6o6 



NA TURE 



[_. \hrit 30, 1885 



temporary stars we have grounds for looking to the 

 tatter, while in the case of stars of the Algol group we 

 have reasons for looking to the former, as a more or less 

 probable cause of the changes we observe. While in 

 ,i Lyras we see that physical changes apparently accom- 

 pany, if they are not connected with the cause of, the 

 light variation. Is it to geometric or to chemico-physical 

 causes that we are to look as the key to the explanation 

 of the ph.-nomena in other groups, say of the large group 

 of Class II.? A few considerations will show the grave 

 difficulties we have to meet. A difference of from five to 

 seven magnitudes between the points touched by the star 

 at maximum and minimum is to be found in the case of 

 many members of Class II. Now, taking the magnitude 

 scale at present generally adopted, having a light-ratio 

 of 2'5I2, a range of five magnitudes would correspond to 

 a difference of light-intensity in the proportion of 100 to 1, 

 while if the range is extended to seven magnitudes, the 

 star's light-intensity at maximum would bear to its light- 

 intensity at minimum a ratio of 630 to 1. These wide 

 differences of intensity of radiation are sufficiently start- 

 ling if they are supposed to occur only once in a while, as 

 in the case of the temporary stars. What are we to say 

 of them if we are to suppose them to occur over and over 

 and over again, in periods of from 150 to 600 days? The 

 subject was discussed in these columns some few years 

 ago, and the difficulties presented were felt to be so 

 serious as to make it hard to accept a theory of this kind 

 as offering a probable explanation of the facts if these 

 stars are to be regarded as sun 5 in the usual sense of the 

 term, though less difficulty might be felt if we could look 

 on them, not as suns in our sense at all, but as small 

 bodies. In this case they would be relatively near to us, 

 and would have a measurable parallax. An inquiry in 

 this direction might prove fruitful. As compared with 

 this theory, the theory that the changes of light may be 

 supposed due to periodic obscurations by bodies or groups 

 of bodies revolving around the variable, presents less 

 formidable objections, though it has, of course, difficulties 

 of its own. A few months ago one of our first authorities 

 on the subject penned the words : " No theory has yet 

 been advanced that will account satisfactorily for the 

 ordinary phenomena of variable stars." It is possible 

 that we must look forward to a future of more or less 

 lengthened patient research before theoretic views can be 

 announced which shall be anything much better than 

 "guesses at truth." 



It is, then, to further work that we must look for further 

 progress, and the recent discoveries in regard to /3 Lyric 

 indicate one direction at least in which research should 

 be made. Is it not possible that some valuable results 

 might be obtained if the spectra of a selected list of 

 variable stars were to be carefully studied with one of our 

 largest telescopes — the several spectroscopic results 

 being co-ordinated with the corresponding position of the 

 star in its light-curve as fixed by a careful determination 

 of its magnitude ? In the discovery of new variables, 

 the determination of their periods and range of variation, 

 and of the general characteristics of their light-curves, 

 good work may be done with instruments of very moderate 

 dimensions ; but for all but the brighter stars the spectra 

 are too faint to be adequately treated but by instruments 

 of the largest size. 



Whether by this means any satisfactory results should 

 be obtained or no, it is evident that in the study of 

 variable stars a point has been reached whence, in order 

 to secure any further advance, it seems needful by some 

 means or other to endeavour to take a new departure. 



THE LATE EARL OF SELKIRK 

 AN Saturday, April 11, 1885, Dunbar James Douglas, 

 ^S sixth and last Earl of Selkirk died, after a short 

 llness, at St. Mary's Isle, Kircudbright ; had he lived till 



the 22nd of the month he would have completed his 

 seventy-sixth year. His death, though it occurred at a 

 ripe age, has proved a sudden and unexpected blow to 

 those who hoped that many years of life might yet remain 

 to one upon whose spare and still vigorous frame, age had 

 as yet apparently made but little impression, and whose 

 mental and physical energy alike gave promise of a still 

 prolonged period of utility. Those who so recently saw 

 him in even more than his wonted health now sadly 

 realise the fact that he has succumbed, like many others, 

 to the evil influences of the treacherous and bitter east 

 winds which for some time swept over our islands, and 

 terminated his valuable life after a short illness of but 

 three weeks. How much he is regretted, how sorely he 

 will be missed, it is impossible to say ; for the removal of 

 one so gifted and so good is an irreparable loss, which 

 will be felt more and more as time progresses, wherever 

 the genial influence of his life and example had been felt 



Elsewhere have been described his ancient lineage, his 

 connection with various great families of historic fame, 

 his political opinions, his public life, the high offices he 

 filled in the State and in his county, the charms of 

 personal character which marked his whole life ; his edu- 

 cation at Eton, his success at Oxford, his travels and ex- 

 plorations in almost every quarter of the globe ; the rich 

 harvest of experience he so assiduously collected and so 

 carefully and accurately remembered ; his thoughtful, un- 

 selfish nature, so loyal, so considerate of others, especially 

 of the weak ; so firm in assertion of all that he believed to 

 be right, so excellent in all relations of public, private, and 

 domestic life, so true a friend, so mindful of all who ever 

 did or tried to do him the slightest service — all this 

 may some day be told again in detail, but need not be 

 dwelt on here in this brief notice, which contemplates 

 rather the side of his nature which turned towards science 

 and took so keen an interest in its progress and welfare, 

 he himself being no mean contributor to its annals. Those 

 who, like the writer, have had the privilege of intimate 

 association with him, in the field, on the moor, in social 

 life, and by the evening fireside, and have listened to his 

 instructive conversation on many subjects connected with 

 natural science, history, geography and biography, and 

 have felt the satisfaction which arises from communion 

 with one whose wisdom and experience seldom erred, 

 who enunciated no crude theory, made no hasty gene- 

 ralisation on imperfect or insufficient data, and whose 

 judgment was tempered, calm and reasonable in all 

 matters submitted to it for decision, must feel that, by his 

 death, science too has sustained a serious loss. 



Lord Selkirk's great erudition and knowledge of men 

 and nature were not derived merely from books. He 

 was, indeed, a great reader, whose memory retained with 

 extraordinary tenacity all the details even to minute 

 particulars of that which he read : his vast stores of in- 

 formation were the result of much travel and study of 

 physical science. Few, indeed, had travelled so far, or 

 seen so much, or with such intelligent appreciation of 

 what the)- did observe. 



His mind was of a truly scientific mould, and accepted 

 nothing on insufficient or imperfect evidence ; his interest 

 in all that was calculated to extend the limits of science 

 was unbounded ; but of all its departments, geology 

 seemed to attract him most : he was a Fellow of the 

 Geological Society, a frequent attendant at its meetings, 

 and a contributor to its proceedings. One paper on 

 " Sea-water Level Marks on the Coast of Sweden," read 

 before the Society in 1867, was of much interest, and 

 shows how closely he had studied that important subject. 

 He was also a Fellow of the Royal Society, and toeflc 

 much interest in its proceedings, but deafness, which 

 affected him early in life and increased with age, pre- 

 vented him from taking an active part in the discussions 

 of the learned societies, or in the debates in the House of 

 Lords, and to a certain extent, therefore, disqualified him 



