February i6, 1922] 



NATURE 



211 



\ 



IS noted already, the earliness of 1920 was most 

 strongly marked in England, S.W. We therefore 

 [conclude that London is at least a week earlier 

 lan Penzance in its fruit flowering ; also that, at 

 [any rate in an early season, while further advance 

 sastward south of the Thames estuary results in 

 iittle change, there is a decided retardation on the 

 jpposite bank as one proceeds in a north-easterly 

 lirection. It is difficult to account for the 

 [Harrow-Watford delay. Further on the cooling 

 finfluence of the North Sea and of east winds may 

 :ome into play. The isophenes cut the East Coast, 

 the direction varying N.E. to N. East-wind 

 exposure may partly account for the retarda- 

 Bon at Purley (Surrey) and on the Wilt- 

 shire downs. It is not easy offhand to 

 Suggest the reason affecting the extreme south- 

 zest, which must be largely influenced by ocean 

 :onditions. One would expect the fruit-flowering 

 season to share in the relative earliness shown by 

 khe means of all twelve flowers (omitting ivy), 

 ranging from February 6 to July 15. One may, 

 lowever, note that, for the first six months, iso- 

 lerms and isohels taken together slightly favour 

 the London area, but in April the reverse was the 

 ise. 



The East Devon and Somerset earliness was 

 [fully expected. Each year the isotherms show a 

 [remarkable uprush of warmth .along the Severn 

 Isea and watershed and a corresponding lie of the 

 'isophenes. In 1920 the isotherm bulge reached 

 the borders of Yorkshire. 



Having thus considered the query raised, an 

 extension of the subject may be of interest along 

 two other lines through London, which I have 

 worked out for the sake of comparison. These 

 are: (i) The L.B.S.C.R. from the Isle of Wight 

 and on by the East Coast route to Edinburgh 

 and Ross-shire; (2) from East Sussex and on by 

 the West Coast route to the Glasgow district. 

 Round London much the same stations come in 

 along all three lines. The comparison is best 

 made by placing the two series side by side, 

 arranged roughly by latitude (5of° to 57f°). The 

 numbers in brackets show the number of stations 

 in each group. 



As one expects, both series give a decided delay 

 with latitude and longitude. Hopkins's corrections 

 for these from London to Ardross Castle ( + 6^° 

 and +4°) give the relative date for the latter 

 April 18. For Glasgow (4^° and 4°) we get 

 April 26, the value round the Firth of Forth 

 (4^°, 3°) being April 12. 



Either Hopkins's Law needs modification for the 

 period in question, more than is indicated by the 

 whole period, or there are special influences at 

 work, such as oceanic effects, prevalence of east 

 winds, and propinquity of hill and mountain 

 masses. Nor need these be mutuallv exclusive. 



To investigate them more complete data are 

 required. For instance, we hope shortly to have 

 mean values for a considerable number of stations 

 over the thirty years of our records. The most 

 obvious effect at present is perhaps the retarda- 

 tion for the spring period in question, due to high 

 elevation, and even more the propinquity of hill 

 and mountain masses. Is this due to the lag 

 effect of their winter cooling? Snow would still 

 be lying on the Welsh mountains in blackthorn 

 days. 



May I, in conclusion, direct the attention of 

 readers of Nature to the need for yet further 

 observers, especially in the districts Indicated by 

 the lacunae in the tables and the fact that the 

 L.S.W.R. from Exeter could not be used? Either 

 my colleague, Mr. H. B. Adames (33 Holcombe 

 Road, Ilford), or myself (Asgarth, Purley) 

 will gladly give further information, . or 

 observing forms can be had direct from the 

 Assistant Secretary of the Royal Meteoro- 

 logical Society, Cromwell Road, S.W. 7. When 

 we see the prominent position elsewhere, 

 especially in the United States, taken by pheno- 

 logical work In its bearing on horth:ulture and 

 agriculture, we realise the need In this country for 

 greater unification In and concentration on its 

 investigations. 



Since the above was in print Prof. Hopkins has 

 sent us the typed copy of an unpublished exhaus- 

 tive discussion of the blocllmatic association 



Mean Flowering Date, Sloe, Chestnut, May, 1920. 



NO. 2729, VOL. 109] 



