Table of contents

The first part of the paper describes a simple and yet precise clamp for strip hinges which facilitates the construction of flexure hinges. The use of this clamping system in various flexure hinges is described and it is believed that it is of fairly general application. The second part of the paper discusses the merits of the single strip hinge, which becomes especially simple to construct by this method, and it is shown that for limited rotations it is often superior in performance to the well-known cross strip hinge. It is suggested that it merits more frequent use as a precise hinge.

A description is given of a simple device whereby, in a gauge measuring interferometer, a direct measurement of the fractional displacement of the fringes on the gauge relative to the fringes on the base plate may be obtained.

An analogue instrument is described which operates by a wheel-on-disk principle. It is relatively simple in construction and is capable of evaluating several harmonic components in one operation.

A soft X-ray spectrometer employing a phosphor, CaWO₄: Pb, in its detector is described. A high signal-to-noise ratio is obtained by modulating the output of the X-ray tube with a periodic voltage applied to an auxiliary electrode and using a synchronous detector. The envelope of the molybdenum M_IV,V-N_II,III emission line at 64 Å was recorded; analysis of this suggests that it contains four components, three of which are attributed to the transitions M_VN_III, M_IVN_II and M_IVN_III.

A temperature stabilizing system is described for the temperature range below 1° K, based on the principle of isothermally demagnetizing a paramagnetic salt pill at a controlled rate to balance the heat input. The system was used down to 0.5° K with heat inputs of up to 1000 ergs per second, giving temperature stability to better than ±2% over periods of the order of an hour. The system is briefly compared with the ³He cryostat, the magnetic refrigerator and the thermal resistance link, and the possibility of application to lower temperatures is considered.

The nuclear induction head described by Richards et al. (1956) has been modified by using a receiver coil the ends of which spiral to the coil axis, by introducing an electrostatic shield around the receiver coil and by adding an adjustment of the pick-up coil axis relative to the transmitter coil axis. The resulting coil structure provides a good balance in a bandwidth several megacycles per second wide without seriously compromising the stability provided by the Richards' head. The head has been used successfully with a spin generator at centre frequencies from 4 to 16 Mc/s.

The axial divergence of the beam in a counter diffractometer causes a broadening of diffraction lines. The use of the variance as a measure of this broadening is reviewed and the work of previous authors is extended to include a diffractometer having two sets of Soller slits of any aperture. For an aperture commonly used in commercial diffractometers, the variance is given as a function of 2θ.

Alpha particle wire-plate corona counters in air can be operated in two modes depending on wire diameter and electrode spacing. Conventional Rosenblum spark detector action occurs at low gaps, while at larger spacings breakdown terminates at the streamer stage of spark development. Advantages of the streamer mode of operation are low counter dead time (0.2 μsec at 300 counts per sec) and absence of electrode corrosion by sparking.

A magnetic balance is described which was used to measure the surface tension forces at the interface between aluminium and liquid bismuth. From this the receding contact angle can be calculated, a knowledge of which is essential for a quantitative study of wetting and corrosion in solid metal-liquid metal systems.

A high temperature microscope is described which permits the observation of sintering processes, etc., at magnifications up to ×150 and at temperatures limited only by the stability of the sample-holding filament. Its use is illustrated by photographs of sintered compacts of alumina and niobia.

A conversion of a readily obtainable military surplus ciné camera to single frame operation is described.

The camera is then suitable for time lapse photography or data recording.

The attachment enables a `true-intensity' tracing to be made with a microphotometer having a thermocouple-galvanometer detector system, using a known characteristic curve. The tracing is produced in ink on 20 cm chart paper, and the accuracy of conversion from plate transmission to intensity is generally to better than 1%, assuming a perfect characteristic curve.