54 BULLETIlSr 119, V. S. NATIOiTAL MUSEUM. 



Photograph of Cugnot's Steam Traction Engine. Original in the Conserva- 

 toire des Arts et Metiers at Paris. 



According to The Science Museum : 



Nicholas Joseph Cugnot, a French military engineer, in 1769 made a steam 

 carriage which, traveling on a common road and carrying four persons, 

 attained a speed of two and a quarter miles an hour, but, the boiler power 

 being insufficient, the supply of steam failed after running twelve or fifteen 

 minutes. These results, however, induced the French Government to order the 

 construction of an engine fpr the transportation of artillery Avhich should be 

 capable of carrying a load of about four and one-half tons and maintaining a 

 speed of two and one-quarter miles on level ground. The machine was made 

 in 1770 by Brezin, to Cugnot's designs, at a cost of £800, but was never tried, 

 and is naw preserved in the Conservatoire des Arts et Metiers at Paris. 



It consists of a heavy timber frame supported on three wheels and carrying 

 in front an overhanging copper boiler. The front wheel has a broad, roughened 

 tire, and is driven by two single-acting, inverted, vertical cylinders 13 inches 

 in diameter by 13-inch stroke. The pistons are connected by a rocking beam, 

 and their motion is transmitted to the driving axle by pawls acting on two 

 modified and reversible ratchet wheels. The distribution of steam to the two 

 cylinders is performed by a four-way cock actuated by a tappet motion. A 

 seat is provided for the driver, who, by means of gearing, was able to steer 

 the machine, the boiler and engine turning together as a fore carriage through 

 fifteen degrees either way. Cat. No. 180,126 U.S.N.M. 



Model of Murdock Locomotive, 1784. Model made in the Museum. 



This locomotive was designed and constructed by William Murdock 

 in Birmingham, England, to test the action of high-pressure steam in 

 propelling vehicles. 



The machine is three-wheeled, a steering wheel in front, and two 

 9|-inch driving wheels connected by a cranked axle behind. There 

 is a rectangular boiler of copper with brazed joints which has an 

 internal flue. A metal cup to hold alcohol is secured below the flue 

 or fire box. 



The steam cylinder is double-acting, is three-fourths of an inch in 

 diameter, and has a 2^-inch stroke. The cylinder and valve chest 

 are partly sunk into the boiler, A small safety valve is seated on the 

 cylinder flange and loaded by a spring finger to retain the necessary 

 steam pressure. A beam is carried by a post at the front end of the 

 model and is connected at the other end with the piston rod, while a 

 connecting rod is carried down to the crank pin of the driving axle. 

 The steam valve is moved by the beam at each end of the stroke by 

 a tappet action. The valve consists of two pistons connected by a 

 tube, the s^Dace between the pistons being always open to the boiler, 

 the exhaust from the lower end of the cylinder escaping through 

 the connecting tube. As the valve derives its motion from the beam, 

 the engine will continue running in either direction once it is started. 



Cat. No. 181,283 U.S.N.M. 



