TABLE 289. 

 HEAT LOSSES FROM INCANDESCENT FILAMENTS- 



(a) WIRES OF PLATINUM SPONGE SERVED AS RADIATORS (TO ROOM-TEMPERATURE SURROUND- 

 INGS). HARTMAN, PHYSICAL REVIEW, 7, p. 431, 1916. 



(b) WIRES or BRIGHT PLATINUM 40-50 CM LONG SERVED AS RADIATORS TO SURROUNDINGS 

 AT 300 K. LANGMUIR, PHYSICAL REVIEW, 34, p. 401, 1912. 



Diameter 

 wire, 

 cm. 



0.0510 



0.02508 



0.01262 



0.00691 



0.00404 



Observed energy losses in watts per cm. 



Absolute temperatures. 



0.22 

 0.17 

 0.13 

 0.12 

 O.II 



700 



0.52 

 0-39 

 0.31 

 0.29 

 0.24 



900 



0.90 



0.68 

 0-53 

 0.48 

 0.41 



1.42 



1.02 



0.79 

 0.72 

 0.61 



1300 



2.03 

 i-45 

 i. ii 

 o.99 

 0.84 



1500 



2.89 



2.00 

 I. 4 6 



1-33 

 1.14 



1700 



4.10 

 2.68 

 i-95 

 1.79 



1-54 



1900 



5-65 

 3-55 

 2.71 

 2.48 

 2.13 



Energy radiated in watts per cm.' 1 



0.0510 



0.02508 



0.01262 



0.00691 



0.00404 



0.002 

 o.ooi 

 o. ooi 



0.000 

 0.000 



0.013 

 0.007 

 0.003 



0.002 

 O.OOI 



0.049 



0.024 



O.OI2 



0.007 

 0.004 



0.137 

 0.067 

 0.034 

 0.019 



O.OII 



0.323 

 0.159 

 0.080 

 0.044 



0.026 



0.67 

 0-33 



0.17 

 0.09 

 0.05 



1.25 



0.62 



0.31 

 0.17 



O. 10 



2.15 

 1. 06 

 0.53 



0.29 

 0.17 



' Convection " losses in watts per cm. 



0.0510 

 0.02508 

 0.01262 

 0.00691 

 o . 00404 



0.22 

 O.I? 

 0.13 

 0.12 

 O.II 



0.51 

 0.38 

 0-31 

 0.29 

 0.24 



0.85 



0.66 

 0.52 

 0.47 

 0.41 



1.28 

 0-95 

 0-75 

 0.70 

 0.60 



1.71 

 1.29 

 1.03 

 0-95 

 0.81 



2.22 

 1.6 7 

 1.29 

 1.24 

 1.09 



2.85 

 2.06 

 1.6 4 

 1.62 

 1.44 



3-50 



2.49 

 2.18 

 2.19 

 1.96 



Thickness of theoretical conducting air film. 



0.0510 

 0.02508 

 0.01262 

 0.00691 

 0.00404 

 Means. 



0.28 

 0.30 

 0.42 

 0.31 

 0.27 

 0.31 



0.42 

 0.32 

 0.43 

 0.37 



0-33 

 0-37 

 0.44 

 0.38 

 0.43 

 0-39 



0.33 

 0.41 

 0.49 

 0.40 

 0.47 

 0.42 



0.36 

 0.45 

 0.56 

 0.43 

 0.56 

 0-49 



0.37 

 0.45 

 0.69 

 0.47 

 0.47 

 0.49 



0.36 

 0.56 

 o.47 

 0.26 

 0.25 

 0.38 



Means. 

 0-34 

 0-43 

 0.54 

 0-37 

 0.41 



to. 43 



* Computed with a = 5.32, black -body efficiency of platinum as follows (Lummer and Kurlbaum): 492 K. 

 0.039; 654, 0.060; 795, 0.075; 1108, 0.112; 1481, 0.154; 1761 K., 0.180. For significance of last group 

 of data, see next page. 



, 0.075; 

 t Weighted mean. 



SMITHSONIAN TABLES. 



