An entire body of philosophy according to the principles of the famous Renate Des Cartes in three books, (I) the institution ... (II) the history of nature ... (III) a dissertation of the want of sense and knowledge in brute animals ... / written originally in Latin by the learned Anthony Le Grand ; now carefully translated from the last corrections, alterations, and large additions of the author, never yet published ... by Richard Blome.

CHAP. V. Of Hail and Snow.

I. Why Hail falls more commonly in the day time than at night. HAIL falls more generally in the day than at night, and oftner in the Spring, Summer and Autumn, than in the VVinter.

The Reason is, because a Cloud cannot be mel∣ted but by Heat, and therefore it is that Hail falls only at that time, when there is sufficient Heat to produce this effect. Wherefore tho' Hail may be generated in the VVinter, Spring, Summer and Autumn, and in the night, as well as in the day; yet does it fall more seldome in the night, and in Winter, because then the Heat is too weak to be re∣flected up to the higher Clouds, so as to dissolve them into drops of water of which Hail is made.

II. Why the less Hail∣stones are Transpa∣rent and the greater Opake. Small Hailstones are sometimes Transparent; whereas the greater are only so towards the Sur∣face, having some Snow within them, and are of a white colour.

The Transparency of Hail proceeds from the coldness of the VVind, which freezeth the drops of water into Ice. Because in this case, the Pores remain much the same as they were before in the

water, through which the Globuli of the 2d Ele∣ment passing without hindrance, transmitted the action of Light every way in Right lines: As was said before concerning Glass. But when the cold VVind approacheth the Flocks of Snow, that are not quite melted, it drives the Heat, that is, the most swiftly agitated subtil matter into their Pores; because the VVind it self, cannot so easily or so swiftly enter them as the Heat or subtil mat∣ter that is in the Air can. Now when this Heat is thus shut up within the Pores of these Flocks of Snow, it endeavours to approach their Circum∣ference, rather than their Centers, because the subtil matter (in the agitation whereof Heat con∣sists) is more freely moved there, and so proceeds to melt them more and more, before they begin to Freeze again, and the most Fluid, that is, the most agitated particles of water, which are else where found in the said Flocks, approach to their Circumferences; the rest of them, which cannot melt so suddainly, abiding about the Centers of them. Which is the reason, why the greater Hail∣stones are Transparent towards their Surface, and inwardly of a white colour.

III. What is the reason of the un∣usual great∣ness of some Hailstones. Sometimes Hail equal in bigness to great Stones falls down from Heaven. And I have heard an acquaintance of mine relate, that he had seen Hailstones as big as ten Eggs. And Historians relate of some that were no less than a mans Fist. In the year 1666, in Gelderland, some were seen of about 3 pound weight.

This bigness proceeds from the Cold VVind, by which the Hail is formed, which driving the Snow downwards from on high, drives many of the Flocks of it together, and by means of the Cold condenseth them into one Mass. Or else we may say, that such great Hailstones are generated in the highest Clouds, and that they encrease con∣tinually all the way they come down, and by this means grow into a great and extraordinary bulk. For it may so happen, that they may meet in their way with much moisture, which sticking to them, may be Frozen into one Mass with them. And by this means the Hail is encreased, by the ad∣dition of new Surfaces or Coats: As we find that Candles by repeated dipping into the melted grease, do still grow thicker.

IV. Why Hail∣stones are of different figures. Hailstones are sometimes of a Spherical figure, and at other times appear under various configu∣rations.

The Reason is, because the Flocks out of which the Hailstones are formed, being seized of the Cold VVind, are congealed by it. For if the Cold VVind, that is the efficient of Hail, meets with drops of water already formed, it makes the Hail∣stones round, save only that it frequently makes them somewhat flattish on that side, where it drives against them. But if it meets with Flocks of Snow that are not quite melted, then it frames them into irregular figures.

V. What is the reason of the great noise that is heard before the fall of Hail. Commonly before the Hail comes down, a great noise is heard in the Air.

This is caused when the frozen drops dash against one another. And when this noise is heard some interval before the Hail falls, it is an Ar∣gument that the said Hail is formed in the upper parts of the Air; so that there is no necessity at all in this case, to have recourse to an Antiperi∣stasis.

VI. How the Snow comes to be con∣densed. We find by experience, that the Snow whereof the Clouds do consist, becomes condensed, and reduced to a less extension.

To apprehend this well, we need only to con∣sider that the Heat which commonly rarefies most Bodies, doth commonly condense Snow, the parts whereof are so scatter'd and divided, that the very least agitation is sufficient to bring them nearer together. Whence it comes to pass, that when the Air which is so near to the Earth, and is al∣ways hotter than that which is at a greater distance from it, begins to raise it self towards the Clouds, either by the driving of some VVind, or by the action of some new Fermentation, which causeth it to swell, it cannot but condense the Snow, whereof the Clouds do consist.

VII. What is the reason of Starry, Rose-like and Hairy Snow. The particles of Snow are commonly figured like Stars, as may be perceived by catching the Flocks of Snow on a dry Cloth, and separating the parts of it from one another: Tho' sometimes also they be found Hairy, and sometimes in the figure of Roses.

The reason of this various Configuration is, because the Flocks of Snow, before that they fall to the ground, do undergo manifold changes in the Air, and according to the vicissitudes of Heat and Cold partake of different figures. Starry fi∣gur'd Snow is formed, when the Leaves of it, as the Heat approacheth, are melted leisurely, so that the Liquor into which they are dissolved spreading it self over the Surfaces of the Leaves, doth fill up all the little inequalities it meets with there; and makes them so smooth and even, as those parts of the Liquid Bodies are, tho' it presently after freezeth there again. For seeing that the Heat then is no stronger, than what is required to resolve those small Capillaments, on all sides surrounded with Air, into water, the others still remaining whole and entire; it cannot be strong enough, to hinder that small quantity of water, that is fallen upon their Icy surfaces, from being congealed a∣gain by Cold. Afterwards this Heat passing through other Capillaments, which every one of the Flocks of Snow have in their Circumference, where they are surrounded with 6 other such like Capillaments, doth promiscuously bend this way and that way those Capillaments which are at the furthest distance from the 6 nearest Globuli, and by this means joyns them to those which stand over against these 6 Globuli. For these being kept Cold by the neighbourhood of the said 6 Glo∣buli, do not melt, but on the contrary do imme∣diately Freeze or turn to Ice, the matter of the o∣thers that are joyned to them; and by this means 6 Points or Rays are formed about every one of the said Flocks, which are capable of receiving divers figures, according as they are more or less comprest, the Capillaments thick and long, and the Heat which forms them slow and moderate. Again, Hairy Snow is generated, when the Icy particles whereof the Flocks do consist, are con∣densed by the Heat, and soon after being Frozen by the Cold, are turned about their Center, and are bound up by other Icy fragments. So like∣wise Snow formed in the figure of Roses is produ∣ced when the Rays that shoot out from the Snow, are bended by the Heat, and falling together with their points, are in that manner congealed again.

VIII. Why Snow is visible in the Night. The Night, which renders most other Bodies invisible, hath not that effect upon Snow.

The Reason is, because Snow consisting of an infinite quantity of little round Bodies, doth reflect the Rays of Light better than any other white Body. For tho' in the Night there be but a very weak and scatter'd Light spread over the Earth; yet there is that in Snow, which by a stronger Reflexion of it, doth make it self visible.

IX. What is the Cause of the great whiteness that is in Snow, and why the same is changed when wa∣ter is cast upon it. An extraordinary whiteness is proper to Snow, which yet it loseth, when mixed with water, and returns to water, whence it proceeded at first.

The Reason is, because Snow is like a Vapour turn'd into Froth, the Flocks whereof consisting of innumerable Globuli, reflect the Light every way; forasmuch as there is never a Point in all those Globuli, from which Rays are not reflected to every Point of the Medium. And this is the Reason why Snow is hurtful to the Eye-sight, be∣cause that by reason of the foresaid Globuli, it darts forth on all sides a fuller and stronger light. Hence it is, that when we come into a House, after we have walked through Fields cover'd with Snow, we cannot well discern the Objects we meet with. It is also found by Experience, that those who live in places that abound with Snow, have weak Eyes; and some tell us, That Souldiers, by long Marches through places cover'd with Snow, have lost their Sight.

X. How the Snow comes to change its colour. But if the new fallen Snow seems to be of a blackish Colour, the Reason is, because some Cavi∣ties are interspersed between the flocks, which swallow up the Rays, and do not rebound them back into the Air. But Snow wholly changeth its colour, when mingled with water, which filling up the Cavities of the Snow, hinders the Reflexion or Refraction of the Rays, and causeth the Light to be modified after another manner. Hence it is that the white Colour of some Fruits, is only ow∣ing to the parts of it that are formed into Bub∣bles: For we see that Apples, when squeezed, lose their Colour, because these Bubbles being broken by this compression, hinders that Refraction which is necessary to constitute a white Colour, as likewise such a copious reflexion of Rays, as is requisite to that purpose.

XI. Why the handling of Snow makes the Hands to glow. Upon the handling of Snow, we find our Hands soon after to glow and burn.

Some suppose this to be done by an Antiperi∣stasis, because when the Cold is driven out, Heat is introduc'd. But we own no such Contrariety in Nature, and therefore rather conclude, that this Heat proceeds from the Frozen particles of Snow, which having the watry humour for their Vehicle, do enter into the pores of the Hand, beat back the Blood, and hinder it from being dispersed through the Veins in the Hands; by which means the Hands swell, and appear of a red Colour. And therefore if we chance to put them to the Fire, we are sen∣sible of a very sharp pricking and shooting pain; for the Fire being forceably thrust into their pores, doth dilate the Icy particles more than ordinary, and doth not drive them thence, without some twitching of the parts. Wherefore we ought to keep our Hands in a moderate warmth, to grow hot by degrees, and so be restored to their former condition.

XII. Snow pre∣serves the Corn in the Ground from being frozen. Snow, tho' it be a Frozen-water, yet doth warm the Earth, and keeps the Corn from freez∣ing.

The Reason is, because the pores of Corn, that is cover'd with Snow, having been drawn toge∣ther by the fore-going Frost, and the Matter of the 2d Element, endeavouring to enter through them, as soon as it begins to thaw, would not fail of rending the Texture of its parts, if it were not hindred by the presence of the Snow, which having nothing in its pores, besides the most subtil matter of the 2d Element, can easily open again the pores of the Wheat by degrees, without tearing them, till they be open'd large enough to let the biggest Matter of the 2d Element pass through them.

XIII. How Snow conduceth to make the Ground fruitful. Snow doth also contribute to the making of the Ground fruitful, if it lye on for some time, and be dissolved by degrees.

The Reason is, because when Snow covers the the Ground, it keeps in the Alimental Juice of Plants, and hinders the strength of the Ground from evapourating into Steams and Exhalations. And therefore Countrymen tell us, that their Grounds yield a more abundant Increase, after they have been a long time cover'd with Snow, because it keeps back those fat Exhalations, which would otherwise break forth, and turns them into Ali∣ment for the Fruits of the Earth. Or, it may be said, that the Snow melting by degrees, doth afford a fat and cherishing Moisture to the Plants; whereby they are fed, and become more vigorous. As is manifest when the Snow is thaw'd, and the Earth expos'd again to the heat of the Sun; and therefore it frequently happens, that in those Mountains that are cover'd with Snow, the Exha∣lations that break forth, do make a kind of Arch or Crust, under which the Grass springs forth very thick.

XIV. How Snow may be hurtful to the Roots of Plants. I know well, that some Physicians are of ano∣ther Opinion, who order Gardiners, to cover the surface of the Ground, in which Plants are set, with Stubble or Straw, to preserve it from the injury of the Snow: But I suppose they do not give these Instructions, because they suppose the Snow to be prejudicial thereunto, but lest the Roots being throughly moistned by the thawing of the Snow, a sharp Cold or Frost following upon it, might freez the Juice within their pores; since it is evident, that the Roots of Plants throughly soak'd therewith, do presently dye; nothing being more hurtful to Plants, than melted Ice or Snow, to chil and kill the Roots after a cold Thaw.