James,
You have to look at the function of the Televel to work through the logic. See post #4. Tail up or tail down doesn’t alter the fact that you have to wind the float to get a reading. You would get a different reading with the aircraft in a different aspect but you would still have to wind the float. In your photo, in the windows that can be seen by my failing eyes, there are some windows at zero and some at 120 gallons, too discrepant for your tail down theory. It really looks like a panel after a long flight, engine oil temp coming down. The later Smiths electric gauge was linked to a cork float on an arm that would rise and float independently, linked to a ‘variac’ that would send a different electric signal, with an old school painted adjustment on the dial if the petrol sloshed to the back of an inclined tank.

Two windows on a Televel wound by one fingergrabbenscheisserschtik implies two tanks serviced by two cables coming out of a twin window, stacked dial display. This is just a guess, because your twin window Televel is a fascinating variant. We need to find one and see if two cables came out the back, or buy one on ebay and smash it open with a hammer to see if there are two stacked dials.:)

Hi powerandpassion

Yes I agree with all that you say, you point out the only bugbear in my applied logic!

If you look at the photo of the engineers panel you can clearly see 14 thin black cables coming down from above, which I assume are the Bowden cables driving the 14 gauges, all the other wires leaving the panel are thick electrical cables.

I conclude that there is only one Bowden drive per dial and so the second display can only be a direct one-to-one scaling (as it is on the later meters) or some sort of gearing has been applied internally.

But as you point out the numerical indications – or lack of – are quite mad! Indeed it was the oddity of these numberings that drove me to set the question to the forum. The only possible explanation I have on reflection is:

1. This is a production photograph and so the dials are not yet calibrated AND
2. The two dial read outs are on two separate discs that are clamped together by a single bolt internally and calibration is done by filling the tank to a known amount then dragging the two discs around so that they are both indicating the right level – then the bolt is tightened.

If that theory is correct then the uncalibrated discs could be at any relative position in the photo – or even the wrong discs – or even no disc(s)!, they are just waiting for the instrument engineer to turn up!! This two disc theory also means that the bulk of the device can be the same for all the meters and only the discs need to be ‘specials’.

I suspect that these are just for the Stirling and as such there are no left anywhere, but I’ll put a search on ebay to monitor if anyone tries to sell one on.

Cheers
James