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The total and external surface areas of nineteen British clay soils were determined from measurements of their water and nitrogen adsorption respectively. In addition, four physical and chemical properties of these soils were determined ; liquid limit, plastic limit, cation exchange capacity, and clay content.The correlation between these six measured properties was examined. Total surface-area, liquid limit, and cation exchange capacity, had correlation coefficients of 0.90 or greater. This is sufficiently high to enable an indication of these three properties to be obtained from measurements of any one of them.The correlation between these three properties and the rest was slightly lower for the plastic limit, and considerably lower for the clay content and external surface-area, although all were significant at the 5 per cent level.

We have developed a three-dimensional ultrasound telepresence system for remote consultation. Three-dimensional ultrasound data-sets can be acquired by relatively unskilled operators. The data are stored in the remote unit and then transmitted to a consultant equipped with a similar unit. A telepresence pointing device enables the consultant to re-slice that data-set in any plane. During the study period, 72 volumetric scans of male and female volunteers aged 18-45 years were performed in Bosnia. Field users of limited ultrasound experience (most with less than 30 min of training) were able to acquire volumetric scans, send volume data and interact with remote consultants over standard communications lines at distances of up to 20,000 km. Communications links from 9.6 to 1500 kbit/s were used. Technical limitations included lack of motion data, lack of colour data, scan artefacts and increased scan-to-diagnosis time. However, our preliminary experience indicates that this technique may eventually prove to be a useful adjunct to telesonography. Further studies of the technique are needed to determine its value in the broader clinical setting.

SYNOPSISThe Paper describes recent research conducted at Cet article dkcrit des recherches r&e&es faites au the Road Research Laboratory upon subgrade moisLaboratoire de Recherches Routibres (Road Reture conditions, with the aim of extending to a search Laboratory) sur les conditions d'humidite des wider range of climates the research already carried sous-sols, dans le but d'etendre a une plus grande out on moisture conditions beneath British pavevariete de climats les recherches deja faites sur les ments. Measurements made under several road and conditions d'humidite sous les revetements britanairfield pavements in both tropical and semi-tropical niques. On y traite des mesures recueillies sous countries are considered. Where the water-table is plusieurs revetements de routes et de terrains d'aviation dans des pays tropicaux ainsi que dans close to the surface it is shown to be the main factor des pays semi-tropicaux. in determining the moisture condition of the subOn montre qu'oh la nappe aquifere est p&s de la grade irrespective of climate. Where the watersurface elle est le facteur primordial permettant de table is deeper, or non-existent, the relation between definir les conditions d'humidite du sous-sol quelque the subgrade moisture condition and the climatic soit la &mat. Lorsque la nappe aquifere est plus water balance is examined, and evidence is preprofonde, ou non existante, on examine la relation sented for a relation between the suction of soil entre les conditions d'humidite des sous-sols et moisture in the subgrade and the Thornthwaite l'equilibre d'eau climatique, et on offre les preuves d'une relation entre la suction de l'eau contenue dans Moisture Index. le sous-sol et l'indcx de teneur en eau Thornthwaite. INTRODUCTIONCertain methods of pavement design, that are available to the road engineer, suffer from the disadvantage that they apply only to the climatic environment for which they were developed. Rainfall and temperature control the soil moisture condition and influence the type and thickness of pavement required for roads and airfields. At the Road Research Laboratory, the applicability of the method already developed for estimating the ultimate moisture condition of subgrades under British conditions (Black, Croney, and Jacobs, 1959) 1 has been examined in more extreme climates.A tentative method of estimating the suction in terms of climatic data has also been developed. SOIL MOISTURE AND CLIMATEThe moisture condition of exposed soil depends principally on the precipitation or rainfall and on evapotranspiration.The change AM over a given time in the number of inches of water stored in an exposed soil profile is equal to R -E -D, where R is the precipitation in inches, E the actual evapotranspiration in inches, and D the drainage in inches, all occurring during that time. The latter term, which includes both surface run-off and sub-surface drainage, is not easy to measure except for certain complete catchment areas, and the moisture balance may alternativeIy be referred to the moisture h...