A

dent, that, by the force of the attraction of the particles, that are between in their pores, these frigid particles being supposed to be flexible and pliable, they will be drawn into such a figure as this, Fig. 2; and this may be done, with invincible force.

And by this means, vacuities will be left in the places from whence these particles were drawn, except other particles of water come in their room. But perhaps the particles in the neighbourhood, are stiffening together at the same time; and, instead of coming to fill up the vacuities, made by the congealing of this parcel, they are drawn farther off themselves, and make the vacuity greater. Besides, the slides of the parcel, as it conforms itself to the figure, (Fig. 2.) will unavoidably thrust out the neighbouring particles, from their places, which, perhaps, are congealed together into stiff parcels. Wherefore, this thrusting must necessarily cause vacuities in another direction, by displacing of these new inflexible parcels of water, which cause the like displacing through the whole mass, as far as particles are contiguous.

Let us still represent the matter in a larger figure, for clearer illustration. Let us suppose the vessel A B C D, (Fig. 3.) full of particles of water, into which the particles of cold getting, glue them together, by parcels, of all manner of irregular figures, and magnitudes: but let us suppose for the present, that there are seven in a parcel, and that the parcels be those which we have marked out by the crooked lines, connecting them. It is all one, as to the room they take up, let them be taken in any other figure whatever. It is evident that they will be drawn into this form, Fig. 3.

B

Fig. 4.

(Fig. 4.) and that they cannot lie in such a form, without far greater vacuities than before, and that, when they are brought in this form, the surface of the water must be considerably lifted above the brim of the vessel, A B C D, and the water will take up much more room than before, let

them lie as close as their figures will allow of. These vacuities will be greater or less, ceteris paribus, according as the parcels congealed, are greater or less.

Now it is very evident, from the foregoing principles, that many of these parcels may be drawn into one, and often will, as we see many bubbles upon the surface of water, run into one. For instance, the gluing particles that hold together the parcel O, (Fig 4.) may happen to catch hold of the parcel G, or F, and thereby they will be drawn into one. This will

be, especially upon an increase of cold, or the incursion of a great plenty of these particles; for whereas there were then no more particles than enough to hold the distinct parcels together, a greater plenty, by filling up the vacuities, will so glue them together, as to make them run one into another.

Now it is certain, that, however hard ice is, and its parts immoveable, yet an increase of cold does make an alteration in the disposition of its parts; for it makes ice swell and rise up like boiling water, and the parts separate, and make innumerable air holes. And it is also certain, that this running of several congealed parts into one, according to these principles, would cause ice to swell, and take up more room. If the parcels F, G, and O, should run into one, and together form themselves into a globular figure, this could not be, without thrusting the parcels H, and I, higher. Nor would the matter be made up by the subsiding of other parts; for the whole is too stiff and stubborn, for some parts to come in the room of others that are moved.

It will also follow, naturally and necessarily, from the same principles, that a great increase of cold will cause cracks in the ice; for suppose the parcels H, I, K, L, and O, by an increase of frigorifick particles, are drawn into one parcel; It is evident this cannot be, without thrusting P, and G, and the parts on each side, farther asunder. And if there be the force of many such parcels united, near together, or in a range, we may suppose the strength will be sufficient to make a crack in the ice.

From the same principles, it is evident that, if the congealing matter get among particles that are so fixed, that they cannot be drawn out of the order that they lie in, it will condense them, and draw them within closer bounds; for drawing together, it is evident is the genuine effect of them, and that expanding and rarifying is accidental, and is caused only by changing the order and texture of the particles. By drawing together. therefore, where there is this drawing together without changing of order, there will be condensing without rarifying: so it is well known, that hard bodies shrink by cold.

And seeing the natural and genuine effect of this frigorifick matter is to draw particles together; and rarifying is only accidentally caused by change in position; it is evident, that if those particles find water already far more rarifying, and its particles more scattered, than such a position would require, as in clouds and vapours, it will condense them, or draw the particles together.

Cold's making hard bodies brittle is also easily explained, on the same principles. It is evidently done by taking away their elasticity. Before they would bend and not break, because the particles were not so im moveable among themselves, but what, when the body was bent, they could move somewhat out of their places to avoid a total separation of one part from another, so that there should be no crack. But these particles, getting in. lock them so fast together, that they are immoveable.

Though there seems to be a necessity of supposing some such frigorifick particles, in order to explain the freezing of Water; yet there appears no manner of need of it at all, in order to explain the consolidating VOL. 1.

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of Wax or Tallow; for their particles seem to be of such a figure, that they tend of themselves to stick together, and that it is only the active particles of heat, that keeps them from adhering one to another, as in metals, and in stones, sand, and ashes, which are all capable of liquefac tion. But if the particles of water are as apt to cleave together, as those of wax, they will need as much heat to keep them asunder. But if not so much, why do they cleave so much more strongly, when they cleave at all. And yet, without doubt, these frigorifick particles cause wax and tallow to be more solid than they would be of themselves.

From the foregoing principles, I think it is easy to account for that painful sensation that is caused in us, which we call cold; for it is necessa ry that these particles should bind the fluids of the body, and interrupt the motions of the blood, and animal spirits; which will contract, strain, and pinch up the vessels, the veins and nerves, and most especially the capillary ones.

For this reason, Water is not so transparent when frozen, and Fat when consolidated with cold, because the particles are so drawn together as to have vacuities.

It is also easy and natural to suppose, that those exceedingly active particles, which cause Heat, should disengage those frigorific particles from others, to which they cleave, and thereby set them at liberty again.

78. ATMOSPHERE, ITS QUALITIES. That different quality of the air in some particular regions or towns, at particular times, that sometimes causes some mortal distemper to rage in such a place, that is not a contagious or catching distemper, when other places, not far off, are free, though the winds every day pass over them, that remove the whole air out of those towns, a great many times in a day, and scatter it to many other places; may arise from noxious, poisonous vapours and steams, that are breathed out at, or near, such places, from the subterraneous eaverns of the Earth, through the various vents and breathing places, that are every where in the upper shell of the Earth, such as springs, and wells, and other unseen chasms. In the time of earthquakes they say they can smell sulphur; which must be by the steam of it coming up through these secret vents.

79. SUN. The Sun appears to me, to be a Liquid Body, at least at its surface, and to a great depth, for three reasons:

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1. That disposition of parts seems to me to be abundantly the most commodious, for the generation and preservation of that most prodigious intestine motion of its parts, which is the cause of so great light and heat. If it be a hard, solid body, then most of its parts are fixed, and move not, and so partake of no intestine motion. We do not see fire generated spontaneously, and of itself, in such hard, solid bodies as iron and stones; but either in fine powders or liquids; whose parts lie loose and are easily put into a violent motion, and are preserved therein the same way that it was generated. If the Sun be a solid body, like stone or iron, and all these particles, in which is this violent intestine motion, in its pores; they would not have fair play.

2. I suppose that those alterations, which are observed in the surface of the Sun, by the aid of the Telescope, do not so well agree with a body, whose parts are solid and immoveable, as with a body that has all its parts lying loose.

3. Because we know of no substance, but what would immediately be come liquid, with such a degree of heat. We see nothing, but what would melt with a thousand times less degree of heat, and with heat far less sub

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tile and penetrating. We see nothing, but what will dissolve, and its parts loose one from another, by little and little, with a slow fire. What strange sort of body therefore must that be, which will endure such a degree of heat, so many ages, and not be dissolved.

Ir may seem strange, that the light of the Sun, which we suppose to be nothing but the light of a great fire, should be so exceedingly different from the light of all fires upon Earth, that is so much brighter and whiter. This may be explained as follows:

1. As to its great brightness, it is nothing but what naturally results from the bigness of the Sun, and that in two ways: (1.) The fire being so big, will naturally and necessarily cause every part of this fire to be immensely hotter and brighter, than otherwise it would be. If a foot square of the Sun be very hot of itself, it will be immensely hotter when it is encompassed, on every side, with the same degree of heat, for many thousands of miles. It is certain, that all the circumjacent parts of the fire add heat to it inversely, according to the square of the distance; and so make it brighter, as well as hotter. It is evident that, if a space in the Sun, of a foot square, be filled with particles, that are very violently agitated in themselves, yet, if to this agitation, there be added the heat of many thousands of miles of a circumjacent fire, they will be more agitated, and therefore these particles, that are sent out, will leap forth so much the more briskly; that is, the light and heat will be so much the greater. (2.) What will naturally exceedingly promote the light and heat, is, the prodigious presence of the Sun's Atmosphere, which is incomparably greater than that of the Earth's Atmosphere. And however the Atmosphere next the Sun be very rare, by means of the prodigious heat, to rarify it; yet, the Renirus is never the less for that, if action and reaction are equal. We know that the renixus of the Air promotes light and heat: thus we see that fire is extinguished by the withdrawing of air.

2. As to the Whitness of the Sun's light, Sir Isaac Newton has demonstrated, that it consists in a proportionate mixture of rays of all colours. And from what has before been said, Redness and Yellowness are caused by the rays being of greater bulk. And we see that the light of culinary fires and of candles is reddish and yellowish, consisting mostly of the bigger sort of rays. And seeing the Sun's rays are white, it must be because there is a greater proportion of blue and green. And this also will be the natural effect of the prodigious bulk and greater heat of the Sun. The more violent the agitation and repercussion of the particles is, the more effectually will their parts be separated and their rays made fine. We know that this does whiten rays, from experience; for the more glowing and hot a fire is, the more white is its light. But there will ensue no manner of difficulty, if we suppose that the particles of the Sun were made at first fine, and the rays therefore whiter. We see brimstone burns blue, and coals red: and why may there not be a body, that has a mixture of both, to cause white.

THE interior parts of the Sun are compressed with immense force, by the parts incumbent: incomparably more than the interior parts of the Earth, by the incumbent Earth; for the quantity of incumbent matter is supposed to be at least 600,000 times greater, and the incumbent weight has its full force upon the parts subjected, being kept loose and fluid, by the heat. The interior particles of the Sun being therefore pressed together, with such prodigious violence, we may suppose, will be ground all to pieces, into particles of the first kind, until the particles are so hard and solid, that so great a force can break them no more:-doubtless as fine

and as solid as the particles of fire and rays of light can be supposed to be:-and perhaps therefore, every way of the same sort, and fitted for the same motions, and to produce the same effects. By their being made so fine, and pressed together with such violence, they must needs, to the utmost, be exposed to each other's force, whether attracting or propelling whence will arise a vehement conflict, and a fermenting and agitation, sufficiently violent, will ensue, to make that prodigious heat and light, and will be constantly preserved by the same pressure. And from the Rays being so exceedingly fine, it may arise that the light of the Sun is white. We many ways find, that even the interior parts of the Earth do diffuse a heat, though not sufficient in such wise to dissolve and inflame the whole globe; but it may be because the pressure is not sufficient, that the Planets are not globes of fire as well as the Fixed Stars.

80. LIGHT. The rays of Light, however small, may yet be so compounded, of lesser Atoms, as that they may be very elastic bodies; and yet be so contrived, as by that gravity, which is universal to them and all bodies, they may run together, with celerity sufficient to cause their Reflexion to be so rapid as is found.

89. COLOURS. We have already supposed that the different Refrangibility of rays arises from their different bulk. We have also supposed that they are very elastic bodies. From these suppositions the Colours of natural bodies may be accounted for: that is, Why some particles of matter reflect such a sort or such sorts of rays, and no other. The different density of particles, whence arises a different attraction, together with their different firmness, will account for all. Some bodies have so little of firmness, and so easily give way, that they are able to resist the stroke of no rays, but the least and weakest and most reflexible rays. All the other rays, that are bigger, and therefore their force not so easily resisted, overcome the resistance of the particles that stand in their way. Such bodies, therefore, appear blue, as the atmosphere, the sky, smoke, etc. Again, it is known that the most refrangible rays are most easily attracted, that is are most easily stopped and diverted by attraction. For, as has been already shown, Refraction and Reflection from concave surfaces is by attraction. Because, therefore, the most refrangibile rays are most diverted by Refraction, and easiest reflected inward from a concave surface, and most diverted by passing by the edges of bodies, it follows that attraction has most influence on the most refrangible rays.

It is also evident that the particles of bodies, that are the most dense, have the strongest attraction. The particles of any body, therefore, may be so dense, and attract so strongly, as to hold fast all the lesser and more refrangible rays, so that they shall none of them be reflected, but only the greater rays, on which the attraction of these particles can have less influence. Hereby the body will become Red.

And as for the intermediate colours, the particles of a body may be so dense, as to hold all the most refrangible rays, and may not be firm enough to resist the stroke of the least refrangible. Hereby the body may become yellow, or green, or of any other intermediate colour.

Or a body may be coloured by the reflection of a mixture of rays. The particles of the body may be able to reflect three or four sorts of rays, and have too strong an attraction to reflect those rays that are less, and too weak a resistance to reflect the bigger rays. Or the colour of a body may be compounded of reflected rays, of very different degrees of refrangibility, and not reflect any of the intermediate colours, by reason of its being compounded of very heterogeneous particles, which have very different de