AtrausT 1, 1899.] 



KNOWLEDGE. 



179 



elected a Fellow of the Eoyal Society in 1864, and received 

 from that learned body a Royal Medal in 1882. In 1879 

 he became President of the Zoological Society, and 

 presided over the anatomy section of the International 

 Medical Congress which met in London in 1881 ; from 

 1883 to 188-5 he served as President of the Anthropologi- 

 cal Institute, and was President of the British Association 

 in 1880, having previously acted as president of the biolo- 

 gical section in 1878 and of the department of anthropology 

 in 1881. Oxford and Cambridge both conferred honorary 

 degrees upon him, and the Institute of France appointed 

 him one of its corresponding members. In the Jubilee 

 year, 1887, he received the honour of C.B., and in 1892 

 he was knighted. Sir William's best-known work is, per- 

 haps, "The Horse; a Study in Natural History, " although 

 several other works emanated from his pen — " An Intro- 

 duction to the Osteology of the Mammalia ; " " Diagrams 

 of the Nerves of the Human Body ; " " Fashion in 

 Deformity," and "Mammalia," in the "Encyclopaedia 

 Britannica," as well as many minor articles on zoological 

 subjects in that ponderous work of reference ; but a large 

 portion of his writings remains entombed in the proceedings 

 of the Royal Society and other learned bodies. Morphology 

 was. however, enriched by the "Memoirs on the Brain and 

 the Dentition of the Marsupialia, ' which he published in 

 1SG5 and 1867, and his papers on the " Characters of the 

 Cranium in the Camivora ' and on the " Evolution of the 

 Cetacea " constitute valuable acquisitions to scientific 

 literature. Sir WUliam stedfastly urged the importance 

 of museums as instruments for the advancement of know- 

 ledge in two ways — by affording facilities for scientific 

 research, and by providing the means for popular instruc- 

 tion ; these views he put in practice during his reign at 

 the Natural History Museum, and the innovations he 

 introduced were attended with excellent results. 



Hetttrs. 



[The Editor* do not hold themselves responsible for the opinioDj or 



statements of correspondents.] 



* 



HONEYSUCKLE FLOWERIXG IN A STRANGE PLACE. 



To the Editors of Knowledge. 



Deab Sibs, — In a beautiful garden at Uckfield, I saw 

 the other day a sight that rather surprised me. A 

 dead branch had fallen from a tree into a lake. From 

 this branch an arm stood some four feet straight out of 

 the water. On the top of this arm has now appeared a 

 honeysuckle, trailing some inches down. The seeds of 

 this plant were no doubt deposited by a bird, but how does 

 it obtain sufficient moisture to be in the healthy condition 

 it is ■? Is it capillary attraction, or are long suckers shot 

 down by the plant into the water '? 



Jos. F. Green. 



THE DISTRIBUTION OF THE ST.LR3. 



To the Editors of Knowledge. 



Sibs, — The subject of Dr. Burns's article in your July 

 issue is one on which I have bestowed a good deal of 

 attention. My earliest articles on it appeared m 

 The Sidereal Messewjer for 1888. In the first of them, I 

 inferred that if the stars of the Hth magnitude were all 

 placed on the surface of a sphere, those of the «-l-lth 

 would be placed on the surface of a sphere with a radius 

 1'585 times greater, and would, therefore, on the hypothesis 

 of uniform distribution, be 2-512 times as numerous. I 

 discovered and corrected my mistake before any other 

 contributor did so, but the curious circnmstance is that 



the wrong figure accorded much better with observation 

 (based on photometric measures) than the right one. It 

 was indeed somewhat too low, but the right figure was 

 considerably too high. 



Argelander's magnitudes cannot be regarded as based on 

 the ratio of 2-512 for one magnitude, and 9-5 being the 

 lowest magnitude mentioned in his tables, he has included 

 imder that head stars of the 10th magnitude and even below 

 that magnitude. Our only real guide is that afforded by 

 photometric measures, in which Pogson's scale was adopted. 

 The various publications of the Harvard Observatory 

 contain the best and most extensive tables at present 

 available. But I should doubt the correctness of any 

 measures as low as the 17th magnitude, and am not at all 

 surprised at the apparently discordant results arrived at by 

 Dr. Bums from an examination of them. 



In my recent little book " An Introduction to Stellar 

 Astronomy," I summarised briefly the results of my previous 

 investigations thus : "So far as I have compared photo- 

 metric measures of stars, I think the theoretical proportion 

 of four to one for the numbers of stars of two successive 

 magnitudes is rarely, if ever, realized. If all stars are of 

 equal intrinsic brightness, and light varies as the inverse 

 square of the distance, a thinning-out commences at 

 (comparatively speaking) no great distance from the earth 

 or sun " (pp. 38-9). And I go on to point out that if the 

 theoretical ratio were even approached in the case of very 

 faint stars, the total sky-light would be vastly greater than 

 it is. Let me illustrate this by comparing the total hght 

 of stars of the 5th and the 105th magnitudes on the 

 hypothesis of uniform distribution. The light of each star 

 is diminished in the proportion of 1"585-"^', but the total 

 number of stars is increased in the proportion of l-oSo^"" 

 to 1. The total light is, therefore, greater in the proportion 

 of 1-585' '^'^ or 10- ' to 1. Written in figures, this would 

 be represented by 100,000,000,000,000,060,000 to 1. The 

 collective hght of the stars of the 105th magnitude would, 

 on this hypothesis, be much greater than that of the sun, 

 and the change made in the total amount of sky-light by 

 the rising and setting of the sun would become utterly 

 insignificant. 



W. H. S. MoNCK. 



THE NEBULA N.G.C. 2237-9 MONOCEROTIS. 

 To the Editors of Knowi,edge. 



Sirs, — The remarkable photograph of the above object, 

 to be found at p. 132 of the June number of Knowledge, 

 must, I think, impress every one who sees it with the 

 great skill of the photographer, Dr. Isaac Roberts, and 

 the perfection to which he has reduced the portrayal of 

 the nebulae. But there are other considerations which 

 have struck me while looking at this picture. The first is 

 the enormous extent of the nebulous matter. If we 

 assume the parallax to be, say 05", which is probably far 

 over the mark, and consequently the real distance under 

 estimated, the diameter, or greatest linear extent (per- 

 pendicular to line of sight) of that portion of the nebula 

 situated in the N.P. part of the whole system, comes out 

 about two hundred and sixty-seven thousand millions of 

 miles ; or, in other words, at least forty-eight times the 

 diameter of Neptune's orbit. But all the separate nebu- 

 losities shown in this picture would seem to be undoubtedly 

 connected ; and we find that the greatest extent of the 

 whole system exceeds one hundred and twenty-seven times 

 the diameter of Neptune's orbit. Such figures convey 

 absolutely no idea of their reality to our minds ; yet unless 

 any one can show that the nebula is very much nearer to 

 us than the generality of the stars, it must be conceded 



