IN THE UNITED KINGDOM AND FRANCE. 



73 



Water is much more effective in this respect ; the heat penetrates to a 

 greater depth within it than on dry land, and it becomes more com- 

 pletely absorbed owing to the far higher capacity for heat of water, and 

 the difference between its diathermanous action on the luminous heat 

 rays entering it from the sun, compared with its action on the obscure 

 rays quitting the particles in the interior of its mass. The incoming 

 luminous rays penetrate freely to a moderate depth; the outgoing obscure 

 rays are stopped almost altogether. These properties, combined with 

 the mobility of water, as I have shown in the publications just quoted, 

 fully account for the storing up of warmth in the tropical currents, and 

 the retention of a considerable portion, which is ultimately given out 

 for our benefit in the waters surrounding these islands. 



The observations made in winter strikingly illustrate these conclusions, 

 and they show that the occurrence of frost may be considered as impos- 

 sible in the waters on the south and west coasts of Great Britain and 

 Ireland. Mr. Whitley, in the essay already quoted, gives the results of 

 observations on sea temperature, recorded in the logs of the Cunard 

 mail steamers, and as their course for some distance beyond Cape Clear 

 is nearly due west, the temperature recorded for 10° of west longitude 

 may be considered as equivalent to that of the sea a little outside Crook- 

 haven at the south-west extremity of Ireland. On this account, I include 

 these facts in the annexed table with the numbers showing the sea and 

 air temperatures determined on the coast of Ireland in 1851. As the 

 temperature of the air was not taken at Bunown and Cushendall, the 

 air temperatures observed at the two nearest stations respectively, namely, 

 at Innisgort lighthouse, in Clew Bay, and at Portrush, may be referred 

 to for comparison. It should be also borne in mind that these are not 

 only mean temperatures (not like those taken at noon), but also that the 

 sea temperatures in 1851 were observed in comparatively deep water, 

 and never in shallows over banks close to the shore. 



Table III. 



Table of Mean Temperatures of the Sea and Air on the Coast of Ireland. 





c3 



s 



s 



- 



OS 



1 

 ft 





■a 



3 



6 



§ 

 >-> 



9 



3 

 < 



1 



■S 

 p. 



U3 



s 



1 











§ 



> 



© 



a 







1 







9 



O 



























9 







9 











In longitude 10 

 W., off Crook 

 haren, 



- i Sea, 



51'G 



500 



51*0 



52-0 



530 



57-0 



59-0 



59-0 



58-0 



55-0 



53-0 



52-0 



64'2 



Oastletownsend, 



f Sea, 

 (Air, 



47-1 

 45*4 



46-6 

 460 



46-8 

 46-1 



49-7 



47'9 



535 



536 



563 



57-0 



603 



607 



61-3 

 6r8 



60-3 

 59'6 



54-8 



54-i 



49-2 



45*7 



48-6 

 46*9 



52-9 



5n 



Bunown, 



. Sea, 



48-7 



494 



50-9 



51-4 



54-4 



57-8 



60-2 



62-9 



615 



55-1 



49*3 



48-1 



541 



Innisgort, . 



. Air, 



46'3 



45'* 



46'3 



47'3 



5*'i 



56-5 



58-3 



6o*9 



58-4 



53'7 



47-3 



47-8 



51*7 



Courtown, . 



( Sea, 

 '\Air, 



46-0 



43'3 



451 



43'8 



45-8 



44"3 



483 



466 



532 



53-5 



58-4 



573 



61-8 

 59*5 



63-5 

 60-7 



60-9 

 56-5 



56-1 



5i-8 



47-9 

 41-6 



46-8 

 4<-i 



528 



50-3 



Donaghadee, 



( Sea, 

 \Air, 



46-5 



43*8 



456 

 43 - l 



456 



43"3 



48-1 

 466 



503 



5o-8 



52*5 



55-8 



55-8 



57-0 



57-4 

 58-8 



57-5 

 56-3 



54-7 

 51-8 



50-1 

 43'9 



49-3 

 45'4 



511 



496 



Cushendall, 



. Sea, 



46-6 



457 



45-6 



47-2 



49'1 



521 



55-4 



57-0 



58-3 



556 



516 



49-4 



511 



Portrush 



/Air, 

 \. Sea, 



43*o 



4^*3 



43'9 



457 



50-2 



55'3 



5-65 



58-8 



55'5 



51*3 



44'4 



44'7 



49'i 





46-9 



45-6 



457 



47-9 



50-6 



54-3 



57 5 



587 



587 



54-9 



49-6 



47-8 



51-5 



