Ellis's Pedistat consists of a platform, A (Fig. 55), twelve inches long and four wide. At one end of this is a block, against which the heel is placed. Outside the borders of the platform are two grooves, EE, along which two upright pillars, CC, may slide. The edges BB, outside the grooves EE, are marked with inches, sub-divided into one-eighths numbered from the heel-block. The pillars are also graduated, dating from the platform level. The usage of the instrument is illustrated by Fig. 56, where S is the milled screw that moves to and fro the pillars AA. A movable rule, cc, is provided with a scale either side from the centre. The shaded portion is a section of a cast of a foot made across the instep. The pillars AA are brought along the groove EE (Fig. 55) until opposite the position of the top of the instep, and the length indicated on the scale BB (Fig. 55) noted. The rule cc (Fig. 56) is now taken, and the starred centre put over the highest part, and the height of the under edge of the rule noted on the pillars AA, and the distances of the "star" from the inside edges of the pillars recorded respectively as inside and outside distances. The point of the highest part of the instep would thus be accurately located by three dimensions.

Fig. 55 Ellis Pedistat.

Fig. 55 Ellis Pedistat.

Fig 56

Fig. 56.