The Ingenious and Curious Pneumatic Motions of Hero

ate the breasts of milk, which after they have given birth, within the term of two or three days, usually arrive in such abundance that, if they are not evacuated to the born babies, they would cause hardness and very grave ills in themselves (the breasts not being emptied). These have, as is known, a body in which there is a hole so large that by resting the vessel on the Breast, the nipple of it enters comfortably inside, and in another part they have a neck so long that they take it in the mouth, then having sucked out the Air that is in the vessel, the milk that comes out of the breast immediately succeeds in place of it. And for those vials that they are also accustomed to use for said effect: they take a glass vial with the neck so wide in the upper part that it is capable of the nipple of the breast, and they heat the body of it well with fire, until the heat penetrating through the vacua the thinness of the glass drives out the Air, filling the body of the vial with the most subtle vapor. And when said body is very well heated, they immediately place the mouth of the neck of the vial to the breast, placing the nipple inside, and because that subtle igneous vapor cannot remain enclosed there, it escapes out through those vacua of the glass through which it entered, and it sets out to rise on high to its place. Even if it is transmuted into aerial substance by the surrounding air, and because through these pores, which are very subtle, the air cannot enter, the body not being able to be a vacuum, it immediately pulls the milk from said breast; and emptying it, it comes to fill itself, and being completely full, it no longer pulls, as also if it is left open in some part, it lets the Air enter into it.

The fires similarly that are lit on the mouths of the furnaces (in which stones, lime, and earthen vessels are baked) are pulled into those furnaces by the vacuum. For the vapor of the fire, having driven out the Air that is inside, vanishes and evaporates on high, and the fire being on the mouth of the furnace prevents the Air from being able to enter; but because there cannot be a vacuum as the vapor vanishes, it is necessary that the fire fill the empty body that would come to remain in the furnace, because as the vapor exits, the entrance to the Air is closed, nor being able to be a vacuum, it is necessary that the fire succeed into it. From which things it is constant with what excellence Hero has proven the non-concession of a vacuum at all, if not violated and outside of nature.