How do I adjust this barometer?

[Tom McIntyre]

If you are serious about your clocks, you need to correct for barometric pressure or have a barometric compensator built into the pendulum.

The NAWCC Museum has a couple of precision regulators with barometric compensators and the Chapter 161 newsletter had an article about designing and building them recently.

Of course if you have a barograph, you can calculate the barometric error on your regulator and correct for it in your readings.

[Ralph B]

Getting slightly off topic, but for those of you who repair clocks for a living, as I do, then adding barometers to your repertoire can add quite nicely to your income. The only unusual tool required is a home-made pressure chamber.
I've also found that a lot of barometer repairs lead to clock repairs.
Along the lines of, " Oh, you do clocks as well ? Because I have this old grandfather clock" etc. etc.

Ralph B.

[Dave B]

If I wanted to adjust a barometer, I'd buy a pound of mercury and make a lab barometer, by filliing a closed glass cylinder with Hg, and inverting it in a 500 ml beaker. After the mercury settled down, I'd measure from the mercury surface in the beaker to the top of the menicsus in the tube.

But I have the glassware and a stand hanging around in the chem lab section of my basement; maybe others don't have that luxury.