A HISTORY OF SCIENCE 



so is it neither more nor less false that a thin plate of 

 brass or ebony swims by virtue of its dilated and 

 broad figure. Also, I cannot omit to tell my oppo- 

 nents that this conceit of refusing to bathe the surface 

 of the board might beget an opinion in a third person 

 of a poverty of argument on their side, especially as 

 the conversation began about flakes of ice, in which it 

 would be simple to require that the surfaces should be 

 kept dry; not to mention that such pieces of ice, 

 whether wet or dry, always float, and so my antago- 

 nists say, because of their shape. 



"Some may wonder that I affirm this power to be 

 in the air of keeping plate of brass or silver above 

 water, as if in a certain sense I would attribute to the 

 air a kind of magnetic virtue for sustaining heavy 

 bodies with which it is in contact. To satisfy all these 

 doubts I have contrived the following experiment to 

 demonstrate how truly the air does support these 

 bodies; for I have found, when one of these bodies 

 which floats when placed lightly on the water is 

 thoroughly bathed and sunk to the bottom, that by 

 carrying down to it a little air without otherwise 

 touching it in the least, I am able to raise and carry it 

 back to the top, where it floats as before. To this ef- 

 fect, I take a ba^ll of wax, and with a little lead make it 

 just heavy enough to sink very slowly to the bottom, 

 taking care that its surface be quite smooth and even. 

 This, if put gently into the water, submerges almost 

 entirely, there remaining visible only a little of the 

 very top, which, so long as it is joined to the air, keeps 

 the ball afloat ; but if we take away the contact of the 

 air by wetting this top, the ball sinks to the bottom 



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