JOINING THE ELECTRIC WAVE AND HEAT WAVE 



SPECTRA 



By E. F. Nichols and J. D. Tear 



[With 2 plates] 

 HISTORICAL 



There are few if any more fascinating chapters in the history 

 of science than those dealing with the development of our present 

 theory of light and the growth of our knowledge gained by careful 

 experiment upon which any acceptable theory must rest. For cen- 

 turies there was strife among " natural philosophers " as to whether 

 light was due to countless myriads of minute imponderable particles 

 called corpuscles, shot out along straight lines in every direction 

 from the source of light, or whether light was an orderly wave 

 motion spreading out equally and radially in all directions in a 

 universal imponderable medium called the ether. 



Some of the most recent fundamental discoveries in radiation and 

 the newer conceptions of atomic structure and discreet energy 

 quanta to' which these discoveries have given rise have raised new 

 questions concerning some of the hard and fast details of the estab- 

 lished wave theory with the likelihood that a partial compromise 

 between these two age-old hypotheses may sooner or later develop. 

 Many physicists are already prepared for a wave disturbance theory 

 of light not quite so harmonious and simply geometric as the 

 smoothly and evenly spreading wave front nor yet so crudely mate- 

 rial and projectilelike as the older corpuscular theory. Much more, 

 however, must be known and done before a new agreement covering 

 all details can be arrived at. 



Historically, Young's discovery of the interference of two beams 

 of light, made in the first year of the last century, was a decisive 

 experiment in favor of a wave theory as opposed to a corpuscular 

 theory, and it would doubtless promptly have convinced all physi- 

 cists had it not been for the very great authority of Sir Isaac New- 

 ton which had come down through more than a century. Newton in 

 his day had vacillated between a wave theory which had recently 

 been quite elaborately worked out by the Dutch philosopher Huy- 



175 



