The works of Thomas Dick . se distances. Fig. 6, shows the manner in which a concavemirrar TU reflects the light of a lamp VW,J^laced in its focus, to great distances. It is in^is waj that the light of the Bell Rock, andother light-houses, is reflected to more thanH^itj or for^ miles distant. ? ,1 ? . ^ . , .Fig-6. , T ? ?. ??-. ?•:??/% ..V //I iSk /^ ^ ^ • Mw^^:^— fife^^r^^-—^ .^\Wi 3 Mi \\i w-z. 1 kr^ Even the sciences ot ElectriiMy and Galva-nism might, in some instances, be rendered sub-servient to the operation^ of art. By means ofthe electrical fluid, models of corn-mills, water-pumps, a
The works of Thomas Dick . se distances. Fig. 6, shows the manner in which a concavemirrar TU reflects the light of a lamp VW,J^laced in its focus, to great distances. It is in^is waj that the light of the Bell Rock, andother light-houses, is reflected to more thanH^itj or for^ miles distant. ? ,1 ? . ^ . , .Fig-6. , T ? ?. ??-. ?•:??/% ..V //I iSk /^ ^ ^ • Mw^^:^— fife^^r^^-—^ .^\Wi 3 Mi \\i w-z. 1 kr^ Even the sciences ot ElectriiMy and Galva-nism might, in some instances, be rendered sub-servient to the operation^ of art. By means ofthe electrical fluid, models of corn-mills, water-pumps, and orreries, showing the diurnal motionof the earth, and the age and phases of themoon, have been set in motion; and there canbe no question, that, in the hands of genius, ititaight be directed to accomplish much moreIhiportant effects. Even the lightning of thedouds, which is only the electrical fluid actingon an ample scale, has been guided by the handgf art, to perform mechanical operations, by. distance of the earth, the Ughttung from thecloud strikes the upper part of the pointed con-ductor, and is conducted downwards to the heartof the stone, which either rends it in differentplaces, or splits it at once into a multitude offiragments. This experiment, which appears tohave been first made in Prussia in 1811, wasattended .with complete success, during the firststorm that passed oyer, after the bar of iron wasinserted in the stone. To brazietsj tinsmiths, coppersmiths, andother workers in metals, a knowledge of Gal-vanism might suggest a variety of useful hints,especially where it is an object of importance tosecure any piece of metallic workmanship fromrust. It is found that when metals are pureand kept separate from each other, they remainfor a long time nntamisbed; but when alloyed,or placed in contact with other metals, theysoon undergo oxidation. Coins composed ofone metal are found more durable than thosecomposed of two ; and the copper sheathing ofslups which
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