Fig. 197
"It has many times been suggested that this strange search-light appearance may be an electrical phenomenon, some form of ether waves which the comet sends forth when under the immediate influence of the sun. But not all comets are alike in this matter, nor does the same comet always act alike on succeeding trips, so that we may not predict what Halley's comet will do on this visit. It would be natural to suppose that Halley's comet, like radium, might in time lose the power to radiate off material, in which case it might at length become wholly invisible to us, even though it continued to travel in its wonted path. Our only way of knowing of its existence then would be that on its returns some of its small pieces might be attracted to the earth and enter our atmosphere as meteors. This sort of thing is continually happening, and may be the last reminders of once brilliant comets.
"For almost a century it has been the common belief that light is merely a wave motion in the ether. Our eyes respond to ether waves of certain length only. Waves a little longer than those which affect our eyes are felt by us as heat waves. Waves still longer than those of heat are the so-called electric waves. These we use in wireless telegraphy. There are still shorter waves than those of light. These affect the sensitive plate in photography. They help to form the green material in the leaves of plants and the brilliant colours in flowers. They assist in the fading of our clothes and the tanning of our skin. These are called chemical waves. Still shorter waves in the ether than those of which we have just spoken are the X rays, and all the strange things which they may do have not yet been determined. Certain it is that they can make dreadful sores in our flesh. They can penetrate through wood and paper, but not metals. They pass readily through flesh, but not bones. All such ether waves are treated in a book by Sylvanus P. Thompson, entitled 'Light Visible and Invisible,' in which he points out that electricity, heat, light, chemical rays, etc., are all alike in being ether waves, and this was suspected by James Clerk Maxwell and others half a century ago, and has come now to be quite generally believed.
"Halley's comet, already having been seen upon this return, must be sending out those ether waves which we call light; whether it is also sending forth some of the other kinds of ether waves may yet be determined."
My audience being chiefly composed of those persons who were present at Harold's birthday party, they pressed me to tell them more about wireless telegraphy and similar matters, and so I agreed to give them at some future date some account of the history of these ideas. But my present purpose was to start an interest in astronomy as an antidote for the wireless epidemic, and so I invited all who desired to do so to come again one week from that evening, bringing with them such opera and field glasses as they might be able to secure. I promised to show them how to make a telescope such as Galileo had more than three hundred years ago. I agreed to go out with them several evenings and scan the sky with our telescopes, and to tell them of some readable books and articles upon astronomical matters.
XXV
HOW THE IDEA OF A UNIVERSAL ETHER DEVELOPED
The evening for the meeting of the Science Club had arrived. Its membership had increased tenfold within a year. At its monthly meetings, which were open to the public, an audience of two hundred, old and young, was usually present—a number about three times that of the regular membership. General science was now the study of this club. At its weekly meetings, which only members attended, the studies of specific topics by individuals, oftentimes illustrated by experiments, were reported. These meetings were held in one of my laboratories, while the open monthly meeting was always held in my lecture room, with some rather famous speakers to instruct the audience. An enthusiastic friend of science had given a fund with the stipulation that we should engage the services of those who both knew their subjects and had acquired the art of presentation. The fund was $10,000 and it yielded $500 a year. I think beyond question it was doing more for science than any other fund of ten times that amount which can be mentioned.