The Pneumatics of Hero of Alexandria

...the air escaping from the vessel. This is nothing other than air being expelled from within. One should not think, therefore, that among existing things there is a nature of the vacuum vacuum coacervatum original: "vacui naturam quandam coaceruatam." A "collected" or "continuous" vacuum, as opposed to tiny voids between particles. that exists as a single mass by itself. Instead, it is distributed in tiny parts throughout the air, liquids, and other bodies.

Perhaps someone might believe that the diamond adamas While "adamas" usually means diamond, in antiquity it referred to any legendary, indestructible substance of extreme hardness. alone is devoid of the nature of a vacuum, since it can neither be burned by fire nor broken, and when struck upon anvils and hammers, it remains entirely intact. This occurs, however, not because it lacks vacuum spaces, but because of its continuous density. For since the corpuscles corpuscula Tiny particles or "atoms" of matter. of fire are thicker than the vacuum spaces within the stone, they cannot enter at all, but only touch the outermost surface.

Therefore, since they do not penetrate the interior, they do not induce heat in it as they do in other bodies. Now, the particles of air do indeed cling to one another, but not at every point; rather, they have certain empty intervals interspersed between them, like the sand found on the shores. Thus, it should be conceived in the mind that the particles of sand are similar to the particles of air, while the air, which...