XxX INTRODUCTION. 
in the temperature of a locality are of even greater importance 
than the amount of rain which it receives. A single excessive 
fall of the temperature for instance, even for a short period, 
may completely destroy an established alien which has 
flourished for many years with average winters. It is not so 
much the possession of a high or low mean annual temperature 
that determines or limits the vegetation in any district as the 
lowest actual temperature occurring there. In this respect 
Kerry owes a great deal to its geographical position. To what 
exact cause the mildness and equability of the winters on the 
west coast of Ireland is really due appears to be a question on 
which expert opinion is much divided. Many still pin their 
faith to the warming influence of the Gulf Stream. Others 
hold that this influence does not extend so far as the Irish 
shores, and that the warming is done by a great oceanic 
circulation which carries the cold polar waters southward 
underneath a northward flow of warm water from the equator.* 
While yet another and more recent authority, Mr. Dickeson in 
the Quarterly Journ. Roy. Meteorl. Soc. for Oct. 1899, contends 
that ‘“‘ the mild winters of our western coasts are not due to the 
heating of the air by contact with a surface of warm water 
brought by a current from warmer regions . . . but to the 
fact that the air has itself come from these warmer regions, 
and is charged with abundant moisture, which sets free vast 
quantities of heat through condensation.” 
While the exact cause appears to be in doubt, the fact 
remains that for each of the seven coldest months in the year, 
October to April inclusive, the temperature of the air at 
Valencia has a higher monthly mean than at any other spot 
in the British Isles, the Scilly and Channel Islands alone 
excepted. The result of thirty years’ observations gives 
Valencia and other portions of west Kerry an average mean 
for January, the coldest month of the year, of 44.5° F., a 
January mean shared by Hyéres, Cannes, Mentone and other 
favourite winter resorts of the: Mediterranean Riviera. The 
hottest month of the year at Valencia is August with a mean 
of 59.5° F., which gives for the west of the county an average 
annual range of only fifteen degrees. The annual mean for 
this locality is 51.1° F., a figure not equalled by any other 
record in Ireland, and only exceeded in the British Isles by 
Scilly with 52.1° and Jersey with 51.7° F. This comparative 
equability of the Kerry climate forms one of its most charac- 
* Vide “ Atlantic Ocean” by Dr. W. B. Carpenter, Hncyclop. Brit., 9th 
Eid., Vol. tit., p. 25. 
