" In the month of August next, a total solar eclipse of the sun will take place, of almost the greatest possible duration, and consequently affording more time than usual for such observations as can be made during the brief interval of totality," wrote Superintendent of the Trignometrical Survey of India Lt Colonel JT Walker to Secretary to Government of India EC Bayley on fourth February 1868 from Dehra Doon.
Archival records with the National Archives show the keen interest which solar eclipse generated among British officials and astronomers.
In this brief interval of about five minutes an opportunity will be afforded for the investigation of the physical nature of Corona and red flames that appear to surround the sun when its light is intercepted by the moon , which happens only during the occasion of total eclipse, wrote Walker.
He wrote nowhere eclipse can be observed under such favorable circumstances as in India and "very many years will elapse" before its recurrence.
He also stresses the need for multiplying the stations of observation for "eclipse may be visible at some places and hidden by clouds at others."
The Royal Society and Royal Astronomical Society provided necessary instruments and trained officers who would be observing the eclipse.
The services of Major Tennant of the Royal Bengal Engineers was taken for making the observations.
Archival records show that major Tennant gave an estimated cost for completing the observations of the total Solar eclipse on Aug.18,1868 of Rs.21,961 and four annas.
Interestingly the "silver glass reflecting telescope"fitted "chiefly for taking sun pictures" supplied to Major Tennant was in great demand .
The Astronomer Royal, G.B.Airy from the Royal Observatory Greenwich needed the instruments for the observation of the total solar eclipse in December 21-22 in 1870, which was to be visible at Cadiz, Gibraltar,Oran and Catania.
Her Majesty's Secretary of State for India wrote to Government of India forwarding the request of Airy.
In May, 1870, the instruments were in Mussoorie being used by Deputy Superintendent Trignometrical Survey of India J.B.Hennessey.
In a memorandum Hennessey writes, "The telescope is a nine and one fourth inch silver glass reflector" and in the "exquisitely clear atmosphere which periodically prevails at Mussoorie , it might be used with advantage in examining the heavenly bodies."
"The special object I proposed myself for examination was the sun.Remembering that nearly a fourth part of the earth's atmosphere is removed from above the observer here ,it appears highly probablehat the heavely bodies will be seen through a good telescope with increased brightness."
The "sun's surface may be advantageously looked into for mottled appearance described as "willow leaves", "rie grains" while the sun sports with their "bridges of light" "solar currents" and numerous other features , exciting universal interest in the astronomical world offer in themselves a vast field of enquiry.
"I only wish it were within my means to pay for the setting up of a first class telescope ,accurately driven ,on one of the Himalayan peaks, and to help in the careful examination of the heavenly bodies, for I am convinced that even with somewhat inferior means at his disposal an observer at Mussoorie must see further into the heavenly bodies than one, for instance in England."
As the instrument had to be sent to Astronomer Royal , Hennessey hoped telescope would be provided with accurate rotary motion essential for spectroscopic purposes and fitted with other appliances for sun researches to fully qualify it for examination of heavenly bodies at Mussoorie. He also hope Viceroy and Governor General of India would concur the expenditure on it.
His only request " if the instrument is sent home overland as directed,it is likely to be almost destroyed on the road by rough treatment to whichitn will be liable in Egypt. Particular care should, therefore be taken to forward it through the Suez Canal, so that once placed on board at Bombay, it need never be moved until arrival in England."
His request was kept by Government of India.