HYDRAULICS AND HYDROSTATICS. 



235 



drives the water through the valve at the bottom of the 

 pump cylinder, and thus the cylinder is filled with water; 

 when the piston is forced down again, the water cannot pass 

 through it, nor back again into the lower part of the pump, 

 and it is forced through the bent pipe into the air vessel, K, 

 or condenser ; and when the piston is raised again the valve 

 shuts, and prevents the water in the air vessel from returning. 

 Thus, by repeated strokes, the water is forced into the air 

 vessel till it rises above the end of the jet pipe, i, and then 

 begins to compress the air, which is more and more com- 

 pressed, as the water rises up the pipe, and the air begins 

 to act forcibly by its spring against the surface of the water, 

 and this action drives the water up through the pipe, i, from 

 which it spouts to a great height, and is supplied by alter- 

 rately raising and depressing the handle, E ; and as the spring 

 cf the air continues while the piston is being raised, the 

 stream, or jet, will be uniform as long as the pump is 

 worked. Price, $5.00 and $6.00. 



Fig. 254. 



Forcing and Lifting 

 Pump in Frame. These 

 models (Fig. 254) consist 

 of a forcing and lifting 

 pump, mounted in a ma- 

 hogany framed stand, 

 having a reservoir to hold 

 water. In the forcing 

 pump there is a variation 

 from the former descrip- 

 tion, the jet pipe being 

 connected near the neck 

 of the air vessel, and not 

 on the top, as before de- 

 scribed. . 



Price, $10.00 and 

 112.00. 



Hydrostatic Instrument for showing the Rise of Water to 

 its Level, and other Experiments. This instrument (Fig. 

 255, next page) consists of a large glass vessel, with a neck 

 on the lower part cemented into a brass cup, and supported 



