Before reading my paper I wish to express my thanks to the President and Council of the Society, and my great appreciation of the privilege accorded to me of speaking before this expert gathering.

My ambitions with regard to the subject of this paper were originally very farreaching, but I soon realised that it would be impossible to cover the enormous field falling under the heading of “ rotating wings,” and at the same time to advance sufficiently into detail to escape the criticism that this was merely a new collection of facts, already known and very general in terms, and therefore possibly only of interest to students of the history of aviation.

In the usual Berry (I) expression of the generalised theorem of three moments (i.e., generalised in the sense that end load deflection effects are taken into account) the lateral loading on a continuous beam is regarded as uniformly distributed over each bay into which the beam length may be divided (either naturally by supports or artificially for convenience of analysis). In this paper the lateral loading is taken as distributed parabolically so that the resulting equations may be used as a sort of Simpson's rule for dealing with any arbitrary loading. By taking into account the “ sinking “ of supports any particular beam can be divided up into a convenient number of bays over each of which the lateral loading may be assumed to be parabolic. We may thus obtain reasonably accurate solutions for the bending moments, etc., in a continuous beam under almost any type of lateral loading.

Wellington, the capital city of New Zealand, is situated in the south of the North Island, among the mountainous masses 2,000ft., high which form the northern shore of Cook Strait. The winds in this latitude are strong and persistent, and this, combined with the venturi effect of the Straits, gives-Wellington a very boisterous climate. The average run of wind per 24 hours is 310 miles and the average number of gales of force 8 or over is in excess of 60 per annum. There is little open ground near the city, and there is no aerodrome site within 30 miles which is free from atmospheric disturbances or topographical defects.