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STEAU-DAGUERREOTYPE-LIG17 SING CONDUCTORS-THE SAFETY LAMP-ELECTRO-PLATIXG AND
GILDING THE ELECTRIC TELEGRAPH.
Each succeeding age and generation vived only a few years longer, he would leaves behind it a peculiar character, bave seen even this performance douwhich stands out in relief upon its an- bled, and still more recently it has, nals, and is associated with it for ever under favourable circumstances, been in the memory of posterity. One is increased in a threefold ratio. signalised for the invention of gunpow- But it is not in the mere elevation of der, another for that of printing; one is mineral substances from the crust of rendered memorable by the revival of the globe, nor in the drainage of the letters, another by the reformation of vast subterranean regions which have religion ; one epoch is rendered illus- become the theatre of such extensive trious by the discoveries of Newton, operations of industry and art, that another by the conquests of Napoleon. steam has wrought its greatest miracles. If we are asked by what characteristic By its agency coal is made to minister the present age will be marked in the in an infinite variety of ways to the records of our successors, we answer, uses of society. Coals are by it by the miracles which have been taught to spin, weave, dye, print, and wrought in the subjugation of the dress silks, cottons, woollens, and other powers of the material world to the cloths ; to make paper, and print books uses of the human race. In this on it when made ; to convert respect no former epoch can ap- into flour ; to press oil from the olive, proach to competition with the pre- and wine from the grape; to draw up
metal from the bowels of the earth; Although the credit of the invention to pound and smelt it, to melt and of the steam-engine must be conceded mould it; to forge it; to roll it, and to the generation which preceded us, to fashion it into every form that the its improvement and its most impor- most wayward caprice can desire. Do tant applications are unquestionably we traverse the deep ?—they lend wings due to our contemporaries. So little to the ship, and bid defiance to the was the immortal Watt himself aware natural opponents, the winds and the of the extent of the latent powers of tides. Does the wind-bound ship dethat machine, that he declared, upon sire to get out of port to start on the occasion of his last visit to Corn. her
?--steam throws its arms wall, on ascertaining that a weight of round her, and places her on the open twenty-seven millions of pounds had sea. Do we traverse the land ?--- steain been raised one foot high by the is harnessed to our chariot, and we combustion of a bushel of coals under outstrip the flight of the swiftest bird, one of his boilers, that the ne plus and equal the fury of the tempest. ultra was attained, and that the power It results, from the official returns of steam could no further
Never- of the Cornish authorities, that as theless the Patriarch of the steam. much power is there obtained from a engine lived to see forty millions of bushel of coals, as is equivalent to pounds raised the same height by the an average day's work of an hundred same quantity of fuel. Had he sur- stage-coach horses.
VOL. XXXVI.-NO, CCXI.
The great pyramid of Egypt stands fore an optical instrument, with which upon a base measuring seven hundred every one is familiar as the camerafeet each way, and is five hundred feet obscura. An exact representation of high. According to Herodotus, its it, on a scale reduced in any required construction employed an hundred proportion, is thus formed upon a plate thousand labourers for twenty years. of ground glass, so that it may be Now we know that the materials of viewed by the operator, who can thus this structure might be raised from adjust the instrument in such a manthe ground to their present position by ner as to obtain an exact picture of it. the combustion of four hundred and If it be desired to make a portrait, the eighty tons of coals.
effect of the posture of the sitter can The Menai Bridge consists of about thus be seen, and the most favourable two thousand tons of iron, and its position ascertained before the process height above the level of the water is is commenced. one hundred and twenty feet. Its When these arrangements have been entire mass might be lifted from the made, the plate of ground glass, on level of the water to its present posi- which the picture was previously formtion by the combustion of four bushels ed, is withdrawn, and the metallic plate, of coal !
on which the picture is to be engraved, Marvellous as the uses are to which is substituted for it. This latter being heat has been rendered subservient, placed in the groove from which the those which have been obtained from plate of ground glass has been withlight are not less so. Ready-made drawn, the picture will be formed flame is fabricated in vast establish- upon it with the same degree of preciments, erected in the suburbs of cities sion, and in exactly the same position and towns, and transmitted in subter- in which it was previously seen on the ranean pipes through the streets and plate of ground glass. buildings which it is desired to illumi. When the light is favourable, four or nate. It is supplied, according to in. five seconds are sufficient to complete dividual wants, in measured quantity; the process. According as it is less inand at every door an automaton is tense, the necessary time may be greater, stationed, by whom a faithful register but never should exceed a minute. In is kept of the quantity of flame sup- general, the shorter the time in which plied from hour to hour!
a picture is made, the more perfect the It resulted from scientific
picture will be, especially if it be a searches on the properties of solar portrait, because the defects of the light, that certain metallic prepara- representation most commonly arise tions were affected in a peculiar man- from the object represented, or some ner by being exposed to various degrees part of it, having shifted its position of light and shade. This hint was during the process.
In that case, the not lost.
An individual, whose name picture presents the object as though has since become memorable, M. it were seen through a mist. The Daguerre, thought that as engraving best portraits we have ever seen pro. consisted of nothing but the represen- duced by this art have been completed tation of objects by means of incisions in four seconds ! on a metallic plate, corresponding to It might be supposed, from what we the lights and shades of the object re- have here said, that it would be al. presented—and as these same lights most impossible, in any case, to oband shades were shown by the dis- tain a perfect representation of the coveries of science to produce on eyes in a portrait, because of the diffi. metals specific effects, in the exact culty of abstaining from winking. It proportion of their intensities—there happens, however, that winking being could be no reason why the objects to a change of position which is only conbe represented should not be made to tinued for an inappreciable instant of engrave themselves on plates properly time, the eve resuming its position prepared !! Hence arose the beauti. immediately, is almost the only moveful art now become so universally ment incidental to a sitter which does useful, and called after its inventor- not affect the precision of the portrait; DaguERROTYPE.
unless, indeed, the action of winking The object of which it is desired to were to be continuedin rapid succession, produce a representation, is placed be. which, in practice, almost never occurs.