In the case of the Broué slipper, it is the animal's own weight that brings about the widening of the heels, the slope or outward incline of the slipper simply causing the inferior edge of the wall at the heels to spread itself outwards instead of sliding inwards on the bearing surface of the shoe. [Illustration: FIG. 77.--THE SLIPPER SHOE OF BROUÉ.] _(e) Einsiedel's_.--Like the 'slipper' of Broué, the Einsiedel shoe depends for its effects upon the slope of the bearing surface. It differs from the Broué in being provided with a 'bar-clip.' This, in addition to gripping the bars like the bar-clips of other expanding shoes, also assists, under the body-weight, in expanding the heels by the pronounced slope given to its upper surface. The expanding force exerted by the body-weight falls thus, through the medium of the bar-clip, clip, _partly_ upon the bars, instead of, as in the Broué, solely upon the wall. We say _partly_ advisedly, for, in addition to the slope upon the outer side of the bar-clips, the bearing surface of the heels of the shoe is _slightly_ sloped outwards also. The good office served by the bar-clip is the lessening of any tendency to strain upon the white line. [Illustration: FIG. 78.--THE SLIPPER AND BAR-CLIP SHOE OF EINSIEDEL.] Those we have described by no means exhaust the number of expansion shoes that have been devised. There are numerous others, many of which are composed of three-hinged portions, the two hindermost of which are gradually separated by a toothed arrangement of their inner margins and a travelling bar, the disadvantage of which is that it is liable to work loose. In the majority of this class of shoe the hinges are placed far forward, one on each side of the toe. They there become exposed to excessive wear. In fact, against the bulk of this form of shoe it may be urged that they cannot be worn by the animal at work, that they are expensive, difficult to make, and easily put out of order. 3. _By Operations on the Horn of the Wall_. _(a) Thinning the Wall in the Region of the Quarters_.--This is best done by means of an ordinary farrier's rasp. The thinning should lessen gradually from the heel for 2-1/2 to 3 inches in a forward direction. That portion of the wall next to the coronary border, about 1/2 inch in breadth, should not be touched. At this point the thinning should commence, should be at its greatest, and lessen gradually downwards until at the inferior margin of the wall the normal thickness of horn is left. The animal is then shod with a bar shoe and the hoof bound with a bandage soaked in a mixture of tar and grease, in order to keep the thinned portion of the wall from cracking. In this condition the animal may remain at light labour.