Earth Temperatures at Kimherley. 



427 



TABLE 8. 



Some Harmonic Constants in the Annual Variation of Earth 



Temperature. 





Epoch, 



Amplitude. 





Vx. 



Vs. 



V3. 



tti. 



U2. 



»3- 



Air Min 



Air Max 



Air (M + »t)/2 



One inch Min 



One inch Max 



One inch (M + »i)/2 



One foot 



Two feet 



Four feet 



Six feet 



92°-35 



109-67 



101-85 



89-83 



115-67 



105-00 



97-40 



91-32 



74-52 



57-10 



316° 23 

 319-10 

 318-22 

 308-17 

 302-15 

 305-67 

 298-45 

 293-07 

 271-58 

 247-30 



238-58 



201-03 



222-50 



90-00 



167-22 



163-30 



162-35 



153-43 



90-00 



63-43 



12-182 

 14-725 

 13-298 

 15-553 

 21-908 

 18-260 

 16-294 

 14-120 

 9-648 

 7-063 



1-699 

 1-604 

 1-626 

 1-558 

 1-762 

 1-683 

 2-181 

 1-730 

 1 -050 

 •669 







-351 

 •232 

 •271 

 -900 

 2-409 

 1-220 

 -386 

 •262 

 •117 

 •075 







The approximate epochs of the annual and semi-annual waves of 

 temperature deduced from Table 8 are : — 



Annual Semi-Annual 



Wave. Wave. 



Air Min Jan. 13 Mar. 24 



Air Max Dec. 28 Mar. 21 



One inch Min Jan. 16 Mar. 28 



OneinchMax Dec. 21 Mar. 31 



One foot Jan. 9 April 2 



Two feet Jan. 15 April 5 



Four feet Jan. 31 " April 15 



Six feet Feb. 18 April 27 



There is a great deal of irregularity in the sequence of these dates, 

 due probably partly to the shortness of the period under review, and 

 to some extent, perhaps, because the average temperatures at depths 

 of 1 or 2 feet are not to be correctly determined (as is plain from 

 Tables 4 and 5) from three observations a day. The epoch of the 

 annual curve of minimum temperature of the surface of the ground 

 follows hard upon that oi the minimum temperature of the air. But 

 this effect seems not to be propagated downwards to any depth, 

 seeing that the epoch for 2 feet is earlier than it is for the surface 

 minimum. On the other hand, the epoch of the annual curve of 

 maximum temperature of the surface of the ground, which falls at 



