Table of contents

The paper describes an attempt to simplify the design of DuMond and Pickels and at the same time to make the gauge an absolute instrument. Details of its construction are given, as well as information about its performance and limitations

An apparatus is described in which use is made of the piezo-electric properties of an X- or A.T.-cut quartz crystal by means of which a wide range of physiological phenomena may be recorded with the use of amplifier-cathode ray tube technique.

The unit contains its own pre-amplifier, is simple to construct and robust, and considerably widens the scope of the usual electrical recording apparatus.

A simple X-ray spectrometer suitable for checking the orientation of a face of a crystal is described. The design is based upon a moving-film principle, and the instrument is very simple in construction, being made almost entirely from standard Meccano parts. Although of more limited application than the usual X-ray ionization spectrometer it is well suited to certain routine measurements, particularly in connexion with the manufacture of quartz piezo-electric elements.

A new combination of measuring instruments with different sets of filters is described which, when acting together with a light source and photoelectric device, provide a convenient and reliable means of controlling by degrees, or in predeterminable steps, a production process, or of inspecting to close tolerances a line of mass-produced objects. A new mathematical thesis supplies the prerequisite to an easy calculation of the densities of the filters.

Experimental facts concerning the simplest and most effective method of using a `dry-ice' and alcohol bath are recorded, and details are given for its preparation for precision measurements.

A machine is described which will perform a purely electric summation of Fourier series. The actual machine constructed can add sixteen sine and sixteen cosine terms, but there is nothing to prevent an increase in the number of terms The sum of the series can be determined directly at intervals of 6° over the range 0-2π The machine is principally intended for performing Fourier synthesis in X-ray crystallography. It can also be used for harmonic analysis.

Report of a discussion held by the Society of Instrument Technology in London on 8 November 1945.