55 
(1) The normal mean temperature of the earth for twenty-five 
years (1861-1885) at Bogenhausen, near Munich, at certain depths, 
is as follows: 
Wisin 
Ther ter ern | tempor. | Ampli- 
Cu Ome ver: Bayar ian | Meters. tere tude. 
eet. | 
| fs 
| Of (Ok 
INI), dle cee eka 2 Sie ae ge See as ea ee Sib 8 yg Bt ne a re 4.2 1.3 9.18 11. 64 
INC ey Ree eK SER E 4 Oe) Det Ui Lee etal 8.2 2.5 9.16 7.64 
TNO), THT Ee Se = I es Ee Ra eee Le nt eee ee ee ee 12.2 3.6 9.12 5, 24 
WO, UW. s sae cet 5 CRESS oe eR ee en ae eee 16.2 4.8 9.12 3.48 
INGE Wise Oe Se ee ae a SReee ee eee 20.2 6.0 9.06 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 2°. 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 4 Bavarian feet, or 1.17 meters, amounts 
to 12.18° C., or very nearly one-third of the original amplitude of 
the atmospheric temperature. The amplitude AP in centigrade de- 
grees at the depth P in meters is represented by log A P=1.2620— 
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 March; 
first mean, 21st May; maximum, 24th August; second mean, 15th 
November. These are therefore separated from each other by inter- 
vals of about 23, 3, 23, 35 months, respectively. For each step down- 
ward of 4 feet, or 1.2 meters, in depth, the occurrence of the epoch of 
extreme tempera ature is retarded on an average 21 days 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 6 meters, where the minimum occurs on the 23d of May, the first 
mean on the 24th August; the maximum 17th November, and the 
second mean on the 24th February. 
(5) The actual temperatures of the ground from 1861 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 18°, 6° and 12°, 7° and 11°, respec- 
tively. 
(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 1s 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. 
