Measurements have been made of cambium temperatures in living trees subjected to mild and fierce fires. Fire resistance depends upon bark thickness: thus only big trees with thick bark can survive unharmed in really severe fires. The rate of change in cambium temperature is related to the thermal diffusivity of the bark, and is largely independent of bark structure or moisture content. A simple mathematical model is used to calculate heat transfer in bark, and the results obtained agree well with experimental measurements made on a variety of trees. Studies of soil temperature and results from experiments on pines are referred to briefly in appendices.

The probability of wildfires, or prescribed fires, occurring in mallee rangelands, is strongly dependent on availability of adequate grass fuel loads. Grass fuels comprise two major elements, a perennial component dominated by the hummock species Triodia scariosa (porcupine grass) and an ephemeral component dominated by the annual/biemial tussock species Stipa nitida (speargrass). Population dynamics and abundance of both fuel elements are, in turn, strongly influenced by rainfall regime, particularly during the seedling recruitment phase. This paper records data on the spatial distributions of different fuels, plant architecture and post-fire seedling recruitment and survivorship of T. scariosa, obtained during field studies on contrasting mallee sites in western New South Wales. In addition, rainfall data extending over c. 100 years were used in a water balance study at one mallee site (Pooncarie); while similar rainfall data were analysed for three mallee sites (Pooncarie, Ivanhoe and Mount Hope) using a filter technique to examine quasi- periodicities of rainfall and potential correlations with known wildfire seasons in the past. Precipitation records from the Meteorological Districts of western New South Wales, and from various towns in the area, were analysed as well. All data sets exhibited strong coherence and the resulting filter curves resembled each other closely, with peaks reflecting 'above-average rainfall' and troughs 'below-average rainfall or drought'- the latter often being associated with El NiiiolSouthern Oscillation events. The management implications of these phenomena, particularly as they relate to major drought events, are discussed in the context of vegetation manipulation based on prescribed fire.

The thermal conductivities of thirty-one polar and nonpolar organic vapors have been determined at pressures up to one atmosphere, over a temperature range from 40 to 160°C. The relation between thermal conductivity and viscosity is discussed in terms of the expression: K0MηCv0=f=ftransCvtrans+fintCvintCv0where, following a suggestion by Eucken, the ratio f is divided into separate components ftrans and fint, corresponding to the different rates of transfer of translational and ``internal'' (vibrational and rotational) energies. Experimental values of f are not in accord with Eucken's original assumption that fint=1. For nonpolar vapors fint increases towards a high-temperature limit which is close to the theoretical value of 1.3. For polar vapors ftrans appears to be less than the theoretical value of 2.5, the decrease depending on the polar character of the molecule. These results are discussed with reference to energy exchanges occurring during collisions between complex molecules.

Rainfall figures from World Weather Records, for towns west of the Mississippi in the United States, have been subjected to filter analysis. Four filters have been used, and the rainfall patterns obtained suggest substantial coherence of the data throughout much of the entire area. The results agree well with earlier work of Mitchell, Stockton, and Meko, who have reported a relationship between the incidence of drought in the western United States and the double (ca. 22 year) sunspot cycle. However, an additional correlation with the (ca. 18 year) lunar cycle is also apparent, particularly on the west coast.

This investigation is an extension of earlier work on rainfall patterns in the western United States. In the present study, rainfall figures from World Weather Records for cities east of the Mississippi have been subjected to filter analysis using the four filters described in the earlier investigation.The results suggest substantial coherence of rainfall data in a broad central area of North America, from the Great Lakes to the Rockies and into southern parts of the Canadian Prairies and Ontario. In this entire region there appears to be a pronounced rainfall 'cycle', of about 22 yr, which exhibits a possible relationship with the double sunspot cycle. However, inland from the U.S. northeast coast and including southern Quebec and the Canadian maritime Provinces, the 'cycle' is different and is closer to 16 yr.Although the earlier investigation pointed to a connection between the lunar cycle of 18.6 yr and rainfall behaviour in the far west of the United States, there is little evidence of a similar connection in the east.