An absolute determination of the acceleration due to gravity

Abstract

Recent advances in the precision obtainable in length and time measurements have made it possible to determine the absolute value of the acceleration due to gravity with greater accuracy than has hitherto been possible. An accurate knowledge of the actual value of the acceleration due to gravity is essential, for example, in connexion with the determination of the absolute unit of electric current by means of the current balance. It has been usual to refer relative gravity measurements made in this country to the absolute value determined at Potsdam by Kühnen and Furtwängler (1906) over 30 years ago, and although relative determinations can now be carried out with an accuracy approaching one part in a million, it appears that the basic Potsdam value may be in error by something between one and two parts in 100,000. Very few absolute determinations have been made within the last 50 years, but those which have been carried out at various stations show discrepancies of this order when related to the Potsdam value by relative determinations.