Comment by ggm

It's interesting that a device based on specifically constructed weights, at a scale to fit in a lab bench experiment (or at least a room) were capable of providing this much accuracy compared to a field experiment which used significantly larger masses, but was probably subject to many many more distorting qualities and estimation/rounding errors.

I can imagine that given enough motivation to chase down accuracy, they could have re-scaled the lead weight experiment to fit larger spaces, larger pendulums, assuming they could control for drafts, pigeons living in St Pauls Cathedral...