THOME WITH LOUD VOICE.

Wanganui Chronicle, Volume LXXVI, Issue 18431, 15 March 1922, Page 6

THOME WITH LOUD VOICE.

WHISPERS THAT BECOME NOISY SHOUTS. HUMAN PULSE ON PAPER. LONDON, January 7 An interesting demonstration of the loud-speaking electrostatic 'telephone was given at the Imperial College of Science by Dr. CampbellSwinton on Thursday. The telephone jn its present form is the invention of 'two Danish engineers, Messrs. Johnsen and Rahbek. The instrument on the lecturer’s table looked like a gramophone with a small horn. Dr. Swinton placed a watch on a microphone connected with the telephone, and immediately the lecture-hall was filled with sounds like rapid and heavy blows of a fist on a tabe. The next experiment was too successful, for the top note of a singer’s voice tn a distant room tore the diaphragm out of the base of the loud-speaking horn. When the instrument had been readjusted, the lecturer announced that he was going to connect it up with a wireless receiver and see whether, any of the numerous wireless stations in the world could be heard at work. WEIRD MUSIC.

The hall was immediately filled with sounds as though dozens of street musicians were practising scales on an assortment of weird instruments. The lecturer explained that, with so many wireless stations ’sending out messages, it was difficult to pick out a given wave length at once, and hence the confusion. Eventually he succeeded in isolating one of these, and the audience clearly heard part of a message from some unknown station rapped out in Morse so loudly that it could easily have been heard 100 yards or so away. After the lecture, which was In connection with the 12th annual exhibition of the Physical and Optical Societies, I visited various rooms, where scientists were examining the wonderful instruments displayed by enterprising manufacturers. In a room filled with the ghostly glow of mercury vapour lamps a representative of Adam Hilger Ltd., invited me to look through the eyepiece of an instrument for demonstrating the physical properties of glass. At first I saw what appeared to be a delicately tinted cloudless sunset afterglow, then a sort of transparent moon came into view. It was explained that this was a lens. My informant held this between his thumb and forefinger and immediately a blue haze spread from the points of contact of his fingers towards the centre lens. He explained that this was due to the effect on the light coming through the lens of strains set up in the glass by the slight heat of his finger-tips. TELL-TALE PULSE.

In another room Dr. Hopwood gave fascinating demonstrations with a spiuniiig-top, apparently formed by a continuous sheet of beautifully coloured flame. This effect was obtained by whirling a vertical piece of red-hot wires round a vertical spindle, much in the same way as the brass rods supporting the horses in a merry-go-round travel about the central shaft. As a climax to these excitements I visited the stall of the Cambridge and Paul Instrument Company, and had the receiver of a Mackenzie Lewis Polygraph strapped to my wrist. The whole instrument is not much larger tha na quarter-plate camera, and it makes your pulse sign the signature in red ink on a moving paper tape. The result is a series of curiously shaped waves, and doctors by examing these and other similar records can tell the state of a patient’s heart. This instrument, which only costs £2O, may find many useful applications outside medical circles.