"German Gymnastics" was all about exercise equipment. The author expounded at length on this or that piece of apparatus which he had invented for swinging oneself up or around on. He called one the pommel horse, another the beam, and another the vaulting horse.
The man was out of his mind, said Gauss, opened the window, and threw the book out.
Hehe. I remember many a P.E. class where I would have agreed with Gauss.