of Heat over Islands. 253 



with those contained in Professor Dove's Tables. In the Table 

 which exhibits the mean annual temperature of twenty-three sta- 

 tions in Ireland, the results marked L are given on Dr. Lloyd's 

 authority. He estimated these numbers from the observations 

 of 1851, by subtracting 0°'3 from each, because in Dublin the 

 temperature of the year was in excess of the mean of twelve 

 years by that quantity. The mean temperatures so deduced are 

 probably much closer to their true values than the uncorrected 

 results of 1851. This maybe noticed with reference to stations 

 where observations were made during other years, such as 

 Armagh and Markree, where the temperature is regularly 

 recorded at the astronomical observatories of Dr. Robinson and 

 Mr. Cooper. 



The observations at Cove were made by Dr. Scott ; at Cork, 

 by Mr. Humphreys and his predecessors at the Royal Institu- 

 tion, also at the barracks ; at Limerick and Kilrush, in con- 

 nexion with the Ordnance Survey ; at Derry, by Mr. Patterson ; 

 at Waterford, by Dr. Cavet * ; at Belfast, under the superinten- 

 dence of Professor Stevelly at the College. 



The isothermals of the northern portions of the two great 

 continents which constitute the old and new worlds, exhibit, at 

 least during the winter, very decided conformity to the same laws 

 as those which are so manifest in the British Isles. 



On examining Professor Dove's large map of the isothermals 

 of Januaiy and July (No. 3 in General Sabine's edition), it 

 appears that during the former month the isothermals which 

 traverse North America run very nearly parallel to its western 

 coast ; then bending, they run nearly parallel to the northern 

 shores of the Gulf of Mexico ; afterwards they ascend towards the 

 north-east, and cut the eastern coast of the United States, Canada, 

 and Labrador at very oblique inclinations. In Europe, those 

 which approach the sea appear in general to be parallel to the 

 coast, as in Scandinavia and on the western and southern coasts 

 of France. In Asia, some of the isothermals approach in shape 

 a rude outline of that great division of our continent, and many 

 appear to cut the northern coast of Siberia almost at right angles 

 to the parallels of latitude, precisely in the same manner as some 

 of those in the British islands, which are not re-entrant curves. 

 These results indicate the existence of the two poles of mini- 

 mum temperature suggested by Sir David Brewster f ; but a 

 more general conclusion may be drawn from the entii-e of the 

 preceding reflections, — namely, that there are nearly as many 

 poles of minimum temperature upon the globe as there are islands 

 and continents distributed over its surface. 



• Wilde, ill the llc'ports of the Census Commissioners. Tiibles of 

 Ikathx, vol. i. t See note t, P- 242. 



