A special meeting of the Monacacy Scientific Club was held on Saturday evening to listen to a paper by Dr. H. E. Licks of Old South Bethlehem on the diaphote, an instrument invented by him after nearly three years of study, and now so nearly perfected that he feels warranted in bringing some few of the results thus far attained to the notice of the public. There were present, besides many scientists of Eastern Pennsylvania, Prof. M. E. Kannich of the polytechnic school at Pittsburg, and Col. A. D. A. Biatic of the Brazilian corps of engineers, who is now in this country making extensive purchases of iron and steel. The meeting was called to order by the president, Prof. L. M. Niscate, who in introducing Dr. Licks made a few remarks, saying that he had had an opportunity to witness a few experiments with the diaphote, and he felt convinced that the fundamental principle therein involved was one that would ultimately cause it to rank with the telephone, the phonograph, and the sub-divided electric light, as one of the most remarkable triumphs of science in the nineteenth century.
Dr. Licks prefaced his paper by saying that the idea of the invention was first suggested to his mind about three years ago by reading accounts of some of the early experiments with Bell's telephone, and that a little later, when Edison brought out the carbon instrument, his studies had become so far advanced as to assure him of its theoretical practicability. By the telephone the sound of the human voice may be transmitted hundreds or thousands of miles away, and, with a microphone attachment, even the faintest whispers distinctly heard. Why then cannot light be transmitted in some similar way, so that by the use of a connecting wire one may distinctly see the image of an object far removed? This, said Dr. Licks, is the form in which the inquiry first suggested itself nearly three years ago, and he felt gratified to be able to exhibit to the club this evening an instrument called the diaphote, in which the practical realization of the idea had been in a great measure satisfactorily attained. The word diaphote, from the Greek dia signifying through, and photos, signifying light, had been selected as its name, implying that the light traveled through or along a wire. Although popularly this might be imagined to be the case, it was really no more so than with sound in the telephone. There the sound waves strike a diaphragm that is set into vibrations, which generate induced electricity along the wire, and cause corresponding vibrations in another distant diaphragm, and the latter hence reproduces similar sounds. In the diaphote, likewise, the waves of light from an object strike a peculiarly constructed mirror joined by several wires with another mirror or speculum; the image of an object in the first modifies electric currents in the wires, and these currents passing quickly onward to the receiving instrument produce there a secondary image. The intermediate wire, as in the telephone, may be hundreds of miles long, yet such is the delicacy and power of the diaphotic plates that the transmitted image of a simple object is almost as distinct as the original, and Dr. Licks feels confident that after the removal of a few obstacles, of a mechanical nature merely, the most complex forms will be reproduced with the strictest fidelity in shade and color.
The diaphote consists of four essential parts, the receiving mirror, the transmitting wires, a common galvanic battery, and the reproducing speculum. Dr. Licks gave a detailed account of the many experiments undertaken to determine the proper composition and arrangement of the mirror and speculum. For the former, he had finally selected an amalgam of selenium and iodide of silver, and for the latter a compound of selenium and chromium. The peculiar sensitiveness of iodide of silver and chromium to light has long been known, and their practical use in photography suggested their application in the diaphote. It was found, however, after many experiments, that their action must be so modified that each ray of light should influence the electric current proportionally to its position in the solar spectrum, and selenium was ascertained to be best adapted to this purpose. At first a small mirror was employed with only a single wire, but the images reproduced in the speculum were indistinct and confused, so that it became necessary to make the mirror of a number of small pieces each about one-third of a square inch in area, and having a small wire attached. In the diaphote exhibited by Dr. Licks to the club the mirror was six inches by four, and had 72 fine wires, which were gathered together into one about a foot back of the frame, the whole then being finely wrapped with insulating covering, and on reaching the receiving speculum each little wire was connected to a division similarly placed as in the mirror. From a common galvanic battery wires also ran to each diaphotic plate, and thus a circuit formed which could be closed or not at pleasure. The theoretical action of the instrument appears now to be the following: The waves of light from an object are conducted through an ordinary camera, so that they fall on certain of the divisions of the mirror when the electric circuit is closed. The light and accompanying heat produces momentary chemical changes in the amalgam of the mirror, which modify the electric current and cause similar changes in the corresponding partitions of the remote speculum, thus reproducing a similar image, which by a second camera may be readily seen by the eye or be thrown upon a screen. Dr. Licks explained how the proportions of selenium in the mirror and speculum should be scientifically adjusted to the size of the divisions and the resistance of the electric current, so as to avoid any blending of the portions of the reproduced image. This he said had been the problem which had caused him the most difficulty, and which at one time had seemed almost insurmountable.
At the close of the paper an illustration was given of the powers of the instrument. The mirror of the diaphote, in charge of a committee of three, was taken to a room in the lower part of the building, and the connecting wires laid through the halls and stairways to the speculum on the lecturer's platform. Before the mirror the committee held in succession various objects, illuminating each by the light of a burning magnesium tape, since the rays from gas are deficient in actinic power; simultaneously on the speculum appeared the secondary images, which for exhibition to the audience were thrown on a screen considerably magnified. An apple, a penknife and a trade dollar were the first objects shown; on the latter the outlines of the goddess of liberty were recognized, and the date 1878 was plainly legible. A watch was held five minutes before the mirror, and the audience could plainly perceive the motion of the minute hand on the screen, but the movement of the second hand was not satisfactorily seen, although Prof. Kannich by looking into the camera thought that it was there quite perceptible. An ink bottle, a flower, and a part of a theater handbill were also shown, and when the head of a little kitten appeared on the screen the club testified its satisfaction by the most hearty applause. After the close of the experiments the scientists extended their congratulations to Dr. Licks, and the president made a few remarks on the probable scientific and industrial applications of the diaphote in the future. With the telephone and the diaphote it may yet be possible for friends, separated by the wide Atlantic, to hear and see each other at the same time, to talk, as it were, face to face. In connection with the interlocking switch system it might be used to enable signal men or the central office to see hundreds of miles of railroad track all at once, thus lessening the liability to accident. In connection with photolithography it might be so employed that the great English dailies could be printed in New York a few hours after their appearance in London.
We learn that Dr. Licks will lecture next week on the diaphote before the American Society of Arts, and that he will make definite arrangements for the manufacture of the instrument as soon as the seven patents for which he has applied are formally issued.