The Ingenious and Curious Pneumatic Motions of Hero

that passes into air. Thus, it is manifest that fire dissolves and transmutes everything coarser than itself. And by the exhalations that occur from the earth, the coarser bodies are transmuted into more subtle substances. Nor in any other way do the dews rise on high, except that the water which is on the earth is attenuated by its exhalation, and this exhalation is produced by a certain fiery substance of the Sun that is in the bowels of the earth, which warms that place; and so much the more if it is sulfuric or bituminous, as such heated matter for the most part generates exhalation, and the waters that are found in the earth become warm for the same reasons. The most subtle part of the dew is therefore transmuted into air, and the coarser part of it, violated by the force of the exhalation, rises somewhat on high, and, cooled by the turning of the Sun, falls again downward upon the earth. But the winds are born from the vehement exhalation of air, thinned and driven by its continuous motion; and the motion of the air is not equally fast, but is much faster in the beginning near the exhalation, and always goes on becoming slower and weaker the further it moves from the place whence it moves, as also happens in heavy things that are carried upward. For its motion is much faster near the place in which is the violence that drives them, and slower in the upper part, because they are not accompanied by the driving force with the same power that began to move them, and for this reason they return again to their natural place from whence they departed, that is, in the lower parts. For if they were always accompanied by the same driving force with equal speed, they would certainly never cease. But as it ceases little by little, the velocity of the moved thing is also seen to cease. And water also is transmuted into earthly substance when, having dug into the earth, we pour water into the hollowed place, which shortly after, being imbibed by the earthly substance, vanishes, and mixing with it, becomes earth. But if there is someone who says that it is constrained, and that it is not drunk by the earth, but evaporates and dries up, either by the heat of the Sun or otherwise, one will truly see that person fall into error. For the same water infused into a vessel of glass, or of copper, or of another dense material, and exposed to the Sun, will not diminish in quantity, except for a small part, over a great span of time. Hence, one sees that water is transmuted into earthly substance, and the viscosity, so to speak, or the mucilage of the earth, and the transmutation of water into earthly substance. The subtle is also changed into a coarser substance, as we see in extinguished lamps, which lack oil; the flame is carried somewhat upward, and as if driven to depart from its own place and head to its supreme place, which is above the air, but, overcome by the many intermixtures of it, it is not carried to the intended place; but mixed and entangled with aerial bodies, it is converted into air. And the same must be understood of air: for if, enclosed in some not-very-large vessel, we submerge the vessel in water, and then uncover it so that the water may enter into it through the mouth above, the air will certainly depart from the vessel, or, overcome by the great quantity of water, it will mix and entangle itself in such a way that it will become water. In the same way, the air corrupted in the cucurbitule small flasks or ventose cupping glasses, and thinned by the fire, exits due to the rarity of the vessel, and the body being made a vacuum, it draws to itself the surrounding matter, whatever its quality may be. But when the flask...