Comments On ‘Technological Choices in Ceramic Production’, Archaeometry, 42(1), 1–76, 2000

Sillar, B., and Tite, M. S., 2000, The challenge of ‘technological choices for materials science approaches in archaeology, Archaeometry 42 , 2–20. Livingstone Smith, A., 2000, Processing clay for pottery in northern Cameroon: social and technical requirements, Archaeometry 42 , 21–42. Sillar, B., 2000, Dung by preference: the choice of fuel as an example of how Andean pottery production is embedded within wider technical, social, and economic practices, Archaeometry 42 , 43–60. Pool, C. A., 2000, Why a kiln? Firing technology in the Sierra de los Tuxtlas, Veracruz (Mexico), Archaeometry 42 , 61–76.     

Computing geochemical mass transfer and water/rock ratios in submarine hydrothermal systems: implications for estimating the vigour of convection

A method of calculating chemical water/rock ratios is presented that enables the estimation of fluid velocities in open, flow‐through hydrologic systems. The approach is based on relating the gain/loss of a chemical species per kilogram of solid phase to the loss/gain of that species in the fluid phase, integrated across a specified length of the flowpath. After examining the underlying approximations of the approach using a one‐dimensional model of seawater moving through a basalt under nonisothermal conditions, the method is applied to representative zones within a two‐dimensional hydrothermal convective system. The method requires that regions within the flow system can be identified in which the direction of flow is steady for an extended period of time. Estimates of fluid velocity are spatial and temporal averages for the length of the flowpath used in the calculation. The location within the flow system and the nature of the alteration reactions determine which species can provide reliable values of the chemical water/rock ratio and useful estimates of fluid velocities. Over the length of the flowpath considered, the calculation of water/rock ratios works best when a species is controlled by a single reaction. Accurate estimates are favoured if the concentration profile of a species along the flowpath increases or decreases monotonically. If the length of the flowpath extends over more than one reaction zone, then erroneous estimates of the water/rock ratio and fluid velocity are more likely. Model calculations suggest that the quartz/silica system should provide reliable estimates for fluid velocity under a wide range of temperature and flow conditions, in particular in those regions of a system at or near quartz equilibrium, so that the aqueous silica concentration is buffered by quartz and correlated with the temperature distribution.     

350th anniversary of Les Passions de I'Ame

1999 marks the three hundred and fifieth anniversary of the publication of Descrates' final work: Les Passions de l'Ame. This short paper commemorates that event and discusses the circumstances contributing to its origin and the questions which it still raises for neuropsychology three hundred and fifty years later.     

Book Notes

Michael Ghertman and Margaret Allen, An Introduction to the Multinationals, London, Mac‐millan, for the Institute for Research and Information on Multinationals, Geneva, 1984, pp.143. $11.95 (paper).

June M. Hearn and W.A. Howard, Australian Industrial Relations: Case Studies, South Melbourne, Macmillan, 1984, pp.vi, 136. $12.95 (paper)

Felix Guattari, Molecular Revolution: Psychiatry and Politics, Harmondsworth, Penguin, 1984, pp.308. $10.95 (paper).

W.E. Connolly, The Terms of Political Discourse, second edition, Oxford, Martin Robertson, 1983, pp. 257. $16.50 (paper)

W.E. Connolly (ed.), Legitimacy and the State, Oxford, Basil Blackwell, 1984, pp. 281. $15.95 (paper)

B. Guy Peters, The Politics of Bureaucracy, 2nd edition, London, Longman, 1984, pp. 294. $29.95 (paper)     

Shortest-Path Distances: An Axiomatic Approach

An axiomatic approach to distance is developed which focuses on those concepts of distance related to movement in space. The most fundamental types of such distances generally involve some notion of shortest paths between points, where the relevant concept of path length can be any additive attribute of paths (such as physical miles, hours spent in traveling, or gallons of fuel consumed). In particular, the shortest-path distance between any two points in space is here taken to be the greatest lower bound on all path lengths between these points. This notion of shortest-path distance is shown to be formally equivalent to a quasimetric, i.e., a distance which satisfies only the classical triangularity axiom for metrics. The main analysis of the paper focuses on the question of whether or not such shortest-path distances can actually be realized, i.e., on whether there exist shortest paths in space. The central result is to establish a general set of conditions under which such shortest paths always exist. In addition, a condition for the uniqueness of these paths is also established.