Societies and Academies

Abstract

LONDON. Geological Society, November 8.—Prof. W. W. Watts, F.R.S., president, in the chair.—Prof. E. Hull: The inter-glacial gravel beds of the Isle of Wight and the south of England, and the conditions of their formation. The Origin and mode of formation of the gravel terraces of the Isle of Wight and the New Forest districts are still open to discussion. The levels of the higher beds on both sides of the Solent up to about 400 feet indicate the amount of subsidence of the whole. area at a time when the stratified gravels, composed mainly of rolled flints, were formed at the margin of the uprising ridges of the Chalk in the post-Glacial epoch, for this part of England. Preceding this was the great uplift by which the British Isles were joined to the Continent as land. By this uplift the English Channel was laid dry, and along its centre there ran a river from its source about the Straits of Dover to its outlet into the ocean through the continental platform. The gravel beds of this district are considered to be the representatives of the high-level gravels of the Midlands and Cromer, also of the “interglacial gravels “of Cheshire and Lancashire, and the shell-bearing beds of the Denbighshire Hills, and of Moel Tryfaen in Wales, at levels of about 1200 feet above the sea.—J. B. Scrivenor: The Gopeng beds of Kinta (Federated Malay States). Gopeng is a prosperous mining centre in the Kinta Valley, close to the granite of the Main Range of the Malay Peninsula. It is shown that not only are the Gopeng beds cut by veins from the granite and altered at the junction with the granite, but they are also faulted down against the limestone. The Gopeng beds, consisting of clays and boulder-clays with some stratified drift, are of glacial origin. This is proved by the inclusion of large boulders in the clay, the physical condition of the components of the clays and their distribution, and by the resemblance of the beds to Pleistocene glacial detritus. No boulders have been found showing striation due to ice action, nor has any glaciated rock-surface been found. The boulders are all decomposed owing to the power of the ground-water in removing silica; and, if the limestone ever presented the features of a glaciated surface, it has been modified by solution owing to the action of ground-water. The petrology of the Gopeng beds is described. The ice from which the detritus was derived passed over a stanniferous granite mass, and the Gopeng beds carry tin-ore throughout. The tin-ore is an original constituent of the beds, but they have been further enriched by tin-ore derived from the Mesozoic granite at their junction with the granite and in the neighbourhood of veins from the granite that have risen through the limestone. The Gopeng beds are considered to be the equivalent in time of the Talchir boulder beds of Orissa; but a petrological similarity is wanting. Physical Society, November 10.—Prof. H. L. Callendar, F.R.S., president, in the chair.—Prof. Coker: The effects of holes and semicircular notches on the distribution of stress in tension members. For the experimental determination of stresses in loaded members an optical examination of a model shaped in transparent material has advantages. Two cases of importance are examined in this way, and the results are compared with those obtained by analysis. The first example relates to the case of a hole in a tension member subjected to a uniformly applied stress p. The values of [px-py)> the difference between the principal stresses, are obtained optically, and they show agreement with the calculated values if the diameter of the hole is not greater than one-quarter of the width of the plate; but beyond this the agreement is not good. For practical purposes it is important to be able to estimate the maximum stress from the value obtained by assuming that the total load on a tension member is uniformly distributed over the cross-section. A formula based on the relationship found in the experiments takes the form where c is the ratio of the width of the member to the diameter of the hole; if c is large compared with unity, this reduces to the simple form mean c+i.