BEYOND THE RED IN THE SPECTRUM ' 



I'.V n. 1 >. I'.AIKOCK 



IWith 2 plulcs] 



One result of the widespread use of radio is a «2;eneral funiiliarity 

 with two terms wiiich liave h>n<; been houseliohl words ainoiiji!; 

 astronomers and i)liysi(ists — wave len<:;th and fiv(iuen(;y. Although 

 some vagueness often adheres to the meaning of these words, they 

 are exceedingly useful to everyone who uses a radio receiving set. 

 What matter if the machinery inside the box is permanently mys- 

 terious, provided a scale on the outside allows one to select the sta- 

 tion he wishes. We all soon learn the proper scale readings to find 

 our favorite stations, and we are accustomed to liear the announcer 

 make his routine statement: "This station operates at a frequency 

 of so many kilocycles by authority of the Federal Radio Com- 

 ndssion." 



In such an ordinary experience as the use of the radio, a point of 

 contact is found with the subject of our discussion — Beyond the 

 Red in the Spectrum. We shall view this topic in its perspective 

 relation to the whole l<nown range of wave lengths, trace a bit of 

 the history of its discovery and development, examine some of the 

 modern methods of studying it. If some idea is conveyed of the 

 reasons why these studies are worth while, our purpose will have 

 been in part accomplished. If, in addition, something of the fas- 

 cination which attends this kind of work is revealed, so that further 

 acquaintance with it appears desirable to you, the results will be 

 still more satisfactory. 



Now as to radio waves, most of us arc chiefly interested in the 

 ordinary broadcasting which may be received with our familiar 

 receiving sets. Such wave lengths, as everyone knows, range from 

 oOO meters down to "200 meters — a difTerence corresponding to a little 

 over one octave in terms of the musical analogy. Only, instead of 

 having just 13 notes in the octave, our radio octave is now divided 

 into some 55 specified wave lengths. Outside the reach of the 



' .\ lecture delivered before tLe CnrncKle Institution, at Wusliiuulon, D. C, Dec. 10, 

 191.'l> ; and at rasadfun, Calif., Feb. 20, lO.'tO. Kcprlntid by permlsKlun from pubUcutloua 

 of the Astronomical Society of the I'acUic, vol. 42, No. 240, April, 1030. 



26005—31 12 105 



