HYDRAULICS AND HYDROSTATICS. 233 



the tube, D, still no mixture or alteration in the state of the 

 liquids will take place, for the lightest occupying the 

 highest situation will retain it undisturbed. But if the 

 lower part be filled with port wine, and the upper with 

 water, the former fluid will ascend through the tube, D, 

 ;uul the latter descend through the tube, C, till they have 

 entirely changed places. Price, $1.50. 



Lifting Pump. (Fig. 252, next page.) Represents a 

 model of the common or lifting pump ; it consists of a glass 

 cylinder or chamber, u c, having a piston or box, c, with a 

 valve opening upwards, the piston being raised or depressed 

 by the rod D and handle E ; also, having a valve, H, opening 

 upwards, at the bottom of the chamber, to which is attached 

 a pipe, A, of sufficient length to reach the water. At the 

 top of the chamber is a reservoir, having a pipe as an outlet 

 for the water. To use, take hold of the handle, E, and 

 thereby draw up the bucket from B to c, which will make 

 room for the air in the pump, all the way below the bucket, 

 to dilate itself, by which its spring is weakened, and then its 

 force is not equivalent to the weight or pressure of the out- 

 ward air upon the water in the vessel below ; and, therefore, 

 at the first stroke the outward air will press up the water 

 into the lower pipe, and after a stroke or two, will penetrate 

 through the valve, H, and occupy the cylinder or barrel, B c. 

 Upon depressing the bucket again, the water cannot return, 

 because any force applied above will necessarily close the 

 valve, H, and the bucket in returning will press upon the 

 water, until the pressure of the water upon the under surface 

 of the valve in G, will open the valve at that part, and 

 escaping through the hole, will occupy a space above the 

 bucket G. The next stroke of the handle will have a double 

 effect, it will draw up the water from the well, as in the 

 former instance, so that it shall again fill the cylinder, but 

 with fresh water ; for it will be readily seen, that the lifting 

 of the bucket after the water has obtained access above it, 

 does not replace that water as before, but the very circum- 

 stance of lifting the handle will close the valve above, and 

 the water will be lifted up at the same time, filling the 

 reservoir, D, which will discharge by the pipe, F. 



Price, $3.00 and $4.50. 



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