228 



AVAILABLE SUNSHINE. 



suus, and for tlie difference between local mean time and 

 standard South African time. P is then the hour-angle of 



Fig. 1. 



the mean sun at the spot of the earth's surface for which 

 the diagram is to be drawn — in other words, it is true local 

 mean time reckoned from noon. 



H orbh Pol e 



S«p.21 



man 21 



Fif 



