Prismatic Globes and Reflectors

The use of the principles of refraction and reflection for changing the direction of rays of light is, of course, one of the oldest branches of modern physics, and today the sciences of optics, astronomy, etc., are based on these fundamental principles. The application of these principles, however, to the use of artificial light is more recent. Numerous experimenters have tried to use either one or the other principle in their efforts to redirect the rays of artificial light, but it remained for Blondel and Psaroudaki to combine both principles into compound prisms and thus lay the foundation of the modern science and art of prismatic glassware for artificial lighting. The principles in their invention were announced in the country in 1897 by the award by the Franklin Institute of the John Scott Legacy Medal to the inventors. Since that time, however, no statement has been made of the numerous and varied advances that have been made, and it is the object of this paper to point out some of the more important steps made in the past ten years.