Am Donnerstag, 5. März 2020 22:55:51 UTC+1 schrieb Jon Elson:

The standard procedure is to turn it upside down, use an eyedropper to
fill the bottom of the tube, and poke a wire down the column to knock any
air bubbles loose. Then, the TRICKY part is to get the tube back right-
side-up without allowing the mercury to escape and air to get back in.

The wire and eye dropper are neat ideas. The problem is getting the reservoir back over the end of the column while the whole thing is in the inverted position. The reservoir is glued together, and I wonder if originally the column was filled first, then the bottomless reservoir was mounted and filled, and finally the bottom of the reservoir was glued on. But I'm reluctant to try and dismantle the reservoir. I think I might damage it.

It seems impossible to do this without getting your hands in the mercury.

Never did me any harm in the past.

Chris