Hydrostatics. 43 



swims in it, displaces exactly as much of the 

 water as is equal to its own weight. 



This fact is proved by a very easy experiment. 

 Put a small boat, #, (fig. 17.) in one scale, and 

 balance it with water in the opposite scale, b. 

 If then the boat is put into the basin, fig. 16, 

 exactly filled with water, it will be found that a 

 certain quantity of the water will run over the 

 brim of the basin, which water, on taking out the 

 boat, you will find will be exactly replaced by the 

 water which before balanced the boat in the op- 

 posite scale, b, fig. 17. 



Hence it is plain, that a boat or other vessel 

 sailing upon the water, displaces exactly as much 

 of the fluid as is equal to the vessel and its lad- 

 ing, and, if more weight is added, it will sink 

 deeper in the same proportion, or, in other words, 

 a weight of water equal to the added lading will 

 be displaced ; whence a laden ship is said to draw 

 more water , that is to sink deeper, than when it 

 is light or unloaded. 



Every body, on the other hand, which is hea- 

 vier than water, or which sinks in it, displaces 

 so much of the water as is equal to the bulk of 

 the body sunk or immersed in the water. Thus 

 it is plain, that if a leaden bullet is dropped into 

 a vessel of water, it will take up just as much 

 room as a small globe of water of equal dimen- 

 sions. On this principle are computed the tables 

 of specific gravities, by means of what is called 

 the hydrostatic balance ; for since every body 



