Museum of Natural History (A.M.N.H.), and Minnesota (U.M.V.P.), Harvard, Princeton (P.U.), Kansas (K.U.), Yale, Montana State, and Nebraska Universities. Similar but slightly later Cretaceous mammals, now at A.M.N.H., were first found in this region in 1938 by Darwin Harbicht, then of Ft. Peck, and an untraced Mr. Moseley. It was while searching for their locality (now named Harbicht Hill) that we were led to the Bug Creek site. 2. A. J. Collier and M. Knechtel, "The coal resources of McCone County, Montana," U.S. Geol. Surv. Bull. 905 (1939). Museum of Natural History (A.M.N.H.), and Minnesota (U.M.V.P.), Harvard, Princeton (P.U.), Kansas (K.U.), Yale, Montana State, and Nebraska Universities. Similar but slightly later Cretaceous mammals, now at A.M.N.H., were first found in this region in 1938 by Darwin Harbicht, then of Ft. Peck, and an untraced Mr. Moseley. It was while searching for their locality (now named Harbicht Hill) that we were led to the Bug Creek site. 2. A. J. Collier and M. Knechtel, "The coal resources of McCone County, Montana," U.S. Geol. Surv. Bull. 905 (1939).Abstract. Electrophoretic mobility of microscopically visible particles is measured from photographs of their oscillatory migration in a low frequency electric field. The measurements are inherently free of gravitational or thermal-convective drifting. Many measurements may be made from one photograph. An automatic timing circuit insures reproducibility and determines the sign of the particles' charge.
