= Plumb-line deflection from cylindrical gravity
{title2=$d\simeq2GL\lambda/(rg)$}
A pendulum of length $L$ in vertical <gravity> $g$ is weakly attracted horizontally by an added long circular cylinder of line <density> $\lambda$. Outside it, $g_h=2G\lambda/r$ at axis distance $r$. Small-angle equilibrium gives horizontal deflection $d\simeq Lg_h/g=2GL\lambda/(rg)$. Removing the cylinder's <mass> reverses the change. It is a before/after differential estimate; finite length, a nonhorizontal radial direction and mechanical motion require corrections.
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