The most ancient of such instruments is certainly the syringe. The Egyptians, says Herodotus (ii., 87), employed the latter in the embalming of common people, for filling the belly with oil of cedar, through injections made per ano, without opening the body and extracting the intestines. Heron, in his "Pneumatics," describes an instrument of this kind, called Pyulgue, which was designed for sucking pus out of wounds.
The following apparatus, also described by Heron, is the first step that was taken toward the production of the pneumatic apparatus properly so called
"Construction of a cupping glass that sucks without the aid of fire."
Let ΑΒΓ (Fig. 1) be a cupping glass (like that which is usually applied to the skin), divided by a partition, ΔΕ. Through the bottom let there be passed two tubes that slide one within the other by friction—ΖΗ being the external and ΘΚ the internal one. In these two tubes, external to the glass, there are two apertures, ΛΜ, that face each other. The extremities of the tubes situated within the apparatus should be open, and the external extremity of ΘΚ should be closed and provided with a key. Beneath the partition, ΔΕ, there is another cock, ΝΞ, like the one just described, save that the corresponding apertures are within the cupping-glass, and are in communication with an aperture in the partition, ΔΕ.
"Things being arranged thus, the keys of the cock are revolved in such a way that the apertures of the one at the bottom of the instrument are in a line with each other, while the cock above the partition remains closed, inasmuch as its apertures do not correspond. The chamber, ΔΓ, being full of air, if we apply the mouth to the orifices, ΛΜ, and suck out a portion of the air, and turn the key of the cock without removing the mouth from the tube, we shall be able to thus keep up a rarefaction of the air in the chamber, ΓΔ. The oftener we perform this operation, the more air we shall remove. Let us now apply the cupping-glass to the skin in the usual way, and open the cock, ΝΞ, by turning the key. A portion of the air contained in ΑΔΕ will pass into ΓΔ, and we shall then see the skin, as well as the subjacent matters that pass through its interstices, that we call unexplored spaces, drawn into the space in which the air is rarefied."
As for the pressure fountain, this had reached perfection as long ago as the Alexandrine epoch. The following description of it is borrowed from the "Pneumatics:"
"To construct a hollow sphere, or any other vessel, in which, if a liquid be poured, the latter may be made to rise spontaneously with great force so as to empty the vessel, although such motion be contrary to nature."
"The construction is as follows: Let there be a sphere of a capacity of about six cotyles (about 2¾ pints) made of some metal tough enough to withstand the pressure of the air that is to be produced. Let us place this sphere, ΑΒ, upon any base whatever, Γ. Through an aperture in its upper part we introduce a tube which runs down to that part of the sphere which is diametrically opposite the aperture, but which leaves sufficient space there for the water to pass. This tube projects slightly above the sphere, to whose aperture it is soldered, and divides into two branches, Η and Ζ, to which are affixed two bent tubes, ΖΜΝΞ and ΗΘΚΛ, that communicate internally with Η and Ζ. Finally, in these tubes, ΗΘΚΛ and ΖΜΝΞ, and in communication with them, there is adapted another tube, ΠΟ, from which issues at right angles a small tube, ΡΣ, that communicates with it and terminates at Σ in a fine orifice.
If, taking the tube, ΡΣ, in hand, we revolve the tube, ΠΟ, the two apertures that face each other can no longer establish a communication, and the liquid that rises will no longer find an outlet. Then, through another aperture in the sphere, we insert another tube, ΤτΦ, whose lower orifice, Φ, is closed, but which has upon the side, toward the bottom, at Χ, a round hole to which is adapted a small valve of the sort called by the Romans assarium. Into the tube, τΦΤ, we insert another and closely fitting tube, ΨΩ. Let us now remove the tube, ΨΩ, and pour liquid into the tube, τΦΤ. This liquid will enter the cavity of the sphere, through the aperture, Χ. The valve will open in the interior, and the air will escape through the apertures in the tube, ΟΠ, of which we have already spoken, and which have been so arranged as to communicate with the tubes, ΗΘΚΛ and ΖΜΝΞ. When once the sphere is half full of liquid, we incline the small tube, ΡΣ, so as to shut off all communication between the corresponding apertures, and then push down the tube, ΨΩ, and drive into the interior of the sphere the air contained in ΤτΦ. This requires some force, as the sphere itself is full of liquid and air, but the introduction is rendered possible through the compression of the air, which shrinks into the empty spaces that it contains within itself. Let us now take out the tube, ΨΩ, again so as to fill the tube, ΤτΦ, with air, and let us push down the tube, ΨΦ, again and force this air into the sphere. On repeating this operation several times in succession we shall finally have in the sphere a large quantity of compressed air. It is clear, in fact, that the air introduced by force cannot escape when the piston-rod is raised, since the valve, pressed by the internal air, remains closed. If then, replacing the tube, ΡΣ, in a vertical position, we set up a communication again between the corresponding apertures, the liquid will be driven to the exterior through the compressed air, and the latter will assume its normal volume again, and press in the liquid beneath it. If the quantity of compressed air is considerable, there will occur an expulsion, not only of the entire liquid, but also of the excess of air.
