55 



(1) The normal mean temperature of the earth for twenty-five 

 years (18()1-1885) at Booenhausen, near Ahniich, at certain depths, 

 is as follows : 



Tbermometov. 



No. I.. 

 No. II. 

 No. m 

 No. IV 

 No. V- 



Ampli- 

 tude. 



C. 



11.(54 

 7.64 

 5.24 

 3.48 

 2.12 



(2) The mean temperature of the earth at a depth of about 1 meter 

 below the surface exceeds the mean temperature of the air | at a 

 meter above the surface] by more than -?°. The important influence 

 of the considerable altitude above sea level of the place of observation 

 is to be recognized in this result. 



(3) The decrease of the annual amplitude with increasing depth 

 for the adopted interval of -i Bavarian feet, or 1.17 meters, amounts 

 to 1:2.18° C, or very nearly one-third of the original amplitude of 

 the atmospheric temperature. The amplitude aP in centigrade de- 

 grees at the dei^th P in meters is represented by log aP=1.2()"20 — 

 0.1508 P. Whence we compute the amplitudes given in the last col- 

 umn of the preceding table. 



(4) The epoch of the occurrence of the extreme and mean tempera- 

 tures for the highest thermometer, No. I, are : Minimum, 2d of ^larch ; 

 first mean, 21st May; maximum, 24th August; second mean, loth 

 November. These are therefore separated from each other by inter- 

 vals of about 2f , 3, 2f, 3^ months, respectively. P^or each step down- 

 ward of 4 feet, or 1.2 meters, in depth, the occurrence of the epoch of 

 extreme temperature is retarded on an average 21 da^^s and that of the 

 mean temperature 24 days; therefore an almost uniform distribu- 

 tion of these dates is brought about down to a depth of 20.2 feet, 

 or () meters, where the minimum occurs on the 23d of INIay, the first 

 mean on the 24th August ; the maximum ITtli November, and the 

 second mean on the 24tli February. 



(5) The actual temperatures of the ground from 18G1 to 1889. at 

 the upper stage of 4.2 feet, or 1.3 meters, or thermometer No. I, did 

 not fall below 2° C. or rise above 17° C. At the lower levels they 

 ranged between 4° and 14°, 5° and 13°, 6° and 12°, 7° and 11°, respec- 

 tivel}'. 



(6) By a careful consideration of the state of the weather it is pos- 

 sible in every case to account for the connection between the fluctua- 

 tions of the temperature of the air and that of the earth. 



The following generalizations refer to the climate of the South 

 Bavarian Plateau only and to the four .seasons of the year: 



(7) In mild and, as usual, rainy, winter months, there is no mate- 

 rial rise in the temperature of the earth relative to the average tem- 

 perature curves, particularly at great depths, but generally a lowering 

 of temperature. 



