F. Waldo — Bruckner's Klimaschwankungen. 149 



tween pressure and rainfall leads us to confidently expect that 

 the long period relations of the former will be more readily 

 recognized than those just found for the latter. For the tem- 

 perature oscillations Bruckner has computed lustra means for 

 many places in 22 extended regions, and he has also made use 

 of Koppen's data for 29 regions. The observations used do 

 not extend much back of the beginning of the present century, 

 except for a very limited number of places, and in nearly all 

 cases they are for the northern hemisphere. 



These investigations give the following periods of relative 

 heat and cold : 



Koppen. Bruckner. 



Warm 1791-1805 Warm... 1791-1805 



Cold 1806-1820 Cold 1806-1820 



Warm 1821-1835 Warm.. 1821-1835 



Cold. 1836-1850 Cold.. 1836-1S50 



Warm 1851-1870 Warm 1851-1870 



Cold 1871-1885 



Only 5 per cent of the material used by Koppen and 8 per 

 cent of that used by Bruckner showed the opposite relation to 

 the ones given ; but perhaps 15 per cent gave no definite re- 

 sults the one way or the other. The following table shows the 

 amounts of excess (+) and deficiency (— ) of temperature re- 

 ferred to the average temperature as determined by many 

 vears of observation. 



Tropics -i-'34° --37° (-'10°) +-20° --05° (--09°) 



Sub-tropics +'66 —-40 +-10 +'59 | —-26 ( + -03) 



Warm temperate .. . +'49 —-56 +'21 + *37 i —-35 +'16 



Cold temperate +"47 —-33 +-20 +-40 --17 +'14 



Cold zone or) 81 _. 2Q 37 69 _ >23 



sub-Arctic ) ^ 



In the first half of the table are the actual differences of the 

 lustra averages from the mean ; and when these maxima and 

 minima are determined by taking into account the values for 

 the lustra on either side, the amounts are somewhat dimin- 

 ished ; these are given in the last half of the table. For the 

 average of the whole earth (so far as observed at the various 

 dates) the times and relative amounts of the maxima and 

 minima are : 



1736-40 --43° 1821-25 +-56° 



1746-50. +'45 1836-40 —-39 



1766-70 --42 1851-55 +-I1 



1791-95.. -f-46 1866-70. +41 



1811-15.. --46 1881-85 --08 



We see, then, that the amount of change in temperature dur- 

 ing the 36 years period of oscillation is about 1° C. or nearly 



