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One of the defects of Daguerreotype, been found disagreeable in Daguerre. as applied to portraiture, arise from otype portraits. This is effected by the impossibility of bringing the en. colouring them by means of dry co. tire person of the sitter at once into lours rubbed into the incisinns 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 hould be at open to objection on artistical grounds, pirecisely the same distance from the are, nevertheless, decidedly jopular, 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, how. are nearest to the lens, will be repre- ever, will, so far as relates te mere mented on a scale a little greater than resemblance, bear comparison to a those parts which are most di tant; 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. erart 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-painters abie distance from the sitter, without those whose productions have raised inconveniently diminishing the size of them above petty feelings-do avail the picture , this expedient, the themselves of the aid of Daguerreodite tnce between the distances of types, where well.executed represen. editierent points of the sitter from the tations of that kind are obtainable ; Hops, will bear so smalla proportion to and they see in this no more degrathe shole distance, that the amount of dation of their art, than a sculptor diatirtion 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 ani it is only the more extensively. days, the most striking and magnifi. errploved practitioners in this business cent are those in which the agency of that ran afford to use them.

electricity has been evoked. The magnitude of these pictures From the moment electric pheno. 'll, 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. sen), later, groups executed by a ing them to the useful purposes of Parisian artist, on plates from fifteen life were eagerly sought for. Although to nistern inches square."

such applications had not yet entered The agency of light and shade has into the spirit of the age as fully as ben successfully used, in the same they have since done, it so happened mander, to produce pictures on paper, that, in this department of physics, a piass, 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 the tranner have 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 atten. Attemp:s have been recently made, tion called to the then recent diis. with more or less success, to remove covery, the phenomena of the Leyden the fiétallic or leaden hue which has Jar, which at that time astonished all

* The Anexan,

at 9. kesal practitioner in Daguerreotype now in Paris is Mr. W. Thompson, an

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of this power din preserving Pm the stroke "9" to fix on the Opis upright rods 12mile, and gilt (at is; and from the Will the outside of

y or down round

, and down her ..tur? Would not hly draw the clectric Polepyre it came nigh hry secure us from istrible mischief."*

ciny one, that after 'nde tied his theory by niment of the kite, Ally drained a cloud i but what is not so

it when the paper killin, explaining his

neting lightning-conprotection of buildings,

wards read before the .. of London, it was re

is of laughter, and was rd as to be deemed un Hug printed in the “ Phi. vansactions.” It was, how-] by an independent pub.

į has attained, as is well storld-wide celebrity.

ng afterwards, the same w of the Royal Society who 14 at Franklin's project, were son to superintend the erec

onductors upon the royal pa. ilien, to gratify the royal spleen od sit the rebellious philosopher of

solted colonies, they rejected the sa copil conductors recommended by annklin, and actually caused blunt awoductors to be placed on the palace. Tranklin, who held the office of Ame. rican Minister in London (the inde. pendence of the United States being ihen recently acknowledged), on hear

Art often presses into its service the discoveries of Science, but it sometimes provokes them. Art surveys the fruit of the toil of the philosopher, and selents such as suits her pur lects such as suits her purposes ; but sometimes, not finding what is suitable to her wants, she makes an appeal to Science, whose votaries direct their researches accordingly towards the desired object, and rarely fail to attain them.

One of the most signal examples of the successful issue of such an appeal presents itself in the safety-lamp.

The same gas which is used for the purposes ofillumination ofour cities and towns (and which, as is well known, is obtained from coals by the process of baking in close retorts) is often spontaneously developed in the seams of coal which form the mines, and collects in large quantities in the galleries and workings where the coal-ininers are employed. When this gas is mingled with common air, in a certain definite proportion, the moisture becomes highly explosive, and frequently catastrophes, attended with frightful loss of life, occurred in consequence of this in the mines. The prevalence of this evil at length became so great, that govern. ment called the attention of scientific men to the subject, and the late Sir Humphrey Davy engaged in a series of experimental researches with a view to the discovery of some efficient protection for the miner, the result of which was, the now celebrated safety. lamp.

Davy first directed his inquiries to the nature and properties of fame. What is flame? was a question which seems until then never to have been answered or even asked.

All known bodies, when heated to a

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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 disc coveries 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 Lon don, in his usual playful manner, his disappointment at not being vet able to find any application of the science be. neficial to mankind :

" Chagrined a little,” he wrote, “that we have hitherto been able to produce notbing in the way of use to mankind ; and the hot weather coming on, when electrical experi ments 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.t A turkey is to be killed for dinner by the electrical shock, and roasted by the electrical jack, I 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-an exalted 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 knowledge all the consideration to which, on their own account, they are entitled, let us not be misunderstood as disparaging the great benefactors of the human race, who have drawn from them those benefits which 50 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.

I 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.

ing this, wrote to one of his friends in Philadelphia:

“The king's changing his pointed conductors for blunt ones is a matter of small importance to me. If I had a wish about them it would be that he would reject them altogether as ineffectual. For it is only siuce he thoucht himself and his family safe from the thunder of heaven that he has dared to use his own thunder in destroying his innocent subjects."

metali, in virtue of which electricity runs along them in preference to uthur substances, and discovering the property of points to attract the electric fiuid, Franklio proceeded at once to the discovery of conductors, or “light ning rols," for the protection of buildings. “If these things be so," wrote he

* May not the knowledge of this power of prints b of use to mankind in preserving brus churches, ships, &c., from the stroke

boatning, luy directing na to fix on the highest points of these eliticis upright rods of iron mal sharp as a nerello, and gilt (at the print) to prevent rusting; and from the ferit of tiu se rols a wire down the outsiile of t'in builling into the ground, or down round ora of the shrouls of a ship, and down her sila till it reaches the water? Would not these pated rola probably draw the clectric

fire out of a cloud before it came nigh m agh to strike, an I therely secure us from tuat most su led and terrible mischief."

It is known to every one, that after this Franklin established his theory by the celebrated experiment of the kite, by which he literally drained a cloud of its lightning ; but what is not so well known is, that when the paper written by Franklin, explaining his project of constructing lightning-conductors for the protection of buildings, was soon afterwards read before the Real Society of London, it was received with peals of laughter, and was Wted so absurd as to be deemed un. worthy of being printed in the “ Phi. losophical Transactions." It was, how ever, printed by an independent pub. lisherand has attained, as is well known, a world-wide celebrity.

Vot long afterwards, the same foen.bers of the Royal Society who laughed at Franklin's project, were called upon to superintend the erec. 11on of conductors upon the royal pa. lace, when, to gratify tbe royal spleen against the rebellious philosopher of the revoited colonies, they rejected the pointel conductors recoinmended by Frankiin, and actually caused blurt C uctors to be placed on the palace.

Frabahunt, who held the office of Ame. rican Minister in London (the inde. pea lence of the United States being tirpa recently acknowledged), on bear.

Art often presses into its service the discoveries of Science, but it sometimes provokes them. Art surveys the fruit of the toil of the philosopher, and selects such as suits her purposes ; but sometimes, not finding what is suitable to her wants, she makes an appeal to Science, whose votaries direct their researches accordingly towards the desired object, and rarely fail to attain them.

One of the most signal examples of the successful issue of such an appeal presents itself in the safety.lamp.

The same gas which is used for the purposes ofillunina:ion ofour cities and towns (and which, as is well known, is obtained from coals by the process of baking in close retorts) is often spon. taneously developed in the seams of coal which form the mines, and collects in large quantities in the galleries and workings where the coal-uniners are employer. When this gas is mingled with common air, in a certain definite proportion, the moisture becomes highly explosive, and frequently catastrophes, attended with frightful loss of life, occurred in consequence of this in the mines. The prevalence of this evil at length became so great, that govern. ment called the attention of scientific men to the subject, and the late Sir Humphrey Davy engaged in a series of experimental researches with a view to the discovery of some efficient protection for the miner, the result of which was, the now celebrated safetylamp.

Davy first directed his inquiries to the nature and properties of fame. What is flame? was a question which seems until then never to have been answered or even asked.

All known bodies, when heated to a

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