190 RAY STANNARD BAKER 



values for them (in every experiment) and you can under- 

 stand what a great number of trials were made, using different 

 combinations, before obtaining results. I presume thousands 

 of experiments were made." 



Many other investigators had been on the very edge of 

 the discovery. They had tried sending strong currents 

 through a vacuum tube containing mercury vapor but had 

 found it impossible to control the resistance. One day, how- 

 ever, in running a current into the tube Mr. Hewitt suddenly 

 recognized certain flashes; a curious phenomenon. Always 

 it is the unexpected thing, the thing unaccounted for, that 

 the mind of the inventor leaps upon. For there, perhaps, is 

 the key he is seeking. Mr. Hewitt continued his experiments 

 and found that the mercury vapor was conducting. He next 

 discovered that when once the high resistance of the cold 

 mercury was overcome, a very much less powerful current 

 found ready passage and produced a very brilliant light; the 

 glow of the mercury vapor. This, Mr. Hewitt says, was the 

 crucial point, the genesis of his three inventions, for all of 

 them are applications of the mercury arc. 



Thus, in short, he invented the new lamp. By the use 

 of what is known to electricians as a boosting coil, supply- 

 ing for an instant a very powerful current, the initial resistance 

 of the cold mercury in the tube is overcome and then, the 

 booster being automatically shut off, the current ordinarily 

 used in incandescent lighting produces an illumination eight 

 times as intense as the Edison bulb of the same candle power. 

 The mechanism is exceedingly simple and cheap; a button 

 turns the light on or off; the remaining apparatus is not more 

 complex than that of the ordinary incandescent light. The 

 Hewitt lamp is best used in the form of a long horizontal tube 

 suspended overhead in a room, the illumination filling all the 

 space below with a radiance much like daylight, not glaring 

 and sharp as with the Edison bulb. Mr. Hewitt has a large 

 room hung with green material and thus illuminated, giving 

 the visitor a very strange impression of a redless world. After 

 a few moments spent here a glance out of the window shows 

 a curiously red landscape, and red buildings, a red Madison 



