U. S. NATIONAL MUSEUM 



BULLETIN 173 PLATE 29 



STEAM Pumps. 



1. Knowles steam pump, 1879 (model; U.S.N.M. no. 309250). See p. 136. 

 2. Frost steam-pump valve, 1890 (model; U.S.N.M. no. 308718). See p. 138. 



