USEFUL NOTICES. 1 15 



heavy nor light, admitted of the operation being performed, aS 



before directed, but I could not defer it to any second line. 



Another artist, of the name of Wedgewood, has, within ft Art of making 



few years past, offered to the public, under sanction of Letters copies byblack 

 3 * ' r tracing paper. 



Patent, the engraver's method of tracing, by means of a piece 



of paper blacked with a pigment, (commonly lamp-black) 

 applied by means of fat or a slowly drying oil. If such papdr; 

 which is sold at the shops, by the name of black tracing paper, be 

 laid upon a leaf of common paper, and another leaf be laid upon 

 that, the whole being disposed upon a firm flat table or plate of 

 wood, or metal, or glass, and any writing be made with a small 

 rounded steel or glass point, two copies will, by the same ope- 

 ration, be produced ; viz. a reverse copy on the upper white 

 paper, and a direct copy on the lower; the latter of which is 

 sufficiently durable to be sent away to a correspondent, and the 

 former will be very legible, as a direct copy, if the paper be 

 thin. 



Dr. Franklin mentioned to the Abbe Rochon* a method of A method of 

 rapidly engraving or marking plates, for multiplying copies. "in^upL^nd 

 He wrote with gummed ink, upon a surface of hard stone or printing from a 

 iron, and powdered his writing with sand, or emery, or cast metallic P late - 

 iron dust ; and when dry, he applied another plate of soft 

 wood, or pewter, or copper, upon the surface, and forced the 

 gritty matter into this last by the action of a press. This last 

 served, in the usual method of copper plate printing, to give a 

 very great number of copies, not neat or beautiful, but suffi- 

 ciently legible. 



The Abbe Rochon proposes, as a better method, to write Another by 

 with a steel point upon a copper plate ready varnished, and etch j^jjj]*' * n 

 the face by a«]ua fortis. Reversed prints being taken from this ter-proofs. 

 etching, he piles these, while wet, along with other damped 

 paper, and passes the whole through a press, which gives an 

 equal number of counter proofs not reversed. 



Both the last mentioned methods may be of use in armies Improvements 

 and under oiher circumstances : but both suppose extensive •* u £g ested « 

 means and apparatus, and only dispense with the engraver's skill. 

 Perhaps it would be an addition to Rochon's method, that the' 



* Rccueil de Memoires, &c. from M L'Abbfc RvjcKoh, ocUvo, 

 Paris, 1 73 J, p. 313, 



1 2 etching 



