AN X-RAY DIFFRACTION STUDY OF HEAT-TREATED CHERT AND ITS ARCHAEOLOGICAL IMPLICATIONS

It has been established that on occasion prehistoric man heat-treated siliceous stones in order to improve their flaking qualities. In this work we have examined samples of heat-treated chert by means of X-ray diffraction and have established that, in most cases, heat treatment causes an X-ray diffraction line broadening which can be interpreted as a decrease in range of crystalline order of up to 40%, in the most extreme case. The implications of this to an understanding of the fundamental mechanisms of fracture and as a tool for archaeological studies are discussed.     

Book reviews

Classical Persian Music: An Introduction. By Ella Zonis. Cambridge: Harvard University Press, 1973. xv + 233 pp. $16.50.

Sasanian Remains from Qasr‐i Abu Nasr: Seals, Sealings, and Coins. Edited by Richard N. Frye. Cambridge: Harvard University Press, 1973. 132 pp + 26 pp. of plates. $12.50.

The School Principal. By Jalal Al‐e Ahmad. Translated by John K. Newton, with an introduction and notes by Michael C. Hillmann. Minneapolis, Minn.: Bibliotheca Islamica, 1974. 144 pp. $5.00.     

The origins of the birth control movement in England in the early nineteenth century

The origins of the birth control movement in England in the 19th cen tury are discussed. The impact of Malthus's "Essay on the Principle of Population" and the activities of such thinkers and reformers as Jermy Bentham, James and John Stuart Mill, Francis Plance, Richard Carlile, Robert Dale Owen, and Charles Knowlton are discussed. The social debate that arose during the century is discussed.