Jan. 30, 1879] 



NATURE 



299 



1875. 



Aug. 20 ... 



» 23 ... 

 Sept. 9 ... 



I, 12 ... 



'^ i::: 



Nov. 20 .. 



+ io*i 

 -29 -6 

 - 7-2 

 -15-8 

 + 7-1 

 + 17*2 

 -i5'i 



+ 26" I 



+ 7'2 



+ 94 



+ 21*9 



+ 3-8 

 + 1-8 



- I "2 

 + 52'0 



+ 53'9 



1877. 

 Aug. 20 



Sept, 



Oct. 

 Dec. 



23 ... 



12 ... 



15- 



8 ... 



10 ... 



13 •• 



+ 62-1 

 + 18-5 



+ 17*1 



+ S4*o 

 + 70-1 

 + 30'6 



If yearly means of the above differences are taken we 

 have : — 



187576 

 1876-76 



- 4-8 

 + 19-4 

 +40-8 



These figures appear to indicate that a perturbation of 

 the period is taking place, which of late has increased 

 the differences between observation and calculation at 

 the rate of about twenty-two minutes annually ; the star 

 is evidently one which deserves close attention at the 

 hands of those observers who are following up the 

 variables. With reference to previous observations of 

 Algol and results derived from them, the reader will best 

 consult Argelander in the seventh volume of the Bonn 

 observations, and Schonfeld in Vierteljahrsschrift der 

 astronomischen Gesellschaft, vi. p. 60. 



The Reappearance of Brorsen's Comet.— It is 

 notified that M. Tempel, director of the observatory at 

 Arcetri, Florence, detected the short-period comet of 

 Brorsen on January 14, in a position north following the 

 nebula No. 4900 of Sir John Herschel's General Cata- 

 logue. The ephemeris by Dr. Schulze, of Dobeln, who 

 has carried on the calculation of the perturbations from 

 the last appearance of the comet in 1873 to the present 

 year, does not commence until February 19, so that it 

 appears to have occurred to M. Tempel that, with his 

 advantages of chmate and optical means, there was a 

 possibility of an earlier observation of the comet, and he 

 has taken steps to that effect accordingly. Dr. Schulze' s 

 elements for 1879 give for the place of the comet on 

 January 14, at 6h. M.T. at Florence, RA. 23h. lom. 38s., 

 N.P.D. 118" 57', which is north — following the nebula 

 named, so that there is no reason to doubt that the 

 object observed, which is described as sm?!!, but brighter 

 than the nebula (one of Sir W. Herschel's second class) 

 is really Brorsen's comet. In this case, however, M. 

 Tempel has succeeded in observing the comet, when, 

 according to theory, it possessed a much less intensity of 

 light than at any previous observation. At the time of 

 his obser\-ation it would be distant from the sun i -42, 

 and from the earth rgiS, whence the theoretical intensity 



of light, represented by 



^A* 



is 0-135 ; the smallest 



value with which it had previously been observed corre- 

 sponded to the last glimpse of the comet at Berlin on 

 June 22, 1857, viz., 0-337. Dr. Schulze' s ephemeris will 

 be found m No. 2220 of the Astronomische Nachrichten, 

 commencing, as we have said, on February 19. On 

 February 7 the comet's position at 6h. G.M.T. is in 

 R.A. 23h. 59-9m., N.P.D. 109= 42', and on February ii, 

 at the same hour, in R.A. oh. 9-9m., N.P.D. 107° 46'. 



SUN-SPOTS AND THE NILE \ 



r\S the 2 1 St instant Mr. Francis Cobb read a paper ! 

 ^-^ on the financial and economical condition of ' 

 Egypt, at the Society of Arts, in which he of course re- 

 ferred to the periodical rise of the Nile, and spoke of the ' 

 desirability of discovering some system in the variations 

 of this nse. Mr. Cobb, in considering this subject, has 

 been naturally drawn to an e.xamination of the sun-spot 

 penod, and has attempted to discover if any relation 

 exists between this period and the variations in the rise 



of the river. The period of Mr. Cobb's examination 

 extends from 1866 to 1878. and as might have been- 

 expected, he finds no relation whatever between any 

 sun-spot maxima and minima, and the maxima and 

 minima of the Nile floods. The years 1866-67 were 

 sun-spot minima ; the rise of the Nile in these years was 

 285 and 24^ feet respectively ; 1872 was a maximum sun- 

 spot year, and the rise of the Nile was 25^ feet ; 1877 a 

 minimum sun-spot year, with 18 feet rise in the river ; last 

 year the rise was 30 feet. As some of the speakers in 

 the discussion remarked, there is at present a desire to find 

 relations between the stupendous cosmical phenomenon 

 of sun-spots, and terrestrial occurrences, without consider- 

 ing local peculiarities. We do not know what might be 

 the result if the records of Nile floods for a century were 

 obtainable, and were compared with the various sun-spot 

 periods during that time ; but we should say beforehand 

 that in considering so literally narrow an occurrence as 

 the rise of the Nile, many local considerations would have 

 to be taken into account, 



"It is impossible to say," Mr. Cobb went on, "that 

 the rule, maximum spots, maximum rainfall, applies to 

 Egypt. The cause of the irregularities of the Nile must 

 clearly be looked for locally, the Blue Nile and Nyanza 

 lakes having probably more to do with the matter than 

 sun-spots. The telegraph, combined with a vigilant 

 series of the operations of the Upper Nile, especially at 

 the confluence of the Blue Nile, will prove more reliable 

 for the protection of Eg>-pt another year than any calcu- 

 lations based upon solar physics." 



We fear Mr. Cobb has but a vague idea of the applica- 

 tion of solar physics to meteorology and other terrestrial 

 phenomena. A perusal of the many letters which appear 

 in Nature from our Indian meteorologists, will show 

 that without a careful consideration of local and regional 

 conditions no deduction drawn from sun-spot periods jJ^r 

 se are of much value. 



In the discussion which followed Dr. Mann endeavoured 

 to draw the attention of the meeting to the science of the 

 subject. While he apparently endorsed Mr. Cobb's opinion 

 that the spots on the sun would not be found to have any 

 direct relation to the high and low Niles, he thought it would 

 be perhaps as well to state exactly how this matter stood. 

 The last development of the search after sun-spot influence^ 

 Dr. Mann said, took the form of the discovery that the con- 

 stantly recurring financial crises in this country were due 

 to the sun-spots ; and he should like to point out what 

 really was the influence of the sun upon the great physical 

 changes going on in the world. There was no doubt that 

 the presence of sun-spots had relation to the amount of 

 force and energy issuing from the sun, and that when 

 spots were abundant more solar energy was thrown out 

 into space. When that was the case, the earth shared 

 with all the other orbs in getting some increased force 

 from the sun. There was no doubt either that movement 

 of every kind on the earth was dependent on solar 

 action ; and when increased energy was thrown out from 

 the sun it told immediately on the water of the earth, and 

 raised more of it into the sky in the form of vapour. But 

 this did not mean that there would be an increased rain- 

 fall in one particular spot, but only that, being more 

 vapour, there would be a greater rainfall over the whole 

 earth. In a case like Egypt, the amount of rainfall was 

 due to the presence or absence of an ocean wind blowing 

 over the high grounds of Abyssinia. Therefore, though 

 no doubt the sun-spots had to do with the total rainfall, 

 they had not necessarily anything to do with the local 

 rainfall in one particular country like Egypt. 



Dr. Mann explained that in these remarks he did not 

 intend to imply that there was not a periodicity and regu- 

 lar order of some kind in social conditions and events- 

 which were connected with the requirements of finance, 

 crisis, and things of that kind. He was quite satisfied 

 that there was. But he thought there was too great an 



