1868.] 



Solar Eclipse 0/I868. 



107 



Reasons for discarding it. — In the first place, I never could with any- 

 kind of illumination train my eye to read the scale, partly because (whether 

 from diffraction or irradiation) the image was never distinct, partly because 

 the figures were illegible. In the next place the little lamp was capricious ; 

 either it refused to keep alight, or it boiled its own oil and melted off its 

 handles, and ended by burning my fingers ! Thirdly, it was an additional 

 weight at the eye- end of the telescope and involved a counterpoise when 

 not in use, and an additional projection to be avoided in every movement 

 — in the dark, — all implying additional distractions and sources of failure. 

 Lastly, I found I could do very well without it — in the preliminary training 

 which I underwent on examining the nebulae. At the same time I must 

 confess that I made an oversight in trusting too much to the illuminating 

 power of a hand-lamp, as will be apparent when I come to describe the 

 actual eclipse-observations. 



7. Smaller Telescopes and Polarizers. 

 The second instrument supplied was an achromatic refractor of 3 inches 

 aperture mounted with vertical and horizontal axes, the socket of the former 

 being supported on a three-legged wooden stand, afterwards replaced by 

 one of greater stability and more convenient height. Two cells, containing 

 a double-image prism and quartz plate, and the combination known as 

 Savart's polariscope, respectively, were supplied for use with this telescope, 

 but without any connecting adaptation. 



8. Hand Spectroscopes. 

 The other instruments were hand spectroscopes for direct vision, four in 

 number, which I was directed to distribute according to circumstances. It 

 is needless to describe these instruments, as they are well known ; but I 

 must venture to correct a statement made at a meeting of the Royal Asiatic 

 Society last December, that they have a magnifying-power of 8 or 10. I 

 do n't think they can be credited with a higher power than 3 ; and I was 

 never able to recognize any of the peculiar characteristics of nebular or 

 stellar spectra, the recognition of which might have been expected with the 

 higher magnifying-power. 



9. Arrival in India and communication with Colonel Walker, R.E. 

 Soon after my arrival in India I communicated with Colonel Walker, 

 with the object of receiving his instructions and of ascertaining whether he 

 had decided on any plan, and, if not, to learn his views with reference to the 

 assistance I might expect from the Survey Establishment. The choice of 

 a station of observation and the disposal of the instruments were also dis- 

 cussed in the course of correspondence. 



10. His Reply, and application to the Indian Government. 

 Colonel Walker's action in this matter has been most gratifying. He 

 immediately promised me the assistance of Lieut. W. Maxwell Campbell, 



