255 



Table 289. 



HEAT LOSSES FROM INCANDESCENT FILAMENTS- 



(a) Wires of Platinxtm Sponge Served as Radiators (to Room-temperature SuRROtrND- 



iNGs). Hartman, Physical Review, 7, p. 431, 1916. 



Diameter 

 wire, 



cm. 



0.0690 

 0.0420 

 0.027s 

 0.0194 



(A) Observed heat losses in watts per cm. 



Absolute temperatures. 



1.70 

 1-35 



2. 26 

 I-7S 

 1.40 

 IIS 



3-01 

 2. 26 

 I. 76 

 1-39 



4.92 

 353 

 2.73 



1400 



6.18 

 4.29 

 3- 23 

 2. 54 



1500 



7.70 

 5-33 

 391 

 3 04 



1600° 



9- 63 

 6.60 



4.67 

 3-64 



1700 



12.15 



8.25 



5-72 

 4-32 



iS-33 



lo. 20 



7.00 



510 



19 25 



12-45 



8.64 



6. 10 



23-75 



14-75 



10-45 



7-35 



(B) Heat losses corrected for radiation, watts per cm (A-C). 



o . 0690 

 0.0420 

 0.027s 

 0.0194 



4-30 

 3-26 



2. 70 



(C) Computed radiation, watts per cm, cr =5.61 X io~".* 



0.0690 

 0.0420 

 0.027s 

 0.019s 



19-45 



11.85 



7.75 



S.47 



(D) Conduction loss by silver leads, watts per cm. 



0.0420 

 0.027s 

 0.019s 



(E) Convection loss by air, watts per cm. 



0.0420 

 0.0275 

 0.019s 



■ This value is lower than the presently (1919) accepted value of 5.72. 



(b) Wires or Bright Platinum 40-50 Cm Long Served as Radiators to Surroundings 

 at 300° K. Langmutr, Physical Review, 34, p. 401, 191 2. 



Smithsonian Tables. 



