Amazing Facts about Radio Sounds that Burn

Radio Record, Volume II, Issue 8, 7 September 1928, Page 3

Amazing Facts about Radio Sounds

that Burn

kils idea of a ray or vibrution fatal.to buman life has Jong held the imugination of the experimen: ter and the general public ‘alike. Death rays have often been "discovered,". and usually exposed as fakes, and volumes have been written of the possible dire consequences of wars waged with destructive electrical vibrations. The conversions of the electrical vibrations into mechanical vibrations hus been suggested, the consequences speculated about, but not till recently accomplish: ed. Although it cannot be said that this discovery has introduced an era of destruction unequalled in history, yet the effects of this accomplishment are so umazing that they add a new chit ter of science. T is quite easy to produce electric Vibrations of a very high With short-wave oscillators, electrons ‘an be made to swing back and forth ju circuits as rapidl, as ten million times a second. However, there is no sount reproducing apparatus that would re spond to these prodigious speeds. If such currents are allowed to flow through an ordinary loudspeaker no thing but silence would prevail. In the first place the diaphragm vf the loudspeaker would be. too bulky and massive to respond to these rapid

vibrations, and even if it were able to respond, the human hearing apparatus would not be able to detect the sounds produced, the limit of hearing being about 16.000 cycles per second. Physical Vibration. (THE problem confronting those endeavouring to transfer these electrical virbrations into mechanical vibrations has been to tind some substance which would respond to vibrations so high. A substance-quurt7 crystal-hus at last been — utilised. The discovery of its usefulness for this has been of great commercial import: ance, especially as this crystal bas proved a great stabilising unit in wire less transmission. When a crystal is placed in a cur rent of high frequency, corresponding to its natural frequency, resonance oc: curs, and the amplitude of the vibra tious of the crystal become very great. The "still? sounds produced in this way are capable of many curious feats. A glass tube vibrated at the rate of 300,000 oscillations per second, will sear the flesh of the fingers if it is squeezed tightly. Benzol on water ix thrown into such violent action that

it is driven off into the air as a fine mist of smoke. Frogs swimming in liquids vibrating at this high rate are killed, and glass tubes eventually sue: cumb to the super-sonic frequencies that disrupt the ordinary molecular organisation. : Curious Effects. WHEN it came to higher frequencies 100,000 to 700,000 cycles, it was found necessary to immerse the crys: tal in an oil bath. A beaker of water lowered toa point beneath the surface of the oil, demonstrated a most remark: able phenomenon. The super-sonic frequencies at which the molecules of oil were responding were instantly communicated through the glass to the: water in the beaker. The surface of the water was at once pushed up into a mound, while millions of minute air bubbles appeared in the fluid. as when water is heated. When subjected to the same process, mercury was blown into clouds of fine particles projected up through the water, which soon became black as ink. MAXIMUM heating effects were produced with a small flat-bottomed

conical flask drawn out to a rod at the top of about 3-millimeter in diameter. The flask was mounted on a solid support in a vertical ring and pinion device, and the distance between the flask and the crystal plate could be accurately adjusted. By bringing pine chips into contact with the top of the. rod, these were caused to emit sparks, and holes were burned through them. A plate of glass placed in coutact with the rod was ground to powder. If a glass tube were coated by a thick coating of oil and the end dipped into an oscillating bath the film immediately gathered itself into a system of equidistant rings showing the positions of the nodes. of the stationary waves formed by the interference of high-frequency vibrations which were at the time running up and down the tube. PeHRAPS the most interesting of all these experiments was that which tested the biological effect produced by the vibration. Red blood corpuscles were completely destroyed and the serum in which they are suspended lest its turpidity and became a red colowr very similar to the solution that would be produced by analine dyes, unicylular organisms, belonging to the lowest orders of the animal and vegetable kingdoms. Protozoa and the lowest Algae, were almost instantly dispatched and the cells torn open.