70 



BULLETIN 119, U. S. NATIONAL MUSEUM. 



and upon the hood rests the smoke-stack. The furnace and its grate 

 are circular and are placed inside of the circle formed by the boiler 

 tubes and thus are inclosed by them. The grate rests on the project- 

 ing ledge of the lower part of the boiler. A single horizontal 

 cylinder with valve chest on top is situated alongside the boiler and 

 transmits its power to a crank shaft on which is mounted a gear 

 wheel. This gear engages a second and larger gear vertically be- 

 neath it, which in turn meshes into a rack rail situated midway 

 between the rails and about on a level with them. Four vertical 

 posts extending downward from the floor of the truck near each 



FIG. 30. — .STEVENS' EXPElil JIEXTAL LOCOMOTIVE, 1825. 



corner and terminating in rollers in contact with the inner face of 

 the rails, guide the truck on the track. 



The locomotive was operated by Stevens on a circular track at 

 Hoboken, Ncav Jersey, and carried six people at a speed of over 

 twelve miles an hour. Cat. No. 181,241 U.S.N.M. 



Original Tubular Boiler Designed and Patented by John Stevens in 1803, 

 and Used on His Experimental Locomotive in 1825. Deposited by the 

 Stevens Institute of Technology. 



The boiler consists of twenty vertical tubes connecting the water 

 chamber at the bottom with the steam chamber at the top. The out- 

 side diameter of the circle formed by the tubes is 12 inches, each 

 tube being 40| inches long by 1^ inches in external diameter. 



