Mr. Latrobes next letter informed the author that he had then a rough sketch of the Peter Cooper machine, taken by his brother, John H. B. Latrobe, Esq., counselor for the company; but he desired to submit the sketch to Mr. Ross Winans, for his examination and opinion, before he translated it.

I have now seen Mr. Winans, and shown him the rough sketch of the Peter Cooper locomotive, referred to in my former letter. I send, upon the next page, a copy of the sketch, which presents as near an approach to a picture of the machine as at this distant day is possible to exhibit. Mr. Ross Winans tells me that Mr. Cooper brought the boiler from New York, in the spring or early in the summer of 1829; and it was on a frame, and rested on four wheels belonging to the company; the road was then used thirteen miles to Ellicott's Mills, and with horsepower. 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. There was a single cylinder of three and one quarter inches in diameter, fourteen and one quarter inches stroke, that projected its piston-rod and connecting rod, so as to take hold of the crank by direct action.

"On the crankshaft, which rested on the dome of the car, was a spur-wheel which geared with a pinion on the forward road-wheels so as to increase speed; the road-wheels being only two and one-half feet in diameter.

"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.

"Mr. Winans says that Mr. Cooper at first proposed to communicate the reciprocating motion of the piston-rod to the road-wheels by an arrangement which I cannot accurately describe, but the experiment did not satisfy Mr. Cooper on trial, and the common crank action was substituted, and the favorable results obtained, which are described in Mr. Winans's letter of August 28, 1830, published in the Railroad Record of Cincinnati, on the 8th of July last. Mr. Cooper, if applied to, could perhaps furnish some interesting additional particulars about this engine, which was undoubtedly the very first American locomotive.

"Mr. Winans, 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. The number, size, and length of the tubes are not known, only their position in the boiler.

"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.

"Your friend's sketch of the horse-car, you sent for my inspection, gives the general idea of it, and it is made with a spirit that shows him to be a good draughtsman and knowing to the 'points of a horse,' better than myself—the thing was as much like one of those horsepower's, of which we see so many, along railways at the stations, for cutting-up wood for the locomotives. The hinged or slatted platform, on which the horse walked, turned round a drum; on this was a spur-wheel working in a pinion on the road-wheel axle; so that this gearing gave considerable speed to the car, with a moderate one to the horse. I remember well the adventure with the cow, mentioned by my brother in his lecture, to which you refer. I agree with him and Mr. Winans that the successful experiment with the Cooper engine was in 1830, as it was the year I entered the Baltimore and Ohio Railroad company's service, and some of the particulars are permanently fixed upon my memory.

In 1829 Mr. Cooper made some experiments with his little locomotive, built upon the principle he first adopted; but, as it did not perform as well as he expected and desired, he changed his plan, and, after some delays, made, as one may say, the first actual experimental trip on Saturday, August 28, 1830. A particular account of this experiment has been given the author by Mr. Winans himself, who was present on the occasion, and took a lively interest in the result. Mr. Winans writes:

"On Saturday, the 28th of August last, 1830, the first railroad car propelled by steam proceeded the whole distance from Baltimore to Ellicott's Mills, and tested a most important principle—that curvatures of 400 feet radius offer no material impediment to the use of steam-power on railroads, when the wheels are constructed with a cone, on the principle ascertained by Mr. Knight, chief engineer of the Baltimore and Ohio Railroad company to be applicable to such curvatures. The engineers in England have been so decidedly of opinion that locomotive steam-engines could not be used on curved rails, that it was much doubted whether the many curvatures on the Baltimore and Ohio Railroad would not exclude the use of steam-power. To congratulate our fellow-citizens on the conclusive proof, which removes forever all doubt on this subject, and establishes the fact that steam-power may be used on our road with as much facility and effect as that of horses, at a very reduced expense.

"The engine" (Cooper's locomotive-engine) "started from Pratt Street depot, taking the lead of a train of carriages. The power of the engine is a little, if any, over that of one horse, and it can therefore only be regarded as a working model. Immediately on front of, and connected with it, was a passenger-carriage containing (including the engine attendants) twenty-four persons. The aggregate weight of carriages, persons, fuel, and water, as nearly as could be ascertained, was estimated to be from four to four and a half tons. Notwithstanding the great disproportion of the moving power to the load, the following highly-gratifying results were obtained; the time was accurately noted by disinterested gentlemen, of the first respectability:

First mile—performed in six minutes and fifty seconds, the steam in the onset not being fully raised. Second mile—performed in five minutes; one minute was lost in altering the switch, to pass from one track to the other. Third mile—traveled in six minutes; two lost in changing from one track to the other, the switch not being in the right place. Fourth mile—was traveled in four minutes and thirty seconds. Fifth mile—occupied five minutes and twenty-five seconds. Sixth mile—traveled in six minutes; one minute was lost in changing to the other track. Seventh mile—traveled in five minutes and thirty seconds; the engine stopped at the middle depot for fifteen minutes to receive a supply of water. Eighth mile—performed in six minutes. Ninth mile—performed in five minutes and forty-five seconds, the engine traversing an ascent of thirteen feet per mile, and encountering the numerous curves which abound in this part of the road. Tenth mile—performed in seven minutes; the engine still ascending at the rate of thirteen feet per mile, and the road much curved. Eleventh mile—in seven minutes and thirty seconds; the same disadvantages of an ascending and curved line of road being still encountered. Twelfth mile—in seven minutes and thirty seconds; the ascent here being increased to eighteen feet per mile and the line curved. Thirteenth mile—in six minutes and thirty seconds, the same disadvantages of an amending and curved line being encountered as on the preceding mile.

"Making the aggregate passage of thirteen miles, under the circumstances detailed, in the space of one hour and fifteen minutes.

"On the return of the locomotive-engine at six o'clock in the evening, the following results were realized, there being four additional passengers, or thirty in all, seated in the attached carriage:

First mile—traveled in five minutes. Second mile—traveled in four minutes. Third mile—traveled in four minutes six seconds. Fourth mile—traveled in four minutes. Fifth mile—traveled in four minutes four seconds. Sixth mile—traveled in four minutes five seconds.(Four minutes occupied in taking in a supply of water.)Seventh mile—traveled in five minutes. Eighth mile—traveled in three minutes fifty seconds. Ninth mile—traveled in four minutes twenty-five seconds. Tenth mile—traveled in four minutes ten seconds. Eleventh mile—traveled in four minutes forty seconds. Twelfth mile—traveled in four minutes fifty seconds. Thirteenth mile—traveled in four minutes fifty seconds.

Making the entire passage of thirteen miles in sixty-one minutes, including the four minutes lost in taking in water at the middle depot. If this be deducted, it will give precisely fifty-seven minutes in traveling the distance.

"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 result, under all the circumstances, is highly satisfactory, and constitutes another triumph of the efforts of American genius."