On Saturday, December 30, 2017 at 12:57:52 AM UTC-5, Emanuel Berg wrote:
What is the theory behind levels?

I've heard that carpenter's are more precise
than those used by bricklayers.

I have examined the ones we have here and there
is no indication as to precision on either so
the only way to tell would be the mortar stains
on one of them...


Precision can often be based on the size of the bubble.

My pet peeve when it comes to spirit levels are bubbles that are too small.

If the bubble is so small that there is a relatively significant gap on both
sides when trying to level something, then the user is left to "eyeballing
level" by trying to get the gaps even via sight. There is certainly a lack
of precision when that needs to be done.

If the bubble is large enough that it almost touches (or perhaps just touches)
the lines, then finding level is not as much of a guessing game.

Compare the full-size bubble in this level...

https://i.imgur.com/TQHLNXE.jpg

....to this short one:

https://i.imgur.com/uZ2WkRh.jpg

All else being equal, which one do you think is more precise?