Dec. 3, 1 88 5 J 



NA TURE 



be, if not "antagonistic to Darwin's theory of Natural Selec- 

 tion," at all events, as I expressed it, " an important emendation 

 of Darwinism." My object, therefore, while reviewing the 

 essay was to show that this is a character which does not belong 

 to it. If I have misunderstood the meaning of its author on 

 this fundamental point, I should have been glad to have received 

 a more express statement of the fact than appears in the above 

 letter ; for I might then have felt that Mr. Dixon's views with 

 reference to the value of his work are in full accordance with my 

 own. As stated in the review, I consider his facts most inter- 

 esting as examples of trivial specific characters — or slight varia- 

 tions of a fixed kind — due to variation presumably unaided by 

 selection ; and when I said that such facts " may be freely pre- 

 sented to the anti-Darwinians," I meant that they might be so 

 presented to any one who supposed them anti-Darwinian. It 

 appeared to me that Mr. Dixon himself regarded them in this 

 light (though not as anti- evolutionary), at all events to the extent 

 of imagining that they had not been suiBciently recognised by 

 Darwinian';. But, as I have said, if such is not his meaning, I 

 am very glad to find myself in agreement with him upon this 

 point. 



1 spoke of these trivial specific characters as "odds and 

 ends," and as of " comparatively rare occurrence," because, 

 although both numerous in themselves and of importance for the 

 purposes of detailed classification, they are insignificant when 

 compared with the whole organising work of natural selection. 

 And if, as Mr. Dixon now repeats, it was the object of his little 

 book "to try and explain the agents " (i.e. the causes) producing 

 these non-purposive specific characters, I can only repeat that in 

 this respect his book has failed in its object. Lastly, my only 

 reason for not mentioning Mr. Dixon's views on natural selec- 

 tion, &c. , was that I found nothing in these views particularly 

 deserving of mention. George J. Romanes 



On Radiation of Heat from the Same Surface at Different 

 Temperatures 



With respect to my recent communication to you on the 

 subject of radiation of heat at different temperatures (p. 85), I 

 wish to remark that the temperature given as the temperature 

 of the surroundings must be taken as only approximate. A 

 remark to this effect was in fact included in the first draft of my 

 note to you, and was inadvertently omitted in the final copy. 



If the glass envelope surrounding the wire were perfectly 

 diathermanous, and likewise the intervening air, then the tem- 

 perature of the surroundings would be simply that of the walls 

 of the room. As it was there is a great difficulty in saying pre- 

 cisely what is to be taken as the temperature of the surroundings. 

 The glass envelope becomes heated to some extent, and will 

 return a certain amount of radiation to the wire. When the 

 vacuum is nearly complete, however, the heating of the glass is 

 slight, and is very small in comparison with the heating when 

 the vacuum is only partial. 



The reason I have not used a metallic envelope blackened 

 inside and cooled outside, is that it is very difficult to attach such 

 an envelope in a satisfactory way to the Sprengel pump. I am, 

 however, hopeful of being able to overcome this difficulty. 



November 28 J. T. Bottomley 



THE NOVEMBER METEORS 

 'T~"HE watch which was kept on November 27 in the 

 -'- hopes of seeing a shower of meteors from the 

 stream connected with Biela's comet was very amply 

 rewarded. At the Royal Observatory, Greenwich, the 

 weather was somewhat unfavourable, the sky being partly 

 clear only at intervals, yet, when the meteors were first 

 seen, between 6h. and 7h. p.m., they were appearing at 

 the rate of from 30 to 40 per minute. The average 

 brilliancy of the meteors was remarkable. The radiant- 

 point as determined at the Greenwich Observatory from 

 a number of paths was estimated to be about R.A. 20°, 

 Decl. 49° N. 



We have received the following communications with 

 reference to the meteor showers : — 



The great display of Andromedes, or meteors of Biela's 

 comet, which occurred on the evening of November 27 

 last, and which fortunately has been widely observed, 



adds another corroborative link to the theory, already 

 demonstrated by facts, connecting comets and meteors. 

 Not only does this stream exhibit a perfect orbital resem- 

 blance to that of the comet with which it has been 

 associated, but it recurs only at the special times when, 

 according to computation, the comet is in the vicinity 

 of that region of its orbit encountered by the earth on 

 November 27. 



Many meteors appeared on the evening of November 

 26 this year, the hourly rate, as estimated at Bristol, 

 being considerably over 100, and they nearly all belonged 

 to the shower from Biela's comet. But the display on 

 that night was not of very exceptional richness, though it 

 gave distinct intimation of what was to follow. The 

 meteors of November 26 were simply the avant couriers 

 of the advancing host, for, as soon as twilight deepened 

 on the following evening, it was seen at once that the 

 shower had greatly intensified. Meteors were falling so 

 thickly as the night advanced that it became almost im- 

 possible to enumerate them. Frequently they came in 

 simultaneous groups of five, seven, or ten, all radiating 

 from the immediate region of the star y Andromeda;, and 

 appeared in every cjuarter of the firmament with that uni- 

 form slowness of movement which is a peculiar feature of 

 the shower. 



The prediction that such a display would occur has 

 thus been completely verified, and the character of its 

 leading features has been precisely conformable to antici- 

 pation. For not only has a meteor-shower occurred at 

 the appointed time, but it has coincided in all its salient 

 attributes with what has been expected. The radiant- 

 point near y Andromedje has been accurately marked, as 

 on November 27, 1872, and the meteors have presented 

 the same visible traits of appearance. 



As to the strength of the display, it has been variously 

 described, but there can be no doubt, from the observa- 

 tions, that it will rank in importance with any similar 

 phenomenon recorded in modern times. At stations 

 where the clearness of the atmosphere permitted its full 

 grandeur to be recognised, it would seem that about one 

 meteor per second was counted, and this means a rate of 

 3600 per hour. 



These facts warrant us in the assumption that the earth 

 has recently encountered a very dense region of the 

 meteor-stream. Notwithstanding that these meteors 

 have to overtake the earth in her orbit, and that they 

 therefore travel with the minimum velocity (about eleven 

 miles per second) possible in the case of such bodies, 

 they have returned in surprising abundance. A far more 

 attenuated system, encountering the earth under similar 

 conditions to the Leonids of November 13, which directly 

 meet the earth in her path, must have originated a more 

 numerous display, because a far greater range of such a 

 stream would be traversed in the same interval. Here 

 the velocities of the earth and meteors would be com- 

 bined by the favourable circumstances of the rciico?it>'e, 

 and the earth would really penetrate the stream at the 

 rate of some forty-four miles per second. But in the 

 instance of the meteors from Biela's comet, they are 

 travelling in the same general direction as ourselves, and 

 it is only their greater native velocities which enable 

 them to catch up the earth, and become visible in the 

 form under which we have just observed them. 



When all the accounts of this remarkable display be- 

 come available for reduction, it will be important to com- 

 pare them with those of its predecessor in November, 

 1S72. Though the present shower has been an obvious 

 repetition of the one just referred to, it may exhibit some 

 differences which it will be essential to investigate. In 

 one respect certainly there would appear to be a want of 

 accordance. We refer to the relative durations of the 

 two displays. In 1872, on November 26 and 28, that is, on 

 the nights preceding and following the great shower, very 

 little sign of it appears to have been observed. It was 



