November, 1903.] 



KNOWLEDGE. 



255 



Man, where it probably breeds, and Dr. T. E. Saxby finds a pair 

 nesting in West Slietland. 



Wii/eoa Breeding in Ireland — A Correetion(Irish Natttralist, 1903, 

 October, p. 275). — In 1901, Mr. Robert Patterson recorded that the 

 Wigeon Lad bred near Belfast (.see Knowledge, 19u1, pp. 183 and 

 205). A bird was flushed from one nest, but was not identified 

 apparently. Mr. Patterson now frankly admits that a mistake has 

 been made, and that the record must be cancelled. The eggs and the 

 down agreed with those of the Wigeon, but. through Mr. Heatly 

 Noble, Mr. Patterson has learnt that the down is not always a reliable 

 test for the identification of duck's eggs, and an examination of the 

 small feathers mixed witli the down from this nest has proved that 

 they belonged to the Shoveler. 



An Unknown Warhler in Oxfordshire. By W. Warde Fowler, M.A. 

 {Zoologist, 19(13, September, pp. 343-348 ).— In these days of the 

 rigid protection of birds tliis article should prove instructive to those 

 who favour extreme protection, as well as to the ornithologist. Mr. 

 Warde Fowler and several of his friends have been tviitehing for the 

 last tliree years a small Warbler in a wood near Oxford. They have 

 been quite unable to identify the bird, and would not shoot it, and 

 the results of their observations are detailed at lengtli by Mr. Fowler 

 in the hope that some one may be able to identify the bird by the 

 details given. From a scientific point of view these observations are 

 quite worthless without the identification of the bird, which is 

 impossible from tlie details obtained. Much personal pleasure was 

 enjoyed, no doubt, by the observers in watching the bird, and in 

 collecting these details, but those who advocate protection at all costs 

 should bear in mind that without the knowledge of birds obtained by 

 systematic study, as well as by observation in the field, protection of 

 birds would never have been possible. 



All contributions to the column, either in the way of notes 

 or photograplis, should be forwarded to Habby F, Withebby, 

 at the Office of Knowledge, 326, High Holhorn, London. 



%ttttt9. 



[The Editors do not hold themselves responsible for the opinions 

 or statements of correspondents.] 



EADIUM AND THE SUN'S HEAT, 



TO THE EDITORS OF KNOWLEDGE. 



Sirs, — The interesting article on radium in Knowledge 

 fur October prompts me to inquire whether the heat- 

 giving property of its complicated atom can be called in 

 aid to explain more satisfactorily the source of the sun's 

 heat? Do we see any analogy at all between this 

 minute atom and the mighty globe of the sun in their heat- 

 giving and hcat-nKiiutaining projierties ? Or docs the 

 discovery of the new element explode the present theory of 

 the source of the sun's heat? p_ j Damania. 



2nd October, 1903. 



[There is no doubt that the discovery of radium compels 

 us to abandon completely some of the conclusions, based 

 u)>on present theories of the origin of the sun's heat. Mr. 

 W. E. Wilson calculates that " 30 grammes of radium per 

 cubic metre of the sun's volume would supjily the entire 

 output " of the sun's energy. He further suggests that at 

 the temperature of the sun, radium may be much more 

 energetic than at our terrestrial tcnuieratures. If so a 

 much smaller weight of radium per cubic metre may 

 sufliee. The computations which Lord Kelvin and other 

 leading men of science have made as to the possible length 

 of time in the past, and in the future, during which the 

 sun could maintain its present energy of radiation, are 

 necessarily entirely set aside, for we can no longer assume 

 th.tt the concentration of the sun's substance from infinite 

 distance has been the sole or even the chief source of its 

 energy. It is not only that radium itself may e.\ist in suffi- 

 cient abundance in the sun to account for its energy, but the 

 same or similar radio-active pro]ierties may be possessed 

 by other of its elements, or by the sun itself as a whole. 

 Prof. G. H. Darwin writes: " Knowing as we now do that 

 an atom of matter is capable of containing an enormous 



store of energy in itself, I think we have no right to 

 assume that the sun is incapable of liberating atomic 

 energy to a degree at least comparable with that which it 

 would do if made of radium "' (Nature, 1903, September 

 24th, p. 496). — E. Walter Maunder.] 



THE LEONID METEORS AND THE MOON. 



TO THIi EDITORS OF KNOWLEDGE. 



Sirs, — An investigatioAinto tlie circumstances connected 

 with the occurrences of the Leonid star- showers shows that 

 there subsistsf^jttie, ,-followLa" relationship between these 

 phenomena anof^tlieljoon. All' the Leonid meteor- showers 

 on record have taken place either at or between new moon 

 and first quarter, or else at "or between full moon and last 

 quarter, with the lunar perigee generally placed at or 

 between full and new moon, the intensity of the phenomenon 

 being greater the nearer the perigee and moon were to 

 her phases of new or full. In the following table a list of 

 these historic star-showers, as given by Prof. Newton in 

 the " Encyclopaedia Britannica," Vol. XVI., p. 110 (9tli 

 Edition), is presented, together with the positions of the 

 moon and perigee at the time of each display : — 



The star-shower toot place iu each instance on the 

 morning of the date given, and therefore local time is used. 

 These displays occurred without exception at or between the 

 time of new moon and first quarter, or else at or between 

 the opposite lunar phases. Our satellite at the time of 

 these showers was thus confined to two opposite quadrants 

 which together equal one-half of her orbit. As far as it is 

 a question of chance, the moon was just as free at any one 

 of these showers to have been in the remaining half. It 

 is excessively improbable, therefore, that this peculiar 

 position of the moon in sixteen successive instances should 

 have been due to mere coincidence. As regards the position 

 of the perigee there is only one notable exception, viz., in 

 the shower of 934, when the perigee was near the moon's 

 first (piarter. This display was of a feeble <-haracter, 

 judging fi-om the ancient account of it. We know from 

 the records describing these phenomena (American Journal 

 of Science and Artt!, 1864, No. Ill), that the showers of 

 1202. 1366, 1799, and 1833 far surpassed the others in 

 brilliancy, and that the meteors were or must have been 

 seen in tens of thousands. These intensely l)rilliant spec- 

 tacles were witnessed at or immediately after the time of 

 new or full moon. It may also be observed that at the 

 time of the occurrence of the first three of these famous 

 star-showers, tiic moon was moving in an orbit, of almost 

 maximum eccentricity, having been in perigee within a 

 few hours of the time when she was new or full. 



It is, perhaps, not surprising to find that the law which 



