go BULLETIN 173, U. S. NATIONAL MUSEUM 



JOHN STEVENS STEAMBOAT ENGINE, 1804 

 Plate 12, Figure 2 



U.S.N.M. no. 181179; original; deposited by Edwin A. Stevens; photograph no. 

 21855. 



This is the high-pressure, reversible steam engine built by Col. 

 John Stevens, of Hoboken, N. J., and used in his successful steam- 

 boat experiments on the Hudson Kiver in 1804. The engine was 

 preserved by members of the Stevens family. In 1844 it was par- 

 tially restored when a reproduction of the original boat was made 

 and run on the Hudson Kiver. The engine is believed to be the 

 oldest steam engine built in the United States now in existence, as 

 well as the oldest complete engine of any that were used here. 



The engine has a double-acting, vertical cylinder, 4I/2 inches in 

 diameter with 9-inch stroke. The piston rod extends upward and ter- 

 minates in a cross arm (cross head) or yoke, from either end of which 

 a connecting rod extends downward to a crankshaft. Two crank- 

 shafts to drive the two propellers of the boat are located one on 

 either side of and slightly below the bottom of the cylinder. Two 

 large cast-iron gears, one on each of the crankshafts, run in mesh 

 and keep the two cranks turning together in the proper relative 

 positions so that the resultant horizontal thrust of the two connect- 

 ing rods on the cross head will be zero. (This method of dispensing 

 with a cross-head guide was used by Dr. Cartwright of England in 

 several small engines erected near London about 1800.) The valves 

 of the engine are 2-way plug valves, one of which serves each end of 

 the cylinder. The valve stem of each valve carries a small spur 

 gear, the two being oscillated by one rack, which moves vertically 

 up and down. The rack that works the valves is driven by a lever 

 and connecting rod from a crank pin on a crank disk, which is car- 

 ried loosely on the end of one crankshaft. 



A collar, which is something less than a complete ring, projects 

 from the back of the crank disk and partially encircles the shaft. 

 A lug projecting from the shaft in the plane of the collar engages 

 with either end of the collar depending upon the direction in which 

 the engine is started. As the lug on the shaft is directly opposite the 

 crank, and the crank pin is located just midway of the ends of the 

 collar, the crank pin will be in the same position relative to the crank 

 when running in either direction. A handwheel geared to the crank 

 disk permits the crank disk to be turned by hand for approximately 

 half a turn ahead of its driven position for starting the engine in 

 the desired direction. 



The engine is exhibited with the original tubular boiler and a 

 reproduction of the boiler feed pump. 



