But not satisfied with this clear definition, Mr. Pretsch has exhibited on a counter in glass cases the plates and blocks themselves for examination by connoisseurs. There are to be seen seven blocks entirely untouched with the graver; the photographic originals of them being partly taken from nature and partly from works of art. There is also a large engraved printing-plate of copper, absolutely untouched; and a second plate, which has been assisted by the graver, and afterwards coated with a very thin film of steel, by which means the copperplates have been made almost as durable as engraved steel-plates.

Therefore we see here the specimens of two processes, viz.,

1. Producing engraved printing-plates of copper, coated with steel, for the copperplate printing-press.

2. Producing engraved printing blocks (surface copper, backed with type metal, mounted on wood, like the cast of a wood engraving), to be printed by the ordinary printing-press with or without types; and by this last process the specimen before our readers is executed.

Both processes preserve the true finger of nature, or the real touch of the artist. The first process is for the best works of the fine arts, and for hundreds of people; the second process, however, is for the million. Photographs in our present time are still perishable, but printer's-ink and paper stand the test of centuries. The influence of light is used in these two processes only for the production of the first engraved surface; having obtained the engraving in the desired effect, the subsequent portion of the processes is mere mechanical skill, however great the number of copies. Our ancestors had only written books, but since the invention of typography, religion, wisdom, and knowledge became universal goods of mankind. The rapidity and cheapness of production by the ordinary printing-press are as well known as the spread of its productions over the whole globe. And what typography has been for the spread of thought, that is photography for the reproduction of authentic illustrations, if they can be printed with ordinary printer's-ink, and by the common cheap process.

To enable our readers to obtain a correct idea of these processes, we introduce a brief explanation of them. An ordinary glass plate is coated with a certain mixture sensitive to the influence of light, and this coating is dried. The photographic negative is placed on the surface of the coated glass plate, both of them are fixed in an ordinary photographic copying frame, and exposed to the influence of light. After sufficient exposure they are taken out of the frame, separated, and the picture now appears in a faint coloured copy on the flat surface of the coated glass plate, which is to be immersed in a bath of powerful chemical action. By this treatment some portions of the picture become more or less raised, and some remain sunk, according to the previous action of light, and exactly corresponding to the lights and

shadows of the picture. In fact, this picture is the main portion of the process; it forms the engraved surface, and therefore must be obtained so as to answer the requirements of the printing-press. A picture can be obtained without much difficulty, but not so easily the picture which will suit a certain purpose. It is marvellous how nature can accomplish this result, but it does so only under certain conditions; she demands great attention, experience, and study of her laws, because they are not easily discovered.

Having obtained in this manner the engraving as it ought to be, though the material is perishable and transient, a cast or mould is made from it; the coating of the glass plate, having served its purpose, is removed, the plate cleaned, and may be used over and over again. The above-mentioned mould, having been made conductive, is used for the purpose of inducing, by means of voltaic electricity, a deposit of copper thereon, forming the matrix from which the printing surface of copper is obtained by repeating the process of electrotyping.

The illustration of a portion of Wells Cathedral, in our present number, has been executed in the above-mentioned second process. The photographic original has been taken from nature by Mr. Francis Bedford, and the engraved block, absolutely untouched by the graver, produced by Paul Pretsch. Only the white portion of the sky, requiring great depth in the block, has been built up in the matrix.

We selected the west front of Wells Cathedral for a specimen of this process, with the double object of testing Mr. Pretsch's powers by giving him a very elaborate subject, which requires great skill on the part of the draughtsman, and great patience on the part of the engraver to produce an accurate representation of it by the ordinary processes of art, and consequently must be very expensive and very apt to be unsatisfactory. Such exquisite figures require to be drawn and engraved with minute care, whereas by the process of Mr. Pretsch the matter is almost as easy as if the subject was a plain wall; and as the magnifying glass can be applied to it to any extent, the renovations of the sculptures, which are numerous, can be at once detected, which cannot be done in an engraving.

This very remarkable series of sculptures was originally executed in the first quarter of the thirteenth century, and it is considered by Professor Cockerell and other high authorities to be absolutely unrivalled in Europe in work of that period. Many of the figures have been renewed, but the greater part are original. Another reason for selecting this subject was to call the attention of the Dean and Chapter, and the architect to the Ecclesiastical Commission, to the very bad effect produced by having four of the windows in this beautiful west front blocked up, in order to save a few pounds. It really does appear almost incredible that they should be suffered to remain blocked up at the present day, and in any ordinary engraving the accuracy of the artist

inted by the ordinary Letterpress, from a Block produced by means of Photography and Electrotype. Absolutely untouched by the graver