A GROUP OF FAMILIAR ARTICLES UNDER THE RÖNTGEN RAYS.
From a photograph by Professor Arthur W. Wright of Yale College, taken through an ebonite plate-holder with fifty-five minutes exposure. It shows a pair of spectacles in their leather case; an awl and a saw, with the iron stem, plainly visible through the wooden handles; a magnifying-glass; and a combination wooden tool-handle with metallic tools stored in the head, and the metallic clamp visible through the lower half.
The next step was to bring more energy into play, still using Leyden jars; and for this purpose Dr. Morton placed within the circuit between the jars a Tesla oscillating coil. He was thus able to use in his shadow pictures the most powerful sparks the machine was capable of producing (twelve inches), sending the Leyden-jar discharge through the primary of the coil, and employing for the excitation of the vacuum tube the "step up" current of the secondary coil with a potential incalculably increased.
While Dr. Morton has in some of his experiments excited his Leyden jars from an induction coil, he thinks the best promise lies in the use of powerful Holtz machines; and he now uses no Leyden jars or converters, thus greatly adding to the simplicity of operations.
In regard to the bulb, Dr. Morton has tested various kinds of vacuum tubes, the ordinary Crookes tubes, the Geissler tubes, and has obtained excellent results from the use of a special vacuum lamp adapted by himself to the purpose. One of his ingenious expedients was to turn to use an ordinary radiometer of large bulb, and, having fitted this with tin-foil electrodes, he found that he was able to get strongly marked shadow pictures. This application of the Röntgen principle will commend itself to many students who, being unable to provide themselves with the rare and expensive Crookes tubes, may buy a radiometer which will serve their purpose excellently in any laboratory supply store, the cost being only a few dollars, while the application of the tin foil electrodes is perfectly simple.
In the-well equipped Jackson laboratory at Trinity College, Hartford, I found Dr. W.L. Robb, the professor of physics, surrounded by enthusiastic students, who were assisting him in some experiments with the new rays. Dr. Robb is the better qualified for this work from the fact that he pursued his electrical studies at the Würzburg University, in the very laboratory where Professor Röntgen made his great discovery. The picture reproduced herewith, showing a human foot inside the shoe, was taken by Dr. Robb. The Crookes tubes used in this and in most of Dr. Robb's experiments are considerably larger than any I have seen elsewhere, being pear-shaped, about eight inches long, and four inches wide at the widest part. It is, perhaps, to the excellence of this tube that Dr. Robb owes part of his success. At any rate, in the foot picture the bones are outlined through shoe and stocking, while every nail in the sole of the shoe shows plainly, although the rays came from above, striking the top of the foot first, the sole resting upon the plate-holder. In other of Dr. Robb's pictures equally fine results were obtained; notably in one of a fish, reproduced herewith, and showing the bony structure of the body; one of a razor, where the lighter shadow proves that the hollow ground portion is almost as thin as the edge; and one of a man's hand, taken for use in a lawsuit, to prove that the bones of the thumb, which had been crushed and broken in an accident, had been improperly set by the attending physician.
