139b. Gouy’s Experiments. The Penetration of Gases into the Glass Walls of Discharge Tubes. Comptes Rendus, March 30, ’96. From trans. by Louis M. Pignolet. From observations with slightly different glass from four tubes, it seemed that the cathode rays cause the gases in the tubes to penetrate the glass where they remain occluded until the glass is nearly softened (after cutting off the current), by heat, whereby they are set at liberty as minute bubbles visible by the microscope, which finally partly combine and become visible to the naked eye.
Halos 1 ft. diam., in clear air, around incandescent electric lamps
of usual size. Cross at center of each halo. [§ 140], p. [143].
Observed by means of a photograph, in 1882, by William J. Hammer.
Mortification of the Ulna. [§ 204].
From sciagraph by Prof Miller.
Under the same conditions, tubes which have been used for a long time exhibit numerous wrinkles, indicating a superficial modification of the glass. These may exist with or without the bubbles.
140. Discharge Tube Surrounded by a Violet Halo. By means of enormous potential and high frequency, the tube was surrounded, Tesla stated, by violet luminosity or halo. [§ 6]. and [74]. From the fact that Lenard obtained a similar appearance in front of the aluminum window, it might be reasonable to conclude that there is some close relationship between the two phenomena.
As an illustration of halo by light, may be mentioned the well known appearance so often occurring in the atmosphere concentrically with the moon, and sometimes surrounding the sun. Under favorable circumstances, (in a mist or dust in the air), a halo, at some distance from a flame or other light is faintly visible. It has generally been assumed that the reason of a halo by light is based upon the laws of reflection, or refraction or both, the bending of the rays taking place, through, or upon the surface of the particles of moisture. Others have held that particles of ice in the upper atmosphere, are the reflectors or refractors, or both. More puzzling has been the attempt to explain the novel appearance reproduced fairly well in the cut, page 140. It is here represented in print for the first time, but the photograph from which it was taken, was at various times, shown to different physicists, some of whom attributed the beautiful effect to the property of interference of light, and naming Newton’s rings as an analogous production. Prof. Anthony in an interview expressed himself as well satisfied that interference could not occur under the circumstances named. He recognized that there was a curved surface of glass which might be considered as made up of an infinite number of layers. The author introduces the matter for the purpose of consideration by others, and especially because it is so intimately connected with the subject of the vacuum tube and electricity. The details must be understood for the purpose of proper appreciation. Mr. William J. Hammer, of New York, had a photograph taken of the large Concert Hall at the Crystal Palace, Sydenham, Eng., by the light of the Edison incandescent lamps with which the Hall was illuminated. This photograph was made in 1882 during the International Electrical Exhibition held at the Crystal Palace. The picture shows a small section of the whole photograph and represents (although probably no one would judge so by looking at the picture) a festoon of pear-shaped incandescent electric lamps, each one hanging downward, and separated from its neighbor by between three and four feet. They were so far away from the camera that a picture of the lamps unlighted, would have represented them as mere specks. The bright circles with the bright central crosses in the centre of the dark spaces were, therefore, fully one foot in diameter, while the lamp bulbs themselves were only about two or three inches thick, as usual. Why then should there be the halos? Why should the crosses appear? And why should the black area be so large? If the electricity and vacuum have nothing to do with it, why should not the halos appear when photographs are taken of flames and other sources of light in the absence of mist and dust? In order to answer questions which will perhaps be proposed, let it be stated that there was no visible dust nor moisture in the room, the photograph being taken early in the evening and at a time when the Hall was not in use. The halos were not apparent except when reproduced by a photograph. The lamps had the usual carbon filaments hanging so that the several filaments were in different planes, and they were of 16 candle power and were connected in parallel circuit, the average E. M. F. being about 110 volts. The lamps were fed by the Edison direct current dynamos. The festoon shown, is one of a dozen or more which were suspended between the columns rising from the gallery and supporting the roof and were hung about forty feet from the floor. The hall was further illuminated by a huge electrolier pendant from the centre of the ceiling. These details were obtained from Mr. Hammer, who planned the installation.
141. Anæsthetic Properties of X-rays.—Tesla reported that he and his assistants tested the action of the rays upon the human system, and found that upon continued impact and penetration of the head by very powerful radiations, strange effects were noticed. He was sure that from this cause a tendency to sleep occurred ([§ 84], at end), and the faculties were benumbed. He said that time seemed to pass quickly. The general effect was of a soothing nature, and the top of the head seemed to feel warm under the influence of the rays. Incidentally, he noticed, as he stated, “When working with highly strained bulbs, I frequently experienced a sudden and sometimes even painful shock in the eye. Such shocks may occur so often that the eye gets inflamed, and one cannot be considered cautious if he abstains from watching the bulb too closely.”
The author calls to mind the reports in the daily press that Edison also noticed that the eyes were in some way sensitive to the rays. The eye, it was reported, became fatigued at the time, and yet later, objects could be more easily distinguished.