A SIMPLE INSTRUMENT FOR MEASURING THE DENSITY OF SOLID OBJECTS

A simple and easily constructed instrument is described for the direct measurement of the volume of solid objects, such as coins, to a high accuracy. The density of the object is readily calculated by dividing the weight of the object by its volume.     

ON THE ORIGIN OF GREY AND BLACK ‘COLOURS’ OF ANCIENT POTTERY: ROLE OF Fe AND Ti4+ IONS

It is shown, from comparisons with the optical absorption of minerals, that the black and grey colours of pottery can arise from Fe²⁺ Fe³⁺ and Fe²⁺ Ti⁴⁺ charge-transfer (or electron-hopping) processes, the cations being located at the centres of adjacent edge-sharing octahedra.     

Models of Space Searching in Urban Areas

City dwellers occasionally must seek jobs, dwellings, or particular services or goods. Two very different ways exist by which the individual may conduct such a search. Lacking prior information, the person may elect to visit perceived possible locations until an appropriate one is found. Alternatively, an address may first be ascertained and then visited by finding a path to it. Clearly, there is a substantial difference between these two methods in terms of the amount of spatial movement they require in order to satisfy the searcher's needs. In this paper, this difference is modeled for situations that vary in terms of the density of acceptable end points of the search, as well as in characteristics of the signs of these end points, their patterns, and the level of information with which the searcher may begin.     

REVIEW

Taruru: Aboriginal Song: Poetry from the Pilbara. By C. G. von Brandenstein and A. P. Thomas. Rigby Ltd., Adelaide, 1974. Pp. i–xx, 1–91. Price $A7.95.