134 



NA TURE 



[December 7, 1893 



for both terms of the variation, Prof. Chandler has thought 

 well to combine short series made in nearly the same longitudes, 

 and so deduced fourteen determinations of the numerical equa- 

 tions for the latitude variation. Reducing the values so obtained 

 to a common epoch, he found that the values of the observed 

 Julian date when the latitude would be a minimum, or when the 

 pole of figure would pass the meridian of the respective stations 

 by virtue of the fourteen months' revolution alone, and of the 

 s 'n's longitude on the observed date when the same phase would 

 occur by virtue of the annual term alone, both decreased 

 from Pu!l,-owa to'vai-ds Madison showing that the direction of 

 the rotations in both the elements was from west to east. In 

 the latter part of the article Prof. Chandler refers not only to our 

 knowledge of the general law of latitude variation, but to the 

 accuracy of the necessary constants which afford us a means of 

 predicting the immediate future course. The minimum of the 

 curve of April, 1893, will be followed by an interval of nearly 

 two years, and will be marked by very slight fluctuations, so 

 that from the maximum of October, 1893, to that of August, 

 1895, or from minimum April, 1893, to that near the beginning 

 of 1895, "there will apparently be but a single decidedly 

 marked period of, say 20-22 months," the total range amount- 

 ing to o""io as against o""56 which prevailed in 1889 and 1892. 

 In May, 1896, the same dimensions as in 1889 will be again 

 attained, and the variation from that time forward to 1898 it 

 will be in full play with the range of o" 5 or o" '6, a period of 

 nearly 390 days which prevailed between 1889 and 1892. In 

 § 2 of the article Prof. Chandler adds a few words as to the 

 reality of these movements of the earth's axis as against the 

 motions being "merely misinterpretations of the observed 

 phenomena "or an illusory effect of instrumental error due to 

 the influence of temperature. Those of our readers who are 

 still sceptical on the subject will learn that the observed law of 

 latitude variation includes two terms, one with a period of 

 fourteen months, and another with twelve months, making the 

 phases come in very different relations to conditions of tem- 

 perature dependent on season, an argument greatly against 

 that brought forward by temperature- variation believers. 



Meteor Shower for December.— No news is yet to hand 

 with regard to the Biela meteors, but we hope soon to receive ac- 

 counts of the display which will give us some idea of the quantity 

 and also of the date of reaching their maximum. The following 

 meteor radiant-points are given by Mr. Denning for the ensuing 

 month, that for the loth lying approximately close to p Gemini 

 in a prolongation of yS and p Gemini, and bemg defined as a 

 "most brilliant shower." 



Date. 



Dec. 8 



Radiant. 



Meteors. 



145 + 7 ••• Swift ; streaks 



8 ... 208 -f 71 ... Rather swift 



10 ... 108 + 33 ••• Swift; short 



24 ... 218 + 36 ... Swift; streaks 



25 ... 98 + 31 ... Very slow 



Refraction Tables. — We have received a small pamphlet 

 extracted from the Mitheihingeii aus dcr Deutschen Schutz- 

 gebieten, Bd. vi., Heft 4, containing refraction tables computed 

 by Dr. L. Ambronn, of the Gottingen observatory. These 

 tables are not intended for such accurate values as are required 

 in observatories with fixed instruments, but are intended to be 

 used by those, who having made astronomical observations, 

 wish to compute them on the spot, using approximate formula. 

 Travellers, especially, will find these tables very useful for 

 wide ranges, both as regards temperature and barometer argu- 

 ments. The tables are based on Bessel's refraction- 

 table formula, and by slightly combining the first two terms, 

 which is no other than the mean refraction, and eliminating the 

 term log T by reducing the height of the barometer to o°C 

 becomes, employing the usual notation : 



log refraction = log a tan c -f A log B^ -f A log 7 

 or 



refraction = tan 2;; B^,A X 7'' . . . . (i) 



To make the correction for the mean refraction additive, the 

 expression can be put in the form : 



refraction = [a tan ;. -}- o tan 2; (7^ - i) ] B/ 

 Table II. gives the expression for the second term in the 

 brackets using the mean refraction (o tans) and the air tem- 

 perature (7) as arguments. For the barometer correction, if 



NO. 1258, VOL. 49] 



a tan z represent the mean refraction corrected for temperature 

 then in equation (i) we may omit 7 and write 

 refraction = (0 tan s) x Bq^ 

 or, refraction (a tan r) x (otan z) [B^^ - i] 

 The second term is taken direct from Table III. using the 

 the mean refraction (corrected for temperature) and the height 

 of the barometer as arguments. 



To obtain the true refraction then, one simply (i) finds the 

 mean refraction for the given zenith distance ; (2) adds then the 

 correction for temperature, and with this corrected mean refrac- 

 tion as argument ; (3) adds the corresponding correction for the 

 height of the barometer. Accuracy up to less than half a second 

 of arc can be obtained. 



GEOGRAPHICAL NOTES. 



The friends of the late Emin Pasha, at the suggestion of Dr. 

 Schweinfurth, have resolved to collect subscriptions for a 

 memorial to com.memorate his long labours in Africa as a 

 naturalist, traveller, and;administrator. There must be many 

 in this country anxious to have a share in such a tribute, and we 

 shall shortly be able to intimate where subscriptions should be 

 sent. The present proposal is to erect a monument in the 

 Silesian town of Neisse. 



By the death of Mr. A. L. Bruce, at Edinburgh last week, 

 the cause of geography and civilisation in Africa has lost a 

 wealthy and judicious promoter. Mr. Bruce, who married as 

 his second wife a daughter of Dr. Livingstone, wasi a director 

 and one of the founders of the Imperial British East Africa 

 Company. He was a devoted friend and warm supporter of 

 Mr. H. M. Stanley, and took a leading position in organising 

 and supporting the Emin Relief Expedition. Mr. Bruce was 

 the originator of the Royal Scottish Geographical Society, of 

 which he acted as treasurer, and in the prosperity of which 

 he took the keenest interest to the last. 



GuiLio Grablovitz has published as a pamphlet a paper on 

 tidal phenomena in the Mediterranean, read at the Itaban Geo- 

 graphical Congress, and entitled "Sulla Osservazioni Mareo- 

 grafiche in Italia e specialmente su quelle fatte ad Ischia." The 

 work done with recording mareographs is of considerable 

 importance and several diagrams are given showing the tidal 

 range and its fluctuations. The mean rise of the water was 11 

 centimetres at San Remo, 24 at Genoa, 12 in the North of 

 Sardinia, from 15 to 22 along the west coast of Italy as far as 

 Ischia, 30 in the Li pari Islands, but only from 2 to 13 round 

 Sicily. In the Adriatic the range increased from 9 centimetres 

 at Brindisi to 48 at Venice, which was the only station 

 showing a range greater than one foot. The curves are 

 recorded on a large scale, the ripples of the calm water in which 

 the mareograph worked bearing a comparatively large ratio to 

 the total tidal amplitude. 



Mont Iseran, in the eastern Alps, is, or rather was, one of 

 the most remarkable mountains on the map of Europe, where 

 it flourished long, although without any physical representative 

 on the mountain-range itself. M. Henri Ferrand, in an enter- 

 taining little b)-ochtire relates its story, showing how it had come 

 to be an accepted belief amongst cartographers that the river 

 Isere had its source in a Mont Iseran. The mountain was fixed 

 in latitude, longitude, and altitude by an Italian surveyor in 

 1809 ; but in the fifties, when Alpine climbing became fashion- 

 able, the discovery was made by climbers that no one in the 

 neighbourhood could point out Mont Iseran. There was a col 

 of that name, but no peak. An exhaustive French survey con- 

 clusively proved that the summit so long honoured on all maps 

 had no real existence, and M. Ferrand tells the whole amusing 

 history remarkably well as a lesson of the value of mountain- 

 climbing, even to scientific topography. 



The telegraphic cable opened last month from Zanzibar to 

 Mauritius and Seychelles is an important link in the cable net- 

 work which is gradually eacompassing the globe. 



THE ANNIVERSARY MEETING OF THE 

 ROYAL SOCIETY. 



'T'HE anniversary meeting of the Royal Society was held in 



the apartments of the Society at Burlington House, 



on St. Andrew's Day, November 30. The auditors of the 



