104j Address. [Feb, 



A very interesting sketch of the History of Telegraphic communi- 

 cation between the United Kingdom and India, by General Sir B,. 

 Murdoch Smith, appears in a recent number of the Scottish Geographical 

 Magazine. 



Photography. 



You will doubtless expect me to tell you something of recent 

 advances in photography : there is, however, little to tell. 



It is gratifying to note the resuscitation of our local Photographic 

 Society and the establishment of new Societies at Bombay, Allahabad and 

 Madras as an indication of the awakened interest in photography 

 brought about by the perfection and simplicity to which the working of 

 gelatine dry plates has now arrived. To the archaeologist these plates 

 are invaluable and permit of an immense deal more work being done 

 than was the case with the old collodion methods, wet or dry. With 

 these plates, which need not be developed on the spot, the explorer 

 can now obtain far more trustworthy records of the strange places and 

 people he visits than was formerly the case when all had to be done 

 by hand and eye. Great improvements have also been made in printing 

 methods, both solar and photo-mechanical, which greatly facilitate the 

 reproduction of photographs for book illustration. 



As the recording pencil of Science in all branches the use of 

 photography is daily extending. In astronomy, microscopy and 

 spectroscopy, especially, its powers of revealing the invisible are in- 

 vahiable and almost indispensable for research. Photographs have been 

 lately taken of nebulae which the most powerful telescopes fail to show 

 to the eye. A complete photographic Survey of the Heavens has been 

 arranged for internationally, and I should have been glad to have seen 

 this country taking part in it, but special instruments and arrangements 

 would be necessary, for which it would be hopeless to ask the aid of 

 Government at present, while so many more important things remain 

 to be done. 



Photographic observations of sunspots and f aculaa are made regularly 

 every day, weather permitting, at the Trigonometrical Branch office, Sur- 

 vey of India, at Dehra Diin, on 8-inch plates and — when any large spots of 

 special importance are visible — with the large photoheliograph, which 

 gives images of 12 inches diameter. Copies of the negatives are sent 

 home to complete the Greenwich observations. The advantage of having 

 this observatory at Dehra Dun is shown by the tables of comparative 

 visibility of the sun at Dehra and at Greenwich. At Dehra the per- 

 centage of invisibility, since 1881, has averaged from 10 to 22 days, 

 white at Greenwich it was from 41 to 60 days between 1880-81 and 

 1885-86. 



