[ATM] How to find Centre of Gravity of an existing telescope

["Bruce MacDonald" <brumac@gmail.com>]

I'm starting to work on making a poncet (equatorial) platform for my
existing commercial 10" dob.

My starting point is here:
http://home.wanadoo.nl/jhm.vangastel/Astronomy/Poncet/e_index.htm

Before I even start planning, though, I'm up against this:

"As shown in figure 1 the virtual polar axis passes through the axis
of the altitude bearings. Idealy this axis passes throught the center
of gravity of the telescope-dobsonian mount combination. In most cases
these points will almost coincide. If the virtual polar axis passes
through a point too far above the center of gravity the motor will
have to push the telescope uphill. It is not unlikely that the
movement will stop. If the virtual polar axis passes through a point
too far below the center of gravity, the telescope will be top-heavy
and, in the worst case, will fall from the platform in its most
extreme (East or West) position. "

Questions:
How does one go about determining the CoG of the telescope/mount combination?

Once found, assuming that the CoG does NOT coincide w/ the altitude
axis, what are the consequences.  I still need to build the table so
that centre of curvature of the arcs is the centre of gravity,
otherwise we have the problems mentioned above.  If the altitude axis
is significantly distant from the centre of gravity, will the ability
to track be compromised?

I can always raise or lower the centre of gravity by adding or
removing weight either above or below as necessary, but in any case, I
still need to figure out how to find the centre of gravity.

Thanks,
Bruce M
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