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Page:Popular Science Monthly Volume 70.djvu/430

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THE POPULAR SCIENCE MONTHLY

Brille (spectacles) is from beryllus, the Latin name of a transparent stone. The French besicles also point to beryl. Bericle is an earlier form of besicle for 'besiculum,' a little beryl. In some of the French dialects the first syllable ber- is still preserved, bnt the Parisian word for spectacles is besicles, in which the original r has been changed to s, according to a phonetic law traceable in other words also. The Spaniards, Italians and Russians have each a native word to designate this article of common use.

There is a passage in Pliny that is usually cited as evidence that something akin to spectacles must have been in use at least in his time. He relates that the Emperor Nero used a precious stone which he calls 'smaragdus,' generally translated 'emerald,' through which he was accustomed to gaze on the gladiatorial combats; or rather, this is what he seems to say. There is, however, little doubt that Dr. Magnus, the latest author to examine the passage critically, is right in holding that it means no more than that the emperor was in the habit of gazing upon an emerald which he used to carry with him for the purpose of resting his eyes when they became tired looking upon shows that were interesting to him. This view is rendered the more probable from the belief of antiquity that green has a restful effect upon the eyesight.

Contrivances for bringing the rays of the sun to a focus in order to produce combustion have been employed almost from time immemorial. A curious proposal bearing on this point is made by Aristophanes in his comedy of the 'Clouds.' Strepsiades, the hero of the play, is greatly harassed with debts and has not the wherewithal to pay. He therefore proposes to his master to get a stone at some chemist's shop of the kind with which they kindle fire, and when the clerk is entering the suit, to stand at some distance and melt it out. As the writing tablets then in use were probably thin boards covered with a still thinner coating of wax on which the writing was done with a pointed instrument, it would not require great heat to effect the purpose. Besides, if, as seems to have been the case and custom, burning-glasses were used to kindle fires, they must have been of considerable size even in a country like Greece where the sun shines very hot most of the year. Moreover, we are told, they were kept in the chemists' shops for this purpose. If by any mishap the sacred fire watched over by the Vestal Virgins in Rome went out, it was rekindled by means of a burning-glass. Polybius, when speaking of the siege of Syracuse by the Romans, B.C. 214, relates that they were unable to take it from the side of the sea because of the engines employed against them by Archimedes, unquestionably the greatest mechanician of the ancient world. Says he: "So true is it that one man and one intellect properly qualified for the particular undertaking is a host in himself and of wonderful efficacy." The Romans were confident that they could take the city 'if one old man could be got rid of.' He