122 H. F. Blanford — On recent Variations in the Sun's Seat. [June, 



established, that the sun's heat varies from year to year. The variation 

 would seem to be so considerable, that it must have an appreciable effect on 

 all terrestrial phenomena, (meteorology of course included,) for the sun's 

 heat is well known to be the source of nearly all life and activity of every 

 kind on the earth's surface. The variation in the absolute quantity of heat 

 can be ascertained only from direct actinometric observations ; and it is 

 to be hoped that these will be undertaken before long at the new sun 

 observatory to be established at Simla under Colonel Tennant. 



The paper will appear in the Journal, Pt. II, No. 1, 1875. 



Mr. W. G. Willson said, that no more interesting subject of investiga- 

 tion at the present time could have been selected by Mr. Blanford than the 

 connection between variations of solar heat and the changes in the sun- 

 spot area. This seemed to be the link required to establish, on a physical 

 basis, Mr. Meldrum's law of connection between sun-spots and cyclones, 

 as well as rainfall. Mr. Norman Lockyer appeared to consider a rainfall 

 periodicity corresponding to that of the sun-spot area as fully established : 

 (Nature, 12th December, 1872). He says that we " should no longer deceive 

 ourselves as to the present state of meteorology. A most important cycle 

 has been discovered analogous in some respects to the saros discovered by the 

 astronomers of old." But it appeared to Mr. Willson that Mr. Meldrum, 

 who first drew attention to the subject, and who subsequently examined 

 tables of rainfall for 93 stations in various parts of the world ; and 

 Professor Brocklesby who had examined for the same purpose tables 

 for 2,200 stations in America, were not equally sanguine. On the whole 

 however they appeared to think that, amid striking anomalies, there was 

 some evidence in favour of the supposed connection between rainfall and 

 sun-spots. Mr. Willson had examined, in August last, tolerably extensive 

 statistics of rainfall for a few stations, with the view of testing the supposed 

 law. He had data for 10 maxima and minima sun-spot periods for 

 Madras. For Bombay 8, for Calcutta 7, for Nagpur 4, for Greenwich 7 

 and for Rome 5. These he had put together side by side with the 

 data given by Mr. Norman Lockyer in his paper in Nature before 

 referred to. These data were 3 maxima and minima sun-spot periods 

 for Port Louis, 3 for Adelaide and 5 for the Cape. The result of the 

 comparison was not on the whole favourable to Mr. Meldrum's supposed 

 law. Counting up, for all the the stations and for all the periods, the cases 

 which were favourable and those which were unfavourable to the supposed 

 law, he found that they were almost exactly evenly balanced, and it was to 

 be remembered that the data given by Mr. Lockyer, which were included, 

 were all favourable. However although no regular rainfall periodicity 

 could be detected for the new stations examined, the total rainfall in max- 

 ima sun-spot periods was, for most of them, somewhat greater than that 



