The objects which the microscope unfolds to our view, curious and wonderful as they are, are often singularly complicated. The eye, indeed, may comprehend the whole which is presented to it in the field of view; but the powers of the pencil fail to express these minutiæ of nature in their innumerable details. What artist could have skill or patience enough to copy them? or granting that he could do so, must it not be at the expense of much most valuable time, which might be more usefully employed?

Contemplating the beautiful picture which the solar miscroscope produces, the thought struck me whether it might not be possible to cause that image to impress itself upon the paper, and thus to let Nature substitute her own inimitable pencil for the imperfect, tedious, and almost hopeless attempt of copying a subject so intricate?

My first attempt had no success. Although I chose a bright day, and formed a good image of my object upon prepared paper, on returning at the expiration of an hour I found that no effect had taken place. I was therefore half inclined to abandon this experiment, when it occurred to me that there was no reason to suppose that the common muriate of silver was the most sensitive substance that exists to the action of the chemical rays; and though such should eventually prove to be the fact, at any rate it was not to be assumed without proof. I therefore began a course of experiments in order to ascertain the influence of various modes of preparation, and I found these to be signally different in their results. I considered this matter chiefly in a practical point of view; for as to the theory, I confess that I cannot as yet understand the reason why the paper prepared in one way should be so much more sensitive than in another.

The result of these experiments was the discovery of a mode of preparation greatly superior in sensibility to what I had originally employed: and by means of this, all those effects which I had before only anticipated as theoretically possible were found to be capable of realization.

When a sheet of this, which I shall call "Sensitive Paper," is placed in a dark chamber, and the magnified image of some object thrown on it by the solar microscope, after the lapse of perhaps a quarter of an hour, the picture is found to be completed. I have not as yet used high magnifying powers, on account of the consequent enfeeblement of the light. Of course with a more sensitive paper, greater magnifying power will become desirable.

On examining one of these pictures, which I made about three years and a half ago, I find, by actual measurement of the picture

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and the object, that the latter is magnified seventeen times in linear diameter, and in surface consequently 289 times. I have others which I believe are considerably more magnified; but I have lost the corresponding objects, so that I cannot here state the exact numbers.

Not only does this process save our time and trouble, but there are many objects, especially microscopic crystallizations, which alter so greatly in the course of three or four days (and it could hardly take any artist less to delineate them in all their details), that they could never be drawn in the usual way.

I will now describe the degree of sensitiveness which this paper possesses, premising that I am far from supposing that I have reached the limit of which this quality is capable. On the contrary, considering the few experiments which I have made, (few, that is, in comparison with the number which it would be easy to imagine and propose,) I think it most likely that other methods may be found, by which substances may be prepared, perhaps as much transcending in sensitiveness the one which I have employed, as that does the ordinary state of the nitrate of silver. But to confine myself to what I have actually accomplished in the preparation of a very sensitive paper.

When a sheet of paper is brought towards a window, not one through which the sun shines, but looking in the opposite direction, it immediately begins to discolour. For this reason, if the paper is prepared by daylight, it must by no means be left uncovered, but as soon as finished be shut up in a drawer or cupboard and there left to dry, or else dried at night by the warmth of a fire. Before using this paper for the delineation of any object, I generally approach it for a little time towards the light, thus intentionally giving it a slight shade of colour, for the purpose of seeing that the ground is even. If it appears so when thus tried to a small extent, it will generally be found to prove so in the final result. But if there are some places or spots in it which do not acquire the same tint as the rest, such a sheet of paper should be rejected; for there is a risk that, when employed, instead of presenting a ground uniformly dark, which is essential to the beauty of the drawing, it will have large white spots, places altogether insensible to the effect of light. This singular circumstance I shall revert to elsewhere: it is sufficient to mention it here.

The paper then, which is thus readily sensitive to the light of a common window, is of course much more so to the direct sun

shine. Indeed, such is the velocity of the effect then produced, that the picture may be said to be ended almost as soon as it is begun.

To give some more definite idea of the rapidity of the process, I will state, that after various trials the nearest evaluation which I could make of the time necessary for obtaining the picture of an object, so as to have pretty distinct outlines, when I employed the full sunshine, was half a second.

9. Architecture, Landscape, and external Nature. But perhaps the most curious application of this art is the one I am now about to relate. At least it is that which has appeared the most surprising to those who have examined my collection of pictures formed by solar light.

Every one is acquainted with the beautiful effects which are produced by a camera obscura, and has admired the vivid picture of external nature which it displays. It had often occurred to me, that if it were possible to retain upon the paper the lovely scene which thus illuminates it for a moment, or if we could but fix the outline of it, the lights and shadows divested of all colour, such a result could not fail to be most interesting. And however much I might be disposed at first to treat this notion as a scientific dream, yet when I had succeeded in fixing the images of the solar microscope by means of a peculiarly sensitive paper, there appeared no longer any doubt that an analogous process would succeed in copying the objects of external nature, although indeed they are much less illuminated.

Not having with me in the country a camera obscura of any considerable size, I constructed one out of a large box, the image being thrown upon one end of it by a good object glass fixed in the opposite end. This apparatus being armed with a sensitive paper, was taken out in a summer afternoon and placed about 100 yards from a building favourably illuminated by the sun. An hour or two afterwards I opened the box, and I found depicted upon the paper a very distinct representation of the building, with the exception of those parts of it which lay in the shade. A little experience in this branch of the art showed me that with smaller cameræ obscure the effect would be produced in a smaller time. Accordingly I had several small boxes made, in which I fixed lenses of shorter focus, and with these I obtained very perfect but extremely small pictures; such as without great stretch of imagination might be supposed to be the work of some Lilliputian artist. They require indeed examination with a lens to discover all their minutiæ.

In the summer of 1835 I made in this way a great number of representations of my house in the country, which is well suited to the purpose, from its ancient and remarkable architecture. And this building I believe to be the first that was ever yet known to have drawn its own picture.

The method of proceeding was this: having first adjusted the paper to the proper focus in each of these little camera, I then took a number of them with me out of doors and placed them in different situations around the building. After the lapse of half an hour I gathered them all up, and brought them within doors to open them. When opened, there was found in each a miniature picture of the objects before which it had been placed.

To the traveller in distant lands who is ignorant, as too many unfortunately are, of the art of drawing, this little invention may prove of real service; and even to the artist himself, however skilful he may be. For although this natural process does not produce an effect much resembling the productions of his pencil, and therefore cannot be considered as capable of replacing them, yet it is to be recollected that he may often be so situated as to be able to devote only a single hour to the delineation of some very interesting locality. Now, since nothing prevents him from simultaneously disposing, in different positions, any number of these little camera, it is evident that their collective results when examined afterwards, may furnish him with a large body of interesting memorials, and with numerous details which he had not had time either to note down or to delineate.

10. Delineations of Sculpture.-Another use which I propose to make of my invention is for the copying of statues and bas-reliefs. I place these in strong sunshine, and put before them at a proper distance, and in the requisite position, a small camera obscura containing the prepared paper. In this way I have obtained images of various statues, &c. I have not pursued this branch of the subject to any extent; but I expect interesting results from it, and that it may be usefully employed under many circumstances.

11. Copying of Engravings.-The invention may be employed with great facility for obtaining copies of drawings or engravings, or fac similes of MSS. For this purpose the engraving is pressed upon the prepared paper, with its engraved side in contact with the latter. The pressure must be as uniform as possible, that the contact may be perfect; for the least interval sensibly injures the result, by producing a kind of cloudiness in lieu of the sharp strokes of the original.

When placed in the sun, the solar light gradually traverses the paper, except in those places where it is prevented from doing so by the opaque lines of the engraving. It therefore of course makes an exact image or print of the design. This is one of the experiments which Davy and Wedgwood state that they tried, but failed, from want of sufficient sensibility in their paper.

The length of time requisite for effecting the copy depends on the thickness of the paper on which the engraving has been printed. At first I thought that it would not be posssible to succeed with thick papers; but I found on trial that the success of the method was by no means so limited. It is enough for the purpose, if the paper allow any of the solar light to pass. When the paper is thick, I allow half an hour for the formation of a good copy. In this way I have copied very minute, complicated, and delicate engravings, crowded with figures of small size, which were rendered with great distinctness.

The effect of the copy, though of course unlike the original (substituting as it does lights for shadows, and vice versa), yet is often very pleasing, and would, I think, suggest to artists useful ideas respecting light and shade.

It may be supposed that the engraving would be soiled or injured by being thus pressed against the prepared paper. There is not much danger of this, provided both are perfectly dry. It may be well to mention, however, that in case any stain should be perceived on the engraving, it may be readily removed by a chemical application which does no injury whatever to the paper.

In copying engravings, &c., by this method, the lights and shadows are reversed, consequently the effect is wholly altered. But if the picture so obtained is first preserved so as to bear sunshine, it may be afterwards itself employed as an object to be copied; and by means of this second process the lights and shadows are brought back to their original disposition. In this way we have indeed to contend with the imperfections arising from two processes instead of one; but I believe this will be found merely a difficulty of manipulation. I propose to employ this for the purpose more particularly of multiplying at small expense, copies of such rare or unique engravings as it would not be worth while to re-engrave, from the limited demand for them.

I will now add a few remarks concerning the very singular circumstance, which I have before briefly mentioned, viz., that the paper sometimes, although intended to be prepared of the most sensitive quality, turns out on trial to be wholly insensible to light, and in

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capable of change. The most singular part of this is the very small difference in the mode of preparation which causes so wide a discrepancy in the result. For instance, a

sheet of paper is all prepared at the same time, and with the intention of giving it as much uniformity as possible; and yet, when exposed to sunshine, this paper will exhibit large white spots of very definite outline, where the preparing process has failed; the rest of the paper, where it has succeeded, turning black as rapidly as possible. Sometimes the spots are of a pale tint of cærulean blue, and are surrounded by exceedingly definite outlines of perfect whiteness, contrasting very much with the blackness of the part immediately succeeding. With regard to the theory of this, I am only prepared to state as my opinion at present, that it is a case of what is called "unstable equilibrium." The process followed is such as to produce one of two definite chemical compounds; and when we happen to come near the limit which separates the two cases, it depends upon exceedingly small and often imperceptible circumstances, which of the two compounds shall be formed. That they are both definite compounds, is of course at present merely my conjecture: that they are signally dif ferent, is evident from their dissimilar properties.

I have thus endeavoured to give a brief outline of some of the peculiarities attending this new process, which I offer to the lovers of science and nature. That it is susceptible of great improvements I have no manner of doubt; but even in its present state I believe it will be found capable of many useful and important applications besides those of which I have here given a short account.

MR. MACKINNON'S NEW PATENT LAW BILL. [From the Commercial Gazette.]

Mr. Mackinnon (the member for Lymington) has already given notice of his usual sessional motion on the subject of the present defective law of patents. It will be recollected that he brought forward a similar measure last session, which was frustrated, as many other useful measures were, by the pressure and mismanagement of public business, the balance of parties, and the obstructive proceedings of the Upper House. Amendments have been already made in the old law of patents; but, although they were well-intentioned, they are admitted by everybody conversant with the subject to be utterly deficient in point of remedy. There is no subject at any time of more vital importance to the commercial interests of this commercial country than the "Law of

Patents." But it is more especially so at the present time-when those commercial interests are so widely involved and so seriously impaired. In the protection desirable to be extended by an equitable and improved patent law, we include all the useful results of scientific discovery; all the improvements of mechanical invention; all the amelioration produced in our manufactures by the encouragement of the Art of Design; and, finally, the protection of Pattern Right in our great calico-printing, cotton, and silk manufactures. It will be evident that in the last departments of national industry alone-the protection of the Pattern Right-(otherwise the copyright of the new design or pattern, upon which the sale of the goods chiefly depends) is a subject of paramount interest to the whole manufacturing class. The importance of Mr. M.'s motion may be inferred from these preliminary remarks. The incompetency of the present Law of Patents to protect invention was one of the prominent grievances established by the evidence before the "Select Committee of Arts and Manufactures." Mr. Martin, the celebrated painter, and several architects and sculptors, produced curious and startling examples of the total incompetency of the present "Patent Law" to protect the property of individuals engaged in the improvements of art, or in the discoveries of science. Again; some of the first manufacturers of the country, on whose combined prosperity its commercial prosperity chiefly depends-such as calico-printers, cotton and silk manufacturers, ironmasters, paper-stainers, brass-founders, and Staffordshire potters-all demonstrated that the present Law of Patents was so deficient in adequate protection as to cut up profits and frustrate improvement in the arts of design, by rendering the purchase of patterns, a profitless and useless speculation. We entertain hopes that Mr. Mackinnon's proposal may remove the chief grounds of grievance, the justice of which has been so undeniably established. The great problem to be solved in the reform of the Patent Laws is to reconcile the individual rights of private property with the general exigencies of free trade. Finally, equity demands that those great benefactors of the human speciesthose "kings of mind," whose victories are bloodless and immortal; those conquerors of natural difficulty on behalf of the whole race who apply the discovery of science to social comfort-who invent useful machinery

-who circulate beneficial ideas, or give impulse and pre-eminence to staple branches of national industry, should be protected in the exertion of their talents, and in the fair enjoyment of the remuneration which that exertion and those talents win and deserve. Reward to such men cannot be too hightoo jealously guarded; nor too permanently secured.

NOTES AND NOTICES.

Wide Velvet Weaving.-At a late meeting of the Society of Arts and Manufactures, the most judicious rewards of the season were bestowed upon two Spitalfields velvet weavers, named Hanshard and Cole, for their invention of a mode of weaving wide velvets. It appeared that rather more than a year ago a velvet shawl two yards square was imported from France, and Hanshard hearing of this, devised a means of performing the same work, and offered to his employers to undertake it at his own risk. He succeeded, and delivered a seven-quarter square, for which he was paid four pounds. Cole knowing also that a wide velvet was in demand, and having seen Hanshard's velvet, also devised a means of effecting the object, which turned out to be the same as Hanshard's, and he undertook, and performed the work for two pounds five shillings. Hanshard endeavoured to keep his means secret, but was undoubtedly the first inventor; he was rewarded with a prize of five pounds; Cole, although a subsequent, appeared also to be an original inventor, and made the process known to the trade immidiately: he was awarded a premium of three pounds. The difficulty to be overcome in weaving a wide velvet was this: the width of the fabric being greater than the stretch of a man's arm, he could not pass the wire containing the silk across it, the wire being so thin and flexible. To obviate this, Hanshard put the wire in a small brass tube, pointed at the end, which held the wire stiff, so that it could be passed across. In working, however, the end of the tube was liable to catch in the fabric and break the thread, and this difficulty was overcome by putting a pointed cap upon the end of the tube after the wire had been inserted. Cole, as stated, followed Hanshard in the invention of the tube, but the cap was solely Hanshard's.

New Silk Mill.-An English manufacturer, residing in Turin, is said to have invented a new silk-mill, the mechanism of which is so extremely simple, that it may be worked by children only 10 years old, and yet produces three times the quantity of twist made by the old mills in the same period, and of a much superior quality.

Another Substitute for Steam.-A correspondent informs us that an ingenious mechanic (Mr. William Dupe, of this city), has discovered a substitute for steam for propelling wheel carriages and ships. The invention, which is a very simple one, acts by condensed air. It is calculated that it will not cost more than one-third of the expense to work it, and will take up a much smaller space than a steam-engine. A model of this invention has been shown to several scientific gentlemen of the University and city, who have expressed their decided approbation of it.-Oxford Chronicle.