270 JIETEOROLOGY AND ALLIED SUBJECTS. 



lias been republished, with some modificatious, iu the Zeitschrift of the 

 Anstriau Meteorological Society'.- In some respects the author has 

 carried his computations further than was done by Meech in his well- 

 known essay on the relative intensity of the heat and light of the sun. 



The following table gives the ratio of * or the relative intensity of 



solar radiation at the outer surface of the atmosphere for the entire 

 year. 



Relative I Relative 



Latitude. intensity. Latitude. iiitensitv. 



0. 30532 



10 30112 



20 28858 



30 2GS32 



40 24122 



50 0.20876 



CO 173G8 



70 144G4 



80 13096 



90 12672 



The relative intensity of the solar radiation is the same for corre- 

 sponding seasons in the north and south hemisphere ; it is a maximum 

 for the whole year at the equator and a minimum at the pole; it is a 

 maximum for the summer season at latitude + 24°; it is a maximum in 

 the spring and autumn at the equator; during the summer season it is 

 greater at the poles than at any other point on the earth's surface. {Z. 

 0. G. 3L, XIV, 1879, pp. 113 to 130.) 



Wild has published a general review of our knowledge of the subject 

 of earth temperature in connection with his publication of the observti- 

 tions at St. Petersburg and Nukuss. He detects some of the errors 

 and fallacies that have hitherto been persistently ditfused in the text- 

 books on meteorology and physical geograph3\ The observations of 

 earth tempera.tures made at Nukuss by Dohrandt were for depths of 

 4.0, 2.8, 1.6, 0.8, 0.4 meters, and the readings were made daily at 7 a. 

 m., 1 and 9 j). m. Besides these a series of hourly readings was made at 

 depths 0.00, 0.05, 0.10, and 0.20 meters under the surface of the earth. 

 This latter series is the only complete one that we possess at the present 

 time for the determination of the diurnal period in the temperature of 

 the earth. 



Observations of the temperature of the air were taken at the same 

 time. With regard to the daily period at Nukuss. it is fouisd that the 

 mean daily maximum of earth temperature at the surface is nearly al- 

 ways equal to that of the atmosphere; but the maxima are much greater 

 in the earth than in the atmosphere, so that the daily amplitude is 2^ 

 times greater at the earth's surface than in the air. During the three 

 summer months the mean temperature of the earth's surface was 55^.2 

 C. The time of occurrence of the minimum of the surface tempera- 

 ture coincides nearly always with sunrise. Warm and dry soil is a 

 worse conductor of heat than the cold damp soil. The influence of tem- 

 perature and humidity upon the conducting power of the earth was 

 shown in several ways, and is one of the remarkable results attained by 



1 



