NavList:

Peter wrote

I guess I'd still recommend a spirit level for general AH use with a reflective mirror, but that points out an annoying hole in the market for these things.  For some reason it's hard to get a spirit level of intermediate sensitivity (20 or 30 arcseconds per division) in a small high-quality metal package (3 or 4 inches) for a reasonable price.  A small machinist's level would be the right product category.

What attracted me to this method was the use of a film of water to create a second image. This eliminated the need to find and buy a suitable spirit level. Just a thought though  - is it necessary to use a level to set the morror up and then use the sun images for final adjustment?

I googled machinists level and they are available for a few hundred dollars which is more than I am prepared to pay for an experiment.

My wife sitting on the table is not the issue, it is the cat jumping up and proceeding to clean himself. My AH uses cooking oil and it is a very good cat detector!!!!