B. TERRESTRIAL PHYSICS AND METEOROLOGY. 51 



turning trade winds passing over the sea; warmer winters 

 and cooler summers, in consequence of the cooling action of 

 the sea and of the rather feeble equatorial current. 3 C^Feb. 

 8,1872,140. 



COMPAEATIYE CLIMATE OF HILL-TOPS AND VALLEYS. 



As the result of a series of investigations upon the compar- 

 ative temperature of hill-tops and valleys, made by Mr. Dines, 

 we are informed that the air on the top of a hill is colder than 

 in the valley in the daytime, and warmer at night. The daily 

 range at the higher station is not so great as at the lower, 

 the difference being about four and a half degrees. In cold 

 weather it is found that the air on the top of a hill is never 

 so cold as that in the valley. The rainfall, also, on the hill is 

 forty per cent, greater than in the valley. These observa- 

 tions were prosecuted in a valley at Cobham and on a hill at 

 Denbies, the difference in height being about six hundred 

 feet. 15 A, April 27, 1872, 530. 



UNUSUAL WEATHER IN THE ARCTIC OCEAN IN 1871. 



The accounts furnished by the Boston Advertiser from the 

 captains and crews of the vessels of the whaling fleet lately 

 destroyed or ice-bound in the Arctic Ocean concur in describ- 

 ing the presence of peculiar meteorological phenomena during 

 the past season. The prevailing summer wind on the north- 

 west coast of Alaska is from the north, and this works the ice 

 off from the land and disperses it, while the northwesterly 

 winds close it up on the shore. As the ice moves off, the 

 ships generally work up by the land, and in that situation 

 find whales in plenty. By the end of the season, when north- 

 westerly winds are prevalent, the ice has become so broken 

 up and melted that it has ceased to be an element of danger, 

 and the vessels are compelled to retire to the northward by 

 heavy ice drifting along the coast from the north, and not from 

 a threatened closing in upon the land. But this season the 

 easterly winds were not so strong and constant as usual, and 

 the ice that had gone off from shore returned in a heavy 

 pack that it was impossible to get a ship through, or even to 

 hold against at anchor. The heavy ice-fields are all com- 

 posed of fresh-water berg-ice, not floe-ice of salt-water. The 

 bergs are not of the immense proportions seen in Greenland 



