212
The Antlia,
[Book II.
hydrostatics: viz. that by which water in open tubes finds its own level:a .fact, of which it may safely be asserted, it was impossible for them notto have known—a fact with which the Indians of Peru and Mexico werefamiliär; and one expressly mentioned by Pliny : “ water, (he observes)always ascends of itself at the delivery to the height of the head fromwhence it gave receipt—if it be fetched a long way, the work [pipe] willrise and fall many times, but the level [of the water] is still maintained.”Besides the testimony of Pliny , fountains and jets d’eau are incontro-vertible proofs that a knowledge of the fact is of stupendous antiquity;they having been used in the east from immemorial ages.
But the proof adduced to establish their ignorance in this particular, isas singulär as the position it is brought forward to sustain, since it equallyestablishes our own ignorance of the same principle ! It has been said,had the ancients known that water finds its level at both extremities of acrooked tube, they would have conveyed it through pipes to supply theircities, instead of erecting those expensive aqueducts which were amongthe wonders of the world, and remains of which still strike the be-holder with admiration:—in reply to this it need only be observed, thatshould any remains of the Croton aqueduct, now constructing to supplythis city (New-York ) with water, be found two thousand years hence,they may, by the same argument, be adduced as proofs that the presentengineers of the United States were ignorant that water poured into aninverted siphon would stand at the same level in both its branches.
The fact is, the ancients did sometimes convey water over eminences insiphons of an easy curvature. a And aqueducts were in some few instan-ces carried through valleys by inverted, siphons. In the reign of Claudius ,an aqueduct was formed to convey water from Fourvieres to the highestpart of the city of Lyons. As valleys of great depth were in the line ofits course, works of an enormous expense would have been required,which might have prevented the execution of the project; consequently,instead of an elevated canal, leaden pipes were substituted, forming aninverted siphon. b
It is uncertain when or by whom the common atmospheric pump wasinvented. It is supposed to have been known to the old Egyptians, andto have been used in the ship in which Danaus and his companions sailedto Greece . c As the antlia of the Greeks, it could not have originatedwith Ctesibius , to whom it has sometimes been attributed, since it orsomeother machine or device is mentioned under that name, by Aristophanes and other writers who flourished ages before him. d There are other in-dications that it was previously known, for either it or something verylike it is mentioned under the name of a siphon. This term it is knownwas a generic one, being applied to hollow vessels, as funnels, cullenders,pipes; and generally to instruments that either raised or dispersed water,as syringes, catheters, fire-engines, sprinkling-pots, &c. e That the ma-chine to which we refer raised water by ‘ suction,’ is apparent from an-cient allusions to it. According to Bockler, “ the Platonic philosophersasserted that the soul should partake of the joys of heaven as through asiphon;” and by it Theophrastus explained the ascent of marrow inbones; and CoTumella the rise of sap in trees. In these instances, it isobvious that neither the ordinary siphon nor the syringe could be intended,but the atmospheric pump; a machine that Agricola described as a