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The forces on ellipsoidal bodies placed obliquely in a converging or a diverging stream can be found direct by calculation of the pressures on the surfaces. It seemed worth while to do this in illustration of the general question, as a rather plausible line of argument had led to erroneous values of the transverse force. The results are found to agree with those of the indirect, but more general, investigation by Professor G. I. Taylor in R. & M. 1166.

IT is probable that the earliest recorded results of model experiments conducted for the express purpose of determining the water resistance of a body relate to the tests made by Beaufoy in the Greenland Dock during the years 1793 to 1798. The results of these tests were made public in 1834, and in the same year Scott Russell commenced a series of model experiments upon ship forms, these tests being conducted in a canal. Based on the results of these tests, Scott Russell formulated his theory of ship resistance, and in his paper to the British Association in 1869 he drew particular attention to the important effect of depth of water upon the wave formation. In 1869 the committee of the British Association recommended that experiments should be carried out on a steamer of known form by towing her at various speeds by means of an apparatus which would register the towing force. To this Mr. Froude, who was a member of the committee, added that so great a variety of forms ought to be tried that it would be impossible, alike on the score of time and expenditure, to perform the experiments with full‐sized ships. The Admiralty, when asked to carry out the proposal, declined to do so, but agreed to carry out Mr. Froude's proposal to try models.

THE present conception of the air flow over aeroplane wings assumes that, in general, the flow pattern conforms closely to that of potential flow (i.e. the inviscid, incompressible flow of hydrodynamic theory) with the exception of a very thin layer of air which is in contact with the wing surface. This layer of fluid, the boundary layer, is characterized by the fact that all phenomena of viscosity (shear forces within the fluid) are restricted to it. Further, it is established that the lift is generated by a circulation about the aerofoil, and that stalling is a result of separation of the boundary layer from the wing surface at or near to the leading edge, with resulting vorticity over the dorsal wing surface, instead of an ordered flow with circulation. Thus at the stall, the circulation suffers a more or less complete breakdown.

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Committee, Reports and Technical Notes of the U.S. National Advisory Committee for Aeronautics, and publications of other similar research bodies as issued

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Committee, Reports and Technical Notes of the U.S. National Advisory Committee for Aeronautics, and publications of other similar research bodies as issued

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Committee, Reports and Technical Notes of the U.S. National Advisory Committee for Aeronautics, and publications of other similar research bodies as issued

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Committee, Reports and Technical Notes of the U.S. National Advisory Committee for Aeronautics, and publications of other similar research bodies as issued

THE increasing size of modern aeroplanes leads to an increasing difficulty in the performance of full scale tests for the determination of strength and stiffness characteristics. The use of models for the investigation of aerodynamic properties is a well established practice and it may soon become necessary to use them for the study of strength and stiffness properties also.

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Committee, Reports and Technical Notes of the U.S. National Advisory Committee for Aeronautics, and publications of other similar research bodies as issued

The distance to take‐off of an aircraft has been previously examined, and in the present report the effect of atmospheric changes on the take‐off run, as in India and the Middle East, consistent with aerodromes of high altitude or under semi‐tropical conditions has been calculated.