How do I adjust this barometer?

[cazboy]

Originally Posted by doug sinclair

Part of the problem with aneroid barometers is that weather bureaus often no longer give atmospheric pressure in inches of mercury. I think some now use kilopascals. If a local weather office near you can give you the current reading in inches (if that is what your barometer reads), then set your barometer to agree with that reading. There should be an adjusting screw somewhere on the instrument. Start out by turning that screw either way carefully to see if the indicator moves. If it does, turn it carefully until the needle stops. Then reverse the screw and turn it the other way until the needle stops. Now, turn the screw back again until the needle reads the correct reading. When the needle stops moving, STOP turning the screw in that direction or you'll ruin the barometer!

I think I had my aneroids out when I was a kid but they left my tonsils . SORRY!!

Seriously, I have a nice radio that gives the weather. Thanks for the tips! In the meantime, I sure like this unit - I might just start collecting barometers...!!

[John Hubby]

Cazboy, the scale above the "Fair" etc on your barometer reads in inches of mercury, with 30.00 at the center. The scale divisions are 0.05 inches each. Go to Weather.com and put in your zip code. The local weather report shows barometric pressure in inches, I just looked at mine locally and it was 30.21. With that you can set the barometer accurately using the adjustment screw. All that is needed is to turn the screw to be sure the needle moves, then turn until it is at the current local pressure reading. I would go past that a little bit and then back off to the correct setting.

[cazboy]

Originally Posted by John Hubby

Cazboy, the scale above the "Fair" etc on your barometer reads in inches of mercury, with 30.00 at the center. The scale divisions are 0.05 inches each. Go to Weather.com and put in your zip code. The local weather report shows barometric pressure in inches, I just looked at mine locally and it was 30.21. With that you can set the barometer accurately using the adjustment screw. All that is needed is to turn the screw to be sure the needle moves, then turn until it is at the current local pressure reading. I would go past that a little bit and then back off to the correct setting.

Thanks John, that puts it in focus for me. OK, so the scale reads in inches of mercury, and I can adjust the barometer to coincide with the pressure reading from weather.com .

I guess I still have a couple of questions. What about the hygrometer part of it? I'm assuming it must be a drum mounted on a bimetal coil. Question: is the bimetal coil considered to be as accurate as the wet/dry bulb approach? I don't think there's any way provided to adjust it. Weather.com says the humidity is 37%, and although it does fluctuate somewhat day-to-day the meter reading on the unit says somewhere in the 80% range, never lower, so it would be nice if it could be regulated.

Also, is anyone here familiar with the maker, Watrous? All my Google searches turn up nearly nothing.

[Tom McIntyre]

For what it is worth, I don't think you should adjust a barometer.

The fact that the barometric pressure at your house differs from that of the weather station, is a truth worth knowing. A small card placed next to the barometer showing the difference between your location and the weather station will tell you what the offset is and what your barometer should read.

If you have an antique wheel barometer, you have to do that unless you want to mess with the pulley inside the back.

[MIchael Pana]

Adjusting a hygrometer is fairly easy. I have used the damp salt method.
Your hygrometer should have an adjusting screw in the back. If it doesnt, you'll have to open the case and look for a tab unto which the coil it attached. You will have to bend the tab to adjust the needle accordingly.
The damp salt method: Take a sealable plastic bag and place the hygrometer and a bottle cap with table salt which has been dampened with water. Use just enough water to dampen the salt. Using too much water and it will not work.
seal the plastic bag and let it stay for at least 12 hrs or more.
The humidity in the plastic bag will be exactely 70%.
Adjust the hygrometer and place it in the same bag again for another 12 hrs.
the Hygrometer should stay at 70 %. Repeat this process until you get the proper reading.
I would clean the coil with a very light blast of air to remove any dust.
My hygrometers read within 1-2% of eachother.
Mike Pana

[Burkhard Rasch]

Great idea and procedure,never heard of that!Thanks!
Burkhard

[Gordon Andersen]

What does a barometer have to do with horology?
I thought this was a forum regarding timekeeping!

G. Andersen
Adams, WI

[harold bain]

Gordon, although a barometer has very little to do with horology, I have on occasion had clocks with barometers in for repair. The last one I had used a hairspring very similar to one in a clock. So in my opinion, there is enough of a connection to make it a worthwhile discussion

[Bruce Barnes]

A lot of clock collectors also collect barometers, including myself, and many of the comments from board members have been of interest and help.
At the Los Angeles Regional at least 4 tables had barometers for sale,from common aneroid to fortin stick barometers.
Regards,
Bruce

[Scottie-TX]

How about this then: I read that there are some places on the planet where variations in atmospheric pressure are so cyclical and predictable that a barometer can be used as a timepiece!