110 



Lieut. J. Herschel's Account of the [Nov. 19, 



15. Peninsular and Oriental Steam Navigation Company's Agent, 



Captain Henry, Superintendent at Bombay. 



Lastly, I communicated with the agents of the Peninsular and Oriental 

 Company at Calcutta and Madras Bay, and eventually intrusted the remain- 

 ing two spectroscopes to the latter for employment on board two vessels, 

 outward- and homeward-bound, which would probably be on the track at 

 the right time. 



16. Memorandum of explanations and suggestions for use of Hand 



Spectroscopes. 



It was necessary, however, not only to distribute these instruments, but 

 also to provide for their being intelligently employed in unpractised 

 hands. I accordingly drew up a short memorandum with the object of 

 putting it into the power of those interested to understand as much of the 

 subject as seemed necessary, and of suggesting the probable appearances 

 which might be presented. A copy of the pamphlet accompanies this 

 Report. 



] 7. Examination ofNebulce as bearing on the main subject. 

 "While these arrangements were in progress I was myself engaged with 

 the equatorial in the examination of the southern nebulae, to which I de- 

 voted as much time as the duties of my profession enabled me to do. The 

 weather was very favourable in March (towards the middle of which month 

 the base-line was completed), in April, and until the middle of May ; but 

 from that time until the latter end of J une, when the instrument had to be 

 despatched, I hardly got a single observation, owing to the setting-in of 

 the south-west monsoon. I congratulated myself on having been able to 

 use the fine nights we had had. The results, showing the nature of the 

 spectra of about fifty nebulae, have been already communicated to your 

 Secretary ; there is therefore no occasion to enter into particulars on this 

 subject here, except as bearing on instrumental peculiarities not previously 

 touched upon, and as suggesting the probabilny that a considerable fami- 

 liarity with the special kind of observation had been acquired, as well as 

 with the individual instrument. Those who are acquainted with the spec- 

 troscope as applied to a telescope will remember that it involves several 

 additional screws to be attended to, and that the finding of these mecha- 

 nically in the dark is no inconsiderable perplexity until habit has taught 

 the way. But this by the way. 



18. The Finder, and the trouble it gave. 

 The finder attached to the telescope has a very low magnify ing-power 

 and decidedly bad definition — so much so that even Saturn can scarcely be 

 recognized with it ; none but the most conspicuous nebulae and clusters 

 are visible ; I have looked in vain for the planetary nebula in Lyra with 

 it, though it was certainly in the field ; and of all the planetary nebulae in 

 the southern hemisphere, only two (Nos. 2102 &4510) are noted by me as 



