How to set up a mercury barometer
How to install your mercury barometer
As part of our restoration service, we also give you advice on setting up your newly repaired barometer. Once you have your barometer safely home, we recommend that you hang it in the place it will remain and leave it there, still plugged for approximately 48 hours. This is to allow your barometer to slowly adjust itself to the ambient temperature it is now going to live in and simply lets everything settle and become stable again. Mercury barometers do not travel well and care is needed in their re-homing.
Once your barometer has acclimatised itself, you can now unplug it and make it work. This is best carried out with the aid of an extra person, we suggest placing a cushion or thick towel on a suitable table or bench to stop the barometer from sliding about. Whilst keeping the barometer upright, open the door in the back; facing the rear of the barometer slowly lean it to the left about 45 degrees, this is where the extra person is needed, carefully remove the cork from the main tube. This may be a little tight, if so then a gentle twisting motion will ease its removal. Holding the metal plunger, withdraw the plug (taking note of any mercury attached to the plug,) and carefully tap the plug against the inside of the tube to shake any droplets of mercury from it. Once removed from the tube, hang the plug from one of the tube retaining wires for future use.
You can now straighten the barometer up to its correct position, again done slowly and carefully. The mercury level will have dropped in your tube now and the open end will contain more mercury than before. The glass weights can now be placed in their respective tubes. With your assistant holding the barometer, with one hand holding the pulley still, carefully remove the masking tape from the silk cords (this tape is low tack and will peel off easily,) pulling it downwards away from the pulley. Now place the larger of the 2 weights in the open end of the mercury tube and slowly lower it until it reaches the mercury. Do not drop it into the tube. The smaller weight can now be placed in the remaining guide tube, again lowered in and not dropped in. Now slowly release the hold you have on the pulley and allow it to slowly turn to settle itself.
Your barometer is now ready to be hung on the wall again and is ready to use. Check the reading of your barometer a few hours after unplugging it to ensure it is reading correct.