The present-day tendency of automobile design is to increase the power/weight ratio of the engine, while at the same time retaining or improving the efficiency, and to reduce the weight of the chassis generally for a given power. The drawing office creates the efficient engine, and the inspection department enables the design to be put into and maintained in effective production. Now, the modern high-efficiency machine is due, amongst other things, to a more accurate knowledge of stress distribution, and consequently the factor of safety, or the factor of ignorance as it sometimes used to be named, may approach unity—provided that the materials used are consistent.

The recent revival of interest in gliding in this country is my excuse for drawing attention to a feature in the wings of birds whose gliding depends primarily on ascending currents, mainly raptores (eagles, vultures, hawks, kites, etc.), especially in the tropics.

Recent developments in the design of rigid airships, as commercial air liners in England and Germany, and for military purposes in America, show a demand for greater lifting capacity, cruising range and speed. The increase in size is mainly responsible for radical changes in the structural arrangement of the transverse frames, introduced by the designers of the British airships, R.100 and R.101.