74 



i^y the number of hours of sunshine, only rejecting the useless night- 

 time, just as one would reject the useless low temperature. In the 

 absence of sunshine records he uses the number of hours between 

 sunrise and sunset, or the duration of diffuse sunshine, and obtains 

 for spring wheat and barley the data given in the accompanying 

 table, where the last cohnnn may be said to give " sunshine hour 

 degrees." 



Sunshine hour degrees. 



We see that the sunshine hour degrees diminish as the latitude in- 

 creases. This diminution ought to be rather more rapid in propor- 

 tion as the actual state of the cloudy atmosphere approaches the theo- 

 retical state of absolute clear sky. 



Thus Halsno and Bodo, localities which have very nearly the same 

 soil, the same altitude, the same orientation, the same distance from 

 the sea, but which are more or less under the influence of the aqueous 

 vapor coming from the Gulf Stream, have a cloudiness during the 

 evolution of wheat of 5.6 and 7; during that of oats, .5.4 and 7; where 

 represents perfect freedom from clouds and 10 completely covered. 



If records of cloudiness could have been used, the numbers in the 

 last column would have been computed like those in the following 

 table : 



'sur^cio^f 



shine. ^^ss. 



Clear sky. 



Average 

 daily 



tempera- 

 ture. 



Spring wheat: Hours. 



Halsno i 2,187 



Bodo j 2,876 



Barley: 



Halsno ! 2,0a5 



Bodo i 2,138 



Tenths. 'Percent. 

 5.6 44 



7.0 30 



5.4 46 



T.O ' 30 



13.0 

 11.3 



11.7 

 11.0 



Hours. 

 12, .506 

 7,8a5 



10.9.51 

 7,a51 



