Influence of Gulf-Stream on Winters of Great Britain. 439 



mercuric iodide and chloride which led me to infer that the 

 molecules of these substances may possess an unusually long 

 mean free path of liquids, I omitted to mention their large 

 coefficients of expansion for heat. 

 August 8, 1885. 



LI. On the Winters of Great Britain and Ireland, as influenced 

 by the Gulf-Stream. By Prof. Henry Hennessy, F.R.S* 



IN the ninth volume of the Proceedings of the Royal 

 Society, p. 324, is printed a letter which I wrote to the 

 late General Sir Edward Sabine, on the influence of the Grulf- 

 stream on the winters of the British Islands. I pointed out 

 that if abnormally cold or warm winters are due to changes 

 in the condition of the comparatively tepid currents bathing 

 our shores, then during cold winters the differences of tempe- 

 rature between the Northern and remaining coasts should be 

 greater than during mild winters. A comparison of the 

 observations made in the months of December 1855, 1856, 

 and 1857 presented precisely this result. The winters of 

 some recent years having exhibited abnormal features as to 

 temperature, I have made a comparison of the results pub- 

 lished by the Meteorological Office, of which the following 

 may be taken as the leading facts. 



In comparing the coast-temperatures of Great Britain, it 

 should be remarked that the island is shaped in an irregular 

 triangular outline, of which the summit is in North Scotland, 

 and the base the south coast of England. For temperature- 

 comparisons it is therefore best to compare the South coast 

 with the West coast and North-east coast. 



In the winters of 1871 and 1881 the month of January was 

 cold in Great Britain, and the following results have been 

 grouped as indicated : — 



1871. (Cold.) 

 West Coast. 



South Coast. 



Helston ...... 41 -1 



Truro 38*9 



Sidmouth 36*6 



Eastbourne. . . , 35*2 



Ventnor 36*8 



Osborne 35*0 



Bournemouth.. 35*1 

 Worthing 34*9 



Mean 



Barnstaple .... 37*0 



Llandudno .... 36*1 



Liverpool .... 33*5 



Cockermouth . . 33*7 



Silloth 33-0 



North-East Coast. 



Holkham .... 32-2 



Boston 31-6 



Hull 31-3 



Whitby .... 31-6 

 Shields 33-0 



367 Mean 34-7 ( Mean 



Excess of South over West coast 2*0 



Excess of South over North-East coast .... 4-8 



Communicated by the Author. 

 212 



,.. 31-9 



