Popular Science Monllili/ 

 record is 



331 



mimmiini temperature it \vi 

 1200 (let;rees. 



The i)rin(iiile upon wliicli the opera- 

 tion of tile sisiiit pyrometer is l)ased is 

 the simple physical law that the intensity 

 of light emitted by a heated body is 

 'iirectiy |)roportioiial to its temperature. 



In iookiiiij throiiijh the pyrometer, 

 two adjacent semicircular fields ol \isioi 

 are obser\i'd, one beinsj; illuminated by 

 the small standardized electric lamj) in 

 the pyrometer 

 and the other 

 by the object 

 whose temper- 

 ature is to be 

 measured. The 

 red ray of the 

 spectrum is 

 used and very 

 slight differen- 

 ces in the 

 intensity o f 

 the heat in the 

 object under 

 in\ estigation 

 produce (|uile 

 perceptible differences in the shade. 



In taking readings, the intensity of 

 the field illuminated by the lamp is 

 adjusted by turning the eye-piece until 

 the line separating the two fields is 

 eliminated, and the corresponding tem- 

 perature is read directly from the dial. 

 The matter of bringing both fields of 

 \ision to correspond is not a jiersonal 



Measuring the White Heat of Molten Minerals. The 

 Shield Protects the Hands of the Operator. The In- 

 strument Also Measures the Heat of Moving Bodies 



one of matching colors. Then- is always 

 a line between the two fields when they 

 do not correspond ; therefore, it is simply 

 u matter of eliminating this line, and any 

 defects of \ision are 

 cciualized. 



The handling of 

 the pyrometer re- 

 Cjuires no special 

 knowledge, and read- 

 i n g s within ten 

 degrees of each 

 other can be 

 made by any 

 workman of 

 a\erage intelli- 

 g e n c e . I n 

 making of),scr- 

 \ations the 

 tempera t u re 

 <if the oliject 

 itself is meas- 

 ured. It is 

 this tempera- 

 ture and not 

 I he heat (A the 

 furnace that 

 determines whether the object is being 

 treated at the proper temperature to pro- 

 duce the effect desired. For metallurgical 

 operations the ideal pyrometer ne\er 

 comes in contact with the heated ob- 

 ject — in fact, no heating of the instru- 

 ment is required, and the readings are 

 taken almost instantanec»usl\'. It can 

 also measure heated mo\ing bodies. 



The Intensity of Light Emitted by a 

 Heated Body, Regardless of Size, Is Di- 

 rectly Proportional to Its Temperature 



In Looking Through the Pyrometer Two 

 Adjacent Semicircular Fields of Vision 

 Are Observed with the Operator's Eye 



