Copyright © Françoise Herrmann
In US2465817 titled High heel shoe, Perugia disclosed a comfortable, and aesthetically pleasing, 4-inch high heel shoe without the use of a platform to compensate for the increased height.
The invention invoked a concave inner sole, designed to prevent the foot from slipping forward under pressure of the heel height. The concave inner sole thus replaced the need for what was perceived as unsightly platforms while still affording extra height, compared to the state of the art in the height of women’s shoes.
In US246817, the high heel and its concave inner sole were embodied in a pump, and described as applicable to other upper shoe designs such as Perugia's marketed, "mask mule" included as an illustration in this post.
A patent drawing, showing the pump embodiment of the invention, extracted from US2465817, titled High-heel shoe, is also included.