1102 



lil this respect I should like to refer to a conclusion of my former 

 invefjtigation : (These Proceedings, Aug. 1905, p. 160 if.) that relard- 

 ation or acceleration of the sun's activity corresponds to analogous 

 phenomena in the meteorological curve. 



The deeper causes underlying both phenomena may be left undis- 

 cussed here. 



It is worth noticing that 1 have not been able to discover in my 

 material either Bruckner's well-known period of 34.8 years, nor 

 that of 12.4 years found by Kaptkyn '), which does not however 

 prove anything against the reality of these periods. 



Leaving theory aside we may now see whether an empirical statis- 

 tical examination of the material leads to useful results. 



Since such a 89year period cannot but be related (o the activity 

 of the sun, which is most apparent in a sun-spot period of about 11 

 yeais, the idea suggests itself to subdivide our period into 8 minor 

 periods of 11 '/s jears. If we wish to avoid an artificial classification, 

 the varying length of the average solar period of about 11 years 

 should not be taken into account; every interval consequently contains 

 11 years, the 45^'' period-year being divided over neighbouring inter- 

 vals in order to retain integers. Hence each interval should be 

 reckoned at 11 Vr years. (This same classification might have been 

 adopted if no relation between the terrestrial and the solar pheno- 

 menon were suggested). 



Within each 11 year interval the positive or negative deviations 

 from the average winter temperature were now determined and ex- 

 pressed in degrees centigrade. The result is seen in table IV, where 

 also, in the second and third rows, the corresponding values are 

 given for the intervals of 22 and 4472 Jt'ars. 



An examination of these statistics shows that in our material 

 there is no certain indication of a fluctuation corresponding to the 

 eleven year solar period ; neither can a longer period than 89 

 years be recognised. 



Most clearly of all a 447, -year period manifests itself ; the diagram, 

 in which only the full-drawn curve represents the doubly smoothed 

 values (17 years combined; scale 1 cm. = 4°0 C. ; all abnormal 

 winters) is given below. (The two curves to the left). 



It may further be stated that nothing points to a gradually 

 increasing or decreasing frequency of severe winters in historical 



1) E. Bruckner, "Klimaschwankungen seit 1700", Vienna and Olmiitz, E. 

 HoLTZEL 1890 ; J. C. Kapteyn, "Tree-growth and meteorolog. factors", Receuil 

 des Iravaux botaniques néerlandais, 1914. 



