244 BENJ. PIKE'S, JR., DESCRIPTIVE CATALOGUE. 



which is represented fitted to a frame with the end of the 

 rod, E, attached to one end of a balance. 



The plate being at the bottom, c D, water is poured into 

 the vessel, so that it rises nearly to A B, but does not rise in 

 the tube. It is then balanced by a weight in the scale, L. 

 If the rod E K is drawn up so as to raise the plate and 

 force some of the water into the tube, the water will seem 

 to weigh more than it did ; and to restore the balance, more 

 weight must actually be put into the scale L. If the vessel 

 is three inches diameter, every inch that the water rises 

 in the tube will require more than four ounces to be added 

 to the weight, whatever be the bore of the tube ; for the 

 pressure of the water in all directions will be increased by 

 the weight of a body of water, whose height is the height 

 of the water in the tube, and whose base is the extent of 

 the surface of the water pressing on the top, A B, of the 

 vessel. Now the top being three inches diameter, its surface 

 is about 7 T j square inches ; and a portion of water one 

 inch high, and 7 T 'j square inches broad, is Yy'j cubic inches 

 of water, which weigh about four ounces. Thus, raising the 

 rod a foot will add three pounds to the apparent weight of 

 the water. 



This principle, from its extraordinary illustrations, is call- 

 ed the hydrostatical paradox ; paradox being a word from 

 the Greek, and signifying something, which, though true, 

 appears when first considered to be untrue. When we are 

 told that any quantity of water, however small, may be so 

 employed as to balance any quantity of water, however 

 great, we are at first startled by the apparent impossibility 

 of the statement. But when -we come to examine it more 

 closely, we find it to be accurately true ; for the small tube 

 in the foregoing figures may be made ever so narrow, and 

 to hold ever so little water, while the wide tube communi- 

 cating with it may be made ever so large, and holding ever 

 so much water ; and the level at which the water stands in 

 both tubes will be the same. So in the scales you may 

 plunge as large a body as you please into the vessel of 

 water, and leave as little water in the vessel as possible ; 

 still, if what you leave stands as high as the whole quantity 

 stood, it will, by weight and pressure together, produce as 

 much effect as the whole quantity of fluid. 



Everything, under these circumstances, depending upon 



