_B._ It will indeed go slower in the proportion of the line A E to the line C E. But the ship will not go so fast as you think sideward: one cause is the force of that wind which lights on the side of the ship itself; the other is the bellying of the sail; for the former, it is not much, because the ship does not easily put from her the water with her side; and bellying of the sail gives some little hold for the wind to drive the ship astern. _A._ For the motion sideward I agree with you; but I had thought the bellying of the sail had made the ship go faster. _B._ But it does not; only in a fore wind it hinders least. _A._ By this reason a broad thin board should make the best sail. _B._ You may easily foresee the great incommodities of such a sail. But I have seen tried in little what such a wind can do in such a case. For I have seen a board set upon four truckles, with a staff set up in the midst of it for a mast, and another very thin and broad board fastened to that staff in the stead of a sail, and so set as to receive the wind very obliquely, I mean so as to be within a point of the compass directly opposite to it, and so placed upon a reasonable smooth pavement where the wind blew somewhat strongly. The event was first, that it stood doubting whether it should stir at all or no, but that was not long, and then it ran a-head extreme swiftly, till it was overthrown by a rub. _A._ Before you leave the ship, tell me how it comes about that so small a thing as a rudder can so easily turn the greatest ship. _B._ It is not the rudder only, there must also be a stream to do it; you shall never turn a ship with a rudder in a standing pool, nor in a natural current. You must make a stream from head to stern, either with oars or with sails; when you have made such a stream, the turning of the rudder obliquely holds the water from passing freely, and the ship or boat cannot go on directly, but as the rudder inclines to the stern, so will the ship turn; but this is too well known to insist upon. You have observed that the rudders of the greatest ships are not very broad, but go deep into the water, whereas western barges, though but small vessels, have their rudders much broader, which argues that the holding of water from passing is the true office of a rudder; and therefore to a ship that draws much water the rudder is made deep accordingly; and in barges that draw little water, the rudders being less deep, must so much the more be extended in breadth. _A._ What makes snow? _B._ The same cause which, speaking of hardness, I supposed for the cause of ice. For the stream of air proceeding from that both the earth and the sun cast off the air, consequently maketh a stream of air from the equinoxial towards the poles, passing amongst the clouds, shaving those small drops of water whereof the clouds consist, and congeals them as they do the water of the sea, or of a river. And these small frozen drops are that which we call snow.