In discussing the Kelvin quadrant electrometer on another list,
it came to me that a similar arrangement might prove useful
as a Cavendish gravimeter arrangement.
What I have in mind is two lead spheres, each sliced on a
horizontal diameter and mounted with their flat faces of each
half sphere a radius apart and their joint diameters almost
touching the opposite pair.
On a beam free to swing in the gap, at each
end a lead cylinder of height just less than a radius, with
the same diameter as the spheres.
Though the geometry is not quite so straight forward to
calculate as the Cavendish spheres, I fancy the arrangement
might have the advantage in compactness and sensitivity.
Would someone care to set out for me the equation of force
rotating the beam against a linear angular resistance from
the suspension as the beam weights move from minimal
to maximal insertion in the gap , please?