to the force of gravity, so Gaspard de Prony realized
you could use this formula and the length of a pendulum
to calculate the local force of gravity.
Independently, Henry Kater had the same realization
but also built and refined the reversable pendulum
with reversable pivot blades
and showed how to use it to calculate
the local force of gravity.
Little g
It turns out that local gravity is affected
by the bulging of the globe at the equator,
by centrifugal force of Earth’s rotation,
by the gravitational pull of the sun and moon,
by the atmospheric pressure and your altitude,
and by the thickness and density of the earth beneath you,
not necessarily in that order.
Gravitational anomalies beacon the tourist
to watch water flow uphill or otherwise indulge
in fantasies related to visual illusions.
Very small differences are imperceptable
except to the skeptical and refined.
Local variation
After your first drink, you feel lighter;
after your last drink, heavier.
Individual gravitas may differ.
In free-fall, you feel no gravity at all.
Between individuals, differences
are greater than between groups.
Trying harder may harden the effect.
Kater’s pendulum was so commonly used to measure the
strength of the gravitational field that instead of expressing the
value in units of acceleration, distance per second squared,
scientists expressed the value as the length of the seconds
pendulum.
Jean Richer was the first to discover, in 1671, that gravity
did not have the same magnitude over the surface of the earth.
This was 244 years before Einstein’s general theory of
relativity.
Kater’s pendulum was so commonly used to measure the strength of the gravitational field that instead of expressing the value in units of acceleration, distance per second squared, scientists expressed the value as the length of the seconds pendulum.
Jean Richer was the first to discover, in 1671, that gravity did not have the same magnitude over the surface of the earth. This was 244 years before Einstein’s general theory of relativity.
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