ELECTRIC AND HEAT WAVES NICHOLS AND TEAR 177 



from surfaces, bent from their course by prisms, and that they trav- 

 eled through space with the velocity of light. 



Hertz's successors worked in two different directions. Righi, 

 the Italian, and a number of other physicists worked toward shorter 

 and shorter electric waves and repeated with them more and more 

 of the classical experiments with light. Sir Oliver Lodge, Guglielmo 

 Marconi, a brilliant young Italian experimenter, Branly, Fleming, 

 and Braun were inspired by the idea of making electric waves a 

 means of signaling and communication. These men, working in- 

 dividually, pushed toward longer and longer waves, because long 

 electric waves carry farther and are not so easily scattered by 

 obstacles as short ones. As we know, Marconi won in the contest 

 of perfecting a practical means of communication without wires, 

 and from his success we now have radiotelegraphy, and with the 

 advent of the vacuum tube amplifier we have the greater marvel of 

 radiotelephony. Thus Hertz worked indefatigably to discover elec- 

 tric waves in order to prove that Maxwell was right in maintaining 

 that light waves were electric waves. Hertz's discovery, with its 

 consequences, is but one of an accumulating number of instances in 

 which astoundingly practical results have followed directly from the 

 most abstruse workings of .the scientific imagination. 



Contemporaneously with the discovery and development of elec- 

 tric waves, great progress was also being made in the investigation 

 of light and heat waves. Explorers were pushing out into the dark 

 spectrum below the longest visible red waves. Among the earlier 

 of these pioneers, and the most brilliant and successful one, was our 

 illustrious countryman, Prof. S. P. Langley, who began his re- 

 searches in 1883, using his newly perfected bolometer. He extended 

 the known spectrum and accurately measured wave lengths down to 

 5.3/*, nearly 10 times the length of yellow light waves. By his 

 researches he not only determined the distribution of energy in the 

 solar radiation but laid experimental foundations for the develop- 

 ment of our present general laws of radiation. A decade later a 

 new method for sifting out and isolating certain long wave radia- 

 tions from the total output of hot bodies, such as a candle flame or a 

 Welsbach gas mantle, was discovered by Rubens and Nichols. This 

 method lead to an extension of our knowledge of long wave lengths 

 and their measurement to waves more than 25 times the longest 

 actually measured by Langley. Another twofold extension was ac- 

 complished by a further advance in method due to Rubens and 

 Wood, and finally, in 1911, heat waves 0.324 mm., or one seventy- 

 fifth of an inch, in length, were successfully isolated, measured, 

 and their properties studied. 



There was, however, still an unbridged gulf between the shortest 

 known electric waves and the longest measured heat waves, for the 



