Andrew wrote:
Is there any logic to which fireplace connects to which chimney?
I live in a 6 storey house from about 1860 (which I don't consider
very, very old...). On the gable wall, there are two stacks with 6
chimneys each. I think the arrangement is

_|1:3:5:6:4:2|_/\_|2:4:6:5:3:1|_

where 1 is the basement and 6 the top floor. Is this the "normal"
arrangement?

Do you have a working fireplace connected to the chimney?
Otherwise, if not capped off, you might try a fog machine.
Or a hoover-bag full of dust, and the hoover on 'blow'.
If you can get to the top, then a radio placed in the fireplace will be
audible through one.