TABLES 283-285. 251 



RADIATION CONSTANTS. 

 TABLE 283. Radiation Formula and Constants for Perfect Radiator. 



The radiation per sq. cm. from a " black body " (exclusive of convection losses) at the temper' 

 ature T (absolute, C) to one at / is equal to 



/= ff ( T^ /4) (Stefan-Boltzmann) ; 



where <r= 1.374 X io~ 12 gram-calories per second per sq. centimeter. 

 =8.26 X io-" " " " minute " " 



= 5.75 X io~ 12 watts per sq. centimeter. 

 The distribution of this energy in the spectrum is represented by Planck's formula : 



where J\ is the intensity of the energy at the wave-length A (A expressed in microns, /x) and e is 

 the base of the Napierian logarithms. 



Ci = 9.226Xio- 28 for/ in ^- -^-==3.86 X io- 22 for /in ^-^ 



5CC ' Cfll CWl . 



6*2= 1.4450 for A in cm. 

 / max = 3.ii x io+ 4 r 6 for /in 



,- = 1.30X10+6 T* for/in^ 



sec. cm* cm? 



A mai T= 0.2910 for A in cm. 



h = Planck's unit = elementary " Wirkungs quantum " = 6.83 X io~ 2T ergs. sec. 

 k = constant of entropy equation = 1.42 X io~ 16 ergs. /degrees. 



TABLE 284. Radiation in Gram-Calories per 24 Hours per sq. cm. from a Perfect Radiator at t C to 

 an absolutely Cold Space (273 C). 



Computed from the Stefan-Boltzmann formula. 



TABLE 285. Values of JA for Various Temperatures Centigrade. 



Ekholm, Met. Z. 1902, used C\ = 8346 and C%= 14349, and for the unit of time the day. 

 For 10, the values for J\ have been multiplied by 10, for the other temperatures by 100. 



SMITHSONIAN TABLES. 



