U. S. NATIONAL MUSEUM 



BULLETIN 173 PLATE 33 



30369; 3*!2.i 



HOT-AIR ENGINES. 



1. Ericsson hot-air engine, 1855 (model; U.S.X.M. no. 251279). See p. 177. 

 2. Rider hot-air engine, 1871 (model; U.S.X.M. no. 308714). See p. 180. 



