Abstract: A mayo stand having a springy material positioned on the mayo stand tray. The springy material is of sufficient softness and thickness so that it is easily depressed downward by the finger and thumb force of a doctor or his assistant so that a surgical tool on the tray is easily graspable. In a preferred embodiment the springy material is cut from a ½ inch thick foam polyurethane sheet and is adhesively attached to a thin, flexible plastic bag. The thin, flexible plastic bag is clean and sterile and covers the mayo stand and the mayo stand tray. Preferably the flexible plastic bag is a single use item that is disposed of following the completion of the medical procedure.

Abstract: A variable speed electric motor to drive a variable load over a substantially continuous range of speed. The motor has a plurality of winding combinations that may be switched into and out of the motor circuit. A torque controller selects the winding combination in response to motor speed to deliver torque efficiently to the load throughout the speed range.

Abstract: A selector device is provided herein for the random selection of a small set of balls from a larger set of balls. It includes a flat box having a transparent cover. The box is divided into an upper chamber and a lower chamber, the upper chamber containing a large set of balls therein, with a small set of the balls having a significantly different appearance from the first set of balls, e.g., by being colored differently. The lower chamber is formed by parallel channels through apertures. The channels are just slightly wider than the diameter of the balls. All connections between the upper chamber and the channels are provided with rounded corners. In this way, each channel has an unimpeded entry mouth from the upper chamber. Finally, spaced-apart, indicia are arranged in longitudinal rows each along a respective channel. In this way, a chance selector device is provided in which the balls have an unhindered access by gravity to the channels, which permits truly random selection.