EMPTY SPACES

Evening Post, Volume CXIX, Issue 108, 9 May 1935, Page 23

EMPTY SPACES

USE IN INDUSTRY

PHYSICISTS ENTERTAINED

Keen industrial physicists, in conference in Manchester, enjoyed as heartily as any less learned audience a good many spectacular lighting experiments. They laughed and applauded when electric valves lit up for no apparent reason, and when globules of mercury, rolled from end to end of a glass tube, set a vivid blue light winning and losing predominance against a stream of light that had been pink, or when the heating of a tube made coloured lights in wavy lines or a sudden vivid glare. But they, also applauded diagrams and equations, when the layman could see no reason for such enthusiasm, and in intervals between lectures they entered alertly into the discussion of a score of technical problems affecting industrial matters from the lighting of a theatre to the manufacture of aeroplanes.

The conference was arranged-by the Institute of Physics. Its general subject is physics as applied to industry, and its special subject was "Vacuum Devices in Research and Industry." The gathering' was welcomed to Manchester University by Sir William Clare Lees, a member of the University Council and a spokesman of Lancashire industry. He pointed out that they had come to a district where physics and technology were in hourly association. He recalled, "as a bond of union between textile industry and the vacuum," that the first artificial silk was produced in 1855 by Swan, as a filament for his electric lamps. The public, Sir William said, recognised the safety, comfort, and amusement which the discoveries of science had brought.

LIGHT OF MANY COLOURS.

The first lecture was by Mr. J. W. Ryde, of the. General Electric Com' pany; on modern electrical illuminating devices. He described (and illus-' trated with many pleasing experiments) the development of the modern method of producing light of varying colours by discharging electricity into gases, such as helium and neon. A difficulty to be overcome was that many gases' gave off their energy hi the form of heat, or other forms that were not visible to the human eye, and so the use of gases was limited to those whose "spectrum was suitable. However, in one.instance, in which to give off a certain green light it was necessary to use' glass that did not allow blue to pass, they had compensated for the loss of brilliance involved by ,the disuse of the blue by transforming ultra-violet rays into green.

Among the applications of the use of electricity in gases were the production (with carbon dioxide) of a daylight lamp for certain leather work and the matching ot colours in fabrics; neon lighting, for" advertisements and aviation beacons; and greatly-improved street lighting.

In the discussion, Dr. C. C. Paterson, head of the General Electricity Company research; department, said that though the industry was extremely Jcompetitiye, the..firms> making electric lamps combined to" share- the results .of their research. He thought the English lamp-makers had put their money on the right horse jn backing the mercury lamp, though there was also a future for the sodium lamp. He expressed pleasure that the progress made in illuminants had bifen turned to the improvement of the miserably low standard of our street lighting rather' 'than merely to economy.

THE PHOTO-ELECTRIC CELL.

The photo-electric cell was dealt with by Mr. T. C. M. Lance, of Baird Television, Ltd., and Mr. R. C. Walker, of the General Electric Company, Ltd. The discussion was mainly on the industrial application of the cell. Among the uses mentioned either by the lecturers or in discussion, in addition to the door thatopens when approached and the sorting of letters, were detecting holes less than a tenth of a millimetre in size; counting newspapers; stopping a rotary press or paper-making machine when the reel of paper breaks; lighting advertising when it goes dusk, whether by day or at night; detecting black smoke, even if it was "whitewashed" by the admixture o ; f steam; and photometric methods which by increasing accuracy had reduced lamps that would last less than 500 hours from 15 per cent, to 1 per cent.

Another remarkable modern instrument,- also used in television, was dealt with by Mr. L. H. Bedford, of A. C. Cossor, Ltd., the cathode ray oscillograph, and its use for measuring and recording rapid electrical effects. It was described by Mr. Watson Watt-in discussion as a bottle and two boxes which gave in portable form a means of measuring time down .to ' onethousandth of a second. '

Mr. Bedford, to- whose work the development of the instalment, was specially attributed, explained how the recording was done by the directing of a beam of electrons on to a,-flat surface covered with fluorescent material, which glows when the electrons are directed on it .

USES OF THYRATRONS,

The session ended with a discussion opened by Mr. L. J. Davies and Mr. A. L. WHiteley, of the British Thom-son-Houston Company, Ltd., on recent applications of mercury vapour rectifiers and thyratrons, These are used in industry when it was necessary to interrupt the .flow of electric current suddenly or frequently. It was stated that till the advent of the thyratron the method of interruption used was fundamentally the same as might have been used by Faraday—the mechanical separation of copper or other conductors, and this had serious limitations in both the frequency" and accuracy with which the current could be started .and stopped. An instance of its use was in resistance seam welding, largely used in the making of aeroplanes. In welding certain metals the continuous application of heat was disastrous and the stopping of the current essential. In making one type of gastight welding, the current had to be interrupted 600 times in a minute.

• In,discussion, Mr. R. C. Walker suggested that jthe. value of the thyratron had been exaggerated, but he had no supporters, and he was answered by Dr. Paterson, who said a machine so specific and precise was bound to have many* uses,. and by Mr. H. de B. Knight, ,\Wio said that in certain processes with glass the thyratron enabled the : heat to get'through "before the glass noticed it 'coming," and so cracking was averted. He. also placed great value on the silencing of welding which the instrument effected. Without it the noise was worse than that of a pneumatic drill.