THOUGHTS ON TIIK N T HI] or THINGS.
swell and to odours grateful and offensive in the impulsion continues for a time, even after the case of animals. Hut the capacity of touch and removal of the impelling body, till it <jraduallj taste, like a prophet and interpreter, delivers to slackens, as in throwing. And here, ayan,. the mind all the modes either of forcible appeal, or of benign and insinuating flattery to the sense, which are incident to inanimate substances, and all the forms they assume under the influence of these affections. For compressions, expansions, corrosions, separations, and the like, are, in things without life, invisible in their progress, and are not perceived till the effect is manifest. But all violence to the organization of animals is accom panied with a sense of pain, according to their different kinds and peculiar natures, owing to that sentient essence which pervades their frames. And from this principle may be inferred the know ledge whether haply any animal possesses seme additional sense, besides those commonly ob served, and what senses and how many can pos sibly exist in the whole circle of animated nature. For from the affections of matter duly analyzed, will follow the number of the senses, if there be only the sufficing organs for the operation of such senses, and the presence of spirit to inform them. Of violent Motion, that it is the rapid Motion and Discursntion of the Particles of a Body, in conse quence f Pressure, but perfectly invisible. VIII. Violent motion, (as it is termed,) by which mis siles, as stones, arrows, cannon balls, and the like, move through the air, is of all descriptions of mo- tion nearly the most familiar. And we may note here, the singular and supine indifference which men have discovered in observing and investi gating this kind of motion. Nor is a faulty way of tracing the nature and power of it attended with only trivial loss; since it is of unlimited use, and as it were the life and informing principle of pro- jectiles, engines, and all the applications of me chanical power. Yet many conceive that they have completely acquitted themselves of their in^r to another inveterate lialut of the same they catch only at the commencement of the thinir indifferent to its progression and termination, an drag in all that follows under the head of the he- ginning; whence, with an overweening haste an<i impatience, they break off their train of thought in the midst. For in what they say of bodies giving way at the impelling force, there is some thing; but why the motion should continue after the urging body is withdrawn, and consequently the necessary alternative of the weaker and stronger body mingling is at an end, of this they say nothing, not sufficiently apprehending the scope of their own observations. Others, however, more attentive and steady in investigating, having marked the force of the air in winds and the like instances, which is capable of throwing down trees and towers, have supposed that the force which urges and accompanies pro jectiles, after the first impulsion, ought to be re ferred to the air accumulating and rushing in behind the body in motion, by the impulse ^of which that body is borne along, like a ship in the expanse of water. And such persons, at least, do not quit their subject, but carry their thought to its conclusion ; yet they, nevertheless, do not attain to the truth. The cause in reality is this. The principal motion seems to be in the parts of the volant body itself, which parts being imper ceptible to vision, on account of their extreme tenuity, escape the notice of men, not sufficiently attentive to their subject, and passing it over with a cursory glance. But to one who gives it a sounder examination, it is clearly evident, that the harder bodies are, they are the more impatient of pressure, the more acutely sensitive to it, as it were; so much so, that if disturbed ever so little from their natural position, they endeavour with great velocity of movement to free themselves from its effect, and resume their original state. To effect which, the several parts, beginning with part in the investigation, if they but pronounce j the part struck, successively propel one another such motion to be violent, and contradistinguish it from natural. And no doubt it is the system of Aristotle and his school, to instruct men what in the same way as an external force, and keep up that motion vigorously ; hence results a con tinuous and, though invisible, intense vibration of to say, not what to think ; to teach a man by what I the parts. And this we see exemplified in glass, devices of affirming or denying, he may get clear , sugar, and similar brittle substances, which, it of a disputant in argument, not how, by force of I they be divided by a blade or edged instrument, thought, he may get clear of a difficulty in the ! are, as it were, in a moment broken down in other conviction of his own mind. Others, rather more j parts distant from the line described by the blade, attentive, laying hold of the position that two Which* evidently proves that the motion of pr*>s- bodies cannot exist in one place, say that it fol- : sure travels to the parts of these suhstai lows as a consequence that the stronger body | cessively. This motion pervading all the parts propel, and the weaker be dislodged: that this dislodging or flight, if a less force is used, con tinues no longer than the duration of the original jn pulse, as in protrusion; but if a greater, the of the body, and trying, as it were, their cc.mp.ict- ness, causes the breaking down of that part, where, from the structure, the cohesion is wL Yet does not this motion, though it agitates and 2M2
