60 



of the maximum temperatures i)f the air, less the temperatures of the 

 soil at 2 p. m. at a depth'of 2 inches was 2.3° F. in July, 1888, and 

 3° F. in August, 1888. On the other hand, the average value of the 

 maximum temperature of the air, less the temperature of the soil at 

 2 p. m. at a depth of 12 inches was 12° F. for the observations here 

 given, scattered through July and August, 1888. 



Temperatures at Brookings, /S'. DaJc. 

 [Lat. 44° 20' N. ; long. 96° 40' W. ; altitude, 1,000 feet.] 



It would appear that the reading of the soil temperature is fre- 

 quently omitted when rain falls; this is a bad practice, but the records 

 suffice to show us that in this dry country and during the summer time 

 the maximum surface temperatures of the soil will not differ much 

 from the maximum temperatures of the air, while the soil tempera- 

 tures at 12 inches will closely follow the mean temperature of the 

 air. The latter mean, viz, one-half the sum of the maximum and 

 minimum record for any day is greater than the mean temperature 

 of the layers of soil at 2 and 12 inches depth, as observed at 2 p. m., 

 by about 6° F. , ' 



