F. Waldo — Bruckner's Klimaschwanlcungen. 145 



ciently long period. While for most of the stations the data 

 are for the period 1830-1885, yet for many they extend 

 farther back, at Paris beginning in 1691-95. In dealing with 

 snch immense masses of data, it would be too burdensome to 

 use single years, and so the averages for five year periods are 

 used; thus 1691-95 refers to the mean for the years 1691-92- 

 93-94-95. The following table contains the average result of 

 these data since 1830. 



Periods of Rain. 

 Deficiency. Excess. Deficiency. Excess. Deficiency o 



Europe 1831-40 1841-55 1856-70 1871-85 



Asia 1831-40 1841-55 1856-70 1871-85 



Australia .. -45 1846-55 1856-65 1866-75 1876-85 



N.America. 1831-40 1841-55 1856-65(71-75)1866-70(76-85) 



Cent, and £ 1831 _ 45 1846-60 1861-75 1876-85 



S. Amer. 



Taken all) 1831 _ 40 1846-55 1861-65 1876-85 



together ) 



The average amplitude of oscillation expressed in per cent, 

 of the total average amount of rain-fall is as follows : Europe 

 16 per cent, Asia 30 per cent, Australia 22 per cent, North 

 America 26 per cent, Central and South America 28 per cent ; 

 the average for all being 24 per cent. That is in the driest 

 period the rain-fall is only £ of that in the rainiest. It ap- 

 pears also that this oscillation is true for the whole of the land 

 surface and that a deficiency in one section is not counter- 

 balanced by an excess in another section. What takes place 

 on the water surface of the globe we do not know with cer- 

 tainty, as the rain-fall observations at sea are not suitable for 

 such investigations, but the sea-coast stations probably indicate 

 fairly well the results for the open ocean. 



It has been suggested that with a shifting towards the east- 

 ward a regular retardation of the time of maximum or mini- 

 mum exists ; but Bruckner shows that no such relation exists 

 either with change of longitude or latitude. As regards the 

 amplitude of the oscillation, it can be said that while it does 

 not vary very much for the same place, yet for different 

 regions of the earth's surface it is by no means the same. In 

 fact there is found to be the general law that intensity of the 

 oscillations of rain-fall increases with the continentality of the 

 region. The average ratios of maximum : minimum and the 

 average rain-fall at the maximum and minimum for the period 

 1830-1880 according to the continental distribution, and also 

 arranged for progressive longitudes are as follows : 



