TEMPERATURE. 



13 



The seasonal variation in temperature in the remote parts is less 

 than 2° C, the lowest temperature found at "42" being 10.4° C, the 

 highest 12.1° C. The variation is greatest near the mouth of the cave. 

 Ice is rarely found as far from the entrance as "10" in winter, but 

 there is little variation in the way of increase of temperature in summer. 

 Even at "i 1, " quite near the entrance, the highest recorded summer tem- 

 perature is 12.2° C. The 

 winter temperature from 

 "10" to the mound becomes 

 considerably lowered, a mark 

 of 3.5° C. being reached at 

 "17," and 8.55° C. at the 

 mound during February. 

 Beyond the mound there is 

 much less variation, a tem- 

 perature below 10° C. being 

 rarely attained. These ex- 

 tremes of low temperature 

 in the inner part of the cave 

 are very temporary. They 

 are produced only by con- 

 tinued severe cold and are 

 not maintained after the 

 severe weather is over. 



Reference to the accom- 

 panying table of tempera- 

 tures shows that the fluctua- 

 tion in the cave tempera- 

 ture, particularly during the 

 winter, is not only seasonal, 

 but that it occurs also with 

 varying meteorological con- 

 ditions, persistently cold or 

 continued mild weather pro- 

 ducing noticeable changes 

 some distance within the 

 cave. The temperatures are 

 given in degrees centigrade. 



The average monthly temperatures for Bloomington for the past 

 six years, as given by the United States Weather Bureau, are : January, 

 0.8° C; February, 1.3°; March, 5.3°; April (no record); May, 18°; 



FiQ. 1. — Diagram showing average temperatures in 

 Mayfleld'sCaveand at Bloomington. 



