Chapter XXXIX: Madam,

Concerning Vapour, Clouds, Wind and Rain, I am of your _Authors_ opinion,[1] That _Water is changed into Vapour, and Vapour into Air, and that dilated Vapours make Wind, and condensed Vapours, Clouds and Mists_; But I am not for his little particles, _whereof_, he says, _Vapours are made, by the motion of a rare and subtil matter in the pores of terrestrial bodies_; which certainly I should conceive to be loose atoms, did he not make them of several figures and magnitude: for, in my opinion, there are no such things in nature, which like little Flyes or Bees do fly up into the air; and although I grant, that in Nature are several parts, whereof some are more rare, others more dense, according to the several degrees of matter, yet they are not single, but all mixt together in one body, and the change of motions in those joyned parts, is the cause of all changes of figures whatever, without the assistance of any forreign parts: And thus Water of it self is changed to Snow, Ice, or Hail, by its inherent figurative Motions; that is, the circular dilation of Water by contraction, changes into the figure of Snow, Ice, or Hail or by rarifying motions it turns into the figure of Vapour, and this Vapour again by contracting motions into the figure of hoar frost; and when all these motions change again into the former, then the figure of Ice, Snow, Hail, Vapour and Frost, turns again into the figure of Water: And this in all sense and reason is the most facil and probable way of making Ice, Snow, Hail, &c. As for rarefaction and condensation, I will not say that they may be forced by forreign parts, but yet they are made by change and alteration of the inherent motions of their own parts, for though the motions of forreign parts, may be the occasion of them, yet they are not the immediate cause or actors thereof. And as for _Thunder_, that clouds of Ice and Snow, the uppermost being condensed by heat, and so made heavy, should fall upon another and produce the noise of thunder, is very improbable; for the breaking of a little small string, will make a greater noise then a huge shower of snow with falling, and as for Ice being hard, it may make a great noise, one part falling upon another, but then their weight would be as much as their noise, so that the clouds or roves of Ice would be as soon upon our heads, if not sooner, as the noise in our Eares; like as a bullet shot out of a Canon, we may feel the bullet as soon as we hear the noise. But to conclude, all densations are not made by heat, nor all noises by pressures, for sound is oftener made by division then pressure, and densation by cold then by heat: And this is all for the present, from,

Madam,

_Your faithful Friend,_

_and Servant._

[1] _Of Meteor., c._ 2, 4, 5, 6.