284 Nature and Optical Efficiencxj of the Mirrors [April 



outside of the semi-circle, the sum of all the products is found to be 

 6OI1, which divided by 180° gives 3.34 as representative of the mean va- 

 lue expressing the number of reflected images throughout the whole cir- 

 cumference, a result which corresponds, pretty nearly, with that formerly 

 obtained which represented less than four and more than three images, 

 and in nearly the same proportion, viz. 



q and- r,r ^ — = 'J-'* — 



^ ISOths 45ths 



In the following table the different spaces have been marked down in 



the order in which they occur,on tracing the circumference from South to 



North, or from a to 6 in the annexed diagram No. 15. 



TABLE 



Of ihe breadths of the various portions of the horizon differently it. 

 lum'nated hy the reflected light, ivith the number of images visible 

 in each. 



Southern Quadrant. Northern Quadrant. 



Breadth of the Number of Breadth of the Number of 



spaces illumi- images seen spaces illumi- images seen 



nated. in ihem. nated. in them. 



E 



Degrees.. 16 



3 



Degrees... 21 



2 



\h .... 



2 





3 



3.^ 



^ 



m y.'.". 



2 



1 



2 



H .... 



1 



3i 



1 



Ok .... 



3 



lOi 



2 



Ol .... 



4 



4 



4 



3| .... 



6 



4 



3 



3 



7 



3 



4 



4 



8 



i| ... 



3 



1 



7 



2| .... 



4 



01 .... 



6 





5 



Oi 



5 



^! 



4 



H .... 



4 



Oi .... 



5 





5 



01 .... 



6 





4 



1 



7 



It 



3 



4 



8 



3 



4 



3 



7 





3 



34 .... 



6 



4 



4 



Of .... 



4 



lOi .... 



2 



Ok .... 





3^ .... 



1 



ll .... 



I 



1 



2 



105 



2 



31 



3 



7i 



3 



H .... 





21 ... 



2 



16 



3 lb 



1 



