886 THE CLIMATE OF IRELAND, AND 



you might see that they have all certain features in common. 

 But in considering the climate of Ireland, and the influences to 

 which it is subject, we may confine our attention to that branch 

 of the circuit of waters which bathes its shores. 



I have said that the Gulf-Stream divides when it reaches the 

 meridian of 38 W., a portion there turning off to the southward, 

 while the greater part bends to the north-east, sweeping along the 

 western shores of Ireland and Scotland on its way to the North 

 Sea. That these warm waters reach the shores of Ireland is 

 proved, not only indirectly, by their effect on the climate but 

 also, directly, by the drift-wood and the fruits of the Tropics, 

 which they often carry thither. Even the living inhabitants of 

 the Tropical seas are thus sometimes transported to our waters. 

 It is only a few years since the bonita, and other tropical fishes, 

 entered the English Channel in vast numbers, and destroyed 

 the pilchard, which is the chief support of the fishermen of the 

 southern coast. 



But although there can be no doubt of the presence of these 

 warm waters on our shores, it was desirable to obtain some 

 measure of their influence ; and accordingly, in the year 1851, 

 when a general system of meteorological observations was carried 

 out in Ireland, the attention of the observers was specially directed 

 to this subject, and measures of the temperature of the sea were 

 taken at several of the coast-stations. When the results were 

 compared with those of the temperature of the air, it was found 

 that the sea was sensibly warmer than the air over the land, the 

 difference amounting, in the mean of the year, to 3'8. The 

 excess is, as might be expected, much greater in winter than in 

 summer : in the latter season it is l-8 only ; in the former, it 

 amounts to 5*7. 



But this difference is by no means a measure of the whole 

 heating effect of the Gulf-Stream ; for the temperature of the air 

 over the land is elevated by the influence of the heated waters 

 which encompass it. We obtain a juster notion of the magnitude 

 of the effect, by noting the course of the lines of equal temperature 

 in the Atlantic. Looking at the map of the isothermal lines 

 which is before us, we observe that, in the Atlantic, these lines all 

 deviate greatly from the parallels of latitude, as they recede from 

 the Equator, their convex summits falling near the western shore of 

 the Atlantic, while their concave summits are on the eastern. It 



