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cate, as, otherwise, the effect of the piece would be much injured. While speaking of mezzotinto engraving, it seems worth while to correct a prevalent error. It is generally supposed, that an acid is employed to corrode the copper for this branch of art ; but this is not the case. Engraving, when acid is to be used, is called etching, a process which we have already described.

This mistake with regard to the use of acid in mezzotinto, may not improbably have grown out of the commonly received account of the invention of this style of engraving. The merit of first using it is attributed to Prince Rupert. Horace Walpole, in his “Catalogue of Engravers," digested from the manuscript of Vertue, says, that, as Prince Rupert was going out one morning from his residence at Brussels, be observed a sentinel very busy with his fusil. On inquiring what he was doing, the man showed him, that the night dew had made some spots of rust on the piece, which he was trying to scrape and polish away. On examining it, the prince perceived something like a figure eaten into the barrel, with innumerable little holes close together like the chased work on gold and silver, part of which the man had already scraped away. It immediately occurred to him, that, by covering a plate with such little holes, so that it would give a black inpression, and then scraping away part of them, the smooth portions of the plate would leave the paper white. He communicated this idea to Vaillant, a painter whom he maintained ; and after many experiments they contrived a steel roller with teeth, which could cut the plate in every direction; and it was then easy to scrape away the roughness where the light was to fall.

This account, however, seems to be incorrect ; for the Baron Heineken, in his “ Idée Générale d'une Collection complette d'Estampes,” speaks of a print engraved in mezzotinto by Colonel de Siegen, an officer in the service of the Landgrave of Hesse. It is a portrait of Amelia Elizabeth, Princess Regent of Hesse-Cassel, which is inscribed in one corner, “ L. de Siegen, inventor, fecit, 1643.” Now it does not appear that Prince Rupert pretended to have made this discovery till nearly twenty years after the date of Siegen's print ; for Evelyn mentions, in his Diary, under March 13th, 1661, that Prince Rupert had just shown him the

new way of graving called mezzotinto. Heineken thinks that Rupert must have learned the art from Colonel de Siegen.

Another mode of engraving, accomplished by the help of an acid, is called aqua-tinta. The outlines of the picture are etched in the copper by the usual process. The ground is then removed, the plate carefully cleaned, and the aqua-tinta grain, as it is called, is applied. In the old method, this consisted of finely-powdered mastic, sifted carefully and equally over the plate, and then made to adhere by gently warming it. It will readily be seen, that, were the acid now applied, it would so act upon the copper between the innumerable fine grains, that an impression taken from the plate would be perfectly black. When the grains of mastic, therefore, have been made to adhere, the artist takes a hair pencil dipped in black varnish, and paints over the grain in those parts of the picture which are to be left entirely white. The acid is then applied, and after it has been suffered to act long enough it is poured off, and the next lightest shade stopped out ; again, the acid is applied for the deeper shades, and so on till the picture is complete. There are several modifications of the process of aqua-tinta engraving, which we omit describing, as it would be difficult to make them intelligible to our readers. One, however, invented we believe by Mr. F. Tukes, of London, and now generally adopted, ought not to be passed by. It is far preferable to the method formerly in use, wearing longer, and giving a grain of much more elegant appearance. The resinous substance to be employed, which is mastic, resin, burgundy pitch, or a mixture of two or more of these ingredients, is dissolved in highly rectified alcohol; and, the plate having been carefully cleaned, the solution is quickly poured over its surface, in such a manner, that the chilling of the varnish, which immediately takes place, may be perfectly equal over the whole. If this is well done, the rapid evaporation of the alcohol causes the resin which it has held in solution to shrink up, presenting a sort of vermiform appearance, and leaving the copper between the particles of varnish open to the action of the acid. The object of the aquatinta is to imitate drawings made with India ink, bistre, sepia, &c. It is well enough adapted for slight subjects generally,

VOL. XLIX. — NO. 104.

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and for large and coarse representations ; but it fails, where minute and accurate detail is required.

We come, finally, to the art of engraving on steel, which has additional interest to Americans as the invention of one of their countrymen. Though there is reason to believe, that five or six of Albert Durer's prints, preserved in the British Museum, were taken from steel plates, and though there is an engraving by J. T. Smith, in 1805, of the ceiling of the Star Chamber in the “ Topographical Illustrations of Westminster,” undoubtedly taken from a steel plate, the art nevertheless does not seem to have been appreciated or understood till several years afterwards. In the year 1818, an inquiry was instituted, respecting the prevention of forgery, by the “ Society for the Encouragement of Arts,” in London ; when it appeared from information gathered by the committee, that bank-notes, with ornamented borders, printed from steel plates, were actually in use in America ; and a specimen of engraving on soft steel, was presented to the Society by Mr. Charles Warren. Soon after this, Messrs. Perkins and Fairman removed to London, and formed a connexion with Mr. Heath, an eminent engraver, for printing notes and other designs from steel plates. The great principle in this branch of the art is, to engrave on soft steel and harden it afterwards ; and the superiority of this kind of engraving, over that on copper, consists in the greater number of impressions which may be taken from steel plates, and the superior delicacy of which they admit in the execution.

In addition to this, Perkins has resorted to another method for increasing the number of impressions. The plate being engraved and hardened, the impression is transferred in a spring press to a cylinder of soft steel, by rolling the latter over the plate several times, under a great pressure. The design is thus transferred in relief to the cylinder, which is then hardened, and may be used to make the same impression on plates of soft steel, or copper, from which prints may then be taken. This process, however, is only used in the preparation of plates intended for bank-notes and calicoprinting. The ordinary engraving upon steel, which has now almost entirely superseded that on copper, is executed upon plates nearly decarbonated. They do not require hardening, as they will give a sufficient number of impressions without it.

There is a species of engraving on copper called the medallic, which has been invented within the last twenty-five years, and is so beautiful a branch of the art that it merits a minute description. The object of this kind of engraving is, to give accurate representations of medals, coins, and bassorilievos of a small size ; and it is effected by applying a machine to the surface of the medal, which will trace a line on the copper corresponding exactly to the outline of the figure on the medal. Those who are familiar with a pentegraph will be able to form an idea of this machine. It is so contrived, that, as it slides over the surface of the coin, every elevation or depression which produces a perpendicular motion in the machine, causes at the same time a horizontal movement at the other extremity, which traces the line on the copper. Every time the machine passes over the coin, a single line is traced on the copper ; and there is a delicately contrived screw, by which the machine may be pushed forward after each line is drawn, so as to make the next line as near to it as the operator chooses. The effect is to give an exact copy of the medal ; and the drawing appears so salient, that we can hardly convince ourselves, at first, that we are looking upon a flat surface.

This beautiful machine will seem the more interesting to our readers, from the circumstance of its having been invented in this country. In the “ Journal of the Franklin Institute of the State of Pennsylvania,” (Vol. X. No. 3, for September, 1832,) we find some account of the invention, in the following passage ;

" In 1817, by the use of a machine which had been invented in Philadelphia, Christian Gobrecht, die-sinker, produced upon copper an engraving from a medal having upon it the head of Alexander of Russia ; from this engraving impressions were taken and distributed. One of these impressions we have seen.

"In 1819, Asa Spencer (now of the firm of Draper, Underwood & Co., bank-note engravers) took with him to London a machine of the kind above alluded to, which was principally designed for straight and waved-line ruling. This machine was used in London during the year just mentioned, and the mode of ruling waved lines, and of copying medals, was then exhibited and explained by Mr. Spencer to several artists,” &c.

In the above extract it will be observed, that we are not expressly informed who was the inventor ; nor do we find it stated anywhere in the communication from which the extract is taken. We have been informed, by numerous artists in Philadelphia, that the contrivance of this ingenious and beautiful machine is undoubtedly to be ascribed to Mr. Spencer; that the machine used by Mr. Gobrecht was constructed by him, and that, consequently, the invention and perfection of the apparatus are the result of his ingenuity.

This branch of the art has received great attention both in England and France. Mr. Bate of London, took out a patent for a machine of this kind, in 1826, and has distinguished himself by the beauty of his medallic engravings. In 1830, a mechanician of Paris, Achille Collas, contrived a similar instrument, having taken the bint from a machine which was used for engraving watch-dials, cases, and snuffboxes, called the tour à guillocher. And in 1834, a publication was commenced in Paris, under the title of “ Trésor de Numismatique et de Glyptique,” which has been published weekly ever since, each part containing four solio plates of medallic engraving, and a sheet of letterpress.

We have treated of the merely mechanical part of engraving. A much more difficult subject remains for us in the consideration of this art in a more extended sense ; its various objects and capacities; the results already produced by it, and the rules which may be deduced from the specimens already before the world for the aid of future artists. It must be remembered, that art exists previously to all rules. It springs up first in the inspired mind, is afterwards visibly displayed, then admired, studied, and commented on. While an art is still in a progressive state, it is obvious, that its nature can only be partially discussed. It may possibly be so far advanced as to indicate with certainty all that it is capable of being made ; but even then, the effect to be produced by this perfection cannot be entirely comprehended. And, if the progress made is less than this, it would certainly be undertaking too much, were any one to attempt to give a satisfactory account of the whole extent of the art.

Now the latter appears to be the case with engraving. We certainly cannot say, that this art is still in its infancy;

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