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The great advantage found in the use of these small
instruments is the better avoidance of the perturbations arising from
draughts of air, and of the very serious influence of the slightest
inequality in temperature.
Other methods have been employed in late years by other experimenters,
such as the method of Baron Eoetvoes, founded on the use of a torsion
lever, the method of the ordinary balance, used especially by
Professors Richarz and Krigar-Menzel and also by Professor Poynting,
and the method of M. Wilsing, who uses a balance with a vertical beam.
The results fairly agree, and lead to attributing to the earth a
density equal to 5.527.
The most familiar manifestation of gravitation is gravity. The action
of the earth on the unit of mass placed in one point, and the
intensity of gravity, is measured, as we know, by the aid of a
pendulum. The methods of measurement, whether by absolute or by
relative determinations, so greatly improved by Borda and Bessel, have
been still further improved by various geodesians, among whom should
be mentioned M.


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