Most sections of the Aircraft Industry with something to make, something to describe or something to sell will doubtless find much to take issue with in what is about to be said. No apologies are forthcoming, however, since it is proposed to speak about, and of, aircraft as found and experienced by pilots and operators.

Along with Lease-Lend the North American idea of high pressure salesmanship appears to have permeated British aeronautical matters together with all the superlatives ending in " ER." Of all mankind's ingenious devices probably none are more full of compromises than aeroplanes, therefore adjectives describing one or more of their aspects may be noteworthy but, when they tend to overflow, a sceptical eyebrow may well be raised.

A method is given for finding the reciprocal of a matrix which is triply partitioned horizontally and vertically in such a manner that the sub-matrices in the principal diagonal are square, but these matrices need not be of the same order. A preliminary rearrangement of the matrix may be helpful.

In theoretical work it is sometimes required to find the reciprocal of a matrix which can be so partitioned that some of the sub-matrices are of simple types, e.g. triangular or nul matrices, and the calculation of the reciprocal may then be facilitated by using formulae for the inversion of partitioned matrices. The same method will be often advantageous in numerical work also. In an earlier paper the reciprocation of doubly-partitioned matrices was treated in a general way and a method was given for triply-partitioned matrices subject to the restriction that the sub-matrices in the principal diagonal are square and of the same order.

This note describes the design and operation of the rig used to test and develop the Canadair CP 107 “Argus” hydraulic systems. The Argus is a maritime reconnaissance version of the Bristol Britannia, redesigned and built in Canada for the R.C.A.F. by Canadair Ltd., Montreal.

It is common practice on both sides of the Atlantic to test as thoroughly as possible before flight the various systems of a new aircraft. This is usually accomplished by the construction of space frames on which the systems are assembled and subjected to simulated flight conditions.

It was decided during the early stages of the design of the Canadair Argus that the deviations from the original Britannia hydraulic systems were great enough to warrant a full scale hydraulic systems test rig, in as compact a form as possible, which would give the desired test conditions and results.

In the November 1955 issue of the Journal there is a Note, “ A New Method for the Numerical Evaluation of Determinants.” I would point out that this method is not new, but is given in “ The Theory of Determinants, Matrices and Invariants” by Turnbull (published by Blackie) at page 340, paragraph 7, under the heading “ Dodgson's Method of evaluating a determinant by condensation.”

Some purely aerodynamical phenomena, which might profitably be investigated by means of electrical analogue computors, are described. No attempt has been made to furnish a complete catalogue of problems but rather to present current issues, the solution of which would aid the development of practical aerodynamics.

Consideration has only been given to those questions which can be solved more suitably by an analogue computor rather than by a digital machine, although the feasibility of partially solving certain of them by the use of an analogue computor, and completing the work with a digital machine, is mentioned.

In scope, the survey includes two and three dimensional aerofoils as well as interference and a number of special problems.

The relative merits of the various forms of analogue computors are not extensively discussed.