128 BULLETIN 173, U. S. NATIONAL MUSEUM 



GIFFARD-SELLERS INJECTOR, 1863 



U.S.N.M. no. 309367 ; original patent model ; transferred from the United States 

 Patent Office; not illustrated. 



This model was submitted with the application for the patent 

 issued to William Sellers, of Philadelphia, Pa., July 21, 1863, no. 

 39313. 



William Sellers, who introduced the Giffard injector into the 

 United States in 1860, immediately invented useful improvements in 

 its construction. This model incorporates an improvement in the 

 packing between the steam and water chambers and effects a mate- 

 rial reduction in the length of the whole injector. 



GIFFARD-SELLERS INJECTOR, 1865 



U.S.N.M. no. 309187 ; original patent model ; transferred from the United States 

 Patent Office; not illustrated. 



This model was submitted with the application for the patent 

 issued to William Sellers, of Philadelphia, Pa., August 15, 1865, no. 

 49445. 



Injectors before this required that the supply of water and steam 

 be constantly regulated by hand and the overflow, which was always 

 provided to permit the escape of water until the jet attained the 

 proper velocity, was also used to permit the excess of steam or water 

 caused by fluctuations in boiler pressure to escape without stopping 

 the operation of the jet. This injector is designed to use the pressure 

 created by an overflowing jet to adjust immediately the parts of the 

 injector to check the tendency to overflow and to use the partial 

 vacuum that will result from an excess of steam over water supply, 

 and to adjust the injector to correct this condition without wasting 

 water at the overflow. These objects are accomplished by means 

 of a "floating" combining tube, which is free to move along the 

 axis of the tube under the influence of variations in the absolute 

 pressure within the overflow chamber and automatically preserve the 

 correct ratio between w^ater and steam supply. 



ROBINSON AND GRESHAM INJECTOR, 1866 



U.S.N.M. no. 309189 ; original patent model ; transferred from the United States 

 Patent Office; not illustrated. 



This model was submitted with the application for the patent issued 

 to John Robinson and James Gresham, of Manchester, England, May 

 29, 1866, no. 55218. 



The feature of this injector is to provide a means of varying the 

 area of the annular space through which the water enters the com- 

 bining tube for the purpose of properly proportioning the steam 

 and water supplies. The combining tube is made free to slide in 



