THE CLIMATE OF GREAT BRITAIN. 279 



in assigning effects to those zones of meteorities 

 which are known to. intersect the earth's orbit, and 

 others which may fairly be assumed to fall within or 

 without that orbit. It may be, perhaps, that the 

 recognised shooting-star periods have, some of them, 

 their counterparts in heat-changes ; but certainly the 

 time has not yet come to pronounce a consistent theory 

 of such effects. The evidence afforded by the Greenwich 

 curve on this point is unsatisfactory, to say the lease. 

 The elevation at the beginning of January, and the 

 marked irregularity in February, correspond to Ertel's 

 views ; so also the fact that large aerolites have fre- 

 quently fallen in the first week in April, about the 

 20th of April, about the 18th of May, early in August, 1 

 about the 19th of October, and early in December, 

 seems to correspond to elevations in the curve ; while 

 depression opposite the 1 2th of May, might be referred 

 to the intervention of the zone of meteors, which causes 

 the now celebrated November shower. But the nega- 

 tive evidence is almost equally strong. Where, for 

 instance, is the elevation which one would expect, on 

 Ertel's theory, in November ? Also, if the cause of the 

 observed irregularities were that suggested by Ertel, 

 the curves for other countries in the northern hemi- 

 sphere should exhibit similar irregularities on corre- 

 sponding dates, which does not appear to be the case. 

 In fact, if there really exist effects due to cosmical 

 causes, these are not likely to be educed from observa- 



1 Keference is not made here to the August shooting-star shower, 

 which takes place a week later than the epoch alluaed to. 



