B. TERRESTRIAL PHYSICS AND METEOROLOGY. 27 



MOVEMENT OF TEMPERATURE WAVES. 







According to Professor Dove, of Berlin, any abnormally 

 low temperature in Europe travels from the east to the west, 

 while any subsequent abnormally high temperature move's 

 from west to east. It is said that these generalizations have 

 been verified by observations extending over almost the 

 whole of Europe and a large portion of the United States of 

 America. I A, June 17, 288. 



INCREASE OF TEMPERATURE IN THE MONT CENIS TUNNEL. 



According to Professor Everett, the increase of tempera- 

 ture in the Mont Cenis Tunnel amounts to one degree of 

 Fahrenheit to every eighty-one feet of depth of descent, a 

 progression slower in amount than that hitherto observed 

 elsewhere. Mr. Symons has found the increase to be one de- 

 gree for fifty-four feet at one place in England, while exper- 

 iments near Paris give one degree for fifty-six feet. In sink- 

 ing a well in Siberia, although the earth was frozen to a depth 

 of about 700 feet, the increase of temperature was one degree 

 in fifty-two feet. 18 A, August 18, 537. 



DIFFERENCE OF MEAN TEMPERATURE AT VARIOUS HEIGHTS. 



The announcement has been made by Mr. Glaisher, the 

 well-known British meteorologist, that the monthly mean 

 temperature of the air at twenty-two feet of elevation is 

 higher than at four feet at all hours of the day and night in 

 January, February, November, and December ; in the after- 

 noon and during the night hours in the months of March, 

 April, August, September, and October ; and in the evening 

 hours and during the night in the months of May, June, and 

 July. He also states that the mean monthly temperature 

 of the air, at twenty-two feet and at fifty feet, is higher dur- 

 ing the evening and night hours through the year than at 

 the height of four feet, and also higher night and day during 

 the winter months. 12 A, November 10, 1870, 37. 



TEMPERATURE OF THE EARTH AT DIFFERENT DEPTHS. 



A commission of the British Association has for some years 

 been engaged in collecting evidence in regard to the temper- 

 ature of the earth at different depths and in different regions. 



