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The Jeffersonian cyclopedia;

a comprehensive collection of the views of Thomas Jefferson classified and arranged in alphabetical order under nine thousand titles relating to government, politics, law, education, political economy, finance, science, art, literature, religious freedom, morals, etc.;
3 occurrences of jefferson cyclopedia
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6537. PENDULUM, Construction of.—
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3 occurrences of jefferson cyclopedia
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6537. PENDULUM, Construction of.—

I have a curiosity to try the length of a pendulum
vibrating seconds here. * * * The bob should
be spherical, of lead, and its radius, I presume,
about one inch. * * * The suspending rod
should be such as not to be affected by heat or
cold, nor yet so heavy as to affect too sensibly
the centre of oscillation. Would not a rod
of wood not larger than a large wire answer
this double view? * * * Iron has been found
but about six times as strong as wood while
its specific gravity is eight times as great. * * * A rod of white oak not larger than a seine
twine, would probably support a spherical bob
of lead of one inch radius.—
To Dr. Robert Patterson. Washington ed. vi, 26.
(M. 1811)