A program of laboratory experiments in gravitation is to be continued and expanded. Emphasis will be on instrumentation for tests of Einstein's weak equivalence principle (EP), and a high accuracy measurement of the gravitational constant G. The instrument best suited for this research is the classic torsion balance. In modern form this instrument is remarkable in its capability to measure slowly varying extremely small forces, but it is now approaching the limits of its abilities when operated at room temperature. An important thrust of this research program will be the development and application of a new generation of torsion balance instruments which operate at cryogenic temperatures with greatly increased sensitivity due to lower thermal noise and greater mechanical stability.
