24 Experiments on the Relative Intensities 



distance through which the Hght of the smaller lamp 

 passes is no more than 20 inches, while that of the 

 greater is made to pass through an additional dis- 

 tance, amounting to more than 100 inches, it is evi- 

 dent that the diminution of the light of the greater 

 lamp, arising from the imperfect transparency of the 

 medium, must be greater than the diminution of the 

 light of the smaller lamp, arising from the same cause ; 

 and consequently that the effects of such diminution 

 would become apparent in the experiment, were they 

 in reality considerable. 



The following table will show the results of the 

 experiments which were made with a view to deter- 

 mine that fact : — 



Experi- 

 ments. 



No. 5 

 No. 6 

 No. 7 

 No. 8 

 No. 9 

 No. 10 

 No. II 

 No. 12 



Distance of the smaller 

 light. 



First dist. 

 Second dist. 

 First dist. 

 Second dist. 

 First dist. 

 Second dist. 

 First dist. 

 Second dist. 

 First dist. 

 Second dist. 

 First dist. 

 Second dist. 

 First dist. 

 Second dist. 

 First dist. 

 Second dist. 



20 

 40 

 20 

 40 

 20 

 40 

 20 

 40 



50 

 100 



50 

 100 



50 

 100 



50 

 100 



Distance of the greater 

 light 



First dist. 

 Second dist. 

 First dist. 

 Second dist. 

 First dist. 

 Second dist. 

 First dist. 

 Second dist. 

 First dist. 

 Second dist. 

 First dist. 

 Second dist. 

 First dist. 

 Second dist. 

 First dist. 

 Second dist. 



Inches. 



lOI 



203 



100.2 



198.3 



100.8 



202.1 



IOI.5 



204 



100 



198 



95-5 

 192.2 



95.1 

 191. 2 



96 

 192.4 



In the four last experiments, instead of the small 

 lamp above described, a common Argand lamp was 



