009)

*RE: Steam pipe question*

Hi Semper,

Thank you very much for the comments and help. I had read too that the musket barrels were used for the flue tubes, but I haven't found any evidence that that was the case. I think that a writer must have miss-quoted someone and it stuck. Mr. Latrobe does state that, "The number, size, and length of the tubes are not known, only their position in the boiler.", but he makes no mention that the tubes were made from musket barrels. 


Confusingly in "Little Journeys to the homes of great business men: PETER COOPER" by Elbert Hubbard, 1894 states "He had made the engine, but now he must make a boiler in which to generate the steam to make the wheels go round. This boiler he made and riveted with his own hands. It stood upright and was as high as his shoulder. It had a furnace beneath. *It contained no tubes*, and the proposition was to fill it half full of water and then boil this water. It took three weeks to make the boiler. It was about as big as the tank in an average kitchen range. There were no water-gauges or steam-gauges. The engineer had to guess as to the pressure he was carrying. When the boiler was complete, the great difficulty was how to carry the steam from the boiler to the engine. There were no wrought-iron pipes then made or sold in America. Cooper took a couple of muskets and used the barrels for pipes to connect his boiler and engine. These were duly soldered into place." Emphasis my own. Hubbard does not say in his book if he had interviewed Cooper or if he had gotten the information from other sources. Although most of the details match what I have found in other sources. 

Winans in a letter to B. H. Latrobe November 20, 1869 said that "The boiler was tubular, and upright in position. Mr. Winans does not recollect the dimensions of it, although he says it lay in his shops for several years. He thinks it was not more than twenty inches in diameter, and, perhaps, from five to six feet high."

Peter Cooper in an interview with the Boston Herald on July 9, 1882 states "I got some boiler iron and made a boiler, about as big as an ordinary washboiler, and then how to connect the boiler with the engine I didn't know... I had not only learned coach-making and wood carving, but I had an iron-foundry and had some manual skill in working in it. But I couldn't find any iron pipes. The fact is that there were none for sale in this country. So I took two muskets and broke off the wood part, and used the barrels for tubing to the boiler, laying one on one side and the other on the other." Cooper continues, "Monday morning, what was my grief and chagrin to find that some scamp had been there, and chopped off all the copper from the engine and carried it away —doubtless to sell to some junk dealer. The copper pipes that conveyed the steam to the piston were gone. It took me a week or more to repair it." He continues, "... the smoke-stack was described as looking "like an aggravated putty-blower.""

I should have given you the full quote instead of the snipped I posted above. I'm thinking that the copper pipes connected the throttle to the piston and that the musket barrels connected the throttle to the boiler. I appears that when they quote an "engine" that it would also include not just the piston, but everything else like the throttle, valve, valve gear, pipes, etc. This Cooper said he had purchased in New York, but doesn't say from whom. 


Yes the 1926 replica isn't at all a good representation of the original locomotive, it was based off a wooden model made by a Major Panghorn in 1894. It doesn't match much of the details I have found at all, so I don't know how well Major Panghorn had researched the engine for his model. That is interesting about it might have been a water tube boiler. Did they have that technology at the time?


I'm planning on making a model, I wish I could do a full-sized version, that would be fun. I'm going to make it in F-scale standard gauge, so 1:20.32 and a gauge of 2.781 inches. I want to make it live steam and I have calculated that in F-scale the boiler would be about 1 inch in diameter and about 3 inches tall. Would this be too small for live steam? Thanks again for your help,


Jason


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## Semper Vaporo (Jan 2, 2008)

*RE: Steam pipe question*

I think I am beginning to see why the replica looked nothing like the original... they wanted it to actually work!!!









 Lessee... 3.5x14 original cylinder becomes a 0.172x0.689 model (.372 cu. in.).

The original boiler was (maybe) 20" by 66" so the model would be 0.984 by 3.248 inches. At "half full" (and assumming no flue tubes taking up space) that would be (0.984*Pi*3.248 = 10 cu. in.) / 2 = 5 cu. in. of water. Water expands by about 1600 times when converted to steam so that is 8000 cu. in. of steam; assuming, say, 25% expansion in the cylinder then you are only using 2000 cu. in. of steam. Divided by the cylinder volume then the cylinder will expell all the steam in 5,000 strokes.

If the boiler pressure is 40lbs/sq.in. then the piston has a power of .172 * Pi times that or 21 lbs, minus pressure losses on the way to the cylinder (friction in the pipes, not necessarily "leaks", but that might need to be taken into account too). Also, that is only applied while the valve is open to the boiler and once the valve closes the pressure drops exponentially as the piston moves. So the actual "work" from it all is considerably less. Without knowing the valve type and the timing it is difficult to estimate what you would get out of it.

Although that 5,000 revolutions seems high, rememberthat small engines tend to run FAST and it would not take long to reach that count. Maybe 2 to 5 minutes?

The accounts of how long the Tom Thumb ran between water fillings was something like 4 to 6 minutes, so my guesses may be a bit low.


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## Grimm (Oct 5, 2009)

*RE: Steam pipe question*

Posted By Semper Vaporo on 27 Nov 2009 04:24 PM 
I think I am beginning to see why the replica looked nothing like the original... they wanted it to actually work!!!










LOL, yes very true.







Thanks for finding those calculations, so it looks like the model wouldn't run for very long. That's ok I'm just doing this engine to get more experience with live steam and model building in general. If I could get the model to run for 5 minutes I would be very happy. According to Winans' report the origional engine ran for more then 30 minutes before taking on more water. 


The only information about the piston that I was able to find was it's dimensions. There might be another passing reference to the valve and gear by Mr. Latrobe in which he says, "In this car-shop, Mr. Cooper had his engine, and here steam was first raised; and it seems as though it were within the last week that the speaker saw Mr. George Brown, the treasurer of the company, one of our most estimable citizens, his father Mr. Alexander Browns Mr. Philip E. Thomas, and one or two more, watch Mr. Cooper, as with his own hands he opened the throttle, admitted the steam into the cylinder, and saw the crank-substitute operate successfully with a clacking noise, while the machine moved slowly forward with some of the bystanders, who had stepped upon it." I'm assuming that the valve was a D-type valve and the valve gear was the type that operated off of the crosshead (I forget what it is called) and that is what caused the "clacking noise". Or maybe he was talking about the piston rod that was connected to the spur gear?


What would you fire a boiler this size with? I was thinking alcohol, kerosene, or even those dry tablets. I was thinking of getting one of the 25 psi safety valves from Jenson but do you think I should go higher, up to 40 psi? Thanks,


Jason


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## Grimm (Oct 5, 2009)

*RE: Steam pipe question*

I had another thought about the two musket barrels. Could the second one be for the exhaust steam to send it back to the boiler and out the stack? I wasn't too sure that Cooper would have been that sophisticated, but it would have been common knowledge at the time. Another problem with this is that he had to make a blower to keep the boiler going. Why would he have made a blower if he had a blast pipe? Maybe because he had just one cylinder that there would not have been enough blast to keep the boiler going and the blower would have been much more constant? 

Jason


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## Semper Vaporo (Jan 2, 2008)

*RE: Steam pipe question*

There are lots more sophisticated formulae for all of this, but not knowing the valve timing it gets to be more like "by guess and by golly"... which is what I did. (Besides, the "exact" forumlae also include some "fudge factors" that are considered "Standard" but can be varied to give you about any answer you want.) That 25% expansion I guessed can vary greatly based on how long the steam port is open and the volume of the steam space at the instant when it closes. If the port closes early then the amount of steam used is very small compared to, say, the port closing at 50% of the stroke. Also, how fast can the steam pass in the pipes from the boiler to the cylinder? Depends on the diameter of the pipes (the whole lenght of them, not just the narrowest point, although that is also very important).

As for one of the pipes being used for a blower; since the descriptions I have read all refer to a "fan" type blower in the stack run by a pully and belt to the axle (the one that failed in the first race where the horse won) I doubt if there as an exhaust powered blower. I have no idea when the exhaust blower was invented.

Also, it must not be that he just needed a longer pipe because the description that was quoted: "one on one side and the other on the other side" implies two separate pipes, so I am also stumped as to why TWO musket barrels. I also thought the quote, "I broke off the wood part" was rather interesting! As was the comment about someone stealing the copper bits overnight... Same vandalous crooks are at it today, stealing copper from homes and off utility poles, etc.

As for your pressure release Safety valves... The setting should be based on two things... how much can your boiler and steam path handle and what is necessary to operate the machine. Most of the boilers we build from copper pipe (IF built right) will handle over 1000 PSI, so that means your safety could be just about anything you might feel like using up to about 1/2 that, which is ridiculous. Keep it as low as you can and still operate the machine for safety's sake. Again it depends on friction and other loses as well as the weight of the engine and a host of otherthings as to how low you can go and still run the thing.

Most small steam motors (properly built) will spin a flywheel on 5 to 10 PSI and move themselves with a boiler on 10 to 20 PSI. So starting with a 25PSI safety is not bad. Many people have a Ruby loco and I think the original Safety was set to about that, but I think many of those have been replaced with a higher pressure valve (40 to 60 PSI) and the engines work lot better and I don't think there has been any compromise in real "safety".

Depending on the engine and all, alcohol or fuel pellets would work fine. I don't know which would be better. I have small stationary boilers that run on both and they both work well. Alcohol seems to "me" to be not quite as safe as pellets since, if spilled, it can run and carry the fire farther, but either way, we are "playing with fire" so caution is required at all times.


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## SteveC (Jan 2, 2008)

*RE: Steam pipe question*

Jason

I think I've nailed down where the reference for the use of gun barrels for tubes. In a book published in 1874 by Mr. William H. Brown. In the extract I made from this book and saved as a PDF file (link to file found below). If you look at the block labeled as -p110-, which refers to that page in the original book. The content of the page is a letter to Mr. Brown from Mr. Benjamin H. Latrobe dated August 4, 1869. In the second paragraph just a little past the middle, where Latrobe is relating that Cooper was the first to suggest the use of a tubular boiler. There is an asterisk which ties to a footnote at the bottom of the page. Where Brown annotates that Mr. Cooper had further clarified that he used gun-barrels for the boiler tubes.

Cooper's 'Tom Thumb'[/b] 

In answer to what fuel was used it was anthracite coal.


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## Semper Vaporo (Jan 2, 2008)

*RE: Steam pipe question*

Curiouser and curiouser... Somewhere I remember a statement that it was just two gun barrels. One place I remember the word "Musket" in association with them and another place, "rifle". I think "Musket" was from Cooper himself so I'd tend to believe that term more.

BUT!

What is the inside diameter of a "Musket" barrel? How long are they, too? If the boiler had these tubes in the length and the boiler was "about 5 or 6 feet in length"; would "Musket" barrels be long enough for that? I bet there are too many variations here to be useful for determining anything.

I am also having some strange visions how he did the "break off the wood part", as he stated it! Were the stock (and possible mid barrel hand-hold), glued on? What'd he do, swing it over his head by the end of the barrel and bring the stock down on a hitching post? Hope it was unloaded!

Unless they were around 2 inches in diameter, then given that there were only two of them, a "flue tube" boiler would not have much heat exchanging area and would be inefficient. If there were "many" barrels then it would be better, but I have this vision of a rifle barrel on the order of 1/4 to 1/3 inch and that is mighty small for flues no matter how many there were! Anthracite coal would be okay with small flues, but I think you'd want a dozen or more.

For reference, the "Rocket" had 25 - 2-inch diameter flues in a 3-ft diameter boiler.

Could you get enough air flow through two flues to efficiently burn coal in a burner of about 20-inch diameter? Anthracite would want plenty of draft!

As a water tube boiler, only two tubes is also terribly inefficient, regardless of the diameter of the tubes, especially since the statements say they were "vertical".

The text you supplied still leaves me wondering what they were talking about... "Tubular boiler" could just mean it was "round on the outside". Or he could have been refering to a water tube boiler, or a flue tube boiler. Not really a helpful statement in context today.

The drawing also leaves out a lot of stuff that the text describes (and even says is there!). I don't see the blower pulley in the stack.

I am not too sure of what kind of cylinder it has. It appears that the piston rod came out the top and used long connecting rods along side to push/pull the crank on an intermediate shaft below the cylinder that was then geared to the front axle.

Apparenly he used copper for the piping away from the boiler (the stuff that was stolen), so I assume he did not feel it was suitable for the boiler innards and that is why he used the gun barrels.

I am sure more professional people that we have worked on this and I have found no conclusive information from anyone to explain what it really was. Apparently, even the people that actually saw it did not know, or could not remember, what it really was like.


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## SteveC (Jan 2, 2008)

*RE: Steam pipe question*

C.T.

If I'm not mistaken the reference to the two muskets came from an interview narrative by Mr. Cooper that was reported in the Boston "Sunday Herald" of July 9, 1882. However, he was referring to making connections from the boiler to the steam engine, not the tubes in the boiler.


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## Grimm (Oct 5, 2009)

*RE: Steam pipe question*

Thanks Semper! That is really helpful. I'm starting to lean towards having a 40 psi safety valve, so hopefully I can push a car too, just like the original. 
As to when they invented the exhaust blower, it was in the mid 1820's. The Stephenson engine Locomotion from 1825 had one. The Stephenson Rocket also had one and it was the engine that really set Cooper's imagination going. For a long time now it has been assumed that Stephenson had invented the exhaust blower, but a letter has surfaced that has changed that. It was a letter from Stephenson to Hackworth and had something to do with Hackworth making the first exhaust blower but I don't know the details. Hackworth worked for Stephenson and was probably the one responsible for the blower in Locomotion. 


Breaking the stocks off of the muskets seems a bit violent.  I can imagine that once he had the stocks off he then cut the back end off of the barrel so it could be used as a pipe. I did some research on muskets and found that in 1826 the US Army was getting rid of all their old muskets and replacing them with more modern firearms. I would think that Cooper probably had easy access to these old guns. I also found some measurements of these muskets and they vary a lot. The barrel lengths varied from 30 to 46 inches long (or longer) and the internal diameter were from 50 cal to 79 cal (that would be 0.5 to 0.79 inches). Still much smaller then the Rocket's flues. I'm with you, I don't think that gun barrels would have made very good flues. It is more likely that it is how Cooper said it was, that they were used to connect the boiler to the engine. Steve's PDF file is very interesting in that Mr. Brown states that " Mr. Cooper has since informed the author that, for want of regular tubes (not then ever used), he substituted gun-barrels for tubes." Sounds like it was a miss-understanding between the two about just what they were talking about. Brown thought they were talking about the boiler and Cooper thought they were talking about tubes.







If it is true that the boiler didn't have any tubes, although I think that it would have had at least one for the draft, then how does that change your thinking on the gun barrels? Maybe my origional thought was correct that because he was forced to use gun barrels, and because they had a small diameter, he had to use two of them to get enough steam to the piston? In this case he put one on each side of the boiler for symetry or as additional supports for the boiler. You can see two supports in Mr. Latrobe's sketches that might be the barrels, at least they are at the perfect height to pull steam from the boiler.


Steve - Thank you for that reference! It helps a lot, especially the bird's-eye-view drawing. He still didn't depict the blower though.









Jason


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## Grimm (Oct 5, 2009)

Thanks Steve for changing the topic name, I think it reflects the subject matter better. I'm going to put my thoughts about the boiler (my F-scale version that is) in my cad software and if you guys could check it for me, that would be great. 

Going on to other topics, I was thinking about the blower and what I have found about it in my research. This is a really difficult part of the engine. It is not shown in Mr. Latrobe's sketches and there are two conflicting accounts about it. The first I found is from a letter from Mr. Winans to Mr. Latrobe and recalled by Mr. Latrobe. In it Winans states, "The fuel was anthracite coal, and an artificial draught, in the firebox at the bottom of the boiler, was created by a fan, driven by a belt passing around a wooden drum attached to one of the road-wheels, and a pulley on the fan-shaft as shown in the sketch." It seems, from this description, that the blower's output was connected to the firebox at the bottom of the boiler, pretty simple no? 


The next snippet of information is from a talk that Mr. Cooper gave at the Master Mechanics Association meeting in 1874 at the Cooper Union Hall. Mr. Cooper states that, "I had feared that I would not be able to get enough steam out of that boiler, so I had attached a blower, such as you never saw, I guess, to a crooked joint on the top of the smokestack. From there I carried a belt down over a wheel on the shaft. When I got up enough speed, the belt ran a blower. I found that I had sufficient power to draw the shavings right though the boiler." Now the blower is up on top of the smoke stack and not down below by the firebox, and this from Mr. Cooper himself. 


So I now have a conundrum of epic proportions.  On one hand Mr. Winans knows his stuff mechanically and it would be strange for him to misplace the blower so badly. On the other hand he may be confusing it with the blowers he had installed on the later grasshopper type engines. The same could be said of Mr. Cooper, the guy who actually built the engine. His recollections have issues as well, for instance the number of people who were on the passenger car and engine keeps changing with each of his retellings. The other problem with Mr. Coopers rememberances is with the smoke stack itself. He had said that " the smoke-stack was described as looking "like an aggravated putty-blower."" I looked up what a "putty-blower" is and it appears to be a kind of blow-dart gun that widened at the end. If the blower was installed at the top of the smoke stack you would think that it would have gotten a different description. The Latrobe sketches do depict the smoke stack with the "putty-blower" end to it. You would think that Mr. Latrobe would have not forgotten such a thing as well and included it in his sketches?


Now we are going into crazy theory mode. Lets say that Mr. Winans is correct that the blower's output went directly into the firebox. One of the most convenient spots to put the blower would be under the floor of the car with the output going through the floor and into the firebox. It would make it easier to hook it up to a drum on one of the wheels that way as well. This would also explain why Mr. Latrobe did not depict it in his sketches as it would not have been easily seen, so he may not have remembered it like the other features of the engine. It's a stretch I know, any other thoughts? 


Jason


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## Taperpin (Jan 6, 2008)

Jason, 
live steam magazine March 1989 had a article on a 3.5inch gauge tom thumb.. lots of usefulk info but boy is that Boiler small..I think alcohol may be the only way of getting enough heat in the limited space for combustion..the Barrel will be about 1 inch diameter. 

Gordon.


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## DKRickman (Mar 25, 2008)

One question comes to my mind.. 

If Tom Thumb's boiler had no flues, why did it need a draft fan? Where did the smoke go? The only thing I can think of is that the boiler would have been essentially a pressure tank suspended inside a larger diameter shell, with the exhaust gasses passing around the outside. Conversely, if it used gun barrels as flues, just how much fuel could you actually burn? Two barrels would not seem to offer much in the way of room for the exhaust.


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## Chris France (Jan 3, 2008)

I can tell you from experience that the replica doesn't work very well either as I've been its engineer a few times. My understanding, and the understanding of pretty much everyone at the B&O Museum is that the gun barrels were used as tubes in the boiler. They would have been more than long enough as the overall dimensions of the boiler mentioned would include the firebox sitting below. The replica which as noted does have a larger boiler only has 3 ft or so worth of tubes between the firebox and smokebox. I'm pretty sure that there was no exhaust blower, and next Sat I'll have to check to see where the replica's fan powered blower puts the air in (although I understand that that may not be correct for the original). I believe that all of the connections between the boiler and cylinder would have been copper and most likely replaced with copper after being stolen as iron pipes would not have been the best for conducting steam under pressure under the conditions on that engine. 

You might try contacting the archivist at the museum, John Maranto, not sure if we have any more resources there than what you have already located, but John maybe able to help.


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## Grimm (Oct 5, 2009)

Thanks Gordon, yes, the boiler is very small. I was thinking of using those tablets to fire it with, so you think that they wouldn't get hot enough? I am thinking of building a working fan blower, in F-scale it might be doable I think. Would that help get the temps up enough? 

Kenneth - My thought on it is that it had at least one center flue for the draft. I'm assuming that if Mr. Cooper didn't have any problem building the outer shell of the boiler, he wouldn't have had any problem making a central flue for it as well. I guess you could add the smoke stack in with that as well.


Chris - Thank you for the pointer to John Maranto, does he have an email address? I did try and contact the B&O museum but they never did respond to my email, maybe they were too busy, or I didn't word it correctly? I'm a bit confused with your statement about the iron pipes not being the best to conduct steam. Is it because they would cool it off too fast? Thanks,


Jason


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## mikemartin (Feb 14, 2008)

I hope I don't step on any toes by posting the following corrections and additions to the volume calculations posted earlier. 

A 3.5" diameter x 14" stroke prototype cylinder scaled to 1:20.3 is done as follows: 

3.5"/20.3 = .172" bore 
and 
14"/20.3 = .690" stroke 

The volume of a cylinder is calculated by mutiplying its height (stroke) by its sectional area (the circular area perpendicular to the primary axis of the cylinder). 

The sectional area is calculated by multiplying, the radius of the bore squared, by pi. 

In this case, 
.690 x (.172/2) ^2 x pi 
which is the same as 
.690 x .086 ^2 x pi 
which is the same as 
.690 x .086 x .086 x 3.1416 = .016 cubic inches (volume) 

The same goes for the boiler but its working volume is significantly less than its gross volume. 

The gross volume of the boiler is: 

20" diameter by 66" height (estimated prototype size) 

20"/20.3 = .985" scale diameter 

66"/20.3 = 3.25" scale height 

gross volume is calculated as for the cylinder: 

3.25 x .493 x .493 x 3.1416 = 2.48 cubic inches (gross volume) 

Working volume would be a fraction of this due to the need to never run the boiler dry, and the fact that you must start with some steam space (i.e. the boiler cannot be 100% filled with water and expected to function). For even a simple pot boiler (no flues) a working height of 1/2 the overal height would be a fairly aggressive design goal (1/4 volume reserved for initial steam space, 1/4 volume reserved for a sfe amount of water left at the end of the run, the balance being "working volume"). In this example, this would reduce the working volume to 1.24 cubic inches of water. 

The difference of volume steam being quoted as 1,600 (1,700 often cited) x that of water is true only for unbounded (pressureless) steam. If we didn't need to do any work with it, that number would be useful. However, the volume of steam created from 1 cubic inch of water diminishes quickly as the pressure rises to useful levels 

at 0 psi 1:1,700 
at 10 psi 1:1,036 
at 20 psi 1:726 
at 30 psi 1:572 
at 40 psi 1:474 (typical of Roundhouse brand locos) 
at 60 psi 1:354 (typical of Aster brand locos) 

So, at say 40 psi, that 1.24 cubiic inches of useable water becomes 588 cubic inches of steam (1.24 cubic inches x 474). 

The voulume of the cylinder is .016 cubic inches which, if double acting, would consume .032 cubic inches of steam per revolution of the engine. In model practice, a solitary double acting cylinder would usually be geared down to provide more torque and a better piston speed to, in part, keep the cylinder warm. 

Because the proposed .172 diameter cylinder has only 11.8% the area of a .500 diameter cylinder, the engine will need even more gearing down than is typical of a larger diameter cylinder to provide adequate torque at the drive axle. (See the end of this post for the area and force calculations.) 

At a conservative 10:1, this would put the steam consumption at .32 cubic inches per wheel revolution (the engine rotating 10 times for each wheel revolution, and the cylinder being filled at each end of its stroke). This works out to 1,838 wheel revolutions per run (588 cubic inches / .32 cubic inches per wheel revolution = 1,838 revolutions). However, steam is not a perfect gas and there are real losses that cannot be neglected. A figure of 75% utilization is probably optimistic, but often quoted. This brings us to 1,378 wheel revs per run. 

So, how long will the engine run? At a scale 30 miles per hour and assuming prototype drive wheels of 24 inch diameter (1.182" diameter at 1:20.3 scale), the wheels would turn over at the rate of 420 revolutions per minute. This works out to a run time of approximately 3.3 minutes. 

Steam consumption will be about 134.4 cubic inches per minute (.016 cubic inches x 2 cylinder fulls per revolution x 4200 engine revolutions per minute = 134.4). For a relatively inefficient pot boiler, this would require approximately 35.5 square inches of heating surface. Unfortunately, there are only 11.6 square inches of surface area on the entire boiler (let alone useable heating surface)! The likely outcome would be a model that has to stop every so often to regain steam pressure before continuing. This means it's time to go back to the drawing board and determine what compromises are necessary in order to find a combination of cylinder size, boiler volume, heating area, and reduction gearing required to make this a viable model. A reduction in stroke and an increase in piston diameter that also produces a net reduction in swept volume (steam consumption) would be a good start. 


> Note that the area of the .172" diameter piston is: pi *r^2 or 3.1416 x .086 x .086 = .023 square inches 
> The above calculated piston area x 80% of the boiler pressure is: .023 x .8 x 40 = .74 pounds of force (not the 21 pounds quoted in Charles' post. 
> The area of a .50 diameter piston (representative of "typical" gauge one practice) is 3.1416 x .25 * .25 = .196 and equates to 6.3 pounds of force with the same boilere pressure of 40 psi. 

Sorry to spend so much time to (try to) let you down gently, but hopefully this helps you understand a little more about the calculations involved in determining run time, gearing, boiler proportions, etc. For a far better treatment than I have provided, see K.N. Harris' book "Model Boilers and Boilermaking". 

Respectfully, 

Mike Martin


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## Grimm (Oct 5, 2009)

Thanks Mike,

No problem on the "letting down", I fully expect to be dropped from a tall height and bounced up and down repeatedly while I learn my way around.







Any and all information is great, I'm going to have to find that book and get it. The boiler I have been planning would even be worse then you calculated above, and a very tiny bit better. I was going with a prototype height for the boiler at 5 feet tall, which is a little less then 3 inches tall and you would have to take away about 1 inch just for the firebox because it's a vertical boiler. So I was planning on having a little less then about 2 inches for the boiler itself. The tiny bit better part is that the pipe that I have which is close to the size I need has an ID of 1.026 inches, so a little bit more room then the prototype. I'm thinking now I might want to increase the height to 6 feet prototypically, that would get me an extra 1/2 inch of space in scale. 

To increase the heating surface area, I was thinking of doing a porcupine type boiler with either cross tubes or bars in the flue. Would this help in that area, this and having a blower fan? Following your calculations I'm getting the following numbers:




1.026" diameter that is 2" tall = 1.65 cubic inches X 75% = .827 usable cubic inches
This = 391.88 cubic inches of steam which = about 918 revolutions of the crank axil.
I was thinking of doing a 2:1 gear reduction, but that looks to be way too low.

The prototypes wheels were 30 inches in diameter (1.48 inches) so I don't know how that will affect things. I'm very interested in hearing your thoughts on how to modify the cylinder to make it work better if you wouldn't mind.


Thanks again for everyone's help on this.

Jason


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## Semper Vaporo (Jan 2, 2008)

Ouch! OOOOH! OUTCH!, MY TOES! OUCH OOWOWOWOWOWOW!

Mike: THANK YOU for correcting my idiocy... I would rather have the correct info disseminated than to have my ego intact. I kept looking at those numbers I came up with and KNEW they weren't right, but was too tired to figure out what I had done wrong... I used Pi*D rather than Pi*R^2... silly me. That set the whole thing down the wrong path since I could not see my initial error the rest were unsee-able, too. Dumb, dumber and dumberest.

Thank you also for you method of correction... no harm, no foul... just the facts. Thanks. (There are many here that could take a lesson from you!)

As for my toes... I always have my iron frogs** on... so really no problems there either!


** ("iron frogs" = Steel Toed shoes)


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## Grimm (Oct 5, 2009)

I was going over the statement made by Mr. Winans where he said, "and a pulley on the fan-shaft as shown in the sketch." I took another look at the birds-eye-view sketch made by Mr. Latrobe and I think I understand Mr. Winans' statement. In the sketch Mr. Latrobe drew in the rear wheel axil so that it spanned the car over the floor boards. I think Mr. Winans mistook the axil to be the fan-shaft to the blower. It also means two more important pieces of information. One he didn't think that the rear (or the front for that matter) axil was positioned over the floor and more importantly he must have been expecting the blower to be unseen behind the boiler. Wow, just had another epiphany. This means too that the fan-shaft stretched all the way across the car. All of this assumes that Winans is correct, which I'm starting to be more comfortable with. The more I read what Mr. Cooper says about the engine the more I'm seeing that he liked to embellish at bit. Not in a bad way, but not (I think) very accurately either. 

Jason


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## Semper Vaporo (Jan 2, 2008)

Cooper probably altered the design of the loco on a daily basis, as needed, based on failed ideas or available materials (gun barrels!). And, I am sure there were many initial tests that were performed before the Board of Directors showed up to witness the "Trial Run".

Also, the Board of Directors may have set the date of the Trial Run and so the Tom Thumb was hacked together as best as possible to make that showing and Cooper fully intended to make more corrections/additions to the design later (and maybe did so).

It could be that Winans had in his possession only a portion of the "final" (altered after the Trial Run, yet "not perfected") design of the Tom Thumb and is recalling the portion of what he had in his shop, whereas the initial tests as well as the Trial Run were in different configurations. And Cooper could be describing the Trial Run configuration or even his "ideal" design, some of which may not have have been installed at the time of the Trial Run (or ever!), or it failed to work as expected and so was removed before the Trial Run, or afterward... He felt that the design theory was valid, but the construction was faulty, so he'd "fix it later", so he is describing what he "would have done".


Example: The blower in the chimney... the belt from the axle to the chimney would have been long and the chimney would have been flimsy (relatively) so keeping proper belt tension would be difficult and the distance from the wheel axle to the pulley would change as stuff warped or twisted as the locomotive moved on the rough track. In the initial tests the belt may have stayed on because they didn't move the loco very far (or it was up on blocks so it didn't move at all). Yet in the Trial Run, out on the road with vibration and twisting of the chassis on the undulating track, it failed (i.e.: the belt slipped off). Thus a design change was implemented to put the blower under/adjacent to the fire box to fan the flames and that is what Winans is describing.

Engineering design is a very fluid process and this "working prototype" was just a "proof of concept" and may not reflect the originally intended design nor the final design.

Even if the Tom Thumb had been preserved, it might not have been preserved in the configuration it was for the Trial Run because I am sure Cooper continued to make changes until the Board of Directors cut off the money for that project and instituted a new one (every design engineer knows THAT scenario!).


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## Grimm (Oct 5, 2009)

Those are some very good points. It does make sense that the configuration of the engine changed, I think that Cooper said as much in his recollections. You did bring up another point to me just now. The drum that the belt ran around was, according to Winans and Latrobe, attached to one of the wheels. If this was the case and the blower was attached to the smokestack, the fan-shaft would have had to be very long to reach out to the wheel regardless of which side it went to. I would imagine that it would have needed some sort of support to work right. Although Cooper says that the drum was attached to the axle so it could have been placed in-line with the pulley on the fan-shaft and worked better. I guess that leaves us in the same predicament as before. Do we know how many trips the engine made besides the trial run? Mr. Winans said in his report to the company that "It is, however, too small and too temporary in its construction to expect a great deal, from the friction of the parts; the heat lost in a small engine being much greater in proportion to the power than in a large one." and "It should also be borne in mind that these are experiments merely, and that several material improvements have already suggested themselves to the inventor." 

Jason


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## Grimm (Oct 5, 2009)

Another thought, you said "Example: The blower in the chimney... the belt from the axle to the chimney would have been long and the chimney would have been flimsy (relatively) so keeping proper belt tension would be difficult and the distance from the wheel axle to the pulley would change as stuff warped or twisted as the locomotive moved on the rough track." This is very true especially if the drum was attached to the rear axle. Because the engine was using Winans friction wheels the axle would have had a lot of play in it. Unless it was attached to the front axle which was supported so it wouldn't move because of the pinion gear. Then Cooper would have had to work around the cylinder frame and it would have been more difficult to line up the pulley with the drum.


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## Taperpin (Jan 6, 2008)

Jason, 
The boiler is going to be difficult, however..if its 1" diameter [is 1,1/4"diameter acceptable? ] maybe you could carry it down through the chassis so the firebox area is underneath , that may give alittle more room, at 2" high water space the flues would be 3/16" diameter and you would only get about 5 or 6 in..alcohol fired with an effective blower [exhaust nozzle up the stack with correct proportions ] it is still only going to give you 4-5 minutes run , unless a feed pump is fitted , and I think there wont be spare cylnider power to do that..Can I suggest you may do better going to the "Crab" or Mud digger engines they will be do able by virtue of boiler size , and what an interesting model it would be. 

Gordon.


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## Grimm (Oct 5, 2009)

Hi Gordon,

Actually I would very much like to to build both a "Crab" and a "Mud digger" one of these days. At this point, even if I can't get the engine to run, I think it will be good. It will give me the chance to learn how to build a boiler and cylinder/pistons, etc. And, in the end, I might have a good display model to show off.







I have ordered some copper for the boiler and some other metal bits and parts including some gears for the engine. Now I need to sit down with my CAD package and put in some quality time. I was thinking of just putting in one flue that is 3/8" in diameter (0.375") and having either cross tubes or rods in it. I was also thinking of having soldering in some rods on the bottom of the boiler, a porcupine boiler I think they call it. That way I can maximize the amount of water in the boiler and hopefully increase the heating surface area without having to go with a larger boiler. I think I may have found a place to get some spoked wheels from too.









Jason


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## Shay Gear Head (Jan 3, 2008)

Another possibility to increase your flue space is to have the boiler jacket stand away from the boiler slightly and use this for additional flue space.


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## Jerry McColgan (Feb 8, 2008)

Hi Jason,

Peter Cooper did not remember ever making any drawings. Perhaps this info will help:

http://1stclass.mylargescale.com/je...operD.jpeg
http://1stclass.mylargescale.com/je...er108.jpeg

http://1stclass.mylargescale.com/je...er109.jpeg

http://1stclass.mylargescale.com/je...er110.jpeg

http://1stclass.mylargescale.com/je...er111.jpeg

http://1stclass.mylargescale.com/je...er112.jpeg

http://1stclass.mylargescale.com/je...er113.jpeg
http://1stclass.mylargescale.com/je...er114.jpeg
http://1stclass.mylargescale.com/je...er115.jpeg

http://1stclass.mylargescale.com/je...er116.jpeg

http://1stclass.mylargescale.com/je...er117.jpeg
http://1stclass.mylargescale.com/je...er118.jpeg






http://1stclass.mylargescale.com/je...er119.jpeg

http://1stclass.mylargescale.com/je...er120.jpeg

http://1stclass.mylargescale.com/je...er121.jpeg

http://1stclass.mylargescale.com/je...er122.jpeg


Good luck,

Jerry


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## Jerry McColgan (Feb 8, 2008)

I forgot to include these:











http://1stclass.mylargescale.com/je...perDi.jpeg
http://1stclass.mylargescale.com/je...perD2.jpeg

Jerry


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## Grimm (Oct 5, 2009)

Bruce - That's a great idea. I'm going to have to think about how to do it. 

Jerry - Thanks, that last image looks a lot like Mr. Latrobe's sketch. 

Jason


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## Jerry McColgan (Feb 8, 2008)

Posted By Grimm on 04 Dec 2009 12:38 AM 
Jerry - Thanks, that last image looks a lot like Mr. Latrobe's sketch. 

Jason 

It may well be. The book is "History of the First Locomotives in America" written by William H. Brown and published in 1871. It is full of first hand accounts and copies of written communications with the people who actually built a lot of the locomotives discussed. The author documented everything exceedingly well.

Jerry


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## SteveC (Jan 2, 2008)

Gentlemen

The following file contains additional information that I've dug up on Mr. Cooper, et al, regarding the 'Tom Thumb' locomotive. There is much redundancy in the information but it provides cross-checking and shows where information originated from. Feel free to download a copy of the file if you like, it's only about 850KB in size.

Peter Cooper File #3[/b]

The following are the U.S. Patents issued to Peter Cooper, don't go crazy trying to dig them up at the USP&TO web site because only one has an active record. _Edit: I stand corrected there are images available just click the respective links attached to the below listed patent numbers. _







There was a fire at the Patent Office in the temporary storage location in December 1836, and originally approximately 2,000 out of 10,000± were recovered. However, attempts to reconstruct as many as possible from alternate sources are ongoing.

In the PDF file linked to above, if you look at Fig 9, on page 28, you'll see a copy of one of the engravings that accompanied Mr. Coopers patent (i.e. U.S. Patent 6,796X). It was included in a presentation made by Mr. Mathias Nance Forney at the New York Railroad Club meeting in Brooklyn, N.Y. on May 15, 1902.

Peter Cooper U.S. Patent Information

U.S. Patent - 2,281X[/b]
Cradle
Peter Cooper; Hempstead, Queens County, New York
March 27, 1815
USPTO Class/Sub: 5/109

U.S. Patent – 3,168X[/b]
Machine for towing boats on canals
Peter Cooper - New York, NY
Jan. 24, 1820

US Patent - 5,086X[/b]
Converting alternate rectilinear to rotary motion
Peter Cooper - New York, NY
Apr. 28, 1828

US Patent - 6,796X[/b]
Steam boiler fire box / Steam engine boiler
Peter Cooper - New York, NY
Oct. 13, 1831

US Patent - 8,706X[/b]
Grinding glass, etc. (Stone polishing)
Grinding and polishing stone, glass, etc.
Peter Cooper - New York, NY
Mar. 24, 1835


You also might find the following interesting.

What is a U.S. X-Patent?[/b]


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## Grimm (Oct 5, 2009)

Thanks Steve!! That information is very good, especially the patent numbers and additional images. You can find some information about the pre-1836 patents, as many of them were reconstructed in 1840 or so. Any patents prior to 1979 are not put in the PDF or other formats, but instead are kept only as tiff format scans. If you search for a patent and it doesn't show anything you can click on the "Images" button and see the tiff images (if you have a plug-in for your browser)(Ooops I didn't see your correction until now







). I found the diagrams for both Cooper's 1831 boiler design and the 1828 rectilinear motion patents. Here are the links to the image files, I converted them to jpg and reduced the size so it would be easier for people to look at them. It's obvious now that some of Coopers re-tellings are about his initial experiments that he eventually abandoned for the more convensional crank type arangement.


Rectilinear Motion patent 1828


Boiler patent 1831

The boiler patent was applied for after the Tom Thumb experiment so I'm assuming that it represents a farther refinement of the origional boiler used in the engine. There are scans of the text for the boiler, but they are the origional hand written entries. They didn't scan them very well and are almost unreadable. I'm going to try some image processing tricks on them and see if I can extract some information. As luck would have it I also found the Ross Winans patent for the friction wheels from 1828. These are the friction wheels he took to England and demonstrated at the Rainhill trials in 1829. 


Winans friction wheel patent 1828

Jason


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## Grimm (Oct 5, 2009)

I'm going to turn my attention to the wheels and the frame of the locomotive. I have found the following quotes about them and gathered them here:

The fourth annual company report 1830, states "This small engine, with a single working cylinder, of three and a half inches diameter, was placed on wheels 30 inches in diameter which were made for other cars. The wheels being small, gearing was used to give velocity."

Ross Winans in a letter to B. H. Latrobe November 20, 1869 states "... and it was on a frame, and rested on four wheels belonging to the company". This has been taken that the company (B&O) gave or allowed the use of a frame and wheels for the engine. Winans continues "On the crankshaft, which rested on the fame of the car, was a spur-wheel which geared with a pinion on the forward roadwheels so as to increase speed; the roadwheels being only two and one-half feet in diameter.". And "The road-wheels were two and a half feet in diameter; the axles had outside bearings upon Winans's friction wheels. The axle on which the pinion was fixed was kept from lateral or longitudinal movement, so as to preserve its position with respect to the spur- wheel."

B. H. Latrobe in The Baltimore and Ohio Railroad: Personal Recollections (1868) states "The machine was not larger than the handcars used by workmen to transfer themselves from place to place; ...". 

Little Journeys to the homes of great business men: PETER COOPER by Elbert Hubbard, 1894 states "The engine and boiler were then placed on a small flat-top wagon and bolted down."

The last piece of evidence is a sketch of the engine done by B. H. Latrobe in 1869 that depicts the frame and wheels but more interestingly an A-frame built on the frame to secure the piston. The sketch was shown to Winans and "after examining the sketch, pronounces it substantially correct as to the general features of the engine; the details, many of course ideal, must be very defective."


Here are my conclusions:

The wheels, it is very evident, were 30 inches in diameter and having spokes as that was the common practice at the time. This is supported by a drawing of a B&O flour car in "Histoire et Description des Voies de Communication aux Etats-Unis, volume 2, 1831" that depicts the wheels as having spokes and 30 inches in diameter. As Winans states above the journals were supported with his friction wheels, this too is supported by the depiction of the flour car. Curiously the friction wheels are not depicted on Latrobe's sketch, maybe one of the defective details?

As to the frame itself, I turned again to the flour car as a good example. It is about 10 feet long which corresponds to Latrobe's comparison to the handcar. Latrobe's sketch depicts a frame that is nothing like the one for the flour car. It is of a similar size though, 11 feet instead of 10 feet. Even though I can never be exactly sure what kind of frame was used I'm going to assume that the flour car's frame or something similar was used. The drawing of the flour car from 1831 is only one year after Cooper's engine was built. It appears that the flour car's frame was in general use by the spring of 1830. There is also plenty of space in the flour car's frame to put all of the extra equipment that was necessary for the working of the steam engine. Mr. Latrobe's birds-eye view of the engine shows a similar boxed-in side panels that are very similar to the flour car as well.

The front axle on the engine was "fixed" to "preserve it's position with respect to the spur-wheel". This is also consistent with having the journals supported with Winan's friction wheels. The friction wheels had a lot of play in them, at the time it was thought that this would help the cars run through the sharp corners on the road. In fact it was a fatal flaw that caused the friction wheels to wear out too quickly. They were dropped from use by the B&O in 1833 or 1834 and were never used on locomotives except Cooper's engine. The easiest method to fix the axle would be to have supports placed on the back side of the wheels. These supports would limit the "lateral or longitudinal movement" of the axle and keep the pinyon in line with the spur gear. Looking at the flour car's frame you could do this a couple of ways. One way would be to place two additional timbers across two of the lateral frame supports and hang metal supports from the bottom of them. Another way would be to place the two additional timbers under the lateral frame supports with cut-outs for the axle. In the cutouts smaller metal supports could be attached to limit the axle movement. 

The A-frame support for the piston is difficult to find support for. The only depiction of it is in the two sketches done by Mr. Latrobe. Although it is a very simple solution that could have been used at the time. There is a lot of evidence for the use of the A-frame for many centuries before 1830 and it should have been common knowledge then. It's a shame that Winans didn't critique the sketch more and fill in the details as he remembered them. It is also obvious that this engine made a great impression on Winans and the other engineers at the B&O. Many of the systems the Cooper engine had were improved on and replicated on later engines, the grasshoppers, coal crabs, and the mud-diggers for example. Given that the engine was thrown together as an experiment, and not having a better solution, I'm thinking of using the A-frame as the support for the piston.

Here is the drawing of the flour car for comparison:











Jason


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## SteveC (Jan 2, 2008)

Jason

Hehehe, thanks for the links, but if you click the first line of anyone of the patent listing (i.e. U.S. Patent - n,nnnX) in my previous reply you'll find that each is a direct link to the respective USPTO TIFF image.









Two things I find interesting regarding the car that was made into Cooper's locomotive.
[*] If you look on page 30 of the 'Peter Cooper File #03' you'll find a photograph with a modern steam locomotive (c. 1906), and a mock-up of the 'Tom Thumb.' Note that there is no A-frame present, and this is a full 20 years prior to the building of the B&O replica built in 1926.

[*] The following image is an excerpt from one of the engravings found at the back of a book commemorating the sesqui-centennial celebration of Baltimore (1730--1880) held at Baltimore, Maryland 11--19 October 1880, and once again there is no A-frame depicted. Note that this instance of a depiction of the 'Tom Thumb' is 12 years before Major Pangborn's model was built in 1892.
[/list] 1730 -- Memorial Volume -- 1880
an account
Municipal Celebration
One Hundred and Fiftieth Anniversary
Settlement of Baltimore
October 11 -- 19 1880
Edited by Edward Spencer
Illustrated by Frank B. Mayer
Baltimore
Printed by King Brothers
1831









[*] If you once again reference the above mentioned file (i.e. Peter Cooper File #03) and look on page 21 where you'll find the excerpt from the book _'Life and Character of Peter Cooper'_ by Charles Edward Lester (c. 1883). On that portion excerpted from page 20 you'll find the following...

_"That machine is still in existence, and many years later, when the hospitality of the city of Baltimore was proffered to him and accepted, it was one of the most enthusiastic and novel celebrations that had ever been witnessed; the first American locomotive being the chief object of curiosity and delight to the citizens of Baltimore, and the numerous distinguished guests who had been invited from other cities."

_Which is the comment that sent me on the search for information to confirm Mr. Lester's above comment. While I did locate confirmation (i.e. the above book and image) that both Peter Cooper (then 89 years of age) and the 'Tom Thumb' were present at the celebration in 1880 (the fiftieth anniversary of its original run). It doesn't provide proof that the image depicted in the engraving by Mr. Mayer was in fact that of the original and not a replica, although somewhere within comments made by Mr. Winans he alluded to the fact that the engine, or at least parts thereof hung around his shops for years. So, I'm still on the hunt for something that will either confirm or refute Mr. Lester's comment.








[/list]


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## Grimm (Oct 5, 2009)

It seems that the closer we get to the details the more difficult it gets.  I was thinking that the original engine was dismantled soon after the trial run because B&O needed all the cars they could get their hands on. If I remember correctly the winter of 1830-31 was a particularly bad one and they were hauling tons of firewood back to Baltimore on every car they could get. Thanks for finding those new images, although it looks like most of them are based off of Mr. Latrobe's sketches, which were done in 1868 or 69. We need to find some from before then, although I have my doubts there are any.  

Jason


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## Grimm (Oct 5, 2009)

I wanted to get some more details on the steam engine itself that Mr. Cooper used. He did mention that he purchased it in New York and that it was made of brass. I did some searching and found that from 1816 until the time that Tom Thumb was constructed there were several firms in New York that made both marine and stationary steam engines. Some of them made the engines out of brass (or bronze?) because suitable iron was difficult and expensive to get. I found some images that are very close to what Mr. Latrobe drew in his sketches. Here is one from the 1820's that looks very much like the one in the sketches, without the "A" frame.











Here is a picture of a model of it. 









Here is another diagram of an engine with a "A" frame to support the engine, also from the 1820's:









Very interesting, I'm going to keep looking and see if I can get a better understanding of how the valves worked, etc.









Jason


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## Grimm (Oct 5, 2009)

Steve, I forgot to thank you for your last image. I hope I didn't come off as being unappreciative of your help. 

I found another image of a similar engine, although this one is one of the first internal combustion engines and has two cylinders. I have included it because it is very close to the same construction that Latrobe drew for Peter Cooper's engine. Notice that two rods that connect the crosshead with the crank shaft and the "A" frame support for the crossheads. I found out that the reason they constructed their engines vertical cylinders was because they thought that there would be uneven wear on the mechanism if they turned them horizontal. This was later found to be untrue. It's funny to think that this one idea would impress itself on to a design so much.







I haven't had much luck in finding images of steam engines from the 1820's, so I still don't have much of an idea how they constructed the valves.







Here is the picture:












Jason


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## Semper Vaporo (Jan 2, 2008)

Just a couple of notes:

I have read in many places that the early steam engines were not reversible. Even those that were required that the valve levers be dissassembled and reassembled differently to effect the reversal of rotation.

In the drawings and photos of the oldest engines you have presented, I cannot make out any method of delivering steam to the top of the cylinder. It appears to me that they might have been single ended. This would simplify the valve mechanism considerably, but I don't see anything to drive it anyway.


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## Grimm (Oct 5, 2009)

Thanks C.T. 

Not reversible, very interesting. I was thinking that with Coopers engine that he would have just pushed the locomotive to start it in the direction he wanted to go. Do you think that would work? 

I'm not sure, but I think if you look at the first photo you can see what looks like a column to the right of the cylinder is the valve "pipe" that supplies steam to the top and bottom of the cylinder. And also look at the last diagram you can see another cylinder (pipe?) just to the right and parallel with the main cylinder. On the diagram you can also see some linkage that might have controlled the valve. Although with the internal combustion engine you wouldn't need feeds at both ends, especially with two cylinders. 

Jason


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## SteveC (Jan 2, 2008)

Posted By Grimm on 12 Dec 2009 10:07 PM 
Steve, I forgot to thank you for your last image. I hope I didn't come off as being unappreciative of your help.
Jason

No sir, not at all, just been busy grubbing here and there looking for additional information.

I know the following is a might bit modern as steam-engines go circa 1830 anyway but I thought they were interesting and might give some direction.

Vert. Portable Steam Engine[/b]


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## Grimm (Oct 5, 2009)

Steve, cool.









That is very interesting, the cylinder throw is very short ,only 4". Do you think that if I shortened my models cylinder from the prototypical 14" to something smaller it would help the boiler keep up better? It's also interesting that that setup gets just a little more horse power then Cooper's engine.


Jason


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## SteveC (Jan 2, 2008)

Jason

That's a question that I couldn't really answer, I have no experience with live steam at all. However, I would think that that's one of those things that doesn't scale all that well from prototype to model. I mean the prototype Lovegrove's operating pressure 60 to 90 psi, wonder what pressure it would take at scale?


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## Pete Thornton (Jan 2, 2008)

the early steam engines were not reversible 
As an ex-B&O Museum Docent, I can tell you that the Tom Thumb replica is sort-of reversible. If my memory serves me correctly, there are two eccentrics and two valve rods, but only one is connected to the valve piston rod. You stop the engine at TDC, unbolt the rod, bolt on the other one, and away you go in the opposite direction. 

Well, actually, on a single cylinder engine, at TDC you don't go anywhere! I asked the driver how he did it, and he showed me the large crowbar that he uses to lever the gears past TDC so the engine can start up.


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## Semper Vaporo (Jan 2, 2008)

Posted By Grimm on 12 Dec 2009 11:30 PM 
Thanks C.T. 

Not reversible, very interesting. I was thinking that with Coopers engine that he would have just pushed the locomotive to start it in the direction he wanted to go. Do you think that would work? 

I'm not sure, but I think if you look at the first photo you can see what looks like a column to the right of the cylinder is the valve "pipe" that supplies steam to the top and bottom of the cylinder. And also look at the last diagram you can see another cylinder (pipe?) just to the right and parallel with the main cylinder. On the diagram you can also see some linkage that might have controlled the valve. Although with the internal combustion engine you wouldn't need feeds at both ends, especially with two cylinders. 

Jason 

The valve has to lag the piston by about 90 degrees of rotation so that the piston is reversing it linear direction (i.e.: in the process of leaving one end of the cylinder) when the steam is admitted into that end in order to push it on its way to the other end. The opposite end must be open to exhaust what is in it to get out of the way of the piston so it can move to that end.

Then the inlet valve is closed and an exhaust valve opened to allow the pressure, in the end the piston just left, to exit while the piston returns. It returns, either because the other end is now pressurized due to the action of the valves at that end or because a flywheel is providing momentum to do so.

If you do not alter the timing of the two valves (inlet and exhaust) at one end and the engine is forced to run in the opposite direction the whole thing becomes a pump forcing the steam (or air) back into the boiler.

A "Push-to-start for direction" only works with some sort of slip eccentric where the valve events get "adjusted" by the motion imparted to the engine when manually forced in one direction or the other.


As for the pipes I can see in the drawings: The steam inlet to each end of the cylinder must be separate so that pressure can be applied to only one end at a time and the opposite end is open to exhaust its contents as the piston advances into it. What I see appears to be one pipe possibly connected to both ends and that makes no sense, so I assume it is either a brace of some sort or what appears to be the connection at the bottom is merely a brace for the pipe itself.

Often there is only one pipe is used for both steam inlet and exhaust at each end of the cylinder (two pipes total on a double acting cylinder). In the modern engine this pipe is just a passage cast or drilled into the integrated cylinder and steam chest casting. I suppose the steam inlet for the bottom of the cylinder might be integral with the valve mechanism mounted on the bottom of the cylinder and the pipe is just a relatively (and inefficient) long passage from the valves (at the bottom) to the top of the cylinder.

The drawings (as reproduced here on MLS) are just too sketchy to make heads or tails out of some of the parts. I cannot tell on some of them if a vertical stripe is a pipe or just a photographic "highlight" on the round cylinder. I am sure that to a person familiar with the particular engine the images are understandable and they could point out what each part is and explain them, but I am not at all familiar with some of these older engines and back-translating the more modern engines and parts that I am more familiar with is mostly guesswork and could be terribly missleading.


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## Jerry McColgan (Feb 8, 2008)

Hello Jason,

Perhaps this has been mentioned earlier but it seems to me that the boiler must have only been around three feet tall (or less). This is based on the pictures which show the boiler to be barely chest high to the men in the picture plus the bird's eye view suggests that about half of the height was taken by the furnace (based on the visible seam).

Further Bob Winans's comments state that the boiler was about the same diameter as a mansion's kitchen boiler attached to many a range but not much more than half as high.

Further he states it was filled with vertical tubes (gun barrels of this length would have been available).

It appears that a man probably could have wrapped his arms around the boiler.

Additionally he states that the steam capacity of the Tom Thumb was only about one-fourteenth that of the Rocket at the same pressure.

The Tom Thumb needed water after only running 7 miles.

I suspect that the reference to the boiler being 5 - 6 feet high was referring to the total length including the furnace and perhaps even a stove pipe. Alternatively the boiler may have started out at 5 - 6 feet but then cut down to a much smaller size.

Twenty inches in diameter (his guess) would allow for a lot more than two gun barrels.

Since he compared the Tom Thumb with the Rocket and referred to the Rocket as having 25 pipes inside a 3 foot wide boiler it seems likely that he was referring to a quantity rather than just two gun barrels.

Since it was an experimental engine Cooper probably used whatever was available at minimal cost.

Just my thoughts,

Jerry


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## SteveC (Jan 2, 2008)

Jason

The following image is a copy of an engraving taken from the following book.

Development
of the
Locomotive Engine
by: Agnus Sinclair
Angus Sinclair Publishing Company
New York
1907 

Can't say that it corresponds to the previous sketches we've thus far ran across, but it sure seems to fit the various written descriptions to a very great extent.


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## Grimm (Oct 5, 2009)

Thanks Pete, that is very interesting. According to one of Mr. Cooper's recollections he said he had a pole to push the engine, maybe when it was in TDC? 

C.T. - Thanks that makes a lot of sense. So it looks that Mr. Cooper's engine would have had driven in only one direction, maybe that is how they determined the front of the loco. I have done some more research on these early steam engines. It appears that some of these engines might have had single-acting cylinders. The steam would have been admitted to the top of the cylinder for the power stroke. Then, on the return stroke, the steam would be transferred from the top of the cylinder to the bottom. The steam would condense in the bottom of the cylinder and create a vacuum that would help the next power stroke. The exhaust from the lower part of the cylinder was controlled by a separate valve. I don't know how this would affect the timing though. 


Thanks Jerry - That is about what I was thinking too. If we can't be sure, I was thinking of erring on the large side, so that maybe I can build a boiler that actually works. I planning on the boiler being about 6 feet tall (3.5 inches in scale), probably larger then the original, and lowering it into the car frame so that it appears smaller like Gordon suggested. As far as I have found it appears that Mr. Cooper did not use musket barrels in the boiler (I think that Mr. Brown misunderstood Cooper in this case), but instead used them to connect the boiler to the steam engine. 


Steve - Again thanks for the image, keep them comming.







This one looks like it was drawn from Major Pangborn's model.

I'm having some doubts about using the flour car's frame for the locomotive. Winans friction wheel patent depicts a very low-slung car, very similar to the frame/car drawn in Mr. Latrobe's sketches. Does anyone know when the flour car was introduced on the B&O? I seem to remember that it was in the spring of 1830, but I can't find the reference now. If true, this would place the introdution of the flour car after Mr. Cooper started his loco, which was around the summer of 1829. Now he could have upgraded when his initial experiment failed and he converted the engine from using his pattent equipment back to the usual crank, but that is a bit of a streach I think. 

Jason


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## Grimm (Oct 5, 2009)

I found some more information and some more thoughts on the steam engine used by Mr. Cooper. If Mr. Latrobe's sketches are correct then the engine would have been a vertical crosshead type steam engine. These were very popular for use in ships until the 1840's and could be very large. It makes sense in that in the 1820's the only real application for steam engines were in ships and stationary engines. I am thinking that the engine would have been double-acting because that would be the only way it would have worked with Mr. Cooper's patented crank replacement device. 

According to James D. Dilts in his book "The Great Road: The Building of the Baltimore and Ohio, the Nation's First Railroad" he states the car Mr. Cooper used was built by Richard Imlay who was building the cars for the B&O at the time. He also states that the journal boxes were different front and back, Winans' friction wheels in back and some other not specified boxes in front. I have my doubts about this though, because Winans specifically states that they had to restrict the front axle so that it wouldn't move and bring the gearing out of alignment. It would seem to me that it would be difficult to replace the journal boxes if the frame of the car was designed specifically for the friction wheels, especially if the frame was similar to Winans' patent. I'm thinking that a simple "L" bracket would have sufficed to keep the axle in line and still use the friction wheel for the journal box. Also I have found out that it was Mr. Latrobe who designed the flour car, so it puts it farther out of the running. I'm thinking of building a cross between Mr. Latrobe's sketches and Mr. Winans' friction wheel patent. It's obvious that the friction wheels used on the flour car and the later passenger cars are a more refined design then what is shown in the patent. 

I'll leave you with another diagram of a marine vertical crosshead steam engine. I think I getting a better idea to design one that will work. 










Jason


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## SteveC (Jan 2, 2008)

Jason

I don't know, my thinking is more along the lines of...
[*] An inverted vertical steam engine (i.e. where the crank is below the cylinder).
[*] The cylinder is double-acting and non-condensing.
[*] The valve would be a vertical slide type.
[/list] I know that the following is a model of what is most likely a more modern vertical steam engine, but it gives you the idea of what I'm thinking. Look to page 7 in the PDF document for a expanded diagram and nomenclature of the engine.

Model Inverted Vertical Steam Engine[/b]


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## Grimm (Oct 5, 2009)

Thanks Steve,

Isn't that what they call a "bottle" type steam engine? I'm with you there but I would also really like to preserve the over head crosshead like it is shown in Mr. Latrobe's sketches. I made a sketch of how I think the valves work for this type of engine. I'm pretty sure you could run the valve off of the crosshead with a lever to change the range of movement.












The steam pipe could be on one side of the valves and the exhaust pipe on the other. Here is another picture of these early engines.












This one has over head crossheads for both the cylinder and the valves.

Jason


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## SteveC (Jan 2, 2008)

Yes, I like that basis better with the overhead crosshead.

The steam engine in the PDF I've seen refered to a a coke-bottle & an a-frame.


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## Grimm (Oct 5, 2009)

Thanks Steve, that's it.

Merry Christmas to everyone. I have found the information I was looking for, finally. Thanks must go to Google which has scanned in a whole bunch of old books with really cool information in them. The one I found the info in was "A manual of the steam engine and other prime movers" By William John Macquorn Rankine, which I think was first published in 1866. It illustrates many of the early engines and he explains how they work, very cool.










C.T - This may also explain why it was so hard to decipher the illustrations and how the valves worked. 

Basically these types of valves were called "long slide valves" or "D-slide valves". Within the valve cylinder was another piston that had a hole running the entire length and through the center. Around the middle of the piston it was recessed for almost the entire length. Both ends of the piston had o-rings or packing to keep the steam from leaking. The hole allowed the spent steam from the top of the main cylinder to exhaust through the bottom of the valve cylinder. The recessed part of the valve piston allowed the steam to enter the main cylinder top and bottom when it moves up and down. Here is the illustration out of the book:











And here is a possible method I came up with to construct them in a smaller scale. You can see how I envisioned the construction of the valve cylinder.











This next drawing depicts a possible method of handling the linkage between the piston rod and the valve rod. I don't know how well this would work in small scale though. It would probably be very difficult to control the speed of the engine, but maybe not. Any thoughts? 












Thanks,

Jason


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## Dan Pantages (Jan 2, 2008)

What site did you find this on?


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## Grimm (Oct 5, 2009)

Here you go. Looks like they have some new agreements with publishers and authors to make it easier to get and purchase the books too. 

Google Books 

Jason


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## Grimm (Oct 5, 2009)

I was doing some more thinking on the frame and journal boxes. According to some of the documentation I found the car the engine was built on, indeed it appears that all cars being built at the time used Mr. Winan's friction wheel journal support. They are not shown on Mr. Latrobe's sketch though. There are several things about the sketches that bother me. One is that the journal supports appear to be very small to be of much use, especially for a car that would have done regular service on the road. It's possible that Mr. Latrobe drew them that way to accentuate the smallness of the engine in general. There might be another possibility that came to me when I was comparing the sketches with Mr. Winan's friction wheel patent. The support axle for the secondary bering on Mr. Winan's patent is much smaller then the main axle of the wheels. It might be that Mr. Latrobe drew what he thought was the support for the main axle, but instead it was the support for the secondary bering.

This make sense for a couple of reasons. If you look at the patent, you can see just how low slung the car is as it is drawn. This brings me back to the other reason I have problems with the sketch. You wouldn't have wanted the axles and wheels to project into the goods area of the car. It just doesn't make sense to build the car that way. In order to do it right you need to bring the goods plateform above the wheels. It would be very difficult to do this if you started with what is depicted in the patent. I suspect that they supported the secondary berings on pedistal journal supports like the ones shown in the sketches. This would bring the main wood load bering beams up to a similar level that they would have been if you were using normal journal boxes. This would be a much easier plateform to build on.


I'm still going to build the frame using the sketches as a guide, although the top plateform will be higher.

Jason


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## Grimm (Oct 5, 2009)

I picked up a new book, "The Great Road, the building of the Baltimore & Ohio, the nation's first railroad, 1828-1853" by James Dilts. It's chocked full of awesome info on the Cooper loco. Dilts' book even has the only known contemporary lithograph of the engine in an 1831 advertisement for a machine shop that helped in it's construction. Now I think I know where the Pangborn model came from becuase it looks very much like the advertisement. There are some major differences though and the people depicted in the lithograph are much too small to fit the scale of the image (maybe thats why the model and the replica are bigger then the origional?). Some things are confirmed for me which is very nice. In the ad you can see the spoked wheels and Winan's friction wheels. Also you can see, like I suspected, that the floor of the engine sits above the wheels. Another interesting thing is that the saftey valves and other equipment are shown. Strangely the smokestack sits to the side of the boiler and not on top of it and the steam pipe to the engine is a long cuving affair. 


It's also interesting that Dilts felt very similar to me about Mr. Coopers recollections. In the book he writes, "Peter Cooper (left), as a successful businessman and philanthropist late in life, often reminisced about the locomotive he built and ran for the B&O Railroad in 1830 and its famous race with the horse, which the horse won. He thus added to the controversy that has arisen over the engine and the event." And also, "The only known contemporary drawing of Cooper's engine appears in this 1831 advertisement (left) for a machine shop that worked on the locomotive, which Cooper later said he built himself, although he could not remember much about it." And, "Cooper was less reticent about the building of the engine and its importance to the railroad. He repeated the story many times, refining it as he went, until at the end, he had put the locomotive, which he called Tom Thumb, together himself in a coachmakers shop, breaking the stocks off muskets to obtain the gun barrels for the boiler tubes. And by running the machine around the railroad's tight curves, he had single-handedly rescued the Baltimore and Ohio from bankruptcy. Actually, Cooper had received a good deal of assistance in building his engine, which did not have a name until Latrobe gave it one in his 1868 speech, and although there was some concern about whether or not steam power could be used on the B&O's sharply curving alignment, the situation was not so drastic as Cooper made it out to be." 


There is other images of the early cars and locomotives in the book, very cool. I think I'm leaning more towards the B&O as the blueprint for my own layout. 


Jason


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## Grimm (Oct 5, 2009)

I have found some more information about the locomotive in Dilts' book. He said that the engine ran for about 6 months after it's famous run in August 28, 1830. So I was wrong about it being dismantled soon after the run. After reviewing the information it looks like there are three main phases that the loco went through during it's life span. The first was Mr. Cooper's attempt to use his ideas for the crank replacement. This is when I think the blower was positioned on the smoke stack and the frame used had inside journals because the crank replacement devise was connected to hubs on the outside of the wheels. This would be consistent with the early horse-drawn carrages used on the road in 1829. When that didn't work the frame was replaced with a new one built by Mr. Imlay in the early part of 1830. A crank was used this time instead of Mr. Cooper's devise and the blower was moved to the bottom of the boiler. This was the second phase of the loco that was to do the famous run in August of 1830. After the run Mr. Winan's commented that, "It should also be borne in mind that these are experiments merely, and that several material improvements have already suggested themselves to the inventor." The engine was farther modified in the next 6 months or so until it must have looked somewhat like the advertisement illustration. This would have been the third and maybe final phase the loco went through before the end of it's life. Many of the designs of the Cooper engine went into the design of the York and the rest of the "Grasshopper" type engines. 

Jason


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## Grimm (Oct 5, 2009)

I stumbled upon a very interesting picture, but first here is the only contemporary image of Cooper's engine from an advertisement from 1831.











Now here is the new image I found:










As you can see from the description this is supposed to be a train from the Newcastle and Frenchtown Railroad in about 1833. But look at how alike the locomotives are. Now a lot of thoughts crossed my mind as to what this means. 


1) The N&FRR made or had made a loco very similar to Cooper's.
2) The N&FRR purchased Cooper's loco from B&O and they modified it.
3) It's not the N&FRR, but instead it's the B&O and shows a later modified version of the loco.

Any other ideas?

This is again started me thinking that I should change my loco's frame so that it looks more like these images. 


Jason


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## Pete Thornton (Jan 2, 2008)

this is supposed to be a train from the Newcastle and Frenchtown Railroad in about 1833. But look at how alike the locomotives are. 

Any other ideas? 


4. They used the only graphic available at the time to show people what they would be producing. 

Richard Imlay probably supplied the woodcuts of his original loco?


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## Grimm (Oct 5, 2009)

Thanks Pete,

That is a very good possibility, either way it very well might be another contemporary description of the locomotive.







It is strange that they would have used this loco as an example, given that there were much more advanced and larger locos around. And the first loco on the N&FRR was an engine built in 1831 by Col. Stephen Long which weighed about 3 times more then Cooper's engine. The engine was a failure and Col. Long pulled it off the road. At that same time, "The railroad directors had arranged as early as June of 1831 for a steam engine to be constructed by Robert Stevenson of New Castle, England for £850. The “Delaware" was to make its maiden voyage on September 1, 1832." Why wasn't the Delaware shown in the illustration? Something fishy is going on here I think.









Jason


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## Pete Thornton (Jan 2, 2008)

The railroad directors had arranged as early as June of 1831 for a steam engine to be constructed by Robert Stevenson of New Castle, England for £850. The “Delaware" was to make its maiden voyage on September 1, 1832." Why wasn't the Delaware shown in the illustration? Something fishy is going on here I think. 
Jason, 

I think you're on to something here - though I don't know what the fish have to do with it! Not sure the two locos are that much alike - one could be a modified 'tom thumb' from M&W the manufacturer, based on Cooper's design? 

It does seem odd that the N&FR would use a drawing of the B&O train, when they had already played with Col. Long's engine and ordered "Delaware" from Robert Stephenson. One would think they were trying to promote their future, not the past. The coaches, especially, are pretty much dead-on Imlay's from the B&O, just like the present replicas in the Museum. So they either bought the loco from the B&O when the latter started building grasshoppers in the early 1830s, or they borrowed the picture/woodcut from the B&O.


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## Semper Vaporo (Jan 2, 2008)

Another odd observation...

In those two woodcuts, notice that the smoke stack is along the side of the larger part (which I assume is the water boiler). This implies that it is a flueless boiler, or what is known as a "pot boiler". This kind of goes along with the idea that it was similar to a kitchen boiler as was mentioned a lot earlier in this thread.

That would also imply that the "gun barrels" were not used as flues but as steam delivery pipes as was asserted previously.

Everybody's drawing has some difference that throws the wrench of the left-handed monkey into the theories. I have to assume that journalism was just as footloose and fancy free with the "truth" back then as they are today... lacking any sort of understanding they only report their "impression" of what they saw, and not the technical details in any sort of preciseness.

Curiouser and curiouser!


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## Grimm (Oct 5, 2009)

C.T.- Interesting, I was wondering if that construction would have made it easier to place the blower at the bottom of the stack as well?

I found some more information about the broadside image. I found an image of the whole broadside that might shine some light on the N&FR image. 


http://www.americanantiquarian.org/broadsides.htm


A broadside was basically a flyer that an individual or company would post everywhere it could to advertise a service or make an announcement. I would imagine that making and printing graphics was just as expensive then as it is today. The printers might have been in a hurry as well and just used an existing image for the broadside. I'm starting to think that it is an B&O image, probably made in 1831 or maybe 1832. The cross-bracing on the handrails would make sense if they were getting weak from use and needed to be re-enforced. It goes back to the fact that this loco was an experiment and never meant to be used for regular service. 


Jason


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## Semper Vaporo (Jan 2, 2008)

I have been wondering about that early description of the blower being at the bottom. A blower in the exhaust side near the fire (bottom of the chimney) would be unadvised, but maybe nobody advised them. Maybe one of the early, "Oopses" that got re-engineered... I even wonder if the blower was an even earlier "add-on" engineering change... not enough steam so someone said to add a "blower" and they didn't know what that was?

In the exhaust side it is sucking air over/through the fire and thus exposing itself to the heat. A mechanical fan, mounted near the top would reduce damage from heat. I tend to think that a venturi arrangement might have been too early in the science but if it were mounted below the chimney to move air up the chinmey and thereby suck air from the fire chamber, there would still be the risk of the air blowing the wrong way and pushing flame out the firedoor.

It could be placed in the air intake below the grates to move air up through the fire (supercharger?), like on a Backsmith's forge, but it would need a way to be shut off if the firedoor is opened to add fuel (same risk of blowing fire at the fireman!), unless some method were employed to get the air flow into the firedoor as fuel is shoved in (something like an overfire jet)... but that sounds like "Engineering Change No. 3".


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