94 Prof. Magnus on the Propagation of Heat in Gases. 



No. 



Position 

 of equi- 

 librium 

 of the 

 needle. 



1 



| Mean. 



Ob- 

 served 

 deflec- 

 tion. 



Differ- 

 ence. 



No. 



Positioi 

 of equi- 

 librium 

 of the 

 needle. 



1 

 Wean. 



Ob- 

 served Differ- 

 deflec- I ence. 

 tion. 



Atmospheric air under 1 atni. pressure. 



Atmospheric air under 4 millims. pres. 



I 



+0-2 



+0-5 



-(-0-5 



00 



00 



00 



+0-35 



+0-5 



+0-25 



00 



00 



11-2 

 11-7 

 11-2 

 110 

 110 



10-85 

 11-2 



10-95 

 110 

 110 



la 



00 



-0-25 

 00 

 00 



-01 

 -01 



00 



120 

 120 

 120 



121 

 121 

 121 



Mean 12-1 



0=100:90-9. 



Mean 110 



Ia:I = 121:ll- 



II 



0-0 



4-0-25 



00 



00 



+0-25 



+0-1 



+0-1 



0-0 



+ 0, 



11-0 

 110 

 110 

 110 



10 9 

 10-9 

 110 

 10-9 



Ila 



0-0 



-0-25 



-0-25 



00 



00 



-01 



-0-25 



-01 



00 



120 

 12-25 

 125 

 12-5 



121 

 12-5 

 126 

 12 5 



Mean 109 Mean 12-4 



Ila: 11 = 12-4: 10-9 = 100: 87-9. 



Ill 



00 

 00 

 00 

 00 

 00 



00 

 C-0 

 00 

 00 



110 

 11-0 

 110 

 120 



110 

 110 

 110 

 120 



Ilia 



-1-75 



-1-5 



-1-5 



-20 



-1-5 



-1-5 



-1-6 



-1-5 



-1-75 



-1-75 



-1-5 



10-5 



11-25 



110 



110 



110 



121 



1275 



12-75 



12-75 



12-5 











III 



a: 111 = 



= 12-5: 



Mean 12-5 



11-2=100:89-5. 



After the observations la and Ila were complete, the air was still under a pres- 

 sure of 10 millims. ; after Ilia it was under 7 millims. 



The relation thus ascertained between radiation through rare- 

 fied air to that through atmospheric air under a pressure of 1 

 atmosphere, agrees so far with that previously given, that I have 

 taken the former as a basis for calculating the relation of the 

 radiation through other gases to that through vacuum. Hence 

 of 100 rays which pass through vacuum, the following quantities 

 pass through the different gases, all under the pressure of one 

 atmosphere : — 



