Chap. 3.]

Forcing Pumps with solid Pistons.

259

CHAPTEE III.

Forcing Pumps with solid pistons: The Syringe: Its uses, materials and antiquity—Employed by tbeHindoos in religious festivals—Figured on an old coat of arms—Simple Garden Pump—Single valve Forc-ing-pump—Common Forcing-pump—Stomach pump—Forcing-pump with air-vessel—Macliine ofCtesibius : Its description by Vitruvius—Remarks on its origin—Errors of the ancients respecting theauthors of several inventions—Claims of Ctesibius to the pump limited—Air vessel probably invented byjii m —Compressed air a prominent feature in all his inventions—Air vessels—In Heron’s fountain—Ap -parently referred to by Pliny—Air gun of Ctesibius—The Hookah.

The earliest machine consistirrg of a cylinder and piston that was ex-pressly designed to force liquids was probably the syringe, an Instrumentof very high antiquitysee its figure in the foreground of the next illustra-tion. To the closed end a short conical pipe is attached whose dimensionsare adapted to the particular purpose for which the instrument is to beused. The piston is solid and covered with a piece of soft leather, hemp,woollen listing, or any similar substance that readily imbibes moisture, inOrder to prevent air or water from passing between it and the sides of thecylinder. When the end of the pipe is placed in a liquid and the pistondrawn back, the atmosphere drives the liquid into the cylinder; whence itis expelled through the same orifice by pushing the piston down : in theformer case the syringe acts as a sucking pump; in the latter as a forcingone. They are chiefly employed in surgical operations, for which theyare made of various dimensions—from the size of a quart bottle to that ofa quill. They are formed of silvef, brass, pewter, glass, and sometimesofwood. For some purposes the small pipe is dispensed with, the endof the cylinder being closed by a perforated plate, as in those Instrumentswith which gardeners syringe their plants.

It has been said that the syringe was invented by Ctesibius , being theresult of his first essays in devising or improving the pump; but suchcould not have been its origin, sihce it is mentioned by philosophers whoflourished centuries before him. It was known to Theophrastus , Anaxa-goras, Democritus, Leucippus, Aristotle , and their pupils : to the rushingof water into it when the pistön was drawn up, these philosophers ap -pealed to illustrate their opposite views respecting the cause of the liquid’sascent, some’ contending that it proved the existetice of a vacuum, othersthat it did not.' To this ancient application of the' syringe, möst of theearly writers on atmospheric pressure allude. a “ It is pretty stränge [ob-serves Desaguliers ] that the ancients, who were no strangers to the natureof winds, and knew a great deal of their force, were yet entirely ignorantof the weight and perpendicular pressure of the aii\ This is evident, be-cause they attribute the cause of water rising up in pumps, or any liquorsbeing drawn up into syringes (commonly called syphons on that account,while pumps were call’d sucking-pumps) to nature’s ahhorrence of a va-cuum ; saying, that it fill’d up with water the pipes of pumps under themoving bücket or piston, rather than suffer any empty space. The syringewas in use, and this notion concerning its suction obtain’d long beforeCtesibius, the son of a barber at Alexandria, invented the pump.” b

a See Rohault’s Philosophy with Clarke’s Notes. Lon. 1723; vol. i. 172. Switzer’sHydrostatics, Preface and 172’. Chambers’ Dict. Ärticles Syringe, Embolus , Vacuum.b Ex. Philos. vol. ii, 249.