HEADQUARTERS OF SURVEY DEPARTMENT. 225 



map of the North.- West Provinces on the scale of eight miles to the 

 inch and a rainfall chart of India with eight gradations of colour 

 were also prepared. The heliogravure process also made steady- 

 progress, and seven plates were turned out, four being for the 

 Geological Survey, one outline map of Simla and Jutog, and two 

 plates of a view of the great Kan-chan-janga mountain. 



In 1883-84 some of the special maps drawn for the Calcutta 

 International Exhibition were prepared for publication, viz., those 

 exhibiting trade routes, distribution of religions, missionary stations, 

 density of population, distribution of languages and river basins ; 

 the rainfall, railway, and telegraph maps having been already 

 published. 



. An elaborate plaster of Paris model map, based on the 32-mile 

 map of India, showing all the hills as well as the scale would allow, 

 was completed for the Colonial and Indian Exhibition of 1886 

 by Major Charles Strahan, E.E. The vertical scale was 12 times the 

 horizontal, hence the highest peaks of the Himalayas were nearly 

 two inches high.* In the same year (1884) a very successful repro- 

 duction of a quarter atlas sheet by the electrotyping process was 

 made by Colonel Waterhouse, the method of scraping away the faulty 

 parts from the matrix being suitable where large corrections on a plate 

 are required and the ordinary mode of cutting out and hammering 

 up from behind might seriously damage the plate. Considerable 

 progress was also made in the various processes of heliogravure by 

 the electrotyping and etching methods, and 79 plates (principally 

 of photographs of Indian art-works taken in the Calcutta Exhibition) 

 were produced. Considerable attention was also given to the 

 reproduction of maps, and some very successful experiments were 

 made in reproducing brush-shaded maps by the photo-etching 

 process. "With suitable original drawings the heliogravure processes 

 can be made to render immense service in the cheap and speedy 

 production of engraved maps. The process of electrotyping was 

 also applied to the duplication of the engraved sheets of the Atlas of 

 India so as to adapt them for temporary issue, pending engraving 

 of the final results, and good progress was also made with the 

 photo-collotype process which was used for plates of coins for the 

 Asiatic Society, for botanical plates, and the like. The principal map 

 completed in the Lithographic Office during the year was a contour 

 map of India in six sheets on the scale of 1 inch to 32 miles. 



* This relief map has since been presented to the Imperial Institute. 

 I Y 20321. p 



