On 12 Mar 2005 04:11:41 -0800, "Bugs" vaguely
proposed a theory
.......and in reply I say!:

remove ns from my header address to reply via email

Sorry, but can you enlarge on this? Not having a go.

Firstly, the lasers we are talking about would not be anywyere near
visible at more than maybe 20 feet.

But apart from that I am not sure what you mean in your description.
Are you talking about setting u0 the level, or calibrating it? With
-some- of these levels, I am not sure they -can- be calibrated.

If you move the level, and place it somewhere else, it will be out of
whack again. What's a rod reading, and how do you ascertain the
difference in elvation unless you have a level to refer to.

Laser levels, like all levels, need to be tested and adjusted before
depending on them for a level line. The so-called peg test only takes a
few minutes and assures you that the level is truly in adjustment.
Use two points about 100 ft. apart for temporary bench marks. Set the
level up close to one of the benchmarks. Take a rod reading on both
benches and note the difference in elevation. Then move the level to a
point near the other benchmark. Take another set of readings. The
difference between the readings is approximately twice the error of the
level.
Adjust the level until both sets of readings are exactly the same. Then
you have a level outlook on the world.
Bugs