SPIRITAL. LIBER.

B 2

For let a sphere be constructed having the thickness of a metal plate, so that it might not easily be broken, and containing about eight cotylae original: "cotylas"; an ancient Greek unit of liquid measure, roughly equivalent to half a pint or 0.27 liters., and closed up on all sides. It is necessary, therefore, to perforate it, and to insert a bronze siphon original: "siphonem"; in this context, Hero refers to a straight, slender tube or pipe rather than a U-shaped siphon., that is, a slender tube, not touching the spot which is diametrically opposite the perforated point, so that water may be able to flow; moreover, another part of it should project outside the sphere by about three fingers’ breadth. It is necessary to seal the edge of the hole through which the siphon is inserted with tin original: "stanno"; likely referring to the use of tin as solder to create an airtight seal., encompassing both the siphon and the outer surface of the sphere, so that when we wish to blow through the siphon with the mouth, the spirit original: "spiritus"; here meaning the air or breath acting as a pressurized force. does not escape from the sphere in any way.

Therefore, let us examine what happens. For since air exists within it—just as in other vessels that are called "empty"—and fills the whole space within it, being pressed against its circumference through a certain continuity; and since finally, as they Referring to the followers of Aristotle or other "Plenists" who argued that a vacuum cannot exist in nature. believe, no place exists that is entirely void original: "vacuo"; a space containing no matter., we would be able neither to introduce water, nor additional air, unless the previous air that was in the sphere departed; and