_B._ I have seen a drop of glass like that of the second figure, newly taken out of the furnace, and hanging at the end of an iron rod, and yet fluid, and let fall into the water and hardened. The club-end of it A A coming first to the water, the tail B C following it. It is proved before, that the motion that makes it is a compounded motion, and gives an endeavour outward to every part of it; and that the motion which maketh cold, is such as shaving the body in every point of contact, and turning it, gives them all an endeavour inward. Such is this motion made by the sinking of the hot and fluid glass into the water. It is therefore manifest that the motion which hardeneth a soft body, must in every point of contact be in the contrary way to that which makes a hard body soft. And farther, that slender tail B C shall be made much more hard than common glass. For towards the upper end, in C, you cannot easily break it, as small as it is. And when you have broken it, the whole body will fall into dust, as it must do, seeing the bending is so difficult. For all the parts are bent with such force, that upon the breaking at D, by their sudden restitution to their liberty, they will break together. And the cause why the tail B C, being so slender, becomes so hard, is, that all the endeavour in the great part A B, is propagated to the small part B C, in the same manner as the force of the sun-beams is derived almost to a point by a burning-glass. But the cause why, when it is broken in D, it breaks also in so many other places, is, that the endeavour in all the other parts, which is called the spring, unbends it; from whence a motion is caused the contrary way, and that motion continued bends it more the other way and breaks it, as a bow over-bent is broken into shivers by a sudden breaking of the string. _A._ I conceive now how a body which having been hard and softened again, may be rehardened; but how a fluid and mere homogeneous body, as air or water, may be so, I see not yet. For the hardening of water is making a hard body of two fluids, whereof one, which is the water, hath some tenacity; and so a man may make a bladder hard with blowing into it. _B._ As for mere air, which hath no natural motion of itself, but is moved only by other bodies of a greater consistence, I think it impossible to be hardened. For the parts of it so easily change places, that they can never be fixed by any motion. No more I think can water, which though somewhat less fluid, is with an insensible force very easily broken. _A._ It is the opinion of many learned men, that ice, in long time, will be turned into crystal; and they allege experience for it. For they say that crystal is found hanging on high rocks in the Alps, like icicles on the eaves of a house; and why may not that have formerly been ice, and in many years have lost the power of being reduced?