Conversazione : Burlington House May 9th, 1934.

  • Royal Society
Date:
1934]
Catalogue details

Licence: Public Domain Mark

Credit: Conversazione : Burlington House May 9th, 1934. Source: Wellcome Collection.

    15/32 page 15
    25. The Metals Research Association. Control of Structure and Soundness of Ingot of Non- Ferrous Metals. (a) Effect of Casting Conditions on Brass Ingots —The exhibit will illustrate the influence of ingot size, composition and pouring conditions on ingot soundness and structure. Particular reference to the effect of turbulence due to penetration of stream and the use of volatile mould coatings, and avoidance of turbulence by use of the Durville (still) casting process. (b) Unsoundness in Aluminiwm Alloy Castings: Causes and Remedies.—The exhibit illustrates (1) Causes of contamination by gases, which are responsible for defects known as “ pinholes.”’ (2) Methods for overcoming these troubles, including treat- ment of the melt prior to casting by various degassing processes, and by solidification under pressure. (3) A study of gas-metal relationships with particular refer- ence to the solid oxide film which is present in molten aluminium. 26. Metropolitan Vickers Electrical Company, Lid. Metropolitan-Vickers Portable Noise Measuring Apparatus. This apparatus enables sustained noises of any type to be measured on the aural balance principle. It consists essentially of a valve oscillator, a calibrated attenuator and a telephone earpiece. The oscillator generates current at 800 cycles which is fed to the telephone through adjustable attenuators. One of these covers a range of 0 to 100 decibels, in steps of 5 decibels, and the other gives a continuous variation of 10 decibels. The apparatus is calibrated so as to indicate directly the intensity of the 800 cycle tone in the telephone in decibels above threshold of 0-0003 dynes/sq. cm., measured in the ear or 0:00021 dynes/ sq. cm., measured in free space. ‘I'he observer places the telephone on one ear and presents the other to the complex noise to be measured. He then adjusts the attenuators until he judges the loudness of the 800 cycle note heard in the telephone to be equal to that of the complex noise. The equivalent value of the complex noise is then read in decibels above threshold from the settings of the attenuators. Metallic Coatings on Glass and Paper, obtained by the Condensation of Metal, Hivaporated an vacuo. Aluminium coatings so obtained have very good reilecting properties and do not tarnish readily. Consequently they are especially suitable for use in optical work,
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