So8 



NA TURE 



[September 24, 1908 



unacquainted with astronomy, we fail to recognise the 

 need for, or the suitabilit)' of, it. Having attempted 

 too much in too Httle space, the author is in places 

 forced to be dogmatic, in others he is inexplicit, and 

 the beginner will find tabular statements which, 

 without external assistance, will puzzle him. 



To a fair extent the book consists of quotations 

 from well-known writers fitted together with such 

 statistics as one usually finds in popular articles ; 

 where the writer's personality appears, we find either 

 dogmatic statements or information which is too 

 loosely or too briefly explained. For example, on 

 p. 28 the reader is told that in 1882, 1893 and 1905, 

 "the disc of tlic sun was covered with spots"; the 

 subsequent explanation of spot zones will but tend to 

 confuse the beginner. In the next paragraph we read 

 that Sir Isaac Newton showed that if " light " be 

 passed through a prism, a band of coloured light, 

 *' known as the solar spectrum," is produced, a state- 

 ment which can only convey the truth when the 

 lieginner either assumes, or knows, that it was the 

 light of the sun that Newton employed. These 

 •examples will suffice to show that, in attempting too 

 much, the author has occasionally lost sight of the 

 fact that he was intending to write a book for be- 

 ginners. Seven reproductions of celestial photographs 

 and drawings illustrate the volume, some of them 

 Iseing from Prof. Max Wolf's beautiful originals. 



W. E. ROLSTON'. 



LETTERS TO THE EDITOR. 



/[The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications.] 



Large Magnetic Storm. 



On September 1 1-12 a large magnetic storm was experi- 

 •enced at Kew. There were minor disturbances earlier in 

 the month, from September 4-6 and from September S-io, 

 and the magnetic traces were by no means absolutely quiet 

 when the storm began. The commencement is, however, 

 clearly indicated in the horizontal force curve (not repro- 

 duced). Starting at about qh. 47m. p.m. on September 11, 

 there was a very sudden change in the force. The move- 

 ment of the horizontal-force magnet was of a type which 

 not unusually ushers in large storms, but it was exception- 

 ally Jarge, representing an increase of about 112 7 in H 

 (i y =:o-ooooi C.G.S. unit) in less than two minutes of 

 time. At the end of this movement H had reached its 

 maximum during the storm. The first movement was 

 followed by oscillations. A very rapid fall exceeding 300 7 

 took place between iih. 35m. p.m. and midnight, followed 

 by an equally rapid but smaller recovery. The other prin- 

 cipal changes in H occurred between i a.m. and 2 a.m., 

 and between 4.40 a.m. and 6 a.m. on September 12. 

 Between 4.40 a.m. and 5.7 a.m. there was a fall of 3007. 

 The extreme range was not shown on the curve, which 

 went off the sheet, but it exceeded 5007. Later on Sep- 

 tember 12, between noon and 7 p.m., there was further 

 disturbance of a much less striking character, but this 

 was probably from a distinct origin, and the storm com- 

 mencing on September 11 may be regarded as terminating 

 about 9.30 a.m. on September 12. On this view, the 

 immediate result was a diminution of about 100 7 in the 

 value of H. Such temporary depressions in H are the 

 usual legacy of magnetic storrns, but the depression in the 

 present instance seems above the average. 



The declination curve, of which a tracing is reproduced 

 on a reduced scale, shows the commencement about 

 9.47 p.m. on September 11 much less prominently. A small 

 but sharp upward movement, representing an increase of 

 about i' in westerly declination, is, however, visible, 

 followed in the course of the next twelve minutes by an 

 easterly movement of about 13'. The most salient features 



are the four peaks or turning points, where a prominent 

 movement to the west terminated, and was followed by a 

 similarly prominent movement to the east. The approxi- 

 mate times answering to these peaks are 11.4 p.m. and 

 11.44 p.m. on September 11, and 1.46 a.m. and 5.14 a.m. 

 on September 12. The extreme easterly position was 

 reached at about 2.53 a.m., and the e.xtreme westerly posi- 

 tion at about 5.14 a.m. on September 12, the total range 

 of declination being about 1° 27'. The movements on 

 September 12 were the most rapid. Between 1.24 a.m. 

 and 1.46 a.m. there was a westerly movement of about 

 51', followed in the course of the next eight minutes by 

 an easterly movement of about 35', while between 2.58 a.m. 

 and 3.28 a.m. there was a westerly movement of about 

 53'. There were no large movements after 6 a.m. 



The vertical force disturbance was of a somewhat unusual 

 tvpe. Whilst there was a certain amount of oscillation, 

 the principal feature was that during the whole duration 



10 

 Septenljer i 



MIOT 2 



Kcw Declination. 



4 G 



September i 



of the storm — from 9.47 p.m. on September 11 to 9.30 a.m. 

 on September 12 — the vertical component, V, was de- 

 pressed below its normal value. The extent of the 

 depression may be judged from the fact that from 

 11.45 p.m. on .September ii to 6.10 a.m. on September 12 

 — i.e. for more than six hours — V did not rise to withm 

 1507 of the value which it possessed when the storm 

 commenced. By 9 a.m., however, on September 12, V 

 had returned to its normal value. Owing to loss of trace, 

 the extreme range of the vertical force disturbance was not 

 recorded. C. CiiREE. 



Observatory Department, National Physical 

 Laboratory, September 14. 



Bouvet Island and the Solar Eclipse of igo8 December 

 22-23. 



A QUESTION having been raised as to whether the total 

 phase of this eclipse will be visible at Bouvet Island, I 

 have asked the Hydrographic Department for the most 

 trustworthy coordinates of the island with the view of a 

 settlement of the matter. 



The position adopted for Bouvet Island on the Admiralty 

 chart of the region is 54° 22' S., 5° 21' E. 



Adopting the elements of the Nautical Almanac, the 

 eclipse of next December for this position is a partial one, 

 the magnitude (sun's diameter= i) being 0-988. The island 

 is about 10' south of the southern limit of the zone of 

 totality. A. M. \V. Downing. 



H.M. Nautical Almanac Office, September 17. 



Ruthless Extermination. 



H.wiNO noticed in your issue of September 3 a most i 

 interesting article on the subject ot the extermination 

 of animals in Africa, I cannot say how indignant I feel 

 that there should be persons who actually advocate the 

 wholesale destruction — by international consent — of the 

 many wonderful species which have been built up in their 

 perfection during countless ages of evolution. ( 



NO. 2030, VOL. 78] 



