318 



GREEK SCIENCE. 



Mechanics. 



Mechanical 

 nventions. 



times, if we except the method of determining the sun's apparent 

 diameter, which has been extracted in the ' History of Astronomy.' 1 , 

 The accuracy of his result is remarkable, if we consider, not only the 

 imperfection of his means in other respects, but that he does not 

 appear to have known any way of observing with one eye at a time, 

 and is obliged to make allowance for the double vision of his two 

 eyes. He was, as were all the mathematicians of that age, a diligent 

 practical observer ; and we are told, that he thought he had discovered 

 the distances of the heavenly bodies from the earth, and from each 

 other ; but that his measures were rejected by the Platonists, as not 

 following that imagined perfection of mathematical proportions, which, 

 they asserted, must necessarily exist. Cicero speaks of an orrery, as 

 we should call it, made by Archimedes, and exhibiting the motion of 

 the sun, the moon, and the planets ; which he uses as an argument 

 against those who deny a Providence. " Shall we," says he, " attri- 

 bute more intelligence to Archimedes for making the imitation, than 

 to nature for framing the original ?" 



Perhaps the most remarkable part of his discoveries were those 

 which he made in mechanics, and his applications of them to practice. 

 We have already seen, that before his time, this branch of science did 

 not exist. In his work on the equilibrium of bodies, he gives a proof 

 of the fundamental properties of the lever, which has never yet been 

 surpassed in simplicity and evidence ; and applies his principles to find 

 the centre of gravity of various spaces, with great ingenuity. In his 

 work on the * Floating of Bodies in Fluids,' he shows a complete in- 

 sight into the nature of fluid equilibrium ; and determines the position 

 in which bodies float in some cases, which can, by no means, be con- 

 sidered as easy, even to modern mathematics. Indeed, without any 

 addition to the principles of Archimedes, the doctrine of equilibrium 

 was capable of being carried to its utmost extent, though among the 

 ancients it appears to have stopped with him. We are told by 

 Pappus, that HERO, a little after his time, proved in what cases there 

 could be an equilibrium in the five mechanical powers; viz., the lever, 

 the wheel and axle, the polyspact or pulley, the wedge, and the screw ; 

 and that he reduced them all to one in principle ; but we cannot be 

 certain that these proofs were strict, for there is nothing satisfactory 

 in the demonstrations given by authors before the time of Stevinus and 

 Galileo ; and an attempt made by Pappas himself to determine the 

 mechanical advantage of the inclined plane is remarkably erroneous. 



We read of many mechanical contrivances of Archimedes, some, 

 probably, merely attributed to him from the celebrity of his name. 

 For instance, an invention something like what are now called Chinese 

 puzzles, in which certain angular pieces of ivory are to be put together, 

 so as, by different arrangements, to produce the resemblance of various 

 objects. But he seems to have turned much of his attention to the 

 construction of machines of extraordinary powers ; and he boasted of 

 1 Page 337 of this volume. 



