The Chronocyclegraph.

All difficulties were not yet overcome, however. It was still necessary to determine direction of movement and length of such motion. To aid in detection of these factors, Gilbreth made use of additional material, and called the unit a chronocyclegraph. The direction was noted on the plate by means of arrow-heads. (See illustration No. 2 C.) These pointed in the direction of the path travelled from the point of origin. It was now possible to measure time motion and direction. To record the distance was less easy, and involved the use of the “penetrating screen.” The space to be photographed was backed by a large sheet of black paper cross-sectioned with white lines at predetermined distances from each other, and then photographed on the spot where movements were to be studied. When exposed, the plate was removed and then used a second time to record the moving light. When developed the negative showed a “motion curve” on a background of cross-sections. (See illustration No. 2 D.) The spatial distance between the intersecting lines was already known, so that to calculate the distance travelled presented no difficulty. By this method we can now check four “variables” as they are termed, namely, length of movement, relative speed, time and direction of movement. (See illustration No. 1.) Using a suitable camera, we are thus able to view the whole process on three dimensions.

The latest extension on Gilbreth's idea is the “construction of a wire model based upon the cross-sectioned chronocyclegraph record. This shews the motion in three dimensions, and attempts to reproduce the precise length of the original movement and each of its parts. On this model are shewn also the arrow heads, so that from it the movement can be studied in as favourable a form as possible.”