EXPLANATION OF FIGURES 17 TO 25 



The figures give the effective radiation in = — : ^ 10 2 , plotted as ordinates 



cm. mm. 



against the time (in hours of the night) as abscissae. The curves are governed 



by the observations given in several of the tables, XIV to XX. For the 



graphical interpretation I have chosen some of the observations that seem to me 



to bring forward, in a marked and evident way, the influence of humidity or 



temperature upon the radiation. They therefore represent cases where either 



the temperature has been almost constant (as on high mountains), and the 



humidity subjected to variations, or where the humidity has been constant and 



the temperature has varied. 



8g 



