From the introduction...'If left indefintely in a constant atmospheric environment, dead vegetation material tends toward a characteristic equilibrium moisture content. since atmospheric conditions in nature usually vary appreciably on a scale of hours, it is only fast-drying materials that can occasionally approach true equilibrium. A knowledge of the equilibrium moisture content (EMC) is thereofe of direct importance in estimating the moisture content of fast-drying fine forest fuels. It is also important for slow-drying fuels as well, because their drying rate depends on the amount of free moisture above EMC, not on the total moisture content. The EMC of a particular fuel depends mainly on the relative humidity, and to a lesser degree on the temperature. Direst sunlight raises the temperature of the fuel and in turn the temperature of the adjacent air;assuming that the water vapor pressure remains constant, the relative humidity of the adjacent air will then be lowered by an amount that can be readily calculated. The effect of direct sunlight on surafce temperature is complicated by the wind, but wind has no effect on temperature or EMC in the absence of solar radiation. A good reference for the joint effect of sun and wind on surface litter temperature and moisture is Byram and Jemison (1943) , and some laboratory work on the litter of Canadian species was done by Van Wagner (1969) . This present paper deals with EMC and how it varies with relative humidity and temperature only.