412 THOUGHTS ON THE NATURE OF THINGS. itself into globules, the diameter of which is j considerably greater than the filament previously formed. In the same way we see that the water | with difficulty admits of being broken into more minute particles, since it does not, without having been shaken, exude by its natural gravity through apertures and crevices, if they be somewhat j minute. It is evident, then, that there is a ten dency to continuity in fluids also, but weak. On the contrary, however, it is strong in solids, and predominates over the natural motion, or that of gravity. For if any one conceives that in a pillar of wood or stone, the upper parts do not through out affect descent, but rather to maintain them selves in entirely the same position, he will easily set himself right, by considering that a column or a similar structure, if the altitude is disproportioned to the base, or exceeds the due relation to it, cannot stand, but is precipitated by its own gravity. So that in very elevated piles of building it is necessary to make them incline to the pyramidal form, and narrow to an apex. What that principle in nature is, however, which determines the intensity or weakness of the affec tion of continuity, will not easily occur to the inquirer. It might, perhaps, be suggested that the parts of solids are more concentrated and compact, those of liquids more lax, or that in liquids there was an ether, the principle of fluidity, which was wanting in solids and the like. But neither of these explanations is reconcileable to truth ; for it is apparent that snow and wax, which can be divided, cast into form, and receive the impression of other bodies, are a much rarer substance than melted quicksilver or lead ; as is proved by a comparison of their weight. But if any one still insists that it is possible that snow or wax, though (as a whole) less gross than quicksilver, may, nevertheless, have its parts dis posed more closely and compactly, yet, that as it is a porous body, containing many cavities and much air, it is, therefore, rendered lighter as a whole : as is the case of pumicestone, which, though in comparing the size of both, it be per haps lighter than wood, nevertheless, if both he ground to a dust, the dust of the pumicestone will outweigh that of the wood, because the porosity bf the formei no longer continues: these are well observed and well objected facts. But what shall be said of melted snow or wax, where the same interstices are now filled up : or what of gum mastic and the like substances, which have no perceptible cavities of the kind, and are yet lighter than several liquids? As to the allegation of an ether by the virtue and impulse of which things are put into the state of being fluid, that, no doubt, is at the first glance probable, and falls in kindly with the common notions: but in the ex perience of actual nature, it is much more hard to aiimit. and inaccurate, being not merely unsup ported by sound reason, but almost repugnant to it. For that other of which they speak, has for its proper effect (surprising as the saying may appear) consistency, rjot fluidity. This is also very well seen in the instance of snow, where, though the substance be a concrete of air and water, and the water and air be separate fluids, yet. the union of the two produces consistency. Should any one object, that this consistency may be occasioned by the condensation of the aqueous part by cold, and not by means of the incorporated air, he will correct himself by observing that froth also, which is a body similar to snow, is not in any way condensed by cold. Yet, if he still press the objection, by saying that in the forma tion of foam there is still an antecedent condensa tion, not indeed by the action of cold, but by agitation and concussion: let him take a lesson from the boys, who with a slight inspiration of air through a pipe or reed, and by the aid of some water rendered rather more viscid by mixing a little soap with it, form a strange turriform con geries of bubbles. The case, in fact, stands thus : bodies at the contact of a friendly or homogeneous body relax and fall to solution ; at that of a dissimilar body they contract and hold themselves erectand aloof. The application, therefore, of an incongruous body is the cause of consistency. Thus we see oil mixed with water, as takes place in preparing unguents, in so far divest itself of the fluidity which before prevailed, both in the water and the oil. On the contrary, we observe paper moistened with water become flaccid and lose its consisten cy, (which was considerable, by reason of the air which had penetrated its pores,) but when moist ened with oil, the cohesion is less affected, be cause it has less congruity with paper. We see the same thing take place also in sugar and the like substances, which soften into commixture with water and wine; and not only blend intima tely with these fluids, but even attact and suck them up. Of the Harmony of sentient Bodies with insentient. VII. The affections of bodies endowed with sense and destitute of it, have great conformity with one another, except that in the sentient body, there is the addition of spirit. For the pupil of the eye corresponds with a mirror and with water, and by a similar property admits and refracts the images of light and of visible objects. The organ, too, of hearing is analogous to the obstructed part of a cave-like passage, from which part the voice and all sound best reverberates. The attractions, also, of inanimate objects, and again their affections of horror and flight, (those I mean which come of their own spontaneous motion,) are correlative to
