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    Copies of the original blueprints can be obtained from the author.


A new instrument to measure a functional-shape property of sand grains is presented. This property, which is called “rollability”, is measured on the inside of a slightly inclined, revolving cylinder mantle. During the rolling shape segregation takes place and the time it takes the grains to emerge from the cylinder is a measure for their rollability.

The measurements are performed on 1/4–phi sieve fractions. Only very little material is needed for a measurement (30–200 mg) and the measurements last on the average 70 sec. Sizes between 88–700 μ are most suitable. Static electricity on quartz—the snag in most similar methods—is eliminated. The repeatability is 1% plus or minus. Since the measurement is completely automatized, personal bias is excluded.

This paper is meant to enable copying of the instrument,1 whereas methodology and results in regional applications have been treated elsewhere (WINKELMOLEN, 1969).