238 Scientific Intelligence. [Sept. 



ture of the air, although I believe that they have very little influence 

 on this variation. On the east side of the promontory of Hela the 

 temperature of the sea rose again to 74*^*16 at 8 a.m. (The air was 

 67*°10). This degree of heat the sea retained as far as Pillan and 

 Konigsberg ; and in Frischen Bay, near Pase, its temperature was 

 as high as 71 -"24, the air being 68° 90. 



The same appearances were observed during the return. The sea, 

 which near Faluwasser at 8 a.m. in four fathoms water, on the 3rd of 

 September, had only a tenjperature of 64° 04 ; and at 9 a.m. in the 

 Gulph of Dantzic, in fifteen fathoms, 63o'5, rose opposite Hela to 

 70°-52, the depth being seventeen fathoms, and the heat of the air 

 from 68^ to 69 '8. But when we again approached the promontory 

 between Rixhofter and Leba, the temperature of the sea sunk gradu- 

 ally to 59°-72, and then to 51°-08. The air was from 63° 5 to 64°'4, 

 and the time noon and 3 p.m. The difference in the temperature of 

 the surface of the sea was thus, in the first voyage 68°*54, 52'^- 16 = 

 16"38; and in the second, 70"*52 — 51°-08 = 19-°44. As we 

 approached Stolpen, without any change in the temperature of the 

 sea or the distance from the shore, the temperature of the water 

 again rose to 62^*6 and 64^4, although the sea was higher, the west 

 wind stronger, and the temperature of the air had sunk to 59*^. Over 

 against Riigenwalrle and Swinemunde the thermometer again rose 

 as high as 68« and 68° 72. 



The cause of the peculiar degree of cold at the promontory between 

 Leba and Rixhofter, is not currents observable on the surface, nor 

 shallows ; nor can the increase in the north latitude be considered 

 the cause ; for, to the east, at the promontory near Pillau, we are 

 nearly under the same parallel, and yet the water is warmer. The 

 cause lies probably at a distance, beyond the sound, and in the motions 

 of the lower layers of water, in an obliquely upward direction, as 

 diminutions of temperature in the atmosphere often depend upon 

 similarly descending currents. Now, as Horner's experiments show 

 that, in mean latitudes, the temperature of the sea sinks scarcely 

 13°-86 at the depth of 100 fathoms, no one will be inclined to refer 

 the phenomenon under consideration to local causes, in the basin of 

 the Baltic, which is only from 15 to 40 fathoms in depth. 



The entrance of the Polar waters into the deep water strata of 

 the Sound, offers us a possible cause ; and the length of the time 

 required in the communication of heat downwards must also, especi- 

 ally during this hot summer, be taken into consideration. In the 

 lake of Geneva, when the surface was at 70° '16, at the depth of 150 

 feet, the temperature had sunk 27^ and in the lake of Annecy, when 

 the surface was at 57°'92, the temperature had sunk 15°*84*. It is 

 evident, from these numbers, that the diminution of temperature 

 depends upon very intricate causes, as in calm water it is more rapid, 

 in deeply agitated water slower, unless currents bring from a distance 

 or push up to the surface colder water. 



The remarkable shape of the Baltic, and its stretching towards the 

 north, influence greatly the relative temperature of the north of 

 Germany, and give to a basin, to a depression in the land, an impor- 

 tance which, if it were dry, would, from its little depth, scarcely be 

 * Pouillet, Elem. de Phys. et de Meteorologie, ii. 676. 



