Page:Popular Science Monthly Volume 52.djvu/879

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on Saturday will enable us to solve some of the enigmas of solar phenomena and constitution."

Source of the X Rays.—Professor Trowbridge, of Cambridge, and J. E. Burbank have recently published (American Journal of Science, February, 1898) the results of an investigation into the source of the X rays. The experiments were conducted with Crookes tubes containing no interval between the anode and cathode, so that no discharge in the usual sense occurred in the tubes. A continuous conductor was led through the rarefied tube, and it was discovered that X rays were given off from every element of this conductor at right angles to its surface when a disruptive discharge occurred in the circuit of which the tube formed a part. This remarkable result was obtained by means of the very high electromotive force from a Planté rheostatic machine which was charged by ten thousand storage cells. Among the interesting data obtained were some regarding the so-called Xray burn. When the back of the hand was exposed to the brush discharge from one of these tubes, a peculiar pricking sensation was experienced and all the symptoms of an X-ray burn developed. The skin when examined under a microscope exhibited centers of inflammation surrounded by regions of lesser degrees of burn. It thus seems evident that the so-called X-ray burn is due to an electrification—a discharge at the surface of the skin—and this electrification may or may not be accompanied by the X rays. The results of the experiments are summed up as follows: 1. A Crookes tube inclosing a continuous conductor is well suited, with the employment of high electromotive force, for the study of electric lines of induction. 2. The direction of the so-called X rays and cathode rays can be changed by electric induction. 3. The so called X-ray burn can be produced by an intense state of electrification. 4. The so-called cathode rays and X rays are given off from every element of a continuous conductor at a high stage of the vacuum in a Crookes tube, both when this conductor constitutes the cathode and when it forms the anode of the electrical circuit. The term electric rays, possibly rays of polarization, would appear to be more comprehensive than the terms cathode rays and X rays.

Early Observations of the Zodiacal Light.—Apparently the earliest mention of the zodiacal light is a notice by Diodorus Siculus, of the appearance in the sky, in b. c. 373, "of a great light for several nights, which was called, from its shape, the burning beam." Nicephorus, in his Ecclesiastical History, tells of a remarkable appearance in the sky for a considerable time during the summer and fall of a. d. 410, which he thought could not be a comet, because it had not a stellar nucleus. Cassini saw a similar phenomenon in March, 1668, and his nephew Maraldi another in March, 1702; but Cassini's observation was of a comet, the head of which was not visible to him, while it was seen in the East Indies and at the Cape of Good Hope. The first person to give a definite description of the zodiacal light was Joshua Childrey, who is quoted by W. T. Lynn in the Observatory as saying that "in February, and for a little time before, and a little after, that month (as I have observed several years together), when the Twilight hath almost deserted the Horizon, you shall see a plainly discernible ray of the Twilight striking up toward the Pleiades or seven stars, and seeming almost to touch them. It is to be observed any clear night, but is best illuc nocte. There is no such ray to be observed at any other time of the year (that I can perceive), nor any other ray at that time to be perceived darting up elsewhere. And I believe it hath been and will be constantly visible at that time of the year. But what the cause of it in nature should be, I can not yet imagine, but leave it for further inquiry."

The Importance of Public Baths.—Some interesting statistics are given by Walter Channing regarding the municipal public baths of Brookline, Mass. The baths were opened in January, 1897, and at the time Mr. Channing's article was written, about the middle of May, there had used the baths 17,089 bathers, or an average of 451 daily. A somewhat curious difference was noted between the number of males and females. The bathers during the last six weeks, for instance, being divided as follows: Men and