i8 3 
i 7°; so very slow is its advance in spring, and so swift its flight 
in autumn. 
Of the influences that modify temperature and give special 
character to the climate of a locality the following need particular 
attention in connection with vegetation. Liability to frost on the 
ground in the early summer and autumn months is an element 
of great value as affecting plant life. There are no open-air 
temperatures taken at Bidston Hill Observatory, but at Southport 
and Chester ground temperatures taken in the open air give the 
following results : — 
FROSTS ON GROUND. 
Southport, 1890-1901 
Chester, 1893-1901... 
4 years out of n in June. 
5 years out of 1 1 in September. 
1 year out of 9 in June. 
2 years out of 9 in September. 
Ground frosts never fail to appear at Southport in May and 
October, and only once in about ten years at Chester. 
The June and September ground frosts may not affect vegeta- 
tion greatly when there is only one in the month, and that of slight 
intensity ; but when, as in September, 1894, Southport, six took 
place, the results are likely to be disastrous. At Chester, three 
slight frosts in June, 1894, are m ost that have been recorded, 
but both the May and October ground frosts are liable to be 
frequent and intense. 
Another modifying element of great influence is liability to cold 
and boisterous winds, especially in spring. The eastern side of 
the Wirral peninsula and the Welsh coast, the northern coast 
line and the inland parts in the N.E. of the area, are exposed to the 
bitter cold N. and N.E. winds that often blow for weeks together 
in the spring, greatly retarding vegetable growth. 
Another element that exerts a very powerful modifying in- 
fluence is the sea and the estuaries. Near these the temperature 
does not rise so quickly in the spring as it does inland, and, con- 
trariwise, the autumn lingers longer on our coasts than in the 
inland and upland parts. 
These facts are important in looking for early and late speci- 
mens. Sheltered nooks must be sought, where good local covering 
shields from the prevailing cold winds, and southern slopes expose 
to the fullest influence of sunshine. 
