LORD RAYLEIGH ON THE COLOURS OF THIN PLATES. 



163 



and to the green of the fourth order. In actual calculation these numbers 

 would not occur (nor indeed those of Table I.), but would be represented by 

 their logarithms. 



From the necessity of determining a large number of points, the calculations 

 ran to great length. They have not been performed throughout in duplicate, 

 but have been so far re-examined as to exclude any error which could appreciably 

 affect the diagram. In many cases neighbouring points verify one another to 

 a sufficient degree of accuracy. 



Table III. — First Series. 



V. 



(24). 



(44). 



(68). 



V. 



(24). 



(44). 



(68). 







•77 



1-65 



2-28 



5200 



2-69 



472 



1-42 



1006-5 



3-82 



6-46 



5-87 



5300 



3-06 



430 



1-95 



1300 



3-75 



5-07 



2-79 



5400 



3-33 



3-78 



2-68 



1500 



3-01 



3-20 



•82 



5600 



351 



2-75 



415 



1604 



2-51 



2-23 



•27 



5800 



3-20 



2'01 



5-03 



1688 



204 



1-49 



■18 



6000 



2-53 



1-77 



4-93 



1755 



1-67 



1-01 



•27 



6200 



1-75 



2-11 



3-97 



1846 



1-20 



•53 



•69 



6400 



1-09 



2-82 



2-74 



1951 



•75 



•26 



1-63 



6600 



0-76 



3-56 



1-85 



2013 



•49 



•26 



2-25 



6700 



0-74 



3-87 



1-71 



2154 



•13 



•67 



3-81 



6800 



0-83 



4-12 



1-75 



2328 



•09 



1-82 



5-44 



6900 



1-00 



4-26 



1-99 



2630 



•99 



4-44 



5-87 



7000 



1-26 



4-32 



2-41 



2927 



2-59 



5-95 



3-37 



7100 



1-55 



4-27 



2-91 



3100 



3-29 



5-77 



1-71 



7200 



1-86 



4-13 



3-41 



3300 



3-78 



4-68 



•59 



7400 



2-45 



369 



417 



3400 



3-81 



4-04 



•58 



7600 



2-83 



3-16 



4-48 



3500 



3-74 



3-17 



•93 



7800 



2-93 



2-76 



4-02 



3600 



3-50 



2-40 



1-59 



8000 



2-72 



2-56 



3-24 



3800 



2-68 



1-26 



3-42 



8200 



2-35 



2'62 



2-45 



4000 



1-67 



•93 



5-08 



8400 



1-89 



2-85 



2-28 



4200 



•79 



1-48 



5-71 



8600 



1-52 



317 



2-52 



4400 



•29 



2-68 



5-02 



8800 



1-32 



3-47 



2-98 



4600 



•35 



3-96 



3-43 



9000 



1-34 



3-65 



3-69 



4800 



•91 



4-91 



1-86 



9200 



1-53 



3-73 



4-04 



4900 



1-33 



5-13 



1-31 



9400 



1-83 



3-67 



3-84 



5000 



1-79 



5-17 



1-03 











The final results, expressed as before in terms of the standards (24), (44), (68), 

 are exhibited in Table III. In the first column are to be found the values of 

 V (expressed in the same measure as A.). Thus, when V = 1688, the illumina- 

 tion vanishes at the point (68) on Maxwell's scale, for which X=1688. If the 

 compound light reflected from a plate of this thickness were analysed by the 

 prism, the centre of a dark band would be found at (68). Although the 

 extinction is absolute at only one point, still the neighbouring region, which 

 naturally contributes most of the colour-component (68), is very obscure, and 



