HOW TO PHOTOGRAPH SOUND.

Auckland Star, Volume XXX, Issue 202, 26 August 1899, Page 5 (Supplement)

HOW TO PHOTOGRAPH SOUND.

AN ASTONISHING DISCOVERY,

Science has made swift progress of late years, particularly in the'realms of sound. There are volumes of theoretical explanations of the mystery of sound, but the very nature of the subject has baffled investigators who have tried to arrive at the altar of tangible knowledge. But perseverance brings its oavu reward, for it is noav demonstrated that sounds can be photographed. At first it seems iucredible (says a London contemporary) that any person, even a scientist, by turning a camera towards the transparent atmosphere, could obtain photographs that are the exact reproductions of the vibrations that certain sounds make on the air;' yet the astonishing feat has been accomplished, and sounds—that is, Avords—have been photographed, although it has not yet been possible to take complete sentences—nothing beyond a few easy monosyllables. The rest.is to follow in the course of time.

It is well to consider the construction of a telephone in order to explain the metuis used for obtaining these remarkable photographs. As is generally known, the voice that speaks into a telephone is directed against a thin, flexible metal plate. The vibrations of the voice are then transmitted through the intervening air to the membrane, and thence conveyed by electrical means to a similar membrane at the other end of the wire. But it has been discovered that other arrangements as well as sheets of metal will take up the atmospheric vibrations which cause sound, and among these are vibratory flames. In the course of experimenting, the plan was tried of employing a flame which was made to flicker by the vibrations of air, the movements of which were caused by the sound under examination, and by means of a rapidly rotating mirror, drawn out so that they could be examined and recorded.

Now, the scientists who have been studying the question of photographing sound substituted a long photographic film for the mirror, arranged on a cylinder, which was made to rotate at a high velocity. With the film and a specially constructed lamp, which ga.-e an intensely bright light, it was found possible to take photographs of the vibrations made by various sounds.

It was clearly demonstrated that the sounds of such words as "die" and "sigh" made vibrations that were similar in form, while words that bore no similarity of sound produced entirely different vibrations. Subsequent experiments were so far satisfactory that, after some words had l>een photographed and connected together so as to form a line of ordinary print, as it were, an effort was made to read the words off—at first a slow, but nevertheless assuring—process. .'

Later, at a special demonstration, better photographs were taken, and these having been connected up together, as in the previous experiment, and the scientists by tlfis time having become familiar Avith the forms of the records, one of the investigating gentlemen, who had purposely absented himself fropi this ' particular experiment, was ultimately able to read off with comparative ease all the words that his colleagues had photographed in his absence, this feat of the reading scientist being basfcd wholly on the forms of the records. He was able to read them off like print.

You may ask, what useful purpose will this discovery serve? At present that remains to be seen. It max be possible fori the business man of the future to speak his correspondence into a machine which will photograph it and enable the man at the other end to read the letter' off the photographic plate just as he would read ah ordinary typewritten letter.

It may also be possible in the future to photograph the speeches of political speakers at big or little meetings, for these sound waves travel oyer an extraordinary distance, and nothing seems impossible in their attaining astounding results; indeed, we are assured already that photographs of words spoken at a distance of nearly a mile away canbe obtained.

Beyond the mere fact of the remarkable discovery of the main principle and the deA'elopment of some details, the whole practically is yet in an embryonic state, and j what may or may not be done with it when . the discovery is perfected is conjecture. i Nevertheless, already speculation is r{fe as to the practical use of the Invention, some regarding it as a mere plaything, while the more optimistic look upon it with considerI able favour. Time' will settle it..