1G4 ANNUAL OF SCIENTIFIC DISCOVERY. 



solar rays while working at it, or it will gradually blacken on the surface; 

 exposure to diffused day-light is allowable." 



Spcnce's Process. A method for taking photographs on wooden blocks, 

 patented by W. Spence, of Liverpool, is described as follows : The white of 

 an egg is beat up into froth with one-half its volume of water, and the face 

 of the block carefully moistened with this by a soft brush, then allowed to 

 dry slowly. A solution composed of fine isinglass, thirty grains, chloride of 

 sodium, two grains, to one ounce of warm water, is now also rubbed over 

 the face of the block, and allowed to dry. The block is now heated, so as 

 to coagulate the albumen of the egg in the pores of the wood under the isin- 

 glass, and another coat of the latter is now applied, until the surface has a 

 glazed appearance. But no more isinglass is allowed than fills the pores of 

 the wood; any excess is removed with a knife. A solution of nitrate of 

 silver is now applied to the wood, and the block placed in the camera, when 

 the picture is taken. The picture is now fixed in a warm solution of sulphite 

 of soda, which removes the gelatine, but allows the albumen to remain; and 

 the picture being taken directly on the wood, can be engraved with more 

 facility than when it is applied on collodion, which is liable to scale off. 

 The improvement cl timed in this process is the application of the albumen 

 in the pores of the wood in such a manner as to form an insoluble base. 

 The nitrate solution is thus prevented from penetrating the pores, while the 

 picture is taken directly on the surface of the Avood itself. 



ENGRAVING WITHOUT AN ENGRAVER. 



One of the most curious of the many remarkable applications of photog- 

 raphy, is that of producing by its means copies of engravings and other 

 works of art. The almost perfect reproduction of a drawing or an engrav- 

 ing without the intervention of an engraver or copyist, would have seemed, 

 a few years back, almost an impossible thing; yet we know that photog- 

 raphy accomplishes it daily. But we have become so familiar with photog- 

 raphy, that we almost cease to wonder at its marvellous doings. Still, the 

 reproduction, true and beautiful as it is, is a photograph, and not an engrav- 

 ing. The London Literary Gazette, Oct. 18-59, calls attention to a new process, 

 by which, it says, " it has been found possible, without even the aid of photog- 

 raphy, in fact, as we may say, by mere mechanical means, to make a 

 perfect fac-simile of an engraving, whether a copperplate or a woodcut, 

 and not only to make a copy of it, but to produce a plate or block for surface- 

 printing that shall yield impressions by the ordinary printing-presses quite 

 equal to the original. But even this is not all. Blocks can by this process 

 be produced, without the aid of any engraver, which shall print these fac- 

 similes, enlarged or reduced to any extent that may be desired. We have, 

 for instance, seen a whole-page woodcut from the Illustrated News reduced 

 to half, and enlarged to double the original dimensions, without any loss of 

 sharpness or vigor, and without the smallest distortion being anywhere dis- 

 coverable even with a lens. So, again, with an old and imperfect map ; and 

 so with an impression from a steel engraving. But it is equally applicable 

 to original designs made with peculiar ink and paper. Without the assist- 

 ance of an engraver, blocks for surface-printing can be prepared from them, 

 either of the same or any larger or smaller size. But further, the blocks for 

 printing can be produced of an altered form, as well as of a different size. 

 Thus the normal pattern for printing on a dinner-service can be reproduced, 





