100

lead, wineskin

This, for a fountain to set upon a table, is more uniform than any other method.

It is asked whether, if the pipe a r were very long and the part that rises up — that is, r c — were short, at what limit the water would issue from the pipe by itself, spurting up through the air. And it is asked the reason why it does not leap up to the height of the surface of the water from which it descends; and at what degrees of height it rises exactly to the surface of that water; and why it then does not follow that proportion exactly.

100

Here it is asked, concerning the water of this vessel, how much more it weighs upon its bottom than upon its sides; and in what part of the bottom it weighs more and less, and by how much; and likewise, in what part of the walls it weighs more still and less. And it is asked of the wind put in by force by the bellows, what force it makes upon the water and upon all the parts of the vessel's walls that sustain that water. And likewise it is asked what quality of force this wind makes upon all the parts of its receptacle; and whoever knows how to define this question well will be able to state exactly the nature of all instruments of water. The 100 pounds of weight that press the bellows make the air push and want to flee from the vacuum of that bellows. And by the 5th of the 3rd, it pushes equally into every part of its dwelling. Hence, the mouth of that bellows being the hundredth part of its quantity, we shall say that one of the hundred pounds of the weight that presses it is the one that pushes at that mouth. So that a single pound of the hundred drives out the air of the bellows, which would be equal to a pound of weight that, leaning with all its power, should stop up that hole. The void of air into which that bellows pours its other air, let us say, receives the bellows' hole 12 times in its walls. Therefore every twelfth part is pressed by one ounce.

The wineskin — or bag, or let us say bellows — all of thin leather, which is pressed by the weight set upon it above. I say that the more it presses, the more strongly it presses. And this does not arise by the sentence of the 5th of the first, which says that the weight which falls more weighs more, because in slow motions it cannot make impetus; yet a little of this could be granted. But such effect derives thus: that the weight of 100 pounds, the hole of the bellows being the hundredth part of its emptiness, to that hole is distributed a single pound of the power of the weight. But when that bellows is pressed so far that it has diminished half of its emptiness, then the mouth of the bellows is the fiftieth part of that emptiness; hence, of the 100 pounds that press the bellows, 2 fall to it. So you see that it has doubled its power. But in bellows that have hard joints of wood, and thick and coarse leathers hard to bend, such increase of blowing of wind could not occur, because the more it is closed the more it resists the weight that presses it; hence such blowing diminishes more. The water that is pushed out of its surface by the fountain of wind will be equal to the power that drives it. This will teach you to measure how much power the weight of the water — which presses through the pipe the reservoir of air — has in that reservoir; and when you have measured its void, then measure the reservoir of the water that escapes, that is, its walls. But to have the true weight of all the water that leaps out of the surface of the other water, you must make the pouring pipe end exactly at the surface of the water. And when it pours, have a woolen cloth, weighed exactly, and of such size that, placing it open and spread out suddenly over the hole whence that water issues, all the water that is in the air falls upon the cloth. Then weigh it, and from what has increased subtract the half, because there is the water that was rising and that was falling; (vertically) for one must not put into the account any but that which rises, which has pushed it.