On 18 Apr 2007 14:17:27 -0700, art wrote:

I've never seen a 'spirit level' being used in a tool room for
accuracy nor could I specify from what you said as to why it should be
used from now on instead of conventional means.

Well, I guess you haven't had much experience in the tool room.
Otherwise you would have been aware of how precession levels used to
set up machinery. They are used often. How do you think those long bed
lathes are adjusted so they are straight, level and parallel? Yes, my
poor misinformed person they use precession levels.

Danny, K6MHE