_B._ Yes, and perhaps also in the southern parts. But I cannot imagine how ice can be made in such agitation as is always in the open sea, made by the tides and by the winds. But how it may be made at the shore, it is not hard to imagine. For in a river or current, though swift, the water that adhereth to the banks is quiet, and easily by the motion of the air driven into small insensible bubbles; and so may the water that adhereth to those bubbles, and so forwards till it come into a stream that breaks it, and then it is no wonder though the fragments be driven into the open sea, and freeze together into greater lumps. But when in the open sea, or at the shore, the tide or a great wave shall arise, this young and tender ice will presently be washed away. And therefore I think it evident, that as in the Thames the ice is first made at the banks where the tide is weak or none, and, broken by the stream, comes down to London, and part goes to the sea floating till it dissolve, and part, being too great to pass the bridge, stoppeth there and sustains that which follows, till the river be quite frozen over; so also the ice in the northern seas begins first at the banks of the continent and islands which are situated in that climate, and then broken off, are carried up and down, and one against another, till they become great bodies. _A._ But what if there be islands, and narrow inlets of the sea, or rivers also about the pole of the equinoctial? _B._ If there be, it is very likely the sea may also there be covered all over with ice. But for the truth of this, we must stay for some farther discovery. _A._ When the ice is once made and hard, what dissolves it? _B._ The principal cause of it, is the weight of the water itself; but not without some abatement in the stream of the air that hardeneth it; as when the sunbeams are less oblique to the earth, or some contrary wind resisteth the stream of the air. For when the impediment is removed, then the nature of the water only worketh, and, being a heavy body, downward. _A._ I forgot to ask you, why two pieces of wood rubbed swiftly one against another, will at length set on fire. _B._ Not only at length, but quickly, if the wood be dry. And the cause is evident, viz. the compounded motion which dissipates the external small parts of the wood. And then the inner parts must of necessity, to preserve the plentitude of the universe, come after; first the most fluid, and then those also of greater consistence, which are first erected, and the motion continued, made to fly swiftly out; whereby the air driven to the eye of the beholder, maketh that fancy which is called light.