September 29, 192 1] 



NATURE 



149 



limited to the taking of stellar spectra and classi- 

 fying them on Lockyer's principle of classification. 

 Adams suggested at once that it might be pos- 

 sible to measure the spectra in the manner he has 

 developed for the* determination of the absolute 

 magnitude of a star, from which its distance 

 might be deduced. This suggestion has been 

 taken up at the observatory with very creditable 

 success. It is obvious that to take up new work 

 of this delicate kind involves much preliminary 

 experiment ; the method depends essentially on 

 estimating the relative intensities of pairs of lines 

 in the same spectrum, and the uncertainties at- 

 tending estimates of intensity are well known ; but 

 these difficulties have been courageously faced. 

 We may quote a sentence from the last report : — 

 "A wedge has been designed and constructed for 

 this purpose, and a preliminary series of measures 

 made to test its suitabilitv. This method of 



been presented to the observatory by his sons. 

 Dr. McClean's own work in classification of 

 spectra, especially for stars in the southern hemi- 

 sphere, and his measurement of some of them by 

 which he discovered for the first time the exist- 

 ence of oxygen in the stars, are matter of history ; 

 and it may safely be asserted that if he were alive 

 to-day to make a choice he could scarcely have 

 found work for his old telescope in closer con- 

 formity with that which it executed in his own 

 capable hands. 



His sons have throughout shown a filial in- 

 terest in the observatory, and their share in the 

 endowment of it has been very generous ; but there 

 are natural limits to private munificence, or at 

 any rate to the purses of one or two individuals, 

 and if the observatory is to prosper as it deserves, 

 further help, which is urgently needed, must be 

 sought for elsewhere ; and this brings us back to 



Fig. 2. — Norman Lockyer Observatory. OflBces and terrace, looking north. 



measuring relative intensities of the lines appears 

 to be quite satisfactory, and two reports on the 

 work which have been sent to the Research Com- 

 mittee have been commented upon verv favour- 

 ably." • 



Should this early promise be maintained, the 

 observatory will have initiated a line of work new 

 to England, and, indeed, so far as we know, new 

 everywhere excepting at Mount' Wilson. Mean- 

 time the former work of classification will not be 

 neglected, and will possibly be extended by adding 

 accurate determinations of the Harvard classifica- 

 tion for comparison with those of the Lockyer 

 classification. Such a systematic comparison must 

 be of great value for arriving at a final standard 

 system, whatever that may be. 



It is a special pleasure to reflect that this work 

 accords so closely with the ideas of the late Dr. 

 Frank McClean, F.R.S., whose telescope has 

 NO. 2709. VOL. 108] 



the question with which we started — viz. Can an 

 observatory, and especially can this particular 

 observatory, be run as a joint enterprise? The 

 idea was put forward first in June, 1914, but the 

 war brought inevitable delays, so that only re- 

 cently has it been possible to face the situation 

 definitely. 



The quickest way to make clear the nature of 

 the suggested new departure is to quote the fol- 

 lowing sentence from the little handbook compiled 

 by Major Lockyer (6d.) giving an excellent 

 account of the observatory : " Anyone can further 

 the interests of the observatory by joining the 

 corporation, either by subscribing a guinea a vear, 

 and thus becoming an annual member, or bv pav- 

 ing lol. and becoming a life member." Com- 

 munications should be addressed to the bonorarv 

 secretary, Capt. W. N. McClean, i Onslow 

 Gardens, London, S.W.7. There are, of course. 



