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STEAN-DAGTERREOTYPE-LIGHTNING CONDUCTORS—THE BAFETY LAMP-ELECTRO-PLATING AND
GILDING-TUR ELECTRIC TELEGRAPH.
Each succeeding age and generation vived only a few years longer, he would leaves behind it a peculiar character, have seen even ihis performance dou. wbich 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 corn respect no former epoch can ap- into four ; to press oil from the olive, proach to competition with the pre- and wine from the grape; to draw up sent.
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.
?-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?-steam 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 go. 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 preci. ments, 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 proconsisted 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 diffimetals 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 eye 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 wero to be continued in rapid succession, produce a representation, is placed be- which, in practice, almost never occurs.
One of the defects of Daguerreotype, been found disagreeable in Daguerreas applied to portraiture, arises from otype portraits. This is effected by the impossibility of bringing the en- colouring them by means of dry cotire person of the sitter at once into lours rubbed into the incisions made focus. To render this possible, it by the action of the light. These would be necessary that every part of coloured Daguerreotypes, though more the person of the sitter should be at open to objection on artistical grounds, precisely the same distance from the are, nevertheless, decidedly popular, lens of the camera obscura, a condition when judiciously executed. which obviously cannot be fulfilled. Artists, and especially miniature. It happens, consequently, that those painters, are naturally opposed to parts of the person of the sitter which Daguerreotype. No miniature, howare nearest to the lens, will be repre- ever, will, so far as relates to mere sented on a scale a little greater than resemblance, bear comparison to a those parts which are most distant; Daguerreotype. The artist can soften and if the instrument be adjusted so as down defects, and present the sitter to bring the nearer parts into very under the most favourable aspect. exact focus, the more distant parts The sun, however, is no flatterer, and will be proportionally out of focus. gives the lineaments as they exist, with
These defects cannot be removed, the most inexorable fidelity, and the but may be so much mitigated as to be most cruel precision. imperceptible. By using larger lenses, Nevertheless, it is known that some the camera can be placed at a consider of the most eminent portrait-paintersable distance from the sitter, without those whose productions have raised inconveniently diminishing the size of them above petty feelings—do avail the picit.t. l; this expedient, the themselves of the aid of Daguerreodifference between the distances of types, where well-executed represen. different points of the sitter from the tations of that kind are obtainable ; lens, will bear so small a proportion to and they see in this no more degrathe whole distance, that the amount of dation of their art, than a sculptor distortion arising from the cause just finds in using a cast of the subject mentioned may be rendered quite im- which his chisel is about to reproduce. perceptible. Large lenses, however, But of all the gifts which Science when good in quality, are expensive ; has presented to Art in these latter and it is only the more extensively- days, the most striking and magnifiemployed practitioners in this business cent are those in which the agency of that can afford to use them.
electricity has been evoked. The magnitude of these pictures From the moment electric phenowill, in a great degree, depend on the mena attracted the attention of the magnitude of the lens. We have scientific world, the means of apply. seen, lately, groups executed by a ing them to the useful purposes of Parisian artist, on plates from fifteen life were eagerly sought for. Although to sixteen inches square.*
such applications had not yet entered The agency of light and shade has into the spirit of the age as fully as been successfully used, in the same they have since done, it so happened manner, to produce pictures on paper, that, in this department of physics, a glass, wood, and other substances, volunteer had enlisted in the army of chemically prepared, so as to be more science, the characteristic of whose or less impressed with some dark co- genius was eminently practical, and lour. The representations obtained soon achieved, by his discoveries, an in this manner bave not, however, the eminence to which the world has since precision and distinctness which are so offered universal homage. Benjamin universally characteristic of the Da- Franklin, a member of a literary guerreotype process.
society in Philadelphia, had his attenAttempts have been recently made, tion called to the then recent diswith more or less success, to remove covery, the phenomena of the Leyden the metallic or leaden hue which has Jar, which at that time astonished all
The most successful practitioner in Daguerreotype now in Paris is Mr. W. Thompson, an American.
Europe. From that moment the views of Franklin were bent on the discovery of some useful purpose to which these discoveries could be ap. plied. Cui bono? was a question never absent from his thoughts. After hav. ing made some of those great discoveries which have since formed the basis of electrical science, and have surrounded his name with unfading lustre, he expressed, in a letter to the secretary of the Royal Society of London, in his usual playful manner, his disappointment at not being yet able to find any application of the science beneficial to mankind :
“Chagrined a little,” he wrote, “ that we have hitherto been able to produce nothing in the way of use to mankind; and the hot weather coming on, when electrical experiments are not so agreeable, it is proposed to put an end to them for the season, somewhat humorously, in a party of pleasure, on the banks of the Schuylkill.* Spirits, at the same time, are to be fired by a spark sent from side to side, through the river, without any other conductor than the water; an experiment which we some time since performed to the amazement of many.† A turkey is to be killed for dinner by the electrical shock, and roasted by the electrical jack, # before a fire kindled by the electrical bottle” (since known as the Leyden phial), " when the healths of all the famous electricians in England, Holland, France, and Germany, are to be drunk in electrified bumpers, under the discharge of guns from the electrical battery."S
craving after utility was the great characteristic of his mind, and may even be regarded as having been car. ried almost to a fault. It has been justly observed by a contemporary writer
That although the application of the properties of matter and the phenomena of nature to the uses of civilised life is undoubtedly one of the great incentives to the investigation of the laws of the material world, yet it is assuredly a great error to regard that either as the only or the principal motive to such inquiries. There is in the perception of truth itself—in the contemplation of connected propositions, leading by the mere operation of the intellectual faculties, exercised on individual physical facts, to the development of those great general laws by which the universe is maintained-anexalted pleasure, compared with which the mere attainment of convenience and utility in the economy of life is poor and mean. There is a nobleness in the power which the natural philosopher derives from the discovery of these laws, of raising the curtain of futurity and displaying the decrees of nature, so far as they affect the physical universe for countless ages to come, which is independent of, and above all, utility. While, however, we thus claim for truth and kuowledge all the consideration to which, on their own account, they are entitled, let us not be misunderstood as disparaging the great benefactors of the buman race, who have drawn from them those benefits which so much tend to the well-being of man. When we express the enjoyment which arises from the beauty and fragrance of the flower, we do not the less prize the honey which is extracted from it, or the medicinal virtues which it yields. That Franklin was accessible to such feelings, the enthusiasm with which he expresses himself throughout his writings, in regard to natural phenomena, abundantly proves. Nevertheless, useful application was undoubtedly ever uppermost in his thoughts ; and he probably never witnessed a physical fact, or considered for a moment any law of nature, without inwardly proposing to himself the question, 'In what way can this be made beneficial in the economy of life.'"||
Although the application of the great principles of science to the practical uses of life cannot be too highly appreciated, it would be a great error to carry this enthusiasm for the useful to such an excess as to exclude a just ad. miration for those high abstract laws, the discovery of which had conferred lustre on the names of our greatest philosophers, and on none more justly than that of Franklin himself. It must be admitted, however, that this
After studying the properties of
A picturesque river which washes the Western suburbs of Philadelphia, and to the valley of which it is the custom of the citizens to make pic-nic parties. In the summer months, the temperature at Philadelphia is so high as to banish to the watering-places all who are not abolutely tied to the town by the exigencies of their business.
† This experiment has been recently reproduced in the investigations connected with the electric telegraph, but without giving credit to Franklin as its original author.
| It will be seen by this hint that the idea of applying electricity, as a moving power, had already occurred to Franklin. & Franklin's Works, vol. v. p. 210. Boston: 1837.
“Lardner on Electricity and Magnetism,” vol. i. p. 41.