394 RAINFALL OF GUERNSEY. 



amount diminishes fairly regularly as we proceed to the west 

 and south-west. I have no doubt that the explanation given 

 in former papers is the correct one, namely, that the prevailing 

 winds being south-west, the rain is lifted by the rise of the 

 land and falls on the lee side, or east of the island. 



The peculiarity of the year is, that although this holds as 

 a rule, the two first months of the year (and in a minor degree 

 during April, July and August) were exceptions to that rule. 

 The falls were in those months, taken together, as follows : — 



St. Sampson's, 10*96 ins., taken as 100 ; l'Ancresse, 

 10-86 in., = 99% ; Eohais, 10-66 ins., = 95°/ o ; Couture, 10*48 

 ins., = 95°/ ; Fort Eoad, 10*16 ins., = 92°/ o ; Cobo, 9*96 ins., 

 = 90%; Les Blanches, 9*76 ins., = 89%; Grange, 9*66 ins., 

 = 88°/ o ; Forest Road, 9*60 ins., = 87%. 



The rainfall of January and February was therefore 

 heaviest at l'Ancresse and St. Sampson's, next heaviest in 

 Town, then at Fort Road and Cobo, and least at Les Blanches 

 and Forest Road. That is, instead of the falling off being 

 from east to west, it was from north-east to south-west. The 

 abnormal conditions only lasted for those two months, but it 

 took quite seven months to wipe out the differences and restore 

 the normal order. 



The explanation is to be found in the strength of the wind. 

 I find that the stronger the south-west wind is the further the 

 rain is carried while being lifted over the island, and several 

 abnormal falls over l'Ancresse are to be thus explained. The 

 mileage of the wind for the two months was 11,810 and 13,520, 

 while the next roughest month was but 10,190 (December), 

 the remaining months averaging about 7,000. The general 

 tendency is, therefore, for the heaviest rainfall to occur over 

 the town side of St. Martin's and the Town, and in a lesser 

 degree to extend to the east coast of the island, and further to 

 diminish in quantity as we reach the south-west and v>est 

 coasts. The only station interfering with this rule is the 

 Grange, which is abnormally low. The causes of the lessened 

 rainfall of the Grange are, as I stated last year, to be found in 

 (a) the shelter of trees, and (b) the indraught of the Vauvert 

 Valley. 



A study of the table will bring out some peculiarities. 

 Take for instance the departure from the normal of the 

 l'Ancresse falls. We now have a nine years' average for this 

 station, and this shows that l'Ancresse is below the Hoskins- 

 Collenette series all through the year. This year, owing to the 

 causes already discussed, it was above during January and 

 February, when it got a good lead. We know that this was 



