14-3 The gravitational constant g 1. The first laboratory determination of Gwas done by Cavendish in 1798 This experiment was selected as one of the top 10 beautiful experiments in Phys 2. It is difficult to improve substantially on the precision of the measured value of g because of its small magnitude 3. This difficulty of measuring g is unfortunate because gravitation has such an essential role in theories of the origin and structure of the unIverse14-3 The gravitational constant G 1.The first laboratory determination of G was done by Cavendish in 1798. 2. It is difficult to improve substantially on the precision of the measured value of G because of its small magnitude. 3. This difficulty of measuring G is unfortunate, because gravitation has such an essential role in theories of the origin and structure of the universe. This experiment was selected as one of the top 10 beautiful experiments in Phys