Help to identify a Steinheil lens

Any clue about which lens is this amongst the Steinheil's different designs and uses? It seems to be symmetric. Barrel diameter is 70 mm. Height is 150 mm. Serial number, according to Agostini, places it in 1879. What intrigues me is the placement of connecting ring. All the Steinheil I have seen the connecting ring is like over the rear element, the barrel does not protrudes inside the camera like in this one. It is strange to see it middle of the lens close to the slot for Waterhouse stops. I don't have it with me. It belongs to a friend of mine who lives far from where I am. Attachment 204575

A bit comparable with respect to the position of the mounting ring, this Steinheil Liesegang 840mm:

https://www.picclickimg.com/d/l400/p...brass-lens.jpg

Yes, thanks Ron, they are similar in proportions of their different elements. Corrado Agostini (only now I realised that I wrote "Corradini", in my post, sorry by that, it is now correct) mentions a Portrait Aplanat produced in three versions from 1874 to 1881. The picture (page 219) shows also a lens with that same look, a sample from Deutsches Museum in Munich. This lens is on sale and I am wondering about buying it or not. The glass is in good order but the barrel, as shown in the picture, is very much corroded. Price wise, I think it is not a bargain: about 330 euros, so I would like to know better which lens it is before making up my mind.

Could you provide the serial number?

Yes, it is 9780.

It was made in Dec 1879 according to H. Thiele's Steinheil book. But the lens type he gave is Tubus 30" which is obviously wrong.
This lens looks very much like an Aplanat.

I am wondering whether it is a regular Aplanat with two pairs of flint or a variation made by Steinheil, from 1874 to 1881, combining F+C - C+F. These are told to be brighter (Agostini) and having a narrower angle of view. I asked the owner to estimate the focal length and mesure the front element diameter. Let us see what he comes with.