17 
ber, the interval being eight months ; at Catherinbourg (56° 
49' N., 60° 35' E.) the first maximum occurs in the second 
week of March and the second about the second week of 
December, the interval being nine months ; at Tiflis (40° 42' N., 
44° 50' E.) and at Lougan (48° 3b' N., 39° 20' E.) the inter- 
val is also about nine months; at Stockholm, and also at 
Milan, the first maximum occurs in the middle of February 
and the second in the middle of December, the interval being 
ten months ; but in the British Islands there is only one 
principal maximum, which occurs about the second week of 
January and which appears to be formed by the union of the 
first maximum of one year with the second maximum of the 
year preceding, the interval between the two maxima being 
twelve months. It is evident, therefore, that these maxima 
move across the two continents in opposite directions, the 
course of the first being from West to East and that of the 
second from East to West. 
As the apparently compound maximum of January is not 
greater than either of the separate maxima, the Author con- 
siders it very probable that both maxima are produced by the 
same disturbing cause, such disturbing cause taking its rise 
in Eastern Asia in the month of November, and gradually 
moving westward until it arrives in the British Islands in 
January ; then reversing its course, it returns with a diminished 
velocity to the region of its origin, where it arrives in the 
month of April, and afterwards rapidly disappears under the 
influence of an increasing temperature, to re-appear later in 
the year on the return of a low temperature. 
As the times of first appearance and of final disappearance 
of the disturbing cause in Eastern and Central Asia, corres- 
pond very nearly with the times of the breaking up of the 
monsoons in the China Sea and Indian Ocean, it is considered 
very probable that the two systems of phenomena are directly 
connected with and dependent upon each other. 
Attention is drawn to a very decided convexity of nearly 
