Birmingham state herald., 1896-10-25
SOUND PHOTOGRAPHED.

Some Wonderful Experiments With the
 Photographic Lens in New Fields.
 If the human eye goes on increasing in usefulness as it has been doing of late, says the New York Herald, it is not at all improbable that eyesight will usurp the functions of hearing. In the past sound has been "heard" only. Marvellous to re- late, 1t has been found possible to see a sound and to photograph it in it's course. This discovery, following closely as 1t has upon the X-ray and other remarkable discoveries, has set the scientific world to thinking what new problems are left for men to solve.
 This latest sensation in science, accord ing to the Vaughn and Cornish M. Sc., shows that if a photographic lens be turned on a Martini bullet in it's flight through the air the photographic plate shows that a dark line of compressed air can be sen in front of the ball. In the path of the bullet on which a lens was turned, in the course of a series of ex- haustive experiments just made public, the hole cut in the air by the projectile could be distinctly seen closing up as the atmospheric waves subsided, and the separated air came together again. It being necessary to bring some sort of light to bear upon the bullet in its flight an electric spark was formed by an in genious method, and by sending the bul- let past two wires that completed an electric current a photograph was ob- tained by the light of the spark thus created.
 This showed an interesting state of things. Besides the dark line formed by the piled-up atmosphere in front Of the bullet and the smoke-like waves in the rear, there appeared on the plate an ar row-headed wave that was caused by the hum of the bullet. This hum broke the atmosphere in arrow-headed sections that could be distinctly seen on the plate
 comparison with the time when the sound was heard with the time when the sound could be seen on the photographic plate proved that the soldier who ducks" when he hears the whiz of bullet is wasting energy, for the bullet has pessed when the sound is heard. Experiments with bullets of greater velocity showed that the arrow-headed air waves were al ways of the same shape, but with an in crease of impact they became sharper at the point.
 The difference between waves of the sea and sound waves, as shown by these interesting experiments. is that there is no noisy moving backward and forward and tossing unanimously, as with wa ter. The air particles, burst asunder by the impact of the projectile, scatter into the atmosphere, thus producing a great CT density This action goes on continu- ously in front of the bullet and on either side.
 The air wave transmits it's energy to the neighboring layer of air, which, be- ing thus compressed, becomes in it's turn the wave front
 The air waves, now that man can see them, by the aid of photographic lens, are shown to be regular and systematic in their habits. When distributed by the flight of the bullet they scatter in arrow headed waves until the disturbing ele- ment has passed on, when the layers of air recoil into their former position. The motion of the air particles was found to be wholly forward and back to rest along the same path.
 Experiments made to ascertain what condition of the atmosphere caused the sounds that are made by the striking of a piano key revealed the fact that the vibration sent out succession of pulsa- tions of the atmosphere, each of which Is an elastic air wave independent of those which precede and follow it.
 The photographic lens showed that the sounds seen were waves, of which the crests are separated by distances of about AZ feet. The particles of air, it could be seen, were caused to make forward and backward swing. During the former the air Is compressed; during the latter 1t Is rarefied, each pulse of compressed air be- ing followed by one of rarefied air.
 Experiments with the vibration of a violin string showed that the air is com pressed and released very suddenly, WHICH glVeS the Snarper sounu oI tne violin as compared with that of the piano.
 An atmosphere disturbance on large scale has very different form of wave front. The eruption of volcano if the photographic lens could be turned on it, would show a great ring-shaped wave front radiating out to all points of the compass, and going half way round the earth. Then this wave would contract when relieved of the pressure and return to the region of the volcano again.
 From observations made during the final paroxyisms of the Krakatoa erup- ton, MT. Cornish is of the opinion that the great air waves if photographic ap- paratus could be constructed that would take them as 1t does the aerial disturb ance made by a. bullet, would show that the waves spread out with diminishing intensity at each journey until they had made several complete circuits of the globe.