"Clive Arthur" wrote in message
...
On 13/04/2021 22:01, Theo wrote:
Fredxx wrote:
Just keep an eye out for any changes.

There might be something you can do in terms of fixing some cheap laser
pointers (firmly) to the structure, and marking out where the beams land.
Then go at different times of day and see if there's any difference.
(turning them off when not in use, obviously!)

(I'm not sure laser pointers are collimated enough, but worth a try
before
going for anything fancier)

Theo


If you have any small cracks, glueing microscope slides across them is a
good way to check for movement. You can pick up a pack of these on eBay
for notalot.

I've always wondered how effective it is to glue a glass slide over a crack.
It depends rather critically on the bond between the glue and the glass
being stronger than the glass itself - otherwise as the wall moves, it
breaks the glue/glass bond (or the glue/wall bond) and the slide remains
intact.