486 



NATURE 



[April 20f 1876 



In a careful examination, however, of the whole argument of 

 the amhors of the " Unseen Universe," it looks to me as though 

 they saw clearly to what their course of reasoning, lis far as this 

 particular point is concerned, tended, but were willing to stop 

 short of the true logical result, believing that humanity was not 

 yet prepared to admit that we are only a small part of one 

 Stupendous whole, a universe of individual life. 



Of the main object and scope of their argument I have 

 nothing to say, only this : if the premises assumed — and they 

 are the assumptions of the modern school of science — are cor- 

 rect, there is nothing unreasonable in the conclusions at which 

 the authors have arrived. 



Note. — Since writing the above I have seen the authors' pre- 

 face to the second edUion of the " Unseen Universe," in which 

 they say: "To reduce matters to order, we may confidently 

 assert that the only reasonable and defensive alternative to our 

 hypothesis (or, at least, something similar to it) is the stupendous 

 pair of assumptions that visible matter is eternal, and that it is 

 ALIVE. If anyone can be found to uphold noti ns like these 

 (from a scientific point of view), we shall be happy to enter the 

 lists with him." If the distinguished authors will confine them- 

 selves to this proposition, that " All visible aggregations of 

 matter, such as our earth and its congeners, are living organisa- 

 tions, in other words, are alive," I think the affirmative can be 

 successfully maintained. 



"Whether matter is eternal and each individual particle or 

 atom of matter is alive, is too far in the interior of the unknow- 

 able to be discussed with any possibility of successful results, 

 and, too, the idea of an atom being a living organisation is 

 directly opposed to the whole theory of atomicity, and scientifi- 

 cally ludicrous in view of that theory. JosiAH Emery 



City of Williamsport, Pa., U.S., March 10 



Prof. Tait on the Earth's Age 

 It is well known that Sir W. Thomson has concluded, from 

 different lines of argument, that the age of the earth, as a body 

 cool enough for habitation, cannot be much greater than a hun- 

 dred million years. 



Prof. Tait, in his "Recent Advances in Physical Science," 

 recapitulates these arguments, but with a different conclusion. 

 lie states the limit of age to be about ten million years. 



As the subject is of immense interest, may I ask Prof. Tait 

 to explain this change of conclusion ? J. D. Everett 



A Relapsed Donkey 



Some years ago on one of the Lucknow roads I met a 

 "Dhobi" (washerman) with some donkeys. I send yoa a 

 picture of one of them, made by a natis'e artist. It shows, I 

 think, the relationship between the zebra and the donkey better 

 than many which I have seen. Mules and horses often show 

 zebra marks on their legs, but I have never before or since seen 

 the marks so well displayed on the trunk and legs as in this 

 donkey. The stripes on the body are blended together at their 

 base, and so are the stripes on the legs blended into bands. At 

 the time I endeavoured to find out whether in the days of the 

 kings of Oudh there had been any zebra in Lucknow which 

 might have bred with donkeys, but could find nothing about it. 

 Had there been a zebra which bred with doakeys, I think theie 

 •would have been more of these striped animals ; but this is the 

 only one I have seen since 1S58. I think it a case of simple 

 atavism. Perhaps you may think it worthy of a record in 

 Nature. All " Dhobis " donkeys are small, wretched creatures, 

 mostly with crooked legs. E. Bonavia 



Lucknow, Feb. 29 



OUR ASTRONOMICAL COLUMN 



Variable Stars.— Mr. J. E. Gore, M.R.LA., of Um- 

 balla, Punjab, calls attention to a star of the sixth magni- 

 tude enteied in Harding's AtUs, between e Leporis and 

 B.A.C. 1553, and which is underlined. Mr. Gore says : 

 "In February of this year, with a 3-inch refractor, I 

 found Harding's 6 m. star a little brighter than the 9 m. 

 star south of it, but less than several 8 m. stars (Harding) 

 Jolloiving. It has a small companion f at about i' ± . 

 Harding's 9 m. stars seem about 10 m," Reading off from 

 the Atlas the position of the sixth magnitude for 1800 



appears to have been about R.A. 73° 32''5, N.P.D. 

 111° 25', whence for i876'o we liave R.A. 4h, 57m. 25s., 

 N.P.D. 111° 18'. This star docs not occur in Argelander's 

 Zones, nor in the Washington Zones in the volumes of 

 observations for 1870 and 1871. 



Gilliss has this note to No. 543 of his Catalogue of 

 1248 stars for 1840 (B.A.C. 3815) : •* Probably variable at 

 very short intervals. Of the seven observations three 

 estimations make it 6th magnitude, three 5th, and the 

 other 56." This star, which was observed by Flamsteed, 

 Bradley, Piazzi, and Taylor, was also observed by Arge- 

 lander on three nights, viz., 1850, March 15, 1851, April 

 22 and 28, the magnitudes being noted on these occasions, 

 5, 7, 6 respectively. It appears not unlikely that if this 

 star is examined at short intervals Gi Hiss's suspicion of 

 variability will be confirmed. It is situate in Hydra R.A. 

 (1876), iih. 2m. 45s., N.P.D. 117° 25'. 



As perhaps connected with the subject of variable stars, 

 we may refer to a remark by Piazzi, applying to his star 

 XVI. 35. He says : " Fortiter micans, intereadem, sequens 

 tranquiila luce splendescit." No. 35 is called 8 m., and 

 the star following 15", and south 18", which did not 

 exhibit the strong scintillation of its neighbour, 6 m. 

 Both stars occur in the Washington Zone, 1847, June 17, 

 magnitudes 7*8 and 67. Also to the remark attached by 

 Lalande to the star of 8'9 mag. observed on the middle wire 

 at 2oh. 35m. 39-55., 1796, August 23, " Beaucoup de scin- 

 tillation" (" Histoire Celeste," p. 242) ; this star is No. 

 40102 Cygnus, of the reduced catalogue, R.A. (1876), 

 2oh. 39m. 23s. N.P.D. 58^ 45'*2. Several of the variable 

 stars are well known to exhibit striking scintillation at 

 times, and perhaps more especially when on the point of 

 diminution ; this has been particularly the case with S 

 Virginia i^Hind. 1851), in whichjiecldish-yellow star flashes 

 of a deeper red are occasionally present, producing an 

 impression of unusual scintillation. 



The star Lalande 34746 Aquila is of a deep orange 

 colour. Its position is erroneously given in the reduced 

 catalogue from the observation 1796, June 25 ; the N.P.D. 

 should be 96"" 43' 28"7. It does not occur in the Zones of 

 Bessel or Santini. Lalande calls it 7m., and it is entered 

 of the same magnitude in the charts of Capocci and Inghi- 

 rami. In September, 1873, it was 7 "8, so that at present 

 a claim to be included in the list of variables is not quite 

 made out ; still as so large a proportion of the highly- 

 coloured stars do prove to be variable, L. 34746 may be 

 worth watching. Position for iS/o'o. R.A., i8h. 38m. 2s., 



N.P.D, 96° 39'-5. 



Several of the variable star's to which attention has 

 been called in this column during the last twelvemonth, 

 are notv in favourable positions for observation. 



The Search for Comets. — No new telescopic comet 

 has been detected since that found by M. Borrelly at 

 Marseilles early in December 1874, an intei-val of more 

 than sixteen months. Perhaps we may altribuvC this cii- 

 cumstance partly to the very unfavourable weather which 

 has prevailed generally during the last year, but it is 

 pretty certain that if a systematic search for these bodies, 

 with suitable instruments, could be instituted by aid of 

 amateurs of the southern heniisphere, cometary astronomy 

 would be greatly the gainer. Such work is not adapted to 

 the routine of the public observatories, nor can they afford, 

 in the actual state of what may be termed the standard 

 astronomy of the other hemisphere, to devote time to it ; 

 but it is an occupation especially within the province of 

 the amateur. If his instrumental means are not equal to 

 the determination of accurate positions, he may content 

 himself with intimating any discovery to tne astronomers 

 in charge of the public establishments who, after receiving 

 indication of the approximate position of any new comet, 

 will no doubt secure observations sufficient for the calcu- 

 lation of the orbit. In this way it is highly probable that 

 the number of known comets of short period may be 

 materially increased, since it is only at certain returns 



