Variations of the plumb-line direction obtained from astronomical and gravimetric observations.

From an analysis of variations of the plumb-line direction meridian component at Józefosław, based on astrometric and gravimetric observations, the authors conclude: In the change of the plumb-line direction at Józefosław one can notice harmonics with periods approximate to 1.0, 1.5, and 0.5 year with amplitudes of about 0″003, and secular change of about 0″001 per year. There is a weak correlation between the plumb-line direction variations and the curve of the mean latitude variations. Variations of the plumb-line direction may partly be explained by variations of the ground water-level, soil humidity and the Earth's deformation resulting from the displacements of the rotation axis.