74 



Capt. Haig's Spectroscopic Observations [Recess, 



V. " Account of Spectroscoj)ic Observations of the Eclipse of the 

 Sun, August 18, 1868, in a letter addressed to the President 

 of the Royal Society. By Captain C. T. Haig, R.E. Com- 

 municated by the President. Received September 21, 1868. 



Poona, 24th August, 1868. 



My dear Sir, — I hasten to send you an account of the observations I 

 have fortunately been able to make at Beejapoor of the total eclipse on the 

 18th instant with one of the hand-spectroscopes sent out by the Royal So- 

 ciety in the care of Lieut. Herschel, R.E., not waiting to let my report be 

 forwarded by Colonel "Walker, R.E., my departmental superior, on account 

 of the delay which would necessarily be caused thereby. 



I may state at once that I observed the spectra of two red flames close 

 to each other, and in their spectra two broad bright bands quite sharply 

 defined, one rose-madder and the other light golden. These spectra were 

 soon lost in the spectrum of the moon's edge just before emergence, which 

 had also two well-defined bright bands (one green and one indigo) about a 

 quarter the width of the bands in the spectra of the flames, this spectrum 

 being again soon lost in the bright sunlight. 



I will now proceed to give a somewhat detailed account of the observa- 

 tions, in which Captain Tanner, Bombay Staff Corps and of the Minar 

 Survey (who, on my earnest solicitation, accompanied me), and Mr. Kero 

 Laxuman, Professor of Mathematics in the Deccan College, took part, and 

 during which Mr. Hunter, Bombay Civil Service, and Dr. Kielhorn, Pro- 

 fessor of Sanskrit in the Deccan College, were present as non-professional 

 observers. 



Our instrumental equipment consisted as follows : — Mr. Kero Laxuman 

 brought an ordinary pedestal-telescope of 2|-inch aperture and 36 inches 

 focal length by Home and Thornthwaite, which he temporarily mounted on a 

 stand equatorially ; and he had a scale fitted inside a 60-power eyepiece, 

 which, however, he was unfortunately not able to use, on account of a fall 

 which his instrument sustained from being blown down by the high wind ; 

 he therefore had to use another eyepiece of power 70, not furnished with 

 a scale. He also had a pocket chronometer beating five times to two seconds, 

 by Arnold and Dent. 



Captain Tanner had an Everest theodolite by Troughton and Simms, 

 having a remarkably good telescope, l-J-inch aperture and 18 inches focal 

 length, and an eyepiece of power 46. 



I had one of the Royal Society's small hand-spectroscopes, and a small 

 6-inch transit theodolite by Troughton and Simms, the cap of the object- 

 glass of which I had cut so as to receive the prism-cap of the spectro- 

 scope, and had fitted one to the other, so that I could at once shift the 

 prism-cap from its own telescope to that of the theodolite, and vice versa. 



