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EAETH TEMPERATUEES AT KIMBERLEY. 



By J. R. Sutton, M.A., Sc.D. 



(Read October 30, 1907.) 



This paper is to be regarded as a continuation of the series 

 planned some years ago, the main object of which is to present 

 the more important elements of the meteorology of the South African 

 Table-land in a form suitable to the requirements of the physicist. 

 It contains a preliminary arrangement and discussion of the earth 

 temperatures at depths of 1, 2, 4, and 6 feet,'^ observed at Kenil worth 

 (Kimberley) during the ten years 1897 to 1906, and at depths of 

 1 inch during the six years 1901 to 1906. The temperatures at a 

 depth of 1 inch are obtained from the readings of a maximum and 

 a minimum thermometer, each enclosed in a glass sheath strapped 

 to a stick, and placed in long horizontal copper pipes just covered 

 with earth. The temperatures of deeper levels are obtained by 

 Symons's method from slow-action thermometers hung by chains 

 in vertical iron pipes. Four sets of readings of earth temperature 

 are made daily, namely : — 



At VIII., 1 foot, 2 feet. 

 „ XIV., 1 foot, 2 feet. 

 ,, XX., 1 foot, 2 feet, 4 feet, 6 feet. 

 ,, XXIII., 1 inch (maximum and minimum). 



The maximum and minimum thermometers are Kew verified, and 

 the due corrections have been applied to each reading. The 

 maximum thermometer has always worked fairly well ; but the 

 minimum thermometer has given a lot of trouble, particularly in 

 the summer months. The great heat of the ground — often exceed- 

 ing 140° Fahr. — has caused a comparatively rapid evaporation 

 from the column and a condensation of spirit at the top of the tube, 

 necessitating frequent adjustment. For this reason the averages 

 of minimum temperature at a depth of 1 inch must be regarded as 

 slightly too low, occasional individual readings perhaps reaching 

 an error of 0°-5. The thermometers used at the four greater depths 



* The depths are approximate. 



