A novel torsion balance for the measurement of the Newtonian gravitational constant

Summary form only given, as follows.A torsion balance has been built for the measurement of the Newtonian gravitational constant that takes advantage of the particular properties of a wide thin torsion strip under heavy load. The test mass is in the form of an assembly of four 0.47 kg masses suspended from a Cu-Se torsion strip 1.25 mm wide and 30 micrometers thick and 80 mm long. The source mass is an assembly of four 10 kg masses that can be turned to different positions with respect to the test masses. Preliminary tests of the system show that the relatively large gravitational signal produces a gravitational signal that, in air at atmospheric pressure, should easily be measurable to 0.1%. As we expect from our previous experience with torsion strips, an excellent zero stability is observed. A measurement of G with an uncertainty of 1% will be made soon to test all the systems and it is hoped to reach an uncertainty of 0.1% within a reasonably short time.