The problem of an expanding ice sheet

The coefficient of expansion of ice is about 30 X 10-6 per FO, or nearly 5 times that of steel, the Bureau of Reclamation made a study of the pressure exerted by an ice sheet during a rise in temperature. Two types of pressure gages were developed. The indentor gage consists of 2 circular sheets of steel held 0.625 inches apart by a steel ring. A hardened steel ball attached to the inside of one plate presses against a polished steel target on the other. Maximum pressure is measured by the amount of indentation. The resistance gage of similar shape can measure continuous pressure by change of resistance of a constantan wire on which a stretching force is applied during pressure. Laboratory experiments have yielded graphs for pressure exerted at various rates of increasing temperature. Two differential equations describing the thermal behavior of ice sheets were solved and the results plotted in a series of curves. Rate of change by mean temperature of an ice sheet can be obtained by multiplication of values read from these graphs. Field measurements have been started but definite results have not yet been reported.