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SWAINGER1 has stated recently that an increase in volume occurs during the plastic flow of duralumin specimens under a tensile test. While it is generally assumed that volume is unchanged during plastic flow, we should like to point out that, in 1939, Glanville and Thomas2 showed that the creep of concrete in compression was characterized by a decrease in volume. The concrete, in fact, flowed into its own voids.

In order to carry out accurate analyses of the gases dissolved in ground-water, a method had to be devised for withdrawing water samples from the soil, free from soil particles and without allowing dissolved gases to escape. Furthermore it was required that the method should be such that successive samples could be taken from one place without disturbing the vegetation. With these points in mind a sampling probe was designed which could be left in the ground as long as needed and could then be easily withdrawn and used elsewhere, and from which ground-water samples could be obtained under conditions minimizing gaseous exchange with the air. The essential element of the probe was a porous cylindrical cup of 80 c.c capacity and with pores of 7-10 i diameter. The cups were made of a material described by the makers, Doulton Industrial Porcelains Ltd., as F10. Its characteristics are that it is highly permeable to water, while providing the necessary filtration. So permeable are these cups that water poured into them is immediately observed to flow out through the walls. Each cup was closed with a rubber bung provided with two glass capillary tubes, one with a fine (about 0-25 mm) and the other with a coarse (about 1.0 mm) bore, for filling and withdrawing water. The assembly of cup and tubes was mounted in a haft of tubular duralumin, which was cut away around the cup in such a way as to allow most of the surface of the cup to be brought into contact with the soil. The lower end of the haft was provided with a conical wooden tip. A hole could be augered into the soil to the required depth and the probe thrust into position. Details of the size and construction of the probes are shown in Fig. 1. They were made in two lengths, 30 and 60 cm, to allow different depths of sampling. They were constructed in 1948; if more were to be made at the present time it would undoubtedly be preferable to replace the glass with nylon capillary tubing, and a plastic material might also be more suitable for the haft. A length of 5 cm of the cylindrical haft immediately above the porous cup was perforated and gave access from the soil to a small chamber sealed off from the rest of the haft. This was intended for the subsidiary purpose of withdrawing soil air if the water table fell sufficiently, and a third capillary tube connected the chamber with the upper end of the haft.

IN the recent lecture on U.S. Methods of Aircraft Production given by Mr. T. P. Wright before the Royal Aeronautical Society the methods shown for cutting duralumin plates will be of interest to many people. Perhaps a brief description of a simple arrangement for cutting small blanks, which has been much used in America, will also be of interest and use to some readers.

When a solid body vibrates, the alternating strain within it induces a correlated dissipation of energy resembling internal static or rubbing friction. No material is purely elastic. Elasticity must be regarded as having a phase angle which varies little, or not at all, with frequency, and in metals is a small fraction of 1°. This friction introduces losses in acoustic apparatus in amounts depending on design, and also on choice and heat treatment of materials. Taking metals as a class, this dissipation is generally least in light materials like aluminum and duralumin, and greatest in the heaviest substances like lead. They may be varied by a factor of as much as 10 by heat treatment.

WITH the exception of those made by K. Honda and S. Konno1 and also those by K. lokibe and S. Sakai2, few measurements of viscous damping in metals have been made. I have made some experiments concerning this problem with the assistance of Mr. K. Kubo3. The metals experimented with were aluminium, duralumin, copper and brass, each in the form of a bar clamped at one end and free at the other. To analyse the result the appropriate solutions of the following equation were used

IT is well known that many materials, including wrought and heat‐treated duralumin‐type alloys, when subjected to fatigue tests in machines employing different stressing and straining actions, may give consistent results under each set of conditions, but the results will not agree from one set of conditions to another. Differences in the form and size of the test piece may also have an effect on the results of fatigue tests. This note discusses certain aspects of the problem of why such differences in test conditions can cause differences in the results of fatigue tests.

A reversible microscope slide made of Duralumin is described which enables both sides of a mounted specimen to be examined at high magnification with equal facility.

With reference to the use of paraffin for the duralumin tubes, Wayne Paulsen has referred to a new base-varnish for skis developed in South America. This varnish has a bakelite base and it goes under the name of “Risch-Rasch.” Paulsen stated that, in his experiments with it as a coating for the duralumin tubes, he was having trouble getting a smooth finish on the inside. It is suggested that the plunger-method be used as described above in “California Cooperative Snow-Surveys: Directions, suggestions, and hints for snow-surveyors.”

At the March snow-survey Ranger Haycock found the duralumin disappointing even in the comparatively shallow snow of the Marys River Basin of the Upper Humboldt, Nevada. In the deeper snow at Independence Lake in the Sierra Nevada, the party also could not get cores with it and unfortunately did not carry a steel sampler to make further comparisons of duralumin and steel. The day was “raw and cold.” However, could not the air have been sufficiently warm to cause moisture on the sampler and consequent freezing of the sampler to the snow? This result had been observed by John T. Ryan in a series of experiments.