Chapter XIII: Madam,

I am glad, you are pleased with my reasons I gave to your propounded question concerning the weight of Water; and since you have been pleased to send me some more of that subject, I shall be ready also to give my answer to them, according to the capacity of my judgment. First, you desire to know, _How it comes, that Water will by degrees ascend through a narrow pipe, when the pipe is placed straight upright; or perpendicular?_ The reason, in my opinion is, that Water, having a dilative nature, when it finds an obstruction to descend or flow even, will dilate it self ascendingly, according as it hath liberty, or freedom, and strength, or quantity; the truth is, water would be more apt to ascend then to descend, were it not for the close uniting of its liquid Parts, which causes its exterior density, and this density makes it of more weight then its nature is; and the proof that water is apt in its nature to ascend, is, that some sorts of vapours are made onely by the dilation and rarefaction of ascending Water. Your second question is, _Why the surface of water seems to be concave in its middle, and higher on every side?_ I answer, The interior figure of water is a circular figure, which being a round figure, is both concave, and convex; for where one is, the other must be; and the motions of ebbing and flowing, and ascending or descending, are partly of that figure; and so according to the exterior dilating strength or weakness, the exterior parts of water become either concave or convex; for in a full strength, as a full stream, the exterior parts of water flow in a convex figure, but when they want strength, they ebb in a concave figure. Your third question is, _What makes frozen water apt to break those Vessels wherein it is contained, in the act of freezing or congealing?_ I answer: The same cause that makes water clear, as also more swell'd then usually it is: which cause is the inherent dilative nature of water; for water being naturally dilative, when as cold attractions do assault it, the moist dilations of water in the conflict use more then their ordinary strength to resist those cold contracting motions, by which the body of water dilates it self into a larger compass, according as it hath liberty or freedom, or quantity of parts; and the cold parts not being able to drive the water back to its natural compass, bind it as it is extended, like as if a beast should be bound when his legs and neck are thrust out at the largest extent, in striving to kick or thrust away his enemies and imprisoners: And so the reason why water breaks these vessels wherein it is inclosed, in the act of its freezing or congealing is, that when the cold contractions are so strong as they endeavour to extinguish the dilating nature of water, the water refilling, forces its parts so, as they break the vessel which incloses them: The same reason makes Ice clear and transparent; for it is not the rarefaction of water that doth it, but the dilation, which causes the parts of water to be not onely more loose and porous, but also more smooth and even, by resisting the cold contractions; for every part endeavours to defend their borders with a well ordered and regular flowing or streaming, and not onely to defend, but to enlarge their compass against their enemies. Your fourth question is, How it comes _that Snow and Salt mixt together doth make Ice?_ The reason, in my judgment, is, that Salt being very active, and partly of the nature of fire, doth sometimes preserve, and sometimes destroy other bodies, according to its power, or rather according to the nature of those bodies it works on; and salt being mixt with snow, endeavours to destroy it; but having not so much force, melts it onely by its heat, and reduces it into its first principle, which is water, altering the figure of snow; but the cold contractions remaining in the water, and endeavouring to maintain and keep their power, straight draw the water or melted snow into the figure of ice, so as neither the salts heat, nor the waters dilative nature, are able to resist or destroy those cold contractions; for although they destroy'd the first figure, which is snow, yet they cannot hinder the second, which is Ice. Your last question is, _How the Clouds can hang so long in the Skie without falling down?_ Truly, _Madam_, I do not perceive that Clouds, being come to their full weight and gravity, do keep up in the air, but some of them fall down in showres of rain, others in great and numerous flakes of snow; some are turned into wind, and some fall down in thick mists, so that they onely keep up so long, until they are of a full weight for descent, or till their figure is altered into some other body, as into air, wind, rain, lightning, thunder, snow, hail, mist, and the like. But many times their dilating motions keep or hinder them from descending, to which contracting motions are required. In my opinion, it is more to be admired, that the Sea doth not rise, then that Clouds do not fall; for, as we see, Clouds fall very often, as also change from being Clouds, to some other figure: Wherefore it is neither the Sun, nor Stars, nor the Vapours, which arise from the Earth, and cause the Clouds, nor the porosity of their bodies, nor the Air, that can keep or hinder them from falling or changing to some other body; but they being come to their full weight, fall or change according as is fittest for them. And these are all the reasons I can give you for the present; if they do not satisfie you, I will study for others, and in all occasions endeavour to express my self,

Madam,

_Your constant Friend,_

_and faithful Servant._