This issue's cover: Unlike standard manually operated proving ring penetrometers, which are sensitive to insertion rate, individuals of widely varying size and strength can generate consistent data with impact penetrometers. Additionally, the same cone can be used across a broad range of substrates including dry soils with high clay content, by simply varying the drop height. See the article by J. Herrick and T. Jones "A dynamic cone penetrometer for measuring soil penetration resistence", p. 1320-1324.