.50 



Drs. J. T. Bottomley and J. C. Beattie on 



is about four to five times that from the bright wires at tho 

 same temperature. In the paper of 1894, already referred 

 to, the radiation from a very brightly polished and burnished 

 silvered copper globe, and that from the same globe sooted, 

 were determined. The highest temperature reached was 

 about 230° C, and in that case the sooted globe lost about 

 ten t>mes as much heat as the silvered globe under the same 

 circumstances. When ihe silvered globe had become tarnished, 

 the radiation from its surface was so much increased that the 

 loss from the sooted globe was only three times that from the 

 tarnished silver. 



Table I.— May 18, 

 Pt 2 , length 42-55 

 same hank of wire, 

 sooted. 



1897. Two Platinum Wires Pt : and 

 cm., diameter 0*0512 cm., from the 

 Pt] left with bright surface, Pt 2 thinly 



Current 







Pt t . 





Pt, 

















Pressure 



in 



.Resist- 



• 



Thermal Energy 



Resist- 





Thermal Energv 



in 



An.peres. 



ance 



Temp. 



lost per square 



ance 



Temp. 



lost per square 



millimetres.: 





in 





centimetre per 



in 





centimetre per 







ohms. 





second. 



ohms. 





second. 

 0-0329x10-4 





! 0-023 



0192 



o 

 17 



0033x10-4 



0-188 



o 

 17 



000025 



0276 



0-208 



33 



5-198 



0-198 



26 



4952 



000025 



0-552 



0259 



89 



25-98 



0209 



36 



20-96 



000045 



0695 



0292 



130 



46-52 



0220 



51 



3502 



0*00045 



I 0-940 



0337 



185 



9797 



0-237 



71 



69-90 



0-00045 



! 1-430 



0-415 



295 



279-80 



0-271 



109 



183-1 



00045 



1-937 



0-484 



453 



599-5 



0-317 



167 



393-0 



0-00060 



2-691 



0-570 



623 



13710 



0377 



249 



912-2 



000050 



3-003 



0-599 



743 



17760 



0-398 



280 



1184-0 



000060 



3-770 



4-446 



1 5-200 



6-604 









0-437 

 0476 

 0-515 

 0-566 



, 343 



i 414 



496 



I 643 



2055 

 31060 

 45170 

 81660 



000500* 

 00360 

 0-00320 

 0-00250 











* Owing to increase in the pressure, the emission here must be consi- 

 derably increased by convection. 



