154 PHILOSOPHICAL TRANSACTIONS. [anNO 1685. 



order to the demonstrations that follow, viz. that we are not to consider bodies 

 as so many lumps of matter, that differ only in bulk and shape; but rather as 

 bodies of peculiar internal textures, on account of which they must be con- 

 sidered as engines, whose operations being assisted by the mechanism of the 

 body wrought on, a great part of the effect is due to the action of one part of 

 the body itself that is wrought on, upon another, assisted by the concurrence 

 of the neighbouring bodies. Hence he notices the chief causes on whose 

 account men are used to overlook or undervalue the efficacy of local motions 

 which are either unheeded, or thought languid. The first thing overlooked is 

 the efficacy of the celerity of small bodies moving through a small space; how 

 great this is, he illustrates by considering the powerful effects of bullets ; the 

 great incalescence caused by the brisk motion in turning of metals, as steel and 

 brass, the fragments t)f which are often so heated, as not only to offend the 

 eye-lids, but even to blister the hands of the workmen; vitrification itself being 

 produced by the common striking fire between a fiint and steel. Neither are 

 fluid bodies incapable of making impressions on solid ones: witness sun-beams 

 in the focus of a burning glass; the flame of a lamp; and even the air in a 

 good wind-gun. Though we are in the second place too apt to think the soft- 

 ness of fluid bodies, and their insensible motion, may hinder them from those 

 effects. But to show the contrary, besides the obvious instances of deluges 

 and storms, he produces many of the strong operations of sounds upon distant 

 and solid bodies. One of the most remarkable of which is the effect of an 

 instrument, though small, by which an engineer could sink ships in a few 

 minutes ; the explosion being so great as to cause a kind of storm in the water 

 round about, and rudely shake vessels that lay at no inconsiderable distance. 

 He observes again that men undervalue the motions of bodies too small to be 

 sensible, though the numerousness enables them to act in swarms: yet how 

 little reason they have for it, he evinces by the operation of the wind in au- 

 tumn ; the solution of sugar in that water where amber, though lighter, sinks 

 and remains entire, by the activity of the flame of spirit of wine; that of the 

 animal spirits in large and bulky animals; the forcible motions produced by 

 glaciation in liquors, &c. 



The modification of the invisible motion of fluids, as to what they may 

 perform on the disposed bodies of animals, is as little regarded; though it is 

 not so despicable, if we may believe Scaliger's story of the sound of the bag- 

 pipe being too diuretical on a Knight of Gascony ; several sorts of noises set 

 the teeth on edge, and a domestic of the author's always bled at his gums, 

 when he heard brown paper torn: add to this, the cure of the tarantula, and 

 two verses of Lucan which seldom fail to put the author almost into the fit of 

 an ague, &c. 



