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“ water forcers,” or, to the application of valves to the ordinary syringe, bywhich it was converted into a forcing pump, either for air or water. Butit is not certain that the last was not done before, for neither Vitruvius norPliny asserts that “ water forcers” were not in previous use. The formersays he applied the principle of “ compressed air” to them, in commonwith “ hydraulic Organs,” “ automatons,” “ lever and turning machines,”and “ water dials,” (Book ix, cap. 9;) hence it may as well be concludedfrom this passage, that he invented these as the pump. It is, indeed, almostimpossible to believe that the Egyptians, of whose sagacity and ingenuity,unrivalled mon uments have come down, did not detect the application bothof the bellows and syringe to raise water long before Ctesibius lived;hence we are inclined to place the forcing pump in its simplest form, withthe syringe and atmospheric pump, among the Works—
“ Of names once famed, now dubious or forgotAnd buried ’midst the wreek of things that were.”
That the forcing pump was greatly improved by Ctesibius , there canbe no question; but that which gave celebrity to his machine was proba-bly the air-vessel, an addition, which though not very clearly described byVitruvius , appears to have originated with him. By it the pump insteadof acting as before like a squirt or syringe produced a continuous streamas in a jet d’eau, a result well adapted to excite admiration, and to giveeclat to his name. The whole account of his machine shows its Connec-tion with and dependence upon air; whereas had it been simply a forcingpump it would have had nothing to do with it: it would have raised waterindependently of it; and without an air-vessel Vitruvius never could haveasserted that it forced water up the discharging tube by means of “ airpressing it upwards.” Compressed air acted a prominent part in all hismachines. In his wind guns, water clocks, and numerous automata; someof the latter in the shape of birds,. &c . appeared to sing, others “ soundedtrumpets,” and these results are said to have been produced with “ fluidscompressed by the force of air.” We may add that he compressed air inhis hydraulic Organs and precisely in the same manner as in the pump,viz : by water, and by either air or water forcing pumps. The commence-ment of his discoveries was the experiment on air with the weight andspeculum in his father’s shop, (see page 122) in which the descendingweight “ compressed the inclosed air” and forced it through the severalapertures into the open air, and thereby produced distinct sounds. “ Whentherefore Ctesibius observed that sounds were produced from the com-pression and concussion of air, he first made use of that principle in con-triving hydraulic Organs, also water forcers, automatons,” &c. Whatprinciple was this which Vitruvius says he applied to water forcers incommon with Organs, &c. ? That of compressed air, as we understandit; and the, employment of which is so evident, in the description ofhis machine already given.
Does any one doubt that the air-vessel was known to, and used byCtesibius '? Let him recollect that Heron, his disciple and intimate friend,has also described it; for the celebrated fountain of this philosopher,which still bears his name, and remains just as he left it, is simply anair-chamber, in which the fluid is compressed by a column of water in-stead of a pump ; and one of his machines for raising water by steam, wasanother, in which the elasticity of that fluid was used in a similar manner.Besides these, there are others represented in the Spiritalia; indeed, agreat portion of the figures in that work are modifications of air cham-bers. At pages 42 and 118, of Commandine’s Translation, are shown