A Pound doesn't always weigh a Pound
If the world were a homogeneous body in the form of a perfect sphere — that is, not flattened at the poles, and without mountain ridges or sea basins -a spring balance on which a 1 lb. weight was placed would register the same result everywhere on its surface. But the world is not composed of homogeneous, concentric layers, nor is it completely spherical. Consequently, the force of gravity -the attracting force of the earth-exhibits small local differences. These differences may be caused by the fact that layers of earth which
are heaviet or lighter than those above them approach the surface of the earth more closely here and there. The 1 lb. weight suspended from a spring balance thus weighs at that point a little more or less than it does at a calibrating point elsewhere. This difference lies in the neighbourhood of 1/10,000,cco0th of a lb. If a grocer, weighing with a spring
balance, should wish to exploit this difference between, say, purchasing and selling points in weighing his sugar, he would need 10,000 daysa good 27 yeats- with a turnover of 1,000 Ibs. of sugar a day in order to save 1 |b. | Crime does not pay! The differences caused by gravity are measured by using very delicate instruments, and by means of a large number of observations made over a great distance. In this way the
geophysicist is able to form a picture of the subsoil. By this means the upward vaulting movements of the earth, which might be collecting places for oil, are determined. But in the final analysis, it is the drilling tig which will have to give the ultimate verdict as to whether or not oil is actually present, The Shell group of oil companies is carrying out gravimetric work in
many countries of the world, and under the most widely varying climatic and topographical conditions, Extensive operations have been carried out, for instance, in the’ coastal swamps of Louisiana. One of the photographs on this page gives a good impression of the work there.
2 of a second series of articles published 6 THE SHELL COMPANY OF NEW ZEALAND LIMITED (Incorporated in England).
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New Zealand Listener, Volume 34, Issue 871, 13 April 1956, Page 27
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367A Pound doesn't always weigh a Pound New Zealand Listener, Volume 34, Issue 871, 13 April 1956, Page 27
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Copyright in the work University Entrance by Janet Frame (credited as J.F., 22 March 1946, page 18), is owned by the Janet Frame Literary Trust. The National Library has been granted permission to digitise this article and make it available online as part of this digitised version of the New Zealand Listener. You can search, browse, and print this article for research and personal study only. Permission must be obtained from the Janet Frame Literary Trust for any other use.
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