m 



KNOWLEDGE 



[February 1, 1899. 



The opposition of 1894 was practically the most favour- 

 able one possible, the least distance of the planet from the 

 Earth being only 0'153. An equally favourable opposition 

 will not occur till 1931, or possibly longer. The opposition 

 of 1900 is the best that we shall have till then. The 

 following is an ephemeris for that opposition : — 



The planet will have a very appreciable loss of light 

 through phase ; at times only three-fourths of its apparent 

 diameter will be illuminated. 



Arrangements are already being made for securing 

 parallax observations at the next opposition, and it is 

 hoped that as many as possible will co-operate in this 

 work, so as to secure the best result attainable. 



The planet is still under observation and is likely to be 

 followed for several weeks longer. Its brightness is now 

 pretty constant, its approach to the sun balancing its 

 recession from the earth. 



The other relations of the orbit, given last November, 

 are scarcely affected by the new elements ; the very singular 

 fact that the planet does not retrograde when in opposition 

 near perihelion is fully verified. 



The synodic period is 2-3146 years, and the following 

 table gives some of the multiples of this period : — 



JSumber of ,. I Number of ,. 



Synodic Periods. ^ <"'"■'• | Synodic Periods. ^^^"• 



2 ... 4-6292 10 ... 23-1460 



3 ... 6-9438 ' 18 80-0898 



6 ... 13-8876 16 ... 37-0336 



7 ... 16-2022 19 ... 43-9775 

 9 ... 20-8314 ! 35 ... 81-0111 



i 89 ... 206 000 



Hence there are three oppositions in seven years, one of 

 which is not observable in these latitudes owing to the 

 great south declination of the planet. Thus, after the 

 opposition of 1900-1, the planet will not be observable m 

 this country till 1905. In that year its position will be 

 much the same as it was in 1898. 



A. C. D. Crommelin. 



THE SHOOTING- OP EAEE BIRDS. 



To the Editors of Knowledge. 



Sirs, — As the destruction of our rarer birds is greatly 

 instigated by those who term themselves ornithologists and 

 bird collectors, it may be not inopportune to address my 

 remarks on this wanton destruction to the readers of 

 a magazine through whose medium many interesting 

 ornithological notes are constantly made public. In 

 almost every issue of Knowledge we find that such and 

 such a bird rare in such and such a neighbourhood has 

 been shot there ! Whatever reason is there for the 

 immediate despatch of every rare bird that appears within 

 gunshot of these collecting-maniacs or their agents ? I 

 do not say give up collections of specimens for scientific 

 purposes, but I do say only collect them from where 

 they can be fairly plentifully found, and where the loss 

 of a few specimens will not mean the extinction of the 

 whole species from that neighbourhood. Again, the excuse 

 that if one collector does not shoot a rare bird another 



will is surely no reason for such conduct. For unless 

 the minority starts by putting its principles of reform 

 into practice never would any reform take place at ail. 

 Nor will I brand this collecting of stuffed skins (what 

 else is it ?) as intentionally or necessarily cruel, for I 

 believe it is not, but 1 will say that it is antagonistic to 

 the true interests of Nature observation — a trait which is 

 the first essential in those who are worthy to receive the 

 name of ornithologists. My plea for bringing this subject 

 before the view of those who probably have had it brought 

 before them often and often, is that only by constantly 

 so doing can public opinion be brought to stamp out this 

 disgrace to us as naturalists — public opinion which alone 

 can effect any lasting change. C. E. Martin. 



Eed Hill Lodge, Compton, Wolverhampton. 

 6th December, 1898. 



MIRA CETI. 

 To the Editors of Kno-wledge. 



Sirs, — As in former years, I give a complete account of 

 my observations of Mira Ceti. 



This variable star has proved to be very interesting to 

 the unaided eye at this apparition. Observations have 

 been made on every possible occasion, the comparison 

 stars used being a. Ceti (2-68), 7 Ceti (3-59), and « Pisoium 

 (8-99). 



1898. Mag. Sky. 



Sept. 16 & 17 ... 3-1 ... Rather misty. 



18 ... 3-1 ... Very clear. 



20 ... 3-0 ... Moonlight. 



21 ... 2-9 ... Moonlight and misty. 

 Sept. 23, 25-28,) „„ ,, ,■ , . 



so! Oct. 2I - 2-9 ... Moonlight. 



Oct. 11 ... 2-7 ... Rather misty. 



12 ... 2-8 ... Extremely clear. 



18 ... 30 ... Extremely clear. 



23 ... 31 ... Bather misty. 



24 ... 3-3 ... Some fog. 

 26 ... 3-4 ... Some fog. 



30,31, Not. 1, 3 3-5 ... Very clear ; moonlight . 



Nov. 5,6 ... 3 5 ... Misty. 



Dec. 7 ... 4-3 ... Very misty. 



9 ... 4-2 ... Very clear. 



The sky was cloudy during the week in which the 

 maximum evidently fell. The approximate date appears 

 to have been October 6th, 1898. 



70, Vincent Square, S.W., Waltbb E. Beslkt. 



January 2, 1899. 



TREE STRUCK BY LIGHTNING. 

 To the Editors of Knowledge. 



Sirs, — In answer to your correspondent " A. C," I think 

 I am right in stating that the majority of electricians 

 would (if they felt themselves called upon to do so) candidly 

 own that this is a matter upon which they have but little 

 definite information. The controversy anent lightning 

 conductors does not actually rage now, but it has by no 

 means been brought to a conclusion. 



This much, however, seems certain, the first action in 

 such a case is electrolytic, and following that there is 

 combustion, more or less perfect. Your correspondent is 

 probably right in his surmise as to the cause of explosion. 

 It may even be that some of the liquid is brought to the 

 spheroidal state. 



The point raised is one calculated to produce a wide dis- 

 cussion. Will the botanists who are also chemists come 

 to our assistance ? 



Howard B. Little. 



23, Pembroke Road, Kensington, 

 London, W., 2nd January, 1899. 



