There is a third peculiarity of the Plumer last that is worthy of notice, and which consists in a hollowing out or concaving of the bottom or sole from the heel forward to the toe, but mostly through the ball. This hollow is designed to be filled up with leather in making the boot, so as to leave the bottom of the sole _flat_, while _inside it is rounded upward_. The object of this change in the shape of the last is to make it conform to the shape of the foot, which it does very closely. But, at the same time, so far as this has any effect upon the foot at all it has an injurious one. The form of the sole of the foot at this place is one that _ought not to be conformed to_ by the sole of the boot. There is a low arch, transversely of the foot, from the ball of the great toe to that of the little one, its two opposite resting points. In nature it is somewhat like the great arch between the ball and heel. To raise the sole under it is like supporting an arch in the middle, which would be absurd. In this case it is entirely unnatural, and only of use _in a boot that is very tight, or much too narrow, where it may do good by preventing the formation of a big wrinkle in the sole of the foot, lengthwise_, which might come from the drawing together of the opposite sides. The following quotation strongly sets forth the impropriety of the new mode. “There has been a good deal said of late about the transverse arch of the foot, and the necessity of supporting it to prevent its breaking down, and the unfortunate possessor becoming splay-footed. Did any one ever hear of an arch requiring support? * * * What is called the _transverse arch_ is in reality a portion of an elliptic spring; and the moment you fill up the natural hollow of the foot you destroy its elasticity. What carriage-maker puts supports under the arches of his carriage-springs? The human foot is a combination of bones and strong muscles _that act as springs_, and at each point where it comes in contact with the ground is placed a cushion to prevent jarring. When the weight of the body is placed upon the foot, it spreads both in _length_ and _breadth_, and it contracts again when the weight is removed; and any artificial support under the hollow of the foot _prevents this expansion and contraction_, and one may as well have a wooden foot, for all practical purposes, as one which has a support under the transverse arch.”[4] As the foot spreads at every step, the arch naturally flattens in the middle, but this is prevented when the sole is built up under it. _It is self-evident that the foot is designed to tread on a flat surface, as its most natural function._ Any attempt to make it tread constantly on a _convex_ one is manifestly wrong. Yet, as said before, it may be of use to prevent a greater evil where people are determined to wear tight or narrow boots in spite of all reason or propriety.