Tables of the characteristic functions of certain types of uniform beams were published by Young and Felgar in 1949. The functions concerned represent (to suitable scales) the principal modes of free flexural vibration, although their uses are far more extensive than is implied by this. Some of the uses to which they can be put are mentioned in Ref. 1 and others are discussed by Felgarand Bishop;they cover both statical and dynamical problems and relate to beams, plates and shells and include problems of elastic instability. In fact these functions can be used in series representations in the same way as circular functions are used in Fourier series.

One of the main uses to which these characteristic functions may be put does not appear to have been described in print, although the relevant formulae are quoted in Ref. 2. The functions can be used in vibration analysis to shorten calculations, sometimes leading to very considerable savings of labour.

About twenty years ago I was invited by the Council to read a paper before the Society, the title suggested being "The Use of Steel in Aircraft Structures." At that time steel, as the material for important parts of main structural members, was giving place to the then new and stronger aluminium alloys, and I decided that the lecture should be on something of growing, and not diminishing, importance; therefore in a paper entitled “ Some Developments in Aircraft Construction ” (March 1934) stiffened sheeted structure in aluminium alloy was chosen as the theme of the subject. The paper was as up-to-date as possible, but it contained no pictures or descriptions of British aeroplane structure of that type because in this country no aeroplanes (except the odd one in which fabric had simply been replaced by aluminium alloy) designed basically in that way had been built.

An instrument is described which measures the time duration of a specified number of complete cycles of an oscillation over the frequency range OT cycles per second to 500 cycles per second. The accuracy of the reading is dependent on the frequency measured and the number of cycles taken; but, in most cases, an accuracy better than 01 per cent is obtainable. The construction of the instrument is described and circuit diagrams given.

It is well known that the performance at high subsonic and transonic speeds of a swept-back wing-body combination in which the wing is untwisted and has the same section at all stations along the span and in which the body is not specially shaped to allow for the presence of the wing, falls far short of what would be predicted for the corresponding infinite sheared wing. For example, with a sweep of 45° and a thickness/chord ratio of 6 per cent it has been found experimentally that a rapid shock-induced increase in drag occurs above a Mach number of about 0·95 and a peak value of CD is obtained at Mach numbers slightly in excess of 1·0, whereas it can be estimated that for the corresponding infinite sheared wing, sonic speed in a direction perpendicular to the isobars (the lines joining points where the pressure is equal) would not be obtained until a Mach number of 1·18 was reached. The poorer performance of the finite swept-back wing results principally from the fact that the pressure distributions for sections near the root and tip are distorted in shape from what would be obtained on an infinite sheared wing and, as a result, the isobars tend to lose some or all of their sweep. With a moderate aspect ratio such as 3, such effects extend over most of the span at high subsonic speeds.

The problem of the stress analysis of circular fuselage frames has been investigated by a number of authors; the analyses are, necessarily, rather mathematical in nature although in some cases the final results have been presented in extremely practical form. The present paper offers, in non-mathematical language, a short account of the fundamentals of the problem and a brief guide to the more important published literature. It also develops an approximate method for the analysis of frames using Lagrange's method for minimising a function of several inter-dependent variables. This method is shown to be particularly suitable for the analysis of frames with large cut-outs, about which little has previously been published. In addition, the underlying parameters which determine the stress distribution are deduced from the theory, and the deductions are compared with previously published work. In general, agreement is good. The paper is written throughout with a view to being of practical use in the actual stressing of frames. Numerical examples and explanations of mathematical methods are included in Appendices.

France, paralysed during many years of a cruel occupation, has been unable to maintain a sustained technical effort, comparable with that of England.

Nevertheless, the work of French engineers was never discontinued. In difficult and sometimes dramatic circumstances, more often than not with only restricted facilities, their work of research continued, stubbornly and in silence.

The employment of aircraft for surveying has become so usual, and so much has been written about it from one aspect or another, that perhaps the time is appropriate to define exactly what is meant by Air Survey; what the surveyor is trying to achieve, and how he is dependent upon the airman to obtain his objectives. To achieve good results from an air survey, closely integrated team work is required. The airman, photographer, instrument specialist, meteorologist and the surveyor each depend upon the other, any weakness in the chain making results more expensive and less effective. The author, as a surveyor, has worked in harmony for a good many years with the “air” side, and it is proposed in this paper to summarise the surveyor's approach and his requirements, and to explain why he seems never to be satisfied with the accuracy achieved. The greater the accuracy of photography, the simpler, quicker and cheaper become methods of using the results to fulfil the desired specification.

The problem of landing an aeroplane under conditions of low visibility hasbeen a subject for speculation for the last twenty years, but it is only withinthe last ten years that it has been given any serious practical attention. Thispractical attention has been forced by the necessity for aircraft to maintainschedule regardless of weather conditions in competition with other forms oftransport.

Although certain schemes involving radio were amongst the earliest proposalsfor a solution of the problem, the first practical work appears to have beenconcerned with methods of a more mechanical or optical nature, including aproposal to deposit the fog by high tension discharge.