228 HEADQUARTERS OF SURVEY DEPARTMENT. 



over plio to -collotype, which was also worked with some success at 

 Calcutta, that the copper plates can be worked on and lettered and, 

 if protected by a coating of steel, are capable of yielding an 

 unlimited number of equally good impressions, whereas the tender 

 gelatine film of the photo-collotype plate will stand no touching up 

 or correction, is difficult to print under varying conditions of 

 temperature and humidity, and at best will only yield a compara- 

 tively small number of good impressions, while all lettering has 

 usually to be added by a separate printing. Consequently, photo- 

 collotype is being discarded in favour of photo-etching. 



The principal applications of the photo-etching process have been 

 for the reproduction of some very delicate drawings of insects in 

 pencil and Indian ink, for the illustration of the " Indian Museum 

 Notes," also for botanical and histological plates from the original 

 drawings or photographs, illustrating the " Memoirs by the Medical 

 Officers of the Army in India." A large proportion of the plates, 

 illustrating Dr. Fuhrer's Report on the Sharqi remains at Jaunpur, 

 both from photographs and line drawings, were done by this process, 

 and no other would have answered so well. It is also steadily 

 utilised for the reproduction of a series of technical drawings of 

 architectural ornaments, &c, taken from the drawings of the 

 Archaeological Surveys and issued for the use of art schools and 

 workmen of various kinds in all the provinces of India. 



Attempts have been made from time to time to apply the process 

 to the reproduction of brush-shaded maps and by its means enable 

 a preliminary issue of the sheets of the Atlas of India to be made 

 ponding the completion of the hill-etching by hand, which is always 

 a tedious operation. There are, however, great difficulties to be 

 overcome in reproducing lines and brushwork together, which have 

 practically prevented its utilisation in this way, although it is 

 always kept in view. The process might be more largely applied 

 to the reproduction of maps in line, but the difficulty has been to 

 obtain a staff of highly trained draughtsmen capable of turning 

 out the original drawings in a sufficiently good style for direct 

 engraving. The necessity for constant corrections on the maps 

 also militates very greatly against the preparation of highly finished 

 drawings capable of competing against hand engravings. The 

 process has, however, been successfully applied to the reproduction 

 of the maps of the Audaman Islands on the J-inch scale, by reduc- 

 tion from the original standard sheets on double the scale, and, no 



