SOLAR DISTURBANCES DURING APRIL, 1913 



BY FRANK C. DENNETT. 



April has yielded very little by way of disturbance upon the 

 sun. His disc was observed every day, but spots were only 

 recorded on four — 5, 6, 7, and 22 — and faculae on ten 

 others— 1, 3, 8, 9, 12,16, 17. 20,23 and 24— whilst he appeared 

 free from disturbance on the remaining sixteen. The 

 longitude of the central meridian at noon on April 1st was 

 260° 37'. 



No. 7. — First seen on the morning of the 5th, as two larger 

 and two or three smaller pores outlining the northern half of 

 an ellipse. These smaller pores changed somewhat during the 

 day, and the leader increased somewhat in size and became 

 divided. The spectroscope showed only very moderate 

 activity to the north-east of the leader, but dark hydrogen 

 flocculi were seen, and also the presence of the dark helium 

 line, D 3 . On the 6th it had increased somewhat, being 30,000 

 miles in length. The area between the spots and for some 

 distance northward looked disturbed, and this was confirmed 

 by the spectroscope, which also showed the presence of dark 



hydrogen flocculi and dark helium. On the 7th only the 

 leader remained amid a faculic display, and died out before 

 the 8th, although the faculae remained visible until the 9th. 



On the 22nd, at 3.30 p.m., there was a small but evanescent 

 black pore situated approximately in longitude 338°, latitude 

 28° S. where the cross is marked on the chart, but it soon 

 became gray, and disappeared. 



A facula around 136°, 16° N. was seen on the 16th, when 

 larger paler faculic areas were situated at 351°, 16° N., and 

 351°, 28° N. The latter being seen also on the 17th. A 

 facula also seen on the 17th at 330°, 9° N. A small facula on 

 the 20th at 81°, on, or close to, the equator. On the 22nd and 

 23rd a faculic area was situated at 273°, 23° N. On the 24th 

 a pale faculic area, too faint for measurement, was round the 

 eastern limb apparently just south-west of the place of No. 7. 



The chart is constructed from the combined observations 

 of Messrs. John McHarg, E. E. Peacock, A. A. Buss, and the 

 writer. 



DAY OF APRIL, 1913. 



20 30 « so a 70 



90 100 110 120 130 M » 160 M 180 190 30 2J0 220 230 M> S) M 270 2S0 31) 300 SO 320 330 Srf 3S0 560 



REVIEWS. 



ASTRONOMY. 



The Solar System. — By G. F. Chambers. Second edition. 

 202 pages. 28 illustrations. 6J-in. X 4j-in. 



(Hodder & Stoughton. Price 1/- net.) 



This is a second edition, partly rewritten to bring it up to 

 date, of a work first published in 1895. The present edition 

 gives no year of publication — a frequent modern fault — but 

 from the date of the preface one can infer that the year was 

 1912 or later. The book is light and of a convenient size for 

 the pocket, also the paper and printing are both good in 

 quality. It has thirteen chapters, of which Chapters II (Sun) 

 and XIII (Comets) occupy seventy-five pages, or more than 

 one-third of the whole. The chapter on the Sun, pages 21 to 

 62, is almost entirely devoted to Sun-spots — in fact, all but 

 four pages, and, though very interesting reading, is out of 

 all proportion to the rest of the chapter and book. In the 

 next edition, which we hope to see during the author's life, we 

 should like to have quite twenty of these pages replaced with 

 something upon other parts of solar physics : for instance, a 

 general account of the beautiful phenomenon of the solar 

 corona, which can certainly be best viewed with a small, or 

 without any, telescope, cannot be adequately given in eleven 

 lines (eighty-one words), nor can the situation be saved by 

 giving an antique illustration. 



The remarks upon scintillations in Chapter V are very 

 useful, interesting and suggestive ; the reference to Tacchini 

 on page 91 we can bear out from personal observations at an 

 altitude of two miles. Likewise the reference, on page 99, 

 to P. Smyth upon the exact similarity of terrestrial and lunar 



volcanoes, we can substantiate from actual rambles among 

 the former and telescopic views of the latter. A brief reference 

 to the excellent results of lunar photography and Saunder's 

 work would not have been out of place. The remarks at the 

 top of page 107 do not appear to be courteously expressed. 

 We are glad to see the remarks on page 108 about the misuse 

 of a revered name. 



Galle does not appear to have sufficient credit given him, 

 on pages 143 and 158, for his pioneer observations. On 

 page 146 we notice an error in the number of satellites for 

 Saturn. The chapters on Uranus and Neptune are concise 

 and full of facts. There is a useful index : we noticed the 

 omission of Aston and Titius, and the references under 

 Satellites might have been extended with advantage. Altogether 

 a book full of interest and facts, not fanciful, not overburdened 

 with numbers, but pleasantly written by that veteran pen and 

 published at such a cost that everyone should possess and 



read Jt F. A. B. 



Annuaire Astronomique et Meteorologique pour 1913. — 



ParC. Flammarion. 49 c annee. 404 pages. 135 illustrations. 



7i-in.X4j-in. 



(Paris: Librairie Ernst Flammarion. Price lfr. 50.) 



A book full of useful astronomical and meteorological tables 



and information, both for reference and for the amateur's 



daily use. Pages 245-390 contain a resume of observations 



and progress in 1912, and the last pages record facts upon the 



scientific jubilee of Flammarion. 



F. A. B, 



227 



