VII. PHOTOGRAPHY. 203 



938. An Instantaneous Photograph. Waves breaking on 

 the shore of Britain in 1876. James Martin. 



939. Engraving with the Aid of Photography. 



MM. Goupil ct Cic.j Paris. 



Proofs obtained by impression with fatty ink on copper plates engraved by 

 hand, the lines on which are obtained by means of a photographic negative, 

 with the use of chemical substances sensitive to the action of light. 



1. " Pollice verso," after the painting by Gerome. 



2. " L' eminence grise," do. do. 



3. " Rembrant dans son atelier " (Rembrant in his studio), after the painting 



by Ger6me. 



4. " II Decamerone " (The Decameron), Sorbi. 



5. "La rentree au Convent " (The return to the Convent), Zamacois. 



6. " Le premier coup de canon " (The first cannon shot), Berne, Belle- 



wurt. 



7. Part of the colonnade of the Louvre, from nature. 



8. Reproduction of a mineralogical fragment, from nature. 



9. Frame containing the two plates from which proofs Nos. 7 and 8 were 



printed. 



940. Thiel Ain6 Pantotype (modification of the Albertype 

 process). Thiel Aine, Paris. 



943. Photo-lithography Process of Simonan and 

 Toovey. Veuve Simonan and Toovey. 



1. Plan of the town of Lie"ge. 



2o Portrait of Archbishop St. Lambert, after an old engraving. 



3-7. Topographical plans, photographed by Capt. Hanot. 



8-13. Six drawings of the " Campagnie des bronzes " at Bruxelles. 



14-15. Two reproductions from a line drawing by Licot de Nivelles. 



16-19. Four archaeological drawings. 



20. Frontispiece of an ancient MS. 



This is a photo-lithographic process, and depends on the fact that if gum 

 be mixed with potassium dichromate, and when dry be exposed to the action 

 of light, it becomes insoluble. A paper is coated with gum and potassium 

 dichromate, and exposed under the negative of a line subject, or under an 

 etching on glass, having a non-actinic ground. When light has sufficiently 

 acted, the paper which has a faint impression of the lines is placed under a 

 pile of damped paper on the surface of a polished lithographic stone, and sub- 

 mitted to pressure for about an hour. The paper is then removed from the 

 surface of the stone, the insoluble part forming the lines leaving with it. The 

 lines of the engraving are thus left uugummed on the stone. A little olive oil 

 is brushed over the surface, when the gum on the stone has been allowed to 

 dry in a dark room. The surface is next washed, which dissolves away 



i :_ *!, !: ~f *i )icture formed of only matter. The stone 



lie roller, and is ready for giving impres- 



the gum, leaving the lines of the picture formed of only matter. The stone 

 is then rolled up with a lithographic 



944. Specimens of Paul Pretsch's Photo-typography. 



Warren De La Rue, F.R.S. 



945. Electro-chemical Process for reproducing on copper 

 lithographic impressions. M. Erhard. 



