340 



NA TURE 



\_Au^ust 23, 1877 



during the present century fall within the group of minimum 

 sun-spot years, the sixth (1854) being also a year of relatively 

 few sun-spots (192 according to Wolf). 



Dr. Hunter's avowed object, however, in writing his pamphlet 

 was to prove that a cycle of drouj^ht sufficient to cause famine 

 existed throughout the -whole of Southern India, and with this 

 end in view he has been content to show that a cycle of rainfall 

 corresponding with the period of solar maculation existed merely 

 for one single station, viz., Madras. 



Having found a decided correspondence between the rainfall 

 of Madras and the eleven-year period of r^un-spots, he thence 

 argues somewhat hastily that the same conditions apply through- 

 out the whole of Southern India. This hasty generalisation from 

 the results of one station situated in a vast continent, the rainfall 

 of which varies completely both in amount and the season in 

 which it falls, according to locality, has been strongly contested 

 by Mr. Blanford, the Government meteorologist, who on making 

 a careful comparison of the rain'alls of seven stations, three of 

 which — Madras, Bangalore, and Mysore — are in Southern India, 

 the others being Bombay, Nagpore, Jubbulpore, and Calcutta, 

 finds that with the exception of Nagpore in Central India, which 

 shows some slight approach to the same cyclical variation which 

 is so distinctly marked in the Madras registers, the rest of the 

 .stations form complete exceptions to the rule adduced for Madras, 

 in many of them thehypolheticalorder of relation being reversed. 

 Mr. Elanford, however, shows that underlying the above irregu- 

 lariti^'s a certain cyclical variation exists on the average at all the 

 stations, the amount nevertheless being so insignificant (not more 

 than 9 per cent, of the to^al (alls) that it could not possibly be 

 considered of sufficient magnitude to become a direct factor in 

 the production of famine. It thus appears that the cycle of 

 rainlall which is considered to be the most important element in 

 causing periodic famines, has only been proved satisfactorilv for 

 the town of Madras. It may perhaps hold for the Carnatic 

 iind Northern Siccars — the country immediately surrounding 

 Madras, though, owing perhaps to the want of rainfall registers 

 in these districts, evidence with regard to this point is still 

 wanting. 



Though Dr. Hunter has thus been only partially successful, I 

 would not attempt to detract in any way from the value of his 

 able pamphlet, so far as it goes, an indirect effect of which has 

 been to stimulate meteorological inquiry and research in the 

 same direction throughout India. The meteorology of this 

 country, from its peculiar and tropical position, is in such com- 

 plete unison with any changes that may arise from oscillations in 

 the amount of solar radiation and their effects upon the velocity 

 and diiection of the vapour-bearing winds, that a careful study 

 of it cannot fail to discover meteorological periodicities in close 

 connection with corresponding periods of solar disturbance. In 

 connection with the previous remarks, and as showing what a 

 close connection exists between solar and terrestrial meteorolojy, 

 I may observe that Mr. Hill, the meteorologist for the North- 

 West Provinces, and myself, have coinciHently discovered the 

 existence of a remarkable cycle in the winter rainfall of Northern 

 India, between the latitudes of 20" and 30°, corresponding in- 

 versely with the period of solar spots, i.e , the maximum winter 

 rainlall coincides with the minimum period of sun-spots, and 

 vice versd. 



As a failure of the winter rains in the Northern Provinces in 

 1860-61 (yiars of niaximnm snn-spot) has been the cause of a 

 >evere famine, this tfieory, if completely established, would not 

 be without its value in the economical admmistration of the 

 North- West Provinces and the Punjab. I have not at present 

 examined the rainfalls of all the stations in the Upper Provinces, 

 but Mr. Hill, having readier access to them than myself, has 

 probably done so to a larger extent, and tells me that the results 

 of his investigations are similar to my own in bearing out the 

 preceding hypothesis. A theory is not wanting to account for 

 this tendency to vary inversely with the sun-spots, if we, 

 according to opinion held by Drs. Hahnand Koppen, Prof. Piazzi 

 Smyth, and Mr. Pogson, the Government astronomer at Madras, 

 assume that the sun's heat is greater in years of minimum 

 sun-spot. For in these years the anti-trade current, the descent 

 of which upon the Himalaya and Northern India in the winter 

 is generally understood to be the vehicle of the rain at that 

 season, would be owing to the increased evaporation over the 

 Southern Indian Ocean, reinforced with a larger supply of 

 vapour than usual, while in years of maximum sun-spot the supply 

 would be smaller. At all events, whatever be the real cause, 

 the facts as far as we have gone, are exceedingly favourable to 

 the existence of such a cycle. Calcutta, though lying close to 



the tropics, and therefore coming in for a small share of winter 

 rainlall, still shows the preceding relation to a wimderful extent, 

 and as its register of rainfall extends farther back than most of 

 the other North Indian rainfalls, furnishes a more trustworthy 

 result than many other statims whose rainfalls registered only 

 for short p< ri ids scarcely afford more than a slight balance of 

 probability in favour of the assumption. The following table is 

 arranged in a double series of years occupying the same position 

 in the spot-cycle, and gives the average rainfall for each double 

 series for the months of November, December, January, 

 February, March, and April, from 1837 to 1S76 inclusive. I 

 have indicated the groups containing the years of maximum and 

 minimum sun-spot. The maximum rainfall will be seen to occur 

 in the latter, and the 11 immum in the lormer group. 



Cakutta Rainfall duritti^ the months of IVovemhery December^ 

 jfanuaiy, Febriiaty, March, and April. 



rainfall o'f 

 Years. group 



8-49 



6-44 



Eleventh series repeated 8 '49 



Further analysis only tends to render the connection still more 

 evident, but I have no time to add anything further. In conclu- 

 sion I need only remark that Jerusalem, which is situated 

 somewhere about the same latitude as Lahore, and receives its 

 total annual supply during the winter months alone, fully bears 

 out the hypothesis as far as records show from 1846 to 1S59. 



Bankipore, Patna E. D. Archibald 



Reproduction by Conjugation 



In Prof Allen Thomson's Inaugural Address to the British 

 Association, I find the following sentence, referring to the 

 simplest form of sexual reproduction among cryptogams, known 

 as conjugation: — "In mote ordinary cases, as in Spirogyra, 

 where the embryo is formed in one of the two cells, it seems to 

 be indifferent in which of them it is formed." If my own expe- 

 rience may be taken as trustworthy and adequate, there is one 

 fact in connection with this phenomenon which would seem to 

 show that it may not be altogether indifferent, and that the dif- 

 ferentiation of male and female elements may be carried back 

 even one step further than is stated by this distinguii-hed biologist. 

 When two filaments — which we may call A and B — are conju- 

 gating, then, as far as my observation has gone, the direction of 

 conjugation is uniformly the same, i.e., either the contents of 

 every cell in A pass over into the adjacent cell of B, or the 

 reverse ; we never find the contents of some of the cells of A 

 passing over into B, and the contents of some of the cells of I! 

 passing over into A. If this is so, and if we call the filament 

 in which the zygospores are ultimately produced A, then it is 

 clear that we may fairly call A the female and B the male fili- 

 ment ; and it would appear certain that there must be some 

 hitherto undetected dillerence between them. My own obser- 

 vations in this respect relate almost exclusively to Spirogyra, 

 and I shall be very glad to know if they are confirmed, or 

 otherwise, by those of more experienced algologists. 



Alfred W. Bennett 



The Greenland Foehn 



Hoffmeyer's facts respecting spells of warm weather in the 

 Arctic winter, as reported in NATURE, vol. xvi. p. 294, are 

 very interesting, but his explanation of them seems demonstrably 

 insufficient. He thinks they are a phenomenon of the same kind 

 with the Foehn of the Alps, which latter he explains by saying 

 that a wind which at its origin is saturated with moisture «ill, 

 when it is forced over a mountain chain, be raised 1" Cent, for 



