805 



(he use of a red, almost monocliioinalio jj;lass on the ooulai'. As the 

 same readings were maiU' as Ijcfoi-e, there seems to be noditïerence 

 of any appreciable amount l)el\veen the two modes of observation. 



g) If all nicols are removed, as well before as behind the p^^ro- 

 meter, the readings remain the same, if the furnace is turned over 

 some angle by means of the table of the microscope. Once more 

 thus the reflection at tlie prism -S is dcmonsl rated to have no real 

 effect on the results. 



h) A nicol N' is adjusted behind the pyrometer, and while /t,„ 

 has a fixed position, it is tuined over 0°, 45°, and 90° respectively. 

 The readings at 850° C. were : 



Rotation of N' over : 



Oo 



45° 



90° 



31 illi- Ampères 

 415 

 413 

 409 



i). Finally the nicol A"^ was placed again before the pyrometer and 

 of course the other one was removed. At 898° C. the readings were now : 

 418 M. A. and 410 M. A.; at 963° C in the same way : 441 IVl.A. 

 and 447 M. A. 



We can thus conclude from it : 



True tempe- 

 rature of the 

 body in ° C : 



Readings in M. A as Radiation-temperatures 



they would be without , forvibrationsin thetwo 



the absorption by the j^^j j directions: 



nicol : F F 



Differences : 



739° 



751 



756 



815 



826 



850 



890 



898 



969 



