WHY A FLAME EMITS LIGHT THE 

 DEVELOPMENT OF THE THEOKY 1 



BY KOBEET MONTGOMEEY BIKD, PH. D. 



As one would naturally suppose, the theory now generally 

 held regarding the nature of an ordinary name and its 

 power to emit light is not altogether the result of modern 

 research, but one which has been evolved from very ancient 

 and hazy notions. Naught else is to be expected when we 

 consider the important place fire has held throughout the 

 development of mankind. It is the first recorded object of 

 his worship, and we have reason to believe that all architec- 

 ture had its beginning in rude structures erected to protect 

 the sacred fire. It is not the nature of man to see phenom- 

 ena so striking as those which attend the consumption of 

 matter by fire and not speculate upon them. But the cen- 

 turies had multiplied and modern times had been reached 

 before man's ideas regarding fire, flame and light became 

 distinct, and the use of these terms differentiated. The 

 best text-books and works on natural philosophy published 

 near the end of the eighteenth century still used the terms 

 with great looseness, and the conceptions of the material 

 nature of flame and light were yet in their death struggles. 



After the corpuscular theory of light had given place to 

 the wave theory, conflicting ideas arose as to why and how 

 a flame emits light waves. When it was agreed that the 

 waves were sent out by solid particles of carbon heated to 

 incandescence, the question of the origin of the carbon, or 

 the chemical changes taking place in the flame, was dis- 

 cussed, and along with this the source of heat which renders 

 it incandescent. The last and most generally accepted 



'Published in Popular Science Monthly, 1903. 

 89 



