Abstract

Joint meeting between Engineering Groups and the British Tunnelling Society

8 April 1975

Some problems of shaft sinking, with particular reference to South Africa P. F. F.

Lancaster-Jones

Shaft sinking at Boulby Mine, Cleveland Potash Ltd. M. Grieves

Film: Daw Mill Shaft Sinking

11 April 1975 Venus and Mercury

Report on the joint meeting of the Royal Astronomical Society, Royal Meteorological Society and the Geological Society. Held at the Scientific Societies Lecture Theatre, Saville Row, London WCi.

By G. E. Hunt & J. E. Guest

The recent successful Mariner 10 space mission to Venus and Mercury has provided a wealth of new information which has dramatically altered our understanding of these innermost planets.

The first session was concerned with Venus, and Dr G. E. Hunt discussed our present knowl- edge of the structure of the atmosphere and clouds. He showed Mariner to pictures of the Venus limb which indicated aerosol layers only 1 km thick in the stratosphere between the 10–50 mb pressure levels. The cloud structure beneath the 50 mb is not known with precision, although a sulphuric acid cloud seems to occur in the 50–100 mb range, the lower atmosphere is opaque to radiation at wavelengths shorter than the microwave, and any information beneath the ubiquitous clouds can only be determined by space probes. Dr Hunt suggested that there is some evidence of two layers of cloud beneath the 50 mb level, but stressed that it was controversial. Although most of the solar energy is absorbed

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