Tesla on Roentgen's Rays

The leading article of the month on the Roentgen rays is Nikola Tesla's contribution on the subject appearing in the Electrical Review. At once on hearing of Roentgen's discovery, Mr. Tesla repeated the learned professor's experiment, and since then has been devoting his energies to the investigation of the nature of the radiations and to the perfecting of the means for their production. He describes in detail the methods he has employed and the arrangement of his apparatus. Suffice it here to say that he has been able to obtain shadows with comparatively short exposures at distances of many feet, while at small distances and with thin subjects, exposures of a few seconds are practicable. The first shadow taken with his improved apparatus was that of a copper wire bent so as to form the word "Roentgen," projected at a distance of eleven feet through a wooden cover over the sensitive plate. A similar impression was obtained through the body of the experimenter, a plate of glass, nearly three-six-tenths of an inch thick, a thickness of wood of fully two inches, and through a distance of about four feet. By improvements in his apparatus Mr. Tesla is confident that he can magnify the effects many times.

Continuing the account of his results, Mr. Tesla says: "The bony structure of birds, rabbits and the like is shown within the least detail, and even the hollow of the bones is clearly visible. In a plate of a rabbit under exposure of an hour, not only every detail of the skeleton is visible, but likewise a clear outline of the abdominal cavity and the location of the lungs, the fur and many other features. Prints of even large birds show the feathers quite distinctly.

"Clear shadows of the bones of human limbs are obtained by exposures ranging from a quarter of an hour to an hour, and some plates have shown such an amount of detail that it is almost impossible to believe that we have to deal with shadows only. For instance, a picture of a foot with a shoe on it was taken, and every fold of the leather, trousers, stocking, etc., is visible, while the flesh and bones stand out sharply. Through the body of the experimenter the shadows of small buttons and like objects are quickly obtained, while with an exposure of from one to one and a half hours the ribs, shoulder bones, and the bones of the upper arm appear clearly on the sensitized plate. It is now demonstrated beyond any doubt that small metallic objects or bony or chalky deposits can be infallibly detected in any part of the body.

"An outline of the skull is easily obtained with an exposure of twenty to forty minutes. In one instance an exposure of forty minutes gave clearly not only the outline, but the cavity of the eye, the chin and cheek and nasal bones, the lower jaw and connections to the upper one, the vertebral column and connections to the skull, the flesh and even the hair. By exposing the head to a powerful radiation strange effects have been noted. For instance, I find that there is a tendency to sleep and the time seems to pass away quickly. There is a general soothing effect, and I have felt a sensation of warmth in the upper part of the head. An assistant independently confirmed the tendency to sleep and a quick lapse of time. Should these remarkable effects be verified by men with keener sense of observation, I shall still more firmly believe in the existence of material streams penetrating the skull. Thus it may be possible by these strange appliances to project a suitable chemical into any part of the body.

"Roentgen advanced modestly his results, warning against too much hope. Fortunately his apprehensions were groundless, for, although we have to all appearance to deal with mere shadow projections, the possibilities of the application of his discovery are vast. I am happy to have contributed to the development of the great art he has created."