1889.] Address. 105 



In the Photographic Office, Survey of India, experiments have been 

 made with the object of improving the ordinary process of photozincogra- 

 phy by impressing the photographic image directly from the negative in- 

 stead of transferring it from a paper impression. The results obtained 

 are sharper and more accurate in scale. The process of heliogravure by 

 the etching method, has made great advances, and is now being largely 

 utilised for the reproduction of photographs from nature or other subjects 

 which are unsuitedfor photozincography, or require finer and more delicate 

 treatment. A large number of the plates illustrating Dr. Fiihrer's forth- 

 coming report on the Archasological Remains at Jaunpur have been 

 reproduced in this manner, and a specimen has also appeared in our 

 "Proceedings." A series of plates, chiefly selected from the draw- 

 ings executed by the Archaeological Surveys, is being reproduced in 

 this manner under the orders of the Government of India, R. and A. 

 Department, for the use of Art Schools throughout the country. 



In this country we depend almost entirely on photography for the 

 rapid multiplication of the maps of our Surveys, and other plans and 

 drawings ; for we have no Keith Johnstons, nor Stanfords hei'e, and no 

 class of professional engravers, draughtsmen, or lithographers to draw 

 upon, though we hope our Schools of Art will in time supply this 

 deficiency. 



It is peculiarly gratifying to me to be able to tell you that the 

 property possessed specially by the eosin dyes, of rendering bromide of 

 silver very highly sensitive to the yellow rays of the spectrum, — a fact 

 which was first announced in this room, in January 1876, — has been 

 turned to useful account in the preparation of the so called orthochro- 

 matic, or isochromatic, plates, which have been found of the greatest use 

 in copying paintings and in photo-micrography, photo-spectroscopy and 

 other purposes when it is desired to photograph objects of a yellow 

 colour, which reproduce so unsatisfactorily by the ordinary methods. 

 During the year I commenced a series of observations on the orthochro- 

 matic properties of different kinds of eosins and hope, if the pressure of 

 other duties permits, to be able to resume them and to lay them before 

 you with further photo- spectroscopic observations of the less refrangible 

 rays, with the aid of the Rowland gratings exhibited at our last meeting. 



Before proceeding further, mention may be made of several mathe- 

 matical papers by Babu Asutosh Mukhopadhyay, that have appeared 

 in our Journal and Proceedings, on Poisson's Integral and on Monge's 

 Differential Equations to the Pai'abola and to all Conies. 



Museums. 

 As the founder of the first Museum in this country our Society 



