New Discoveries in Acoustics.

A description of the Pyrophone, an early sound synthesizer utilizing tubes and fire.

The Pyrophone.—Mr. Frederic Kastner, musician and physicist, has invented an instrument which he calls the pyrophone, and which is illustrated in a recent number of Les Mondes. It depends upon the principle first developed by Prof. Le Conte, of Philadelphia, that two or more isolated flames, burning within tubes, will vibrate in unison so long as they are kept separated. By selecting tubes of different lengths and calibers, a sort of organ has been constructed, the mechanism consisting of a device whereby the performer can cause the separation of any two flames at will, thus producing the sound corresponding to the hey struck. The music is described as being very effective, “imitating the human voice with a mystical timber, and susceptible of producing, in religious music, the most marvelous effects.”

Photographing Sound.—It is proposed to combine with the above described instrument another apparatus, invented by König, consisting of a little drum, over which is stretched a very elastic skin; the gas, which by its separation, as above described, produces the tones, is made to pass through this drum, when it can be ignited as usual; if now the note is struck, the gas-light commences to shake in a remarkable manner, but always in a similar way for the same note, and if we look at the flames in a rotating mirror, we obtain peculiar figures, which change according to the different notes, and by using a combustible gas of chemical power, we can photograph these peculiar figures, a fact to which we have called attention on page 97 of our May number.

According to recent experiments, the photographic power of the various gases employed to take pictures has been determined as follows: Oxyhydric light, 1; a jet of nitric oxid passed through carbon di-sulphid, 6; a jet of oxygen in carbon di-sulphid, 7. The nitric oxid gas is the one upon which the most attention is now bestowed, and a lamp has been constructed by which pictures can be taken at night very successfully and at trifling expense. The adaptation of the gas to the sound apparatus is the next step required. If the invention proves successful, there is every reason to expect that it can be applied to the photographing of speech, as well as musical notes. The same principle could be applied to a burglar-alarm. Instead of allowing an ordinary gas-jet to burn in a bank or public office over night, Kastner's system of tubes could be employed, in which were suspended thin leaves of platinum. Any sound, such as the rattling of keys, would cause the flames to spread out, and the two pieces of foil would be thus brought in contact, and they being connected with a battery, would ring the alarm-bell. Such a contrivance as this has actually been invented.

To this we may be permitted to add that the editor of this journal as long ago as 1860, attempted to introduce the use of such singing gas-flames for the purpose of a burglar-alarm, but in a much simpler way than here described. He afterward obtained a United States patent for the same.