Abstract: A system for measuring the distance between two objects, for determining the center between two objects and for triangulating the height of a tall object. In measuring the distance between two objects, an initial count is started when a first ultrasonic pulse is transmitted. The initial count is stopped when that pulse is received. The second pulse is transmitted only after a delay interval where the delay interval begins at the start of the initial count and is substantially equal to the maximum range time of a transducer. The restarted count is stopped when the second pulse is received, and the resultant count is displayed as a number related to the total distance between the objects.

Abstract: A sheath-core yarn and methods of preparing it are disclosed. A sheath of aramid fibers surrounds a continuous filament core composed of an amorphous silica product containing at least 96% silica and having the thermal performance of a refractory material. The yarn is useful in woven or knitted safety garments which must provide protection under such severe conditions as splattering molten steel.