Tables 283-285. 25 I 



RADIATION CONSTANTS. 

 TABLE 283.— Radiation Formulse 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 P is equal to 



J =. a {T^ — t^) (Stefan-Boltzmann) ; 

 where (T= 1.374 X 10-12 gram-calories per second per sq. centimeter. 

 = 8.26 X lo-'i " " " minute " " " 



^5-75 ^ IQ— 12 watts per sq. centimeter. 

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



/,=c,x-'[>-i]- 



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



the base of the Napierian logarithms. 



. p-ram. cal. ,.^ ^w, r t- "watts 



Ci = 9.226x 10-23 for/ m^ 5-=3.86X 10-22 for/ m 



^ ^ -^ sec. cm? ^ cm A 



C-i^ 14450 for A. in cm. 



, . ™c r ,. sram. cat. ^, _i_^ ^<; r r- "watts 



/„„=rii X10+* T^iox/in"- ^ = 1.30X10+^ T^ for/m j 



•^ -^ sec. cm.'' cni.^ 



\^^T^ o.2C)io for A in cm. 



h = Planck's unit = elementary "Wirkungs quantum " = 6.83 X 10-2' ergs. sec. 



k = constant of entropy equation^ 1.42 X lo-^s ergs. /degrees. 



TABLE 284.— Radiation In Gram-Calories per 24 Hours per sq. cm. from a Perfect Radiator at t° 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. igo2, used ^ = 8346 and €«=: '4349, and for the unit of time the day. 

 For 10°, the values for Ja have been multiplied by 10, for the other temperatures by 100. 



SlMITHSONIAN TaBLES. 



