86 Curative Influence of the 



southern coast a higher and more steady temperature during 

 the winter season, than any other portion of our island. These 

 effects being chiefly derived from aspect, security from the 

 effects of piercing winds, and from the influence which the 

 temperature of the ocean exerts on the superincumbent atmo- 

 sphere ; that of the surface water of the sea being greater dur- 

 ing this period of the year, than the temperature of the sur- 

 rounding air. Dr. Harwood remarks — that 



*' To account for this difference, it appears that the impressions 

 of heat, which are imparted by the sun's rays to the surfaces of the 

 waters, and of the earth, are disposed of very differently ; that heat 

 which is received ©n the surface of the land, being slowly admitted, 

 and feebly communicated to the dense earth below, loses much of 

 its intensity by freely imparting it to the circulating air ; while on 

 the contrary, such rays of light and heat as fall on the surface of the 

 ocean, without this sudden check to their progress, penetrate the 

 bosom of the deep to a greater or a less depth, in proportion to its 

 transparency. Thus their limits are confined to a few fathoms from 

 the surface, and their influence becomes gradually diffused through 

 this upper stratum of water. From hence, probably, and from that 

 law which ordains that the cooler portions of fluid should remain at 

 a depth proportioned to their coolness, or that of their superior spe- 

 cific gravity, the important result follows — that^during the winter half 

 of the year, the temperature of the surface of the sea is greater than 

 the mean temperature of the air, tending to produce, by the well 

 known property which heat possesses, of equally diffusing itself 

 through contiguous bodies, that equality in the latter, which can 

 only be expected to be experienced, in this variable climate, in shel- 

 tered situations on the coast ; situations which, like detached islands, 

 consequently experience comparatively httle of that powerful change 

 from summer to winter, which is felt on wide extended continents. 

 Thus I may remark, that on the 8th of January last, when the ther- 

 mometer stood at 35° on the Hastings' beach, I found it rise to 40^ 

 on being introduced into the surface-water of the sea ; and on the 

 12th of February, the coldest day of the present year, when it stood, 

 in the same situation, at 28°. 5, on immersion, it rose to 39°. 



"There is, however, another very efficient cause for the more ele- 

 vated temperature of the ocean; I allude to the action of its cur- 

 rents, and the succession of its tides, by constantly mixing and 

 combining that surface-water, which has, in various latitudes, been 

 differently affected by the solar beams. 



"Kirwan has given to the sea, between the latitudes 50^ and 51*^, 

 which may be considered that of the south coast of England, a 

 monthly mean temperature as follows : 



January. . . 42°. 5 April .... 52°. 4 



February . . 44 .0 May .... 58 .0 



March ... 50 ,0 June .... 61 .0 



