MECHANICS AND USEFUL ARTS. 125 



pittern-books for lace manufacturers, we see no reason to doubt its success. 

 It can never supersede the work of the draftsman in books of science. 

 Messrs. Bradbury & Evans's folio plates would form an admirable substi- 

 tute for an herbarium, if they could produce fac- similes in relief of all 

 plants alike, with their botanical detail in its natural condition ; but the 

 objects represented have to be submitted to an amount of pressure which 

 destroys all the parts not hard enough or flat enough to resist it, so that 

 we have merely representations of crushed plants. The process is as fol- 

 lows : The specimen is placed on a polished steel plate, and upon this is 

 placed a polished plate of soft lead. The plates are then passed, sandwich- 

 like, between the cylinders of an ordinary copper-plate printing press, 

 subject to a pressure of 800 to 1000 hundred weight, and the softer of the 

 two metal plates, being sensitive of the faintest impression, affords a beauti- 

 ful matrice for the casting of a type-plate, from which a fac-simile of the 

 object may be printed. The embossed printing for the use of the blind 

 sxiggests a resemblance. Impressions of hard subjects, such as fossil fish, 

 have been procured by taking a cast of them in gutta percha, and sub- 

 mitting that to the sandwich-pressing process in place of the object. A 

 very clever fac-simile of a crushed plant is produced, and all the detail 

 that can resist crushing is impressed on the lead with a fidelity and 

 promptness quite beyond the reach of manipulation ; but it is obvious that 

 only such thin and delicate subjects as sea-weeds or macerated leaves can 

 escape destruction in the process. No sufficient detail of the flower or 

 fruit of a plant can be produced for botanical purposes. 



GLYPTOGRAPHY. 



This art is the invention of Mr. John Doulevy, of New York, and its 

 object is to produce colored impressions at a comparatively small expense, 

 and with a precision and elegance of finish which have hitherto been 

 unattainable by the processes of engraving or lithography. Its principal 

 characteristic is the use of intaglio types instead cf the ordinary types in 

 relief, combined with peculiar plastic processes, by which colored plates, 

 adapted to every variety of chromatic effect, can be printed by the operation 

 of the common typographic press. Hitherto typography has been limited to 

 impressions of a uniform color, without aiming at illuminated letters or 

 pictorial embellishments. In Chromo-glyphotype, the process is directly 

 the reverse of ordinary typography, or printing in relief. The relief 

 types are raised above, the intaglio types are sunken into, the surface of 

 the plates. The impression produced from relief type is taken from the 

 letter, leaving it without back-ground. The impression produced from 

 intaglio type is taken from the entire surface of the block in which the 

 letter is engraved, presenting the letter in the midst of a back-ground, either 

 plain, or with any variety of ornament, as may be desired. Thus is given 

 a uniform, unbroken, equally-tinted surface, in which the letters appear 

 as if they were etched upon a copper plate, sunk into the body of a wood 



