upon the Flowering of Plants. 



153 



the average of the preceding years up to 1865, so that the average 

 is different for each year; thus the diagram for 1880 indicated the 

 differences of the flowering in that year from the means of the 

 previous fifteen years, that for 1881 from those of the previous 

 sixteen years, and that for 1882 (which is given herewith) from those 

 of the previous seventeen years. It must be observed, however, 

 that the variations are generally so slight (from the large number 

 of years already taken) that in most cases they are the same for all 

 three years. 



A few words must now be said about each diagram. In that for 

 188U it was observed that January was very cold, February and 

 half of March were warm, and then every succeeding week (except 

 the first week in April) more or less cold. On referring to the 

 flowering it was seen that till the middle of March {i.e., as long as the 

 weather continued warm) plants were behind their proper averages, 

 and then for eight or nine weeks were before them, a break of a 

 cold week in the middle of April destroying the uniformity, and 

 after that vegetation was uniformly backward. Thus, as long as 

 the weather continued warm plants were late, and as soon as the 

 weather turned cold plants were early. The evident solution of this 

 apparent paradox is clearly that plants require time to get influenced 

 by the weather, and as far as this diagram showed that period is 

 about five or six weeks. 



From the diagram for 1881 it was seen that during the first 

 six months there were only six weeks whose mean temperature was 

 above the average, and those only occurred at scattered intervals ; 

 it was also damp till the middle of March, and then singularly dry. 

 As might have been expected plants were almost uniformly late till 

 the beginning of June, and even then they might be considered, as 

 a whole, fairly backward. 



A marvellous difference occurred in 1882. Till the end of the 

 first week in February, the weather was cold, but then a warm 

 period set in, lasting till about the end of the first week in April, 

 when the weather began to turn colder, and the temperature of both 

 April and May was hardly above its proper amount. June and 

 July were decidedly cold, but it was not till the middle of June that 



