TIME VARIATIONS OF THE CALIBRATION OF THE WORDEN GRAVITY‐METER*

Precision calibration tests carried out with a Worden gravimeter in environment conditions as varied as possible have led to the following conclusions. The secular variation curve of the calibration shows that the secular relative variation has been very appreciable in the first year of life of the instrument, precisely of 1.3 × 10⁻³ in 13 months, while it has been practically zero in the second year. This must be ascribed to the fact that at the beginning of the operations the gravity‐meter had just arrived from the factory with its measuring body renewed.

On the other side the effect of 24°C of temperature difference between two series of determinations reveals itself in a variation of 0.0022 of the value of the calibration, so that it can be established that the variation of the calibration is I‰ for each 10°C of temperature variation.