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Astronomic determinations by the united states coast and geodetic survey and other organizations

1925; Elsevier BV; Volume: 200; Issue: 4 Linguagem: Inglês

10.1016/s0016-0032(25)90189-5

1879-2693

Hugh C. Mitchell,

Optics and Image Analysis

In 1971 the Istituto Geografico Militare established a small net of trigonometric points — measured with the maximum possible accuracy — through the Strait of Messina, in the area under study for the road and railway connection between Sicily and the Continent.A net with four points in Sicily and three points in Calabria, at distances ranging from 3 to 9 km, was established and angles and distances were measured as well as two pairs of reciprocal astronomic azimuths. The trigonometric points were monumented in a special way to avoid variations due to an accidental local shifting of the station pillars.In 1973, the angular, distance and astronomic measurements carried out in 1971, were measured again with the aim of ascertaining if planimetric movements had occurred between the points of the net. A comparison between the positions of the points obtained from the two sets of measurements shows very small variations that are at the limit of the approximation deriving from the order of accuracy of the measurements carried out.