On Tue, 3 Nov 2009 at 01:12:05, comp.john
wrote in uk.sci.weather :

On 2009-11-02, Scott W wrote:
Hello all, is it possible to recalibrate these instruments. I have
come into possession of one that reads too low on minum temp and too
high on maximum temp. It is like the mercury needs to be pushed back
around the tube somehow to bring the max / min scales in line.

Maybe there's a bubble somewhere? I've had to do this with mine which is
just a relatively cheap one from a garden centre. What I did was firmly
grip it and swing it round a few times in an arc. I did say firmly grip
it

Not to mention making sure you're well away from any obstacle...
--
Paul Hyett, Cheltenham (change 'invalid83261' to 'blueyonder' to email me)