Tables 312 and 31 3 



3*7 



TABLE 312. — Black Body Spectrum Intensities 

 Auxilliary table for J\ at any temperature (Menzel, Harvard Observatory) 

 Let Jo = intensity for To = io,ooo° K.; for another temperature T° K., we have the 

 relationship 



J I Jo = [\ 5 (e cMa - I) ]/[\*(e n/XT - I) ]. 



Let X = \o7V7\Then 7 (7yT ) 6 . e.g., to find J\ for o.5m, 6ooo°K., we take o.5 M = X X 

 10,000/6,000 or X = 0.3/1, Jo for 0.3^ = 1.2977 X io 16 , whence J — 1.2977 X io 16 X 

 (6000 / 1 0000 ) 6 or 1.01 X io 15 . 



In the following table J\ is for io,ooo° K.; A X io n is intensity at wave length Xju. X is 

 given in n but in plotting it should be used in cm (one m = io -4 cm) that the area under 

 curve be in ergs. 



hc/k = 1. 43187; 271-hc 2 = 3.69728 c.g.s. units. A change in C\ may be allowed for by a con- 

 stant factor, in c 2 by taking a different value for T so that 1.4319 X 10,000 = CiT. One 

 ergcm^sec." 1 = 2.389 X I0~ 8 cal.i6- cm 2 - sec 1 . 



TABLE 313. — Values of J\ for Various Temperatures Centigrade 



Ekholm, Met. Z. 1902, used C!=:8346 and C 2 = 14349, and for the unit of time the day. 



Smithsonian Tables. 



