The New Zealand Primary Gravity Network

Abstract

Between 1947 and 1955 the Department of Scientific and Industrial Research established the New Zealand Primary Gravity Network, a set of 437 control points for gravity observations in the North and South Islands of New Zealand. The gravity differences between nineteen stations were measured with the Cambridge pendulum apparatus, and between all stations with a North American gravity meter. Initially the network observations were reduced separately in the North and South Islands; the resulting gravity values constitute the New Zealand Provisional System, which has remained the basis for recording gravity results within New Zealand. Subsequent adjustment of the network, both to make it internally consistent and to bring it into agreement with the first order world network based on Potsdam, has resulted in a revised set of values of gravity, which constitute the New Zealand Potsdam System (1959), and which differ by an average of + 5·0 mgal from the New Zealand Provisional System values. Values of gravity and of free air and Bouguer anomalies are given for the 437 network stations.