26 



DR. WOLLASTON'S METHOD OP COMPARING THE LIGHT 



IV. Reduction of the preceding observations of the Sun and Sinus. 

 If all the light of the sun, which falls on the thermometer-bulb, be reflected 



by it, the light of O = [ ^jf ^Vx^Jx /" ]' ^ *^^ ^'^^* ^^ ^^"^^' ^"^ ^^^^^ 

 there are seven observations of the sun compared with a candle, and seven of 



Sirius, there will be forty-nine different values of the expression n xQ x d x I ♦ 

 which are all inserted in the following Table. 



5.331.671 

 49 



= 108.809 



Hence the mean result of the foregoing experiments is that, supposing none 

 of the Sun's light to be lost on reflection at the thermometer-bulb, 



O's light = 108.8092 x light of Sirius 



= 11.839.533.000 X the light of Sirius ; 



but, allowing for the loss of nearly half the light on reflection, that 



O's light = 20.000.000.000 X the light of Sirius. 



