Bronze spheres

Measurement of journal displacement was based on the inclination of spring hinges which were supported at one end onto the periphery of the shaft through bronze spheres. This inclination was reproduced bymirrors, changes in inclination of which were measured by an optical system shown in Fig. 3. This consisted of a microscope 2 which was used to observe cross-wires which were at the focus of a lens 4. Light from a pointolite ... 

An armillary sphere consists of a series of bronze or brass rings, most of which can be moved, all set in an outer horizontal ring, which is fixed atop a pedestal. We use it to calculate the positions of stars and planets at various times of the year. The horizontal ring, which is called the Horizon Ring, unsurprisingly, is wider than the others, like a circular table with a very large round hole cut in it. It is possible to set small objects on it, or balance larger ones, and what I had found on it was a book bound in brown leather. 

Names copper spheres, copper powder, bronze powder, brass powder... 

Material resources often have controlled a nation s rise—and fall. Ancient Egypt developed bronze from its copper and tin, and weapons therefrom enabled it to dominate its sphere when copper ran out, Egypt succumbed. Similarly a silver mine gave Athens this noble metal for trading with its exhaustion Athens deteriorated. Energy resources today are equally important to national attainments, although the world s economics and politics now are very much more complicated than those of the ancients. 

Fig. 16.6 Unit cell of the Fm3m structure of KY3F10. The large bronze (light gray) spheres substitute for yttrium atoms, the medium blue (gray) ones for potassium atoms, and the small black ones for fluorine atoms. Reprinted with permission from Ref. [8]. Copyright 2012 by American Physical Society...

Comments SI = silicate filler, CF = carbon fibres, HS = heat stabilized, GS = glass spheres, CK = chalk, Cu = copper, Br = bronze, HI = high impact. 

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