November 29, 1900] 



NA TURE 



107 



p. 180. Francofurti, 1599 ; H. Billingsley, the first English 

 translation of the "Elements of Euclid," Fol. 42. (London, 

 1570); N. Tartalea Brisciano, " Euclide," Fol. 32. (Venelia, 

 1565) ; J. Peletarius, " In Euclidis Elementa Geometrica 

 Demonstrationum Libri sex." Prop. 32. Appendix a Campano, 

 PP- 33. 34- (Lugduni, 1557). 



It is much to be regretted that in this country so little im- 

 portance is attached to the history of mathematics ; otherwise, 

 such mistakes as those mentioned by Mr. Tucker would not be 

 repeated from one text book to another. 



Galway, November 17. George J. Ai.lman. 



Instruments of Precision at the Paris Exhibition. 



In your issue of November 15 (p. 61) is an account of 

 " Instruments of Precision at the Paris Exhibition," in which it 

 is stated that a catalogue of 250 pages has been prepared by the 

 German Association of Mechanicians and Opticians. May I ask 

 you to state in some future issue how that catalogue can be 

 obtained, as I am anxious to get a copy of it ? 



E. T. Warner. 



H.M.S. Britannia, Dartmouth, November 21. 



I AM much interested in the article in the number of Nature 

 for November 15, on optical and other instruments at the Paris 

 Exhibition. Although I visited the exhibition, I did not see the 

 exhibit, as I went too soon after the opening. I should much 

 like to obtain the catalogue mentioned. Will you kindly tell me 

 where I should be able to obtain one by writing for it ? 



H. Davidge. 



Seafield Park College, Crofton, Hants, November 17. 



[For information as to the German Catalogue of Scientific 

 Instruments, application should be made to Dr. Robert Drosten, 

 Bureau de I'Exposition allemande des Instruments de Precision, 

 Classe 15, Section 3, Exposition Universelle, Paris. If Dr. 

 Drosten is not in Paris, letters will probably be forwarded. The 

 .secretary of the German Committee of Management is Prof. St. 

 Lindeck, Reichsanstalt, Charlottenburg, Berlin, who no doubt 

 would send a catalogue. — Ed. Nature.] 



ON SOLAR CHANGES OF TEMPERATURE 

 AND VARIATIONS IN RAINFALL IN THE 

 REGION SURROUNDING THE INDIAN 

 OCEAN} 



I. 



'T^HE fact that the abnormal behaviour of the widened 

 -*- lines in the spectra of sunspots since 1894 had been 

 accompanied by irregularities in the rainfall of India sug- 

 gested the study and correlation of various series of facts 

 which might be expected to throw light upon the 

 subject. 



The conclusions already arrived at from bringing 

 together the results of several investigations undertaken 

 with this view may b*e stated as follows : — 



(i) It has been found from a discussion of the chemical 

 origin of lines most widened in sunspots at maxima and 

 minima periods that there is a considerable rise above the 

 mean temperature of the sun around the years of sunspot 

 maximum and a considerable fall around the years of 

 sunspot minimum. 



(2) It has been found from the actual facts of rainfall in 

 India (during the S.W. monsoon) and Mauritius, between 

 the years 1877 and 1886,'- as given by Blanford and Mel- 

 drum, that the effects of these solar changes are felt in 

 India at sunspot maximum, and in Mauritius at sunspot 

 minimum. Of these the greater: is that produced in the 

 Mauritius at sunspot minimum. The pulse at Mauritius 



1 By Sir Norman Lockyer, K.C.B., F.R.S., £nd W. J. S. Lockyer, M.A. 

 (Camb.), Ph.D. (Gott.). Paper read before the Royal Society on 

 November 22. 



2 This period was selected because the Kensington observations of 

 widened lines only began in 1879, and the collected rainfall of India has 

 only been published to i886. 



NO. 1622, VOL 63] 



at sunspot minimum is also felt in India, and gives rise 

 generally to a secondary maximum in India. 



India therefore has two pulses of rainfall, one near 

 the maximum and the other near the minimum of the 

 sunspot period. 



(3) It has been found that the dates of the beginning of 

 these two pulses on the Indian and Mauritius rainfall are 

 related to the sudden remarkable changes in the behaviour 

 of the widened lines. 



(4) It has been found from a study of the Famine 

 Commission reports that all the famines therein recorded 

 which have devastated India during the last halt" century 

 (we have not yet carried the investigation further back) 

 have occurred in the intervals between these two pulses. 



(5) It has been found from the investigation of the 

 changes in (i) the widened lines, (2) the rainfall of India 

 and (3) of the Mauritius during and after the last maximum 

 in 1893 that important variations from those exhibited 

 during and after the last maximum of 1883 occurred in 

 all three. 



It may be stated at the same time that the minimum 

 of 1888-1889 resembled the preceding minimum of 1878- 

 1879. 



(6) It has been found from an investigation of the Nile 

 curves between the years 1849 and 1878 that all the lowest 

 Niles recorded have occurred between the same intervals. 



(7) The relation of the intervals in question to the 

 droughts of Australia and of Cape Colony, and to the 

 variations in the rainfall of extra tropical regions generally 

 has not yet been investigated. We have found, however, 

 a general agreement between the intervals and the rain- 

 fall of Scotland (Bucban), and have traced both pulses 

 in the rainfalls of Cordoba (Davis) and the Cape of 

 Good Hope. 



(8) We have had the opportunity of showing these re- 

 sults to the Meteorological Reporter to the Government 

 of India and Director-General of Indian Observatories, 

 John Eliot, Esq., CLE., F.R.S., who is now in England, 

 and he allows us to state his opinion that they accord 

 closely with all the known facts of the large abnormal 

 features of the temperature, pressure and rainfall in India 

 during the last twenty-five years, and hence that the in- 

 ductions already arrived at will be of great service in 

 forecasting future droughts in India. 



Solar Physics Observatory, October 26. 



Addendum. 



Since Meldrum and one of us called attention, in 1872 

 to a possible connection between sunspots and rainfall, 

 there has been a large literature upon the subject which 

 it is not necessary for us to analyse ; it may be simply 

 stated that, in spite of the cogent evidence advanced 

 since, chiefly by Meldrum, and in later years by Mr. 

 Hutchins,^ it is not yet generally accepted that a case for 

 the connection has been made out. 



What has been looked for has been a change at 

 maximum sunspots only ; the idea being that there might 

 be an effective change of solar teinperature, either in 

 excess or defect, at such times ; and that there would be 

 a gradual and continuous variation from maximum to 

 maximum. 



At the same time, it is possible that the pressure con- 

 nection, first advanced by Chambers, is now accepted by 

 meteorologists as a result of the recent work of Eliot. 



The coincidence, during the last few years, of an 

 abnormal state of the sun with abnormal rain in India, 

 accompanied by the worst famine experienced during the 

 century, suggested to us the desirability of reconsidering 

 the question, especially as we have now some new factors 

 at our disposal. These have been revealed by the study, 

 now extending over twenty years, of the widened lines m 

 sunspots, which suggested the view that two eflfects ought 

 to be expected in a sunspot cycle instead of one. 



1 "Cycles of Drought and Good Seascns in South Africa, 1889." 



