How does my 1918 German barograph work? (Replogle mechanical drum)

On Friday, October 30, 2020 at 4:45:30 PM UTC-4, AS wrote:
On Friday, October 30, 2020 at 2:56:53 PM UTC-4, Charles Gosse wrote:
On Friday, October 30, 2020 at 2:27:19 PM UTC-4, Charles Gosse wrote:
On Thursday, October 29, 2020 at 6:10:20 PM UTC-4, Herbert Kilian wrote:
On Thursday, October 29, 2020 at 2:16:14 PM UTC-5, Charles Gosse wrote:
I have a 1918 German barograph, photos are at the URL below. It appears complete but I do not know how to make it work. Apparently it has to be wound-up. I also have a photo of the underside of the metal tray, if you need to see that.

https://www.aeroconservancy.com/flugzeug
That's the kind of device you'd expect hanging above the basket of a hydrogen balloon. A precious piece of aviation history!
Hello Herbert,
I am really unfamiliar with google Groups. After you responded here I received an email with your response, as well, and tried to reply to that in gmail with photos but Google responded that they couldn't find the rec.soaring address. Anyway,I can't figure out how to add a photo here. Can you tell me?
Charley
Here is a photo of the underside. The green arrow points toward a clock-work mechanism that seems completely turned tight. What action or button starts the drum to turn?
https://www.dropbox.com/s/eh95drbxcy...0side.jpg?dl=0
Here is a photo looking down at the drum.
https://www.dropbox.com/s/mxjbxz70xw...0drum.jpg?dl=0
Charles,

thanks for the picture of tray's underside. You are correct - the key is used to wind the clock.
If you look at the front side of the Barograph - the one that has the handle on it, you can see a sliding lever in the lower left corner. Slide that lever to the left until it snaps upwards into the detent. That starts the clockwork. The detent prevents an accidental stop of the recording. The second function of that lever is to move the recording arm onto the drum to create the trace. In your case, it looks like there is a small ink reservoir at the tip of the arm, which draws the line. Other options were a stylus, which scratched the trace onto a waxed paper or onto a layer of soot on an aluminum foil, etc.

Let us know if you can get the clock to tick. ;-)

Uli
'AS'
I slid the lever over to the left but I can't raise it up into the detent because there's this other metal arm in the way.
https://www.dropbox.com/s/fsfqx3blos...lever.jpg?dl=0
I flipped it over and took a photo of the underside. On the right is the lever and on the left is the thing in the way.
https://www.dropbox.com/s/t6cazpshtv...0view.jpg?dl=0
I'm clueless.