14 



KNOWLEDGE 



[January 1, 1896. 



On St. Andrew's Day, Lord Kelvin delivered his retiring 



address as I'rosident of the Uoyal Society. Eeferring to 

 the losses of members sustaiued by the Society during the 

 past year, he mentioned Cayley, one of the makers of 

 mathematics ; Fran/, Neumann, one of the most |)rofound 

 and fertile of all the workers in mathematical physics of 

 the nineteenth century ; Huxley, a man who can ill be 

 spared, a resolute and untiring searcher after truth, and 

 an enthusiastically devoted teacher of what he learned 

 from others and what he discovered by his own work 

 in biological science ; Louis Pasteur, who, before he 

 entered on his grand biological work, made a discovery of 

 first-rate importance in physics and chemistry — the 

 formation of crystals visibly right-handed and left-handed 

 from one solution — and who, by the line of research to 

 which he devoted most of his life, conferred untold benefits 

 on humanity and the lower animals. Lord Kelvin went 

 on to describe the further work on the nature of argon, 

 and the discovery by means of spectrum analysis of a new 

 element identitied with the one called helium, found thirty 

 years before to exist in the sun. After dealing with 

 the awards of the various medals — the Copley medal to 

 Dr. Karl Weierstrass for his investigations in pure 

 mathematics. Royal medals to Dr. .Tohn Murray for his 

 editorship of the report of the ClmUeniier expedition 

 and to Prof. Ewiug for his investigations on magnetic 

 induction in iron and other metals, and the Davey medal 

 to Prof. Ramsay in recognition of his work on argon and 

 helium — Lord Kelvin concluded by referring to the keen 

 regret which he felt that the live years during which he 

 had presided were past, and that he ceased to be the 

 President of the Royal Society. 



Utttcrs. 



[The Editors do not hold themselves responsible for the opinions or 

 statements of correspondents.] 



VABIABLE STARS. 

 To the Editors of Knowledge. 



Sirs, — The statements in my note in June (1895) 

 Knowledge, as to the variations in period and fluctuations 

 in light of Mira and R Leonis at their last appearance, 

 having been fully verified by the observations of Mr. 

 H. M. Parkhurst, of Brooklyn, New York, published in 

 the Astronomical Journal of June 2nd and August 5th, and 

 by your own correspondents, Messrs. Corder and Backhouse, 

 to whom my thanks are due, that question may be regarded 

 as settled, and in a way very gratifying to the present 

 writer. 



And now, with your permission, I will inquire what has 

 been the experience of observers on your side with R 

 Scutum Sobieski this season. The star has long been 

 observed, and, like those mentioned above, is regarded by 

 the professionals, and those having large telescopes, as a 

 " chestnut," and is neglected. But if there is any relation 

 between variable stars and cometary and other random 

 things, as is supposed, their observation by careful 

 observers with small apparatus may lead to important 

 results. 



The magnitude of R Scuti, as given by Webb, vol. ii., 

 is at maximum 4-7 to 5-7, at minimum 6 to 9. The 

 Companion gives the foHowing ephemeris : — Minimum 

 July 6th, maximum August 6th ; minimum September 

 11th, maximum October IGth. The minima, according to 

 Webb, are alternately bright and faint, and Klein says the 

 period is irregular. I took up the star, and estimated its 

 light by comparison to be — July 25th, 5-7 magnitude ; 



August 6th, 6-8 ; August 2l8t, 5-7 ; August 28rd, 5-6 ; 

 September .'ith, 0'2 ; September IHth, 6-5 ; September 22nd, 

 7-00 ; October 4th, 7-5 ; October 5th, 8-0; October Hth, 80 ; 

 October 10th, 7-8 ; October 12th, 7-(! ; October 14th, 75 ; 

 October 15th, 7'4. 



From these observations it appears that the star is 

 behind time in period as well as in light, and that the 

 light lluctuatos. Of the four stars, A, r, (/, and c, cast of it, R 

 has been the faintest since October 1st ; <!, by photometric 

 measure, is 7'17 magnitude, falling below over half a 

 magnitude on October 5th. 



Memphis, Tenn., U.S.A. Davu) Flanery. 



SECOND liLOOMTXG OF TllK HOLLY. 

 To the Editors of Knowledge. 



SiES, — Among the many second flowerings resulting from 

 the exceptional clemency of the past autumn is one which 

 I have never noticed here before, viz., that of the holly. 

 This district forms part of the high plateau of the Midlands, 

 and our well-known holly woods stand upon so high an 

 elevation as to be exposed to winds from every direction. 

 Nevertheless, a second flowering has occurred this autumn. 

 I found one tree to-day bearing both the red berries from 

 the spring blooming, and a second and plentiful crop of 

 partially opened flower-buds. 



Alfrkd J. Johnson. 

 Boldmere, Sutton Coldfield, 

 December 8th, 1895. 



Notices of iSoolts. 



Notes on the Nebular Thcon/. By William Ford Stanley, 

 F.R.A.S., F.G.S., &c. (Kegan Paul.) Illustrated. 

 Although much has been written in support of the nebular 

 theory of Kant and that of Laplace, few original thoughts 

 have been added to it, and quantitative data have been 

 markedly deficient in connection with the subject. There 

 is little doubt that celestial bodies can be arranged in 

 regular order, from nebulfe, " without form and void," 

 through symmetrical nebula; like Andromeda into stars 

 connected with streams of nebulosity, and then into the 

 finished product ; and the form of a nebula in any par- 

 ticular stage of its development is probably the result of 

 the action of gravitation upon it while in the preceding one. 

 But this arrangement is only a scenic one ; and though 

 the spectroscope helps very considerably to define the order 

 of celestial evolution, much yet remains to be done in 

 determining the mathematical and physical conditions 

 which lead to the observed differences in structure. Mr. 

 Stanley has treated the subject in a philosophic manner, 

 and his contribution deserves serious attention. It is 

 difficult to trace his arguments in the short space of a 

 review, but we may say at once that they bear the impress 

 of original thought. To begin with, Mr. Stanley points 

 out that the full consideration of the nebular theory 

 requires the existence of a more attenuated form of gaseous 

 matter than the nebulre. This material he terms the 

 pneuwa, which he supposes to have pervaded all space, 

 to contain all the chemical elements, and to represent 

 the state of infinite diffusion proposed by Helmholtz. It 

 is suggested that the mode of condensation which renders 

 nebulous matter visible to its extreme outlines is purely 

 chemical, and takes place within the exterior surface of the 

 nebula only. Chemical action is, indeed, believed to cause 

 the degradation of the pneuma to a gas or a nebula. 

 Having traced what he considers to have been the mode 

 of formation of stellar and solar systems from the original 



