A HISTORY OF SCIENCE 



sink. Galileo contends that water is non-resistant, 

 and that bodies float or sink in virtue of their re- 

 spective weights. This, of course, is merely a re- 

 statement of the law of Archimedes. But it remains 

 to explain the fact that bodies of a certain shape will 

 float, while bodies of the same material and weight, 

 but of a different shape, will sink. We shall see 

 what explanation Galileo finds of this anomaly as we 

 proceed. 



In the first place, Galileo makes a cone of wood or 

 of wax, and shows that when it floats with either its 

 point or its base in the water, it displaces exactly the 

 same amount of fluid, although the apex is by its 

 shape better adapted to overcome the resistance of 

 the water, if that were the cause of buoyancy. Again, 

 the experiment may be varied by tempering the wax 

 with filings of lead till it sinks in the water, when it 

 will be found that in any figure the same quantity of 

 cork must be added to it to raise the surface. 



"But," says Galileo, "this silences not my antago- 

 nists ; they say that all the discourse hitherto made by 

 me imports little to them, and that it serves their 

 turn; that they have demonstrated in one instance, 

 and in such manner and figure as pleases them best 

 namely, in a board and in a ball of ebony that one 

 when put into the water sinks to the bottom, and 

 that the other stays to swim on the top ; and the matter 

 being the same, and the two bodies differing in nothing 

 but in figure, they affirm that with all perspicuity 

 they have demonstrated and sensibly manifested what 

 they undertook. Nevertheless, I believe, and think 

 I can prove, that this very experiment proves noth- 



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