METEOROLOGY AND ALLIED SUBJECTS. 325 



the earth's surface depends ui^ou the rate of diiuiuution of temperatui^e 

 from the equator to the poles, and the distribution of pressure depends 

 upon the intensity of the atmospheric currents. If, therefore, the solar 

 radiation varies with the sun's spots, there must be a i)arallel variation 

 in terrestrial temperatures ^nd pressures. {Z. 0. O. Jf., XIV, p. 302.) 



Blanford has investigated the question of a compensation between 

 India and Kussia in the variations of mean atmospheric pressure during 

 one sun-spot cycle. Already in 1877 Eliot had called attention to the 

 fact that, through the whole year, the pressure over India had been 

 above the average, and that this condition extended to such distant 

 regions as New South Wales and Victoria, Blanford having found that 

 an excess of pressure also prevailed over the greater part of Asia, and 

 also of the Indian Ocean. By comparison of the records from 1847 to 

 1862, Blanford now finds that throughout the whole of the Indo-Malayan 

 region an oscillation of the barometric pressure existed, coinciding nearly 

 with the sun-spot cycle. The greatest atmospheric ijressure coincides, or 

 immediately follows, the epoch of minimum frequency of sun spots, and 

 the minimum pressure corresponds with the sun-spot maximum ; or, 

 considering the result of Koppen's investigation, the highest pressure 

 agrees closely with the epoch of greatest mean temperature of the air. 

 On this point he says: "In reference to the nature of the physical 

 causes that bring about this oscillation in the pressure of the air between 

 the Indo-Malayan region and the x)lains of Eussia, and conforming to 

 the sun-spot cycle, our knowledge is still much too incomplete to 

 attempt a satisfactory analysis." {Z. 0. G. M., XV, 1880, p. 158.) 



In the remarks on the above by Dr. J. Hann, he suggests that with- 

 out more special deduction it is still quite clear that the period of in- 

 creased energy in the solar radiation will also be a period of increased 

 energy in the general currents of the earth's atmosphere. {Z. 0. G. M., 

 XV, 1880, p. 161.) 



Balfour Stewart in some remarks on long variations of rainfall, says: 

 The currents in the earth's atmosphere are regulated by two considera- 

 tions, of which one is a constant while the other is variable. The con- 

 stant element is the time of rotation of the earth round its axis, while 

 the possibly variable one is the intensity of the solar radiation. If, 

 then, it is also true that we have not only a long period of variation in 

 the intensity but also in the distribution of terrestrial atmospheric cur- 

 rents, and if we consider the great intiuence of local peculiarities upon 

 rainfall it would be too much to expect that the annual irregularities 

 shall everywhere attain their maxima and minima at the same time. It 

 is perfectly possible that some places may have maximum whiie others 

 have a minimum, and still others have a double instead of a simple 

 period. We are, therefore, not yet in a position to determine experi- 

 mentally the long i^eriods of rainfall for the whole earth, since wo only 

 have as yet a few selected stations. The diversity of results obtained, 

 by Meldrum, Kawson, and others is in accordance with the above 



