Progressive lumbermen know that it costs more to produce lumber from small logs than from larger logs, and that on the average the unit value of lumber produced increases with both log diameter and quality. However, measuring the difference between costs and values for logs or trees of different size or quality classes requires detailed studies of sawmill operations. The most complete southern study of this kind was made by the Southern Forest Experiment Station in cooperation with the Crossett Lumber Company between 1935 and 1938. This, like the former southern pine milling studies, was made at a large band mill--in which the cost of handling small logs is generally higher than at the small or medium-sized circular mill. Average log size and minimum-sized log were also greater than commonly prevail at smaller mills.