'54 



SCIENCE PROGRESS 



highly polished sheet of zinc is covered with a film of albumen 

 treated with bichromate of ammonia, and a print of the negative 

 obtained on it. In the negative the lines of the original drawing 

 are absolutely clear, and the remainder is dense ; in the resulting 



Specimen of an illustration reproduced by line process. 



From an illustration by F. H. Jackson in Rambles in the Pyrenees. 



print the lines are hardened by the action of light, while the 

 remainder is unaltered. The plate is then taken into a dark 

 room, inked with a roller, and allowed to soak in a bath of cold 





