Inventors at Work, with Chapters on Discovery

by George Iles

Light.

Professor Langley conducted another inquiry of fascinating interest, this time respecting those natural light-producers, the fireflies, especially the large and brilliant species indigenous to Cuba, Pyrophorus noctilucus. As the result of refined measurements with the spectroscope and the bolometer, the most delicate heat detector known to the laboratory, he said: “The insect spectrum is lacking in rays of red luminosity and presumably in the infra-red rays, usually of relatively great heat, so that it seems probable that we have here light without heat.” When we remember that ordinary artificial light is usually accompanied by fifty to a hundred times as much energy in the form of wasteful and injurious heat, we see the importance of this research. If light can be produced without heat by nature, why not also by art?

Cuban firefly, life size.