6 REPORT 1875. 



dew, Humboldt, Dove, Buys Ballot, Jelinek, Quetelet, Hansteen, Kupffer, Forbes, 

 Welsh, Glaisher, and others have done much to give us an accurate kaovsrledge of 

 the distribution of terrestrial temperature. 



Great attention has likewise been given to the rainfall of Great Britain and 

 Ireland, chiefly through the exertions of one individual, Mr. G. J. Symous. 



To Dove we are indebted for the law of rotation of the wind, to liedfield for the 

 spiral theory of cyclones, to Francis Galton for the theory of anti-cyclones, to 

 Buchan for an investigation into the disposition of atmospheric pressure which 

 precedes peculiar types of weather, to Stevenson for the conception of barometric 

 gi-adients, to Scott and Meldrum for an acquaintance with the disposition of winds 

 which frequently precedes violent outbreaks ; and, to come to tlie practical applica- 

 tion of laws, we are much indebted to the late Admiral FitzRoy and the system 

 ■which he greatly helped to establish for our telegraphic warnings of coming storms. 



Again, the meteorology of the ocean has not been forgotten. The well-known 

 name of Maury will occur to every one as that of a pioneer in this branch of inquiry. 

 FitzRoy, Leverrier, Meldi-um, Toynbee, and others have likewise done much ; and 

 it is understood that the meteorological offices of this and other maritime countries 

 are now busily engaged upon this important and practical subject. Finally, the 

 movements of the ocean and the temperatures of the oceanic depths have recently 

 been examined with very great success in vessels despatched by Her Majesty's 

 Government ; and Dr. Carpenter has by this means been able to throw great light 

 iipon the convection-currents exhibited by that vast body of water which girdles 

 our globe. 



It would be out of place to enter here more minutely into this large subject ; and 

 already it may be asked, what connexion has all this with that part of the address 

 that went before it ? 



There are, however, strong grounds for supposing that the meteorology of the 

 sun and that of the earth are intimately connected together. Mr. Broun has 

 shown the existence of a meteorological period connected apparently with the sun's 

 rotation, five successi\e years' observations of the barometer at Singapore all giving 

 the period 2o-74 days. Mr. Baxendell, of Manchester, was, I believe, the first to 

 show that tlie convection-currents of the earth appear to be connected somehow 

 with the state of the sun's surface as regards spots ; and still more recently Mr. 

 Meldnmi, of the Mamitius observatory, has shown, by a laborious compilation of 

 ships' logs, and by utilizing the meteorological records of the island, that the 

 cyclones in the Indian Ocean are most frequent in years when there are most sun- 

 spots. He likewise affords us grounds for supposing that the rainfall, at least in 

 the tropics, is gi-eatest in years of maximum solar disturbance. 



M. Poeyhas found a similar connexion in the case of the West-Indian hun-icanes ; 

 and, finally, Piazzi Smyth, Stone, Koppen, and, still more recently, Blanford have 

 been able to bring to light a cycle of terrestrial temperature having apparent reference 

 to the condition of the sun. 



Thus we have strong matter-of-fact grounds for presuming a coimexion between 

 the meteorology of our luminary and that of our planet, even although we are in 

 complete ignorance as to the exact nature of this bond. 



If we now turn to terrestrial magnetism the same connexion becomes apparent. 



Sir Edward Sabine was the first to show that the disturbances of the magnetism 

 of the earth are most violent during j^ears of maximum sun-spots. Mr. Broun has 

 shown that there is likewise a reference in magnetic phenomena to the period of 

 the sun's rotation about his axis, an observation recently confirmed by Ilornstein ; 

 and still more recently Mr. Broun has shown that the moon has an action upon 

 the earth's magnetism which is not altogether of a tidal nature, but depends, in 

 part at least, upon the relative position of the sun and moon. 

 _ I must trust to your forbearance if I now venture to bring forward considera- 

 tions of a somewhat speculative nature. 



We are all familiar with the generalization of Hadley ; that is to say, we know there 

 are undercun-ents sweeping along the sm-face of the earth from the poles to the equator, 

 and upper currents sweeping back from the equator to the poles. We are likewise 

 aware that these currents are caused by the unequal temperatm-e of the earth ; they 

 are, in truth, convection-cuneuts, and their course is determined by the positions of 



