126 BULLETIN 173, U. S. NATIONAL MUSEUM 



water into the boiler against the pressure of the steam therein. This 

 de%dce was the invention of Henri Jacques Giffard, of France, en- 

 gineer and mathematician. About 1849 Giffard became interested in 

 the development of dirigible balloons and the designing of light- 

 weight steam engines and boilers to power them. In this connection 

 he invented the feed- water injector as a light-weight substitute for the 

 steam pump as a means of supplying water to the dirigible boiler. 

 On May 8, 1858, Giffard received French letters patent for his 

 "injecteur automoteur," a simple combination of nozzles and tubes by 

 which a jet of steam draws water into the injector, imparts to it a 

 high velocity, and discharges the rapidly moving stream of water 

 into a gradually enlarging passage in which the stream slows down 

 and the energy apparently lost in diminishing velocity is converted 

 to an increase in pressure sufficient to overcome the pressure in the 

 boiler. 



The original injector was made by M. Flaud & Co., of Paris, and 

 is now preserved there in the Conservatoire des Arts et Metiers. 

 The theoretical analysis that Giffard made of the action of the steam 

 jet and of the laws of velocity, acceleration, and pressure was so 

 sound that the curves of nozzles and tubes laid down by him for the 

 original model are still followed where the elementary form of the 

 injector is manufactured. For his invention Giffard was awarded 

 the Grand Mechanical Prize for 1859 by the Academic des Sciences of 

 France. 



The story is told that subsequent improvements in the design and 

 performance of his dirigibles permitted Giffard to use heavier pumps, 

 and he abandoned the development of the injector until he was urged 

 by Sharp, Stewart & Co. to permit them to introduce the injector 

 into England. It is further related that this firm suggested that 

 it be introduced into the United States and recommended William 

 Sellers & Co., of Philadelphia, to accomplish this. On April 24, 1860, 

 Giffard was issued United States Patent no. 27979, and William Sel- 

 lers commenced the manufacture of the Giffard injector the same year. 

 The model submitted with the application for the patent, actually 

 the first injector in the United States, was made by M. Flaud, the 

 maker of the original one, which it greatly resembles. 



The injector was applied to several locomotives during the first 

 year and after several years slowly overcame all opposition, to take 

 its place as a dependable method of replenishing locomotive and sta- 

 tionary boilers. 



The development of the injector has been to make it as nearly self- 

 adjusting as possible under fluctuations in steam pressure and water 

 supply, to improve its lifting action, to make it self-starting after 

 interruption of the water supply, and finally to incorporate in it 

 the functions of an exhaust steam feed-water heater. The develop- 



