472 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



the live steam reaches the discharge port, its free escape pro- 

 duces a reduction of pressure in the working chamber. The 

 discharge-valve then closes, the steam-valve cuts off further 

 entrance of steam, and the body of water in the central press- 

 ure chamber opens the suction-valve and causes an instan- 

 taneous condensation of the entire volume of steam in the 

 working chamber, so as to produce a vacuum therein, the 

 consequence of which is to till the said chamber with water. 

 The suction-valve then ceases, and the momentum acquired 

 by the water flowing up the suction-pipe operates to fill the 

 pressure chamber. As the one chamber is thus filling, the 

 steam current operates to force the water out of the opposite 

 cliamber, so that a constant flow is kept up in the discharge 

 pipe. The steam-valve is balanced, and means are provided 

 to prevent injury by dirt or grit. 6 i>, XXXIIL, 273. 



VERTICAL MOVEMENT OF VESSELS UNDER HIGH SPEED. 



A well-known builder of fast steam-vessels, Mr. Thornev- 

 croft, proves that at high rates of sjjeed the body of a vessel 

 actually rises above its normal load water-line, and as the 

 speed is increased continues to rise still higher. This con- 

 clusion was reached from experiments conducted with a steel 

 torpedo launch lately built for the Austrian government, and 

 with which a speed of 19.4 knots was attained. The difter- 

 ences in level were determined by means of three plumb-bobs 

 hanging from a bowsprit, at various distances in front of the 

 bow, from observations with which the altered water surface 

 was measured, and some very instructive diagrams made 

 therefrom. From these it was shown that up to a speed of 

 about 12 knots the vessel sank more deeply in the water, but 

 on being driven to a higher speed she seemed to make an 

 almost sudden leap upward, and continued gradually to rise 

 above the normal water-line as the speed increased 6 D, 

 XXXIIL, 276. 



INFLUENCE OF WIND ON PROJECTILES. 



Since the introduction of rifled guns it has become a mat- 

 ter of importance to eliminate, as far as possible, every cause 

 of incorrectness in artillery practice. One of the chief of 

 these is the force of the wind ; and Major Maitland, of the 

 Royal Artillery, endeavors to supply the means of making 



