Abstract: An abdominal support swivel chair is comprised of a support base with a plurality of leg arms having casters and radiating about the base frame in a common horizontal plane. An adjustable center post assembly extends vertically from the center of the support base and along a central vertical axis. A seat is secured to a frame connected at a top end of the center post. The seat has a rear buttocks support section and a central narrow frontal projecting section merging therewith through opposed side thigh cavities. An abdominal support pad is secured to an adjustable support arm connected to the saddle frame. The support arm has an upper securing end section adapted for securement of the abdominal support pad and to position same inclined forwardly. The adjustable support arm extends forwardly of the frontal projecting section and aligned therewith and has an adjustable connecting mechanism to position the abdominal support pad for the comfort of a user person above the frontal projecting section.

Abstract: A magnetic field position sensing device for sensing the position, on a front surface of a wall, of a magnet of known magnetic field intensity secured to a rear surface of the wall. The sensing device has a magnetic field transducer which produces signals proportional to the strength of the magnetic field detected. These signals are treated in a microcontroller and compared to a reference signal value representative of the magnetic field intensity of the magnet, when not obstructed, whereby to generate signals to a display device which displays a numerical value indicative of the thickness of the wall. Audible/visual signaling devices are also provided whereby to direct the movement of the sensing device by a user person to locate same on the front surface of the wall substantially adjacent the magnet and this is accomplished by displacing the sensing device in a diminishing spiral path.