148 THE SCIENTIFIC PAPERS OF 



Plates 20 and 27, is employed. This consists of two short tubes B 

 and C, fixed side by side in a rocking frame, each of which can be 

 brought into line with the circuit tube T at pleasure. Each end of 

 the rocking frame is faced, and works against the faced side of a 

 boss on the end of the circuit tube. Three annular grooves are 

 turned in the faced side of the boss round the end of the circuit 

 tube, for the purpose of preventing the leakage of air between the 

 ends of the rocking frame and the bosses. One of the tubes B in 

 the rocking frame is used as the sending or " through " tube, and 

 is simply a hollow cylinder of the same internal diameter as the 

 circuit tube T ; when this is in line with the circuit tube, a earner 

 can pass through the instrument without being stopped, and this 

 tube is also used for putting carriers into the circuit. The other 

 or receiving tube C has a perforated diaphragm at its down-stream 

 end, so as to arrest the carriers when it is placed in line with the 

 circuit tube, as in Figs. 11 and 12. This receiving tube is D- 

 shaped in section, with a flat cover, which can be taken off if 

 required ; as for instance, to remove carriers, in the event of two 

 arriving at once and so preventing the rocking frame from being 

 moved. The flat cover is furnished with a pane of glass, to 

 enable the attendant to see when a carrier has arrived. In order 

 to prevent the continuous flow of air in the whole circuit of tube 

 from being impeded by the receiving tube being left in the circuit 

 after it has caught a carrier, a by-pass F for the air is provided, 

 which communicates with the circuit tube T at both ends of the 

 instrument. A sliding rod H, Fig. 10, held on suitable supports, 

 is supplied for pushing the carriers out of the receiving tube, 

 when intercepted and brought out of the circuit. The manipula- 

 tion for sending and receiving the carriers is exceedingly simple ; 

 and a treadle is provided for moving the rocking frame with the 

 foot. 



RAISING OF WATER. A second application of the improved 

 steam jet is to the raising of water. For lifts not exceeding 20 feet 

 a steam-jet exhauster could be used with advantage in situations 

 where the erection of an engine and pumps would be attended 

 with considerable cost and inconvenience, or where the work to be 

 done was of short duration or of an occasional character, such as 

 in draining lands, &c. When employed for this purpose the 

 exhauster would be applied in the manner shown in Fig. 13, 



