298 



Dr. W. J. S. Lockyer. 



Such a cycle, if of sufficient intensity, should cause a variation from 

 the normal circulation of the Earth's atmosphere, and should be indi- 

 cated in all meteorological and like phenomena. 



It is not intended to go into any detail as regards such terrestrial 

 variations, but it may be noted that much important work has been 

 done on the investigation of changes in climates by Professor Eduard 

 Bruckner,* who expended immense labour during many years in the 

 promotion of the inquiry. Professor Bruckner did not restrict his 

 discussion to observations made over a small area or for a short interval 

 of time, but utilised those made in nearly every part of the civilised 

 world, and extending as far back in point of time as possible. Further, 

 he did not restrict himself to the discussion of the observations of one 

 or two meteorological phenomena, but examined critically all likely 

 sources from which such changes as he expected could be detected. 

 Thus he sought variations "in the observations of the height of the 

 waters in inland seas, lakes, and rivers ; in the observations of rainfall, 

 pressure, and temperature ; in the movements of glaciers ; in the fre- 

 quency of cold winters ; growth of vines, &c. 



The result of the whole of the investigation led him to the conclu- 

 sion that there is b, periodical variation in the climates over the vjJwk earth, 

 tJie mean length of this period being 34*8 ± 0*7 years. 



It may be of interest to remark, that so convinced was Professor 

 Bruckner of the undoubted climate variations that he deduced, and so 

 certain was he that such variations could only be caused by an external 

 influence, that he investigated Wolf's sunspot numbers to see whether 

 such a cycle was indicated. 



Misled by the long period of variation of sunspots of fifty-five years 

 as suggested by AYolf , he was led to conclude that his climate variation 

 was independent of the frequency of sunspots. He sums up his con- 

 clusion in the following words f : — 



"Die Klimaschwankungen vollziehen sich unabhangig von den 

 Schwankungen der Sonnenflecken-Haufigkeit ; eine 55-jahrige Periode 

 der AVitterung, wie sie der letzteren entsprechen wiirde, ist in unseren 

 Zusammenstellungen nicht zu erkennen." 



Nevertheless, he was led to make the bold suggestion, that such a 

 variation as he sought must really exist in the Sun, but might j)ossibly 

 be independent of sunspots. He finally concluded that the climate 

 variations are the first symptom of a long period variation in the Sim, 

 which probably will be discovered later. 



In the light of the present communication Professor Bruckner's 

 conclusions are of great interest, because not only does the length of 



* ' G-eographische Abhandlungen Wien,' Baud 1, Heft 2, p. 155, 1890. " Klima- 

 Scbwankungen seit 1700 nebst Beinerkungen iiber die Klimaschwankungen der 

 Diluvialzeit." 



t ' Klimaschwankungen,' Bruckner, p. 212. 



