Spirit Levels

My first question: Why spirit? and not water, oil, acetone, mercury or maple
syrup?

I have a hunch it has something to do with the effects of surface tension
near the ends of a short vial. But I can not explain it rigorously.

Viscosity should affect speed but not sensitivity.


Second: What impacts the sensitivity in terms of linear motion/angle?
Specific Gravity and Surface tension?

Some vials are shape in an arc convex on top. Why? To me this seems to
reduce sensitivity. At the extreme, a toroidal vial should be useless, you
could turn it 180 and see the bubble on top.
Again I have a hunch that the surface tension at the ends is of fundamental
importance.

Can somebody shed some light on this ancient technology?

Thanks

Mauro

Dear MG:

"MG" <[Only registered users see links. ]> wrote in message
news:OtN4i.12480$[Only registered users see links. ].pas.earth link.net...

Did you check wiki:
[Only registered users see links. ]
.... due to its low freezing point.


Silicone or mineral oil would work better if it was only
viscosity effects...


Froude number for the free surface
Reynolds number for the bulk flow
Capillary number for the effect of the bubble / meniscus


It does. It also makes it more forgiving, allowing to to feel
how close you are to level... before shooting across to the other
side.


Put it in a bar. You could know the "precise" angle of the bar.


David A. Smith

Dear MG:

"MG" <[Only registered users see links. ]> wrote in message
news:OtN4i.12480$[Only registered users see links. ].pas.earth link.net...

Did you check wiki:
[Only registered users see links. ]
.... due to its low freezing point.


Silicone or mineral oil would work better if it was only
viscosity effects...


Froude number for the free surface
Reynolds number for the bulk flow
Capillary number for the effect of the bubble / meniscus


It does. It also makes it more forgiving, allowing to to feel
how close you are to level... before shooting across to the other
side.


Put it in a bar. You could know the "precise" angle of the bar.


David A. Smith