“Like a child which hides behind a wooden door to shield itself from the bullets of a machine gun, our young radiologists believe they are safe when they have donned their gloves and examine their patients behind a sheet of lead glass. But, unfortunately, these enable them only to avoid those superficial skin affections caused by the most absorbable rays of the spectrum. “But they receive, alas, those other radiations which are more penetrating, and these slowly produce lesions of all the ductless glands in the body, whose internal secretions we now know to be of such vital importance in the bodily economy.” The modern employment of 200,000 volts under three milliamperes gives rise to the need of great caution in the use of X-rays. Even the health of persons in adjoining rooms or buildings, Dr. Contremoulins believes may be imperiled. In the _Popular Science Monthly_ for October, 1921, this veteran radiologist makes some startling revelations. To quote a few passages: “In April, 1896, five months after the discovery of X-rays—or Roentgen rays, as they are also named in honor of their discoverer—a pose of eight hours was required for a correct radiograph of a profile head, the tube being placed ten inches from the sensitive plate. “In April, 1921, a similar image was obtained in four hours at a distance of 90 yards from the apparatus. This means that the radiation with modern apparatus is more than 20,000 times stronger than was possible in 1896. “With the very weak radiation that I have used for my experiments, corresponding to the ordinary radiographic and radioscopic work, it has been easy for me to obtain images of metallic objects and human bones placed on a sensitive plate 15 feet from the radiating source, although the rays pass directly through a slab of marble an inch thick, a sheet of lead one-tenth of an inch thick, and a flooring eight inches deep, built of oak boards and rough plaster. “Fifty feet from this same source I have been able in four hours to fog a photographic plate placed behind a wall of brick and stone 20 inches thick. Also in the same time I have obtained a correct radiograph of a skull and a crab, 262 feet from the X-ray machine. All these experiments were made with a 17-centimeter spark and two milliamperes of current. “If photographic plates are so readily affected by these rays, we must admit that animal cells also are affected to an appreciable degree. The X-rays that are being used to cure a patient may at the same time inflict radio-dermatitis on other persons exposed to their influence in adjoining rooms or buildings. Nothing will suffice for safety but to cover the walls and floors of X-ray rooms with sheets of lead from a quarter to half an inch thick, according to the power of the source and its distance from the lining....