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HISTORICAL VIEW OP THE

guished author to whom these books have been ascribed,have led critics to deny the genuineness of both treatises.Some have considered them (but especially the catop-trics) as the compilations of some ignorant pretender toscience; whilst others have supposed them to havebeen vitiated versions of an original treatise, which it ison all hands believed Euclid actually did compose, andof which these works are careless extracts or unskilfulabridgments.

The mechanical enquiries begun by Archimedes wereextended by Ctesibius and Hero in the school of Alex-andria a century later, or about u.c. 150. They werethe first who, by an analysis of all mechanical enginesinto their primary elements, reduced all their actions tosome combinations of five simple principles, to whichthey gave the name of ivyapcn;, or mechanical powers;the same system which is retained at the present day.

In hydrostatics, after the developement (as we haveseen) of some of the most essential principles by Archi-medes , it does not appear that any very material ad-vances were made ; though several of his successorsenriched the science by practical improvements.

It is uncertain when the common pump was first in-vented ; but with the knowledge possessed long beforethis period it must have been an easy application.That since the pressure of the air acts on the surface ofthe water in the reservoir, but is removed from that inthe tube, the latter ought to be forced up, was a con-sideration much too simple to accord with the prevalentnotions of a philosophical theory; and nature’s abhor-rence of a vacuum had already been established as amore logical explanation of this class of phenomena.It is certain, however, that the principle must have beenpractically known before the more complex applicationof it in the forcing-pump, which was the invention ofCtesibius, perhaps the greatest mechanic of antiquityafter Archimedes . It was produced almost exactly inthe form of the modern fire-engine. To the same phi-losopher are also ascribed the clepsydra, or water-clock,and the air-gun.