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The technical and the legal aspects of aircraft noise having been adequately covered by others the present paper does not stray unnecessarily into those specialised fields but confines itself largely to the practical aspects of this very wide subject. It examines under six headings what can be done in practice, and covers in some detail what has been done at Heathrow. It describes several of the more interesting arrangements at other international airports, and with reference to the differences between them, poses some questions which must be answered when planning an automatic noise monitoring system. It concludes with reference to some features which, although desirable, may not be practicable for Heathrow.Before talking about what can be done about noise in the vicinity of an airport it is important to emphasise that worthwhile control can be achieved only as a result of co-operation between the civil aviation and airport authorities, the airlines and the pilots. Such co-operation exists at Heathrow but continuous effort is required to keep it effective.

The introduction of rational performance requirements governing the operation of civil transport aircraft has given rise to a need for accurate and detailed information on obstructions in the vicinity of aerodromes. This paper states the origin and nature of the requirement and describes a survey technique, a particular application of terrestrial photogrammetry, which was used to meet it.In the United Kingdom and in other member countries of the International Civil Aviation Organisation considerable progress has been made towards the rationalisation of performance requirements governing the operation of civil transport aircraft.

Nuclear bodies have been consistently observed in the epithelial cell component of normal thymuses from children with congenital heart disease and in the pathological thymuses derived from patients with myasthenia gravis, with or without thymoma. They have also been identified in a few normal adult thymuses. On the basis of their ultrastructural appearances they have been termed either simple or complex nuclear bodies. In normal tissue their incidence was higher in children than in adults, and they were numerous in thymuses showing evidence of thymitis and in thymomas. In children and adults the nuclear bodies were of simple type, whereas in the myasthenic groups there was a greater incidence of the complex type. Although most commonly seen in the epithelial cell nuclei, nuclear bodies were also found in lymphocytes, plasma cells, and mesenchymal reticular cells, in fibroblasts and endothelial cells, and in the thymic striated muscle (myoid) cells. It is concluded that nuclear bodies are a constant nuclear organelle not only of thymic epithelial cells, but also of most other cells. Their function is unknown, but their incidence in the different cell types present in the available material suggests that they are in some way associated with states of nuclear hyperactivity.

The introduction of rationalised performance requirements governing the operation of civil transport aircraft has given rise to a need for accurate and detailed information on obstructions in the vicinity of aerodromes.

WINDING high tensile steel wire on cylinders, or pressure vessels to increase their strength and resistance to internal stresses, is not a new principle. The Royal Ordnance Factories strengthened gun barrels in this way during the 1914–18 war, and in the years since the Royal Aircraft Establishment, Farnborough, has experimented with pressure vessels (fig. 1). The application of two layers of wire is intended to give a ‘fail safe’ condition to damp down the effects of a burst cylinder.