On Apr 20, 6:53 pm, Robatoy wrote:
On Apr 20, 5:13 pm, "Lee Gordon" wrote: They would sure appear to be parallel and for all practical purposes would
be, but in truth they would be between 1 and two ten-thousanths of a degree
off.

If we are going to split hairs then:

The error from the theoretical parallels would vary both with altitude
and location on the globe.
A geodesic error will cause different errors on the two strings as the
earth is not a perfect sphere.

I am going from the standpoint that the centre of the base (at 25
feet) is at a perfect 90-degrees to the line running to the centre of
the planet. The errors to that line will be different for each bob.

Thought I'd clarify my position.