86 TABLE 57.— CHANGES DUE TO A CHANGE IN c 2 



The adoption of a new value for r 2 changes the calculated values for A by an amount 

 that varies indirectly with both the wavelength and the temperature for values of \T 

 <3000, as follows : 



dJ\_ —dd 



A ~ \T 



that is, a larger value of d results in a smaller value of A. Values of this correction factor 

 for this change in c 2 have been calculated and are given in the tables for five temperatures 

 and a range of wavelengths that cover the visible spectrum. As these percentage correction 

 factors are given they are the percentage of the A for 14320//. deg that must be subtracted 

 from it to give /»3so. 



A change in c 2 also results in a different value of the extrapolated temperature as meas- 

 ured with an optical pyrometer for a definite ratio of brightness. Thus 



\r. tJ ciKTo 77/ 



To the accuracy necessary for most work, values for other wavelengths, other tempera- 

 tures, or other values of r 2 within these ranges can be found by interpolation. 



Part 1. — Percentage change in J x for a change in c 2 from 14320 to 14380^ degrees 



Part 2. — Change in temperatures, AT, extrapolated from 1336 to the temperature T 

 given, c 2 changed from 14320 to 14380^ degrees 



T°K 1500°K 1800°K 2000°K 2S00°K 3000°K 3S00°K 4000°K 5000°K 



AT —.6 -2.4 -4.1 —8.7 —15.5 -22.3 -33.0 —56.4 



SMITHSONIAN PHYSICAL TABLES 



