Abstract: The motion of a caged laboratory animal is recorded by providing in the floor of the cage a platform which tilts slightly into one of four quadrants in response to the location of the animal within the cage. The tilting of the platform activates a switch for each quadrant, the output of the switches being recorded as a function of time. The platform has a fulcrum cone located at the center of gravity and is mounted over a platform support. The platform support includes a central pivot point over which the fulcrum cone of the platform is mounted and four upstanding posts which are located at the midpoints of the sides of the platform support. The elevation of the posts at the sides is slightly lower than the lower surface of the platform when it is balanced about the central pivot point. The switches are located at the corners of the platform support.

Abstract: A rotating vacuum shaft assembly includes a housing, a hollow shaft positioned in an opening in the housing and at least one seal made of a fluorocarbon polymer material disposed in the region around the shaft to permit a vacuum to be drawn through the shaft while it is rotated. The seal has deformable ribs which contact the surface of the shaft and the internal walls of the housing, the ribs deforming when a pressure difference exists across the seal thereby enhancing the quality of the seal.