178 HOOKE'S VIBRATORY THEORY. 



Drumsticks. By this means the sand in the dish which 

 before lay like a dull and inactive body, becomes a perfect 

 fluid; and you can no sooner make a hole in it with your 

 finger, but it is immediately filled up again and the upper 

 surface of it levelVd. Nor can you bury a light body, as a 

 piece of cork, under it, but it presently emerges and swims 

 as it were upon the top ; nor can you lay a heavier on the 

 top of it, as a piece of lead, but it is immediately buried in 

 sand and (as it were) sinks to the bottom. Nor can you 

 make a hole in the side of the Dish but the sand will run 

 out to a level, not an obvious property of a fluid body, as 

 such, but this does imitate ; and all this merely caused by 

 the vehement agitation of the containing vessel; for by this 

 means each sand becomes to have a vibrating or dancing 

 motion so as no other heavier body can rest upon it unless 

 sustained by some other on either side ; nor will it suffer 

 any body to be beneath it unless it be a heavier than itself. 

 Another instance of the strange loosening nature of a 

 violent jarring motion or a strong and nimble vibrative one, 

 we have from a piece of iron grated on very strongly with a 

 file ; for if into that a pin be screwed so firm and hard that, 

 though it has a convenient head on it, yet it can by no 

 means be unscrewed by the fingers ; if, I say, you attempt 

 to unscrew this whilst grated on by the file it will be 

 found to undo and turn very easily. The first 

 of these examples manifests, how a body actually 

 divided into small parts, becomes a fluid. And the latter 

 manifests by what means the agitation of heat so easily 

 loosens and unties the parts of solid and firm bodies. Nor 

 need we suppose heat to be anything else, besides such a 

 motion ; for supposing we could mechanically produce suck, 

 a one quick and strong enough, we need not spend fuel to 



