206 



Sir John Conroy on the Distribution 



Ordinates of 



Difference 



Ordinates of 



/3 



the disper- 



divided bv 100 



the heat-curve 





sion-curve. 



(«). 



(£)• 





7260 









6790 



4-70 



22-4 



47— B. 



6320 



4-70 



190 



40— C. 



6000 



3-20 



159 



5-0 



5750 



2-50 



137 



5-5— D. 



5500 



2-50 



11-8 



4-7 



5260 



2-40 



10-3 



43— E. 



5070 



1-90 



8-8 



4-6-6. 



4900 



1-70 



7*5 



4-4 ™ 

 4-l _F - 



4750 



1-50 



6-2 



4610 



1-40 



50 



3-5 



4490 



1-20 



4-0 



3-3 



4380 



110 



3-3 



3-0 



4270 



110 



2-5 



22— a. 



4170 



1-00 



1-8 



1-8 



4070 



1-00 



1-3 



1-3 



4000 



•70 



1-0 



1-4 



3930 



•70 



•7 



1-0— H. 



3880 



■50 



•5 



1-0 



The Table shows that the numbers thus obtained for the 

 intensity of the heat in different portions of the spectrum lie 

 close together for the region between B and F, the maximum 

 being near D, and that from F to H the intensity diminishes. 



It would further appear that the curve for the distribution of 

 heat of MM. Fizeau and Foucault is in reality a dispersion- 

 curve, drawn to some scale of wave-lengths, for the particular 

 prism used by them; and the diagram shows how very similar 

 the curves for the intensity of the heat, and for the dispersion 

 of the prism are to one another. 



The heat-curve reaches the x axis at a short distance on the 

 more refrangible side of H 2 , the wave-length of that line being 

 3932. The axis was taken as 3900 on the scale of wave-lengths 

 to which the curve is drawn, and therefore the ordinate of 

 the curve at B, measured in tenths of an inch, as proportional 

 to the difference between this number and the wave-length of 

 B, and the height of the ordinates at the other lines calculated 

 on this assumption. 





Measured. 



Calculated. 



Difference. 



B ... 



2-10 







C ... 



1-87 



1-88 



+ •01 



D ... 



1-34 



1-41 



•07 



E ... 



-95 



•97 



•02 



b ... 



-88 



•90 

 •68 



•02 



F ... 



-63 



•05 



Cr ... 



-22 



•29 



•07 



Mean difference ... +'04 



