HYDRAULICS AND HYDROSTATICS. 



'231 



to sink. The jar is covered at its mouth air-tight 

 with a piece of gum elastic, over which is tied a 

 piece of fancy leather. If the leather be now 

 pressed inwards with the finger, the water being 

 almost incompressible, and the air highly so, that 

 contained in the little images will yield to the com- 

 pressing force, and becoming contracted water, will 

 enter, and the images thus becoming specifically 

 heavier than they were at first, will descend to- 

 wards the bottom of the jar ; on the pressure above 

 being removed, the air in each image recovering 

 its elastic force, will expel the water, and the 

 images will rise as before. 



Price, - $2.50 and $4.00. 



Figures, only, $1.00 and $2.00. 



The Siphon (Fig. 248) is an instrument used 

 to decant fluids, or convey them from one place, 

 over an obstacle that is higher than their surface, 

 to another that is lower ; its form is exceedingly simple, be- 

 ing nothing more than a crooked tube. 



If a common siphon, with one side longer than the other, 

 be filled with water, and inverted or held with the open 

 ends downward, the atmospheric pressure acting equally on 

 both sides, and the liquid columns being unequal, the water 

 will escape through the longest leg, falling in virtue of its 

 specific gravity ; but if, when such a siphon is filled, its 

 shortest leg be plunged beneath the surface of the water, 

 not only will the liquid all run out of the longer 

 leg, but it will also rise in the shorter and be dis- 

 charged from the other in a continued stream, till 

 it sinks below the open end of the shorter leg ; 

 if the siphon be used without previously filling it 

 with the liquid about to be decanted, though 

 the liquid will rise in the shorter leg, it will not 

 ascend beyond its own level so as to pass over 

 the bend in the tube and escape, unless it be 

 drawn out of the longer leg. 



The siphon represented here has an additional 

 tube, open at the upper end, and communicating 

 below with the longer leg of the siphon; the 

 shorter leg then being plunged in any vessel of 

 liquor, the opening in the longer leg is to be 



Fig. 248. 



