Scovill / American Optical made a number of of cone or tapered bellows cameras.  The following is an excerpt from American Optical/Scovill Back Focus Tapering Bellows Field View Cameras - Chronology and Design detailing the history of Scovill/American Optical camera models of this basic type.

Flammang's Revolving Back View Camera Back Focus Model - Variations:

     There are currently at least five variations of Flammang's Revolving Back View Camera Back Focus model, and one counterfeit copy.  The differences between the variations are due to 1) push-pull or rack and pinion focus, 2) whether the vertical (forward-back) swing is hinged at the bottom or at the middle of the rear standard, and 3) lacquered brass or nickel-plated brass hardware:

Flammang's Revolving-Back View Camera Back Focus Variation 1.0:  1) push-pull focus having a lever in the rear to secure it, 2) vertical swing hinged at the bottom of the rear standard (as in catalog engravings) and 3) lacquered, draw-filed brass hardware.  This is the camera configuration as depicted in the engravings in American Optical/Scovill catalogs and other advertisements.

Flammang's Revolving-Back View Camera Back Focus Variation 1.5:  same as Variation 1.0, except that it has rack and pinion focus rather than push-pull focus.  Thie example of this Variation also has its label altered to indicate that it was made for W.H. Walmsley & Co. instead of the usual American Optical and Scovill Mfg. Co. label.  Additional examples will have to be seen of this variation to know whether the configuration was specified by Walmsley, or whether the variation was already being offered by American Optical.

Flammang's Revolving-Back View Camera Back Focus Variation 2.0:  1) push-pull focus having a lever in the rear to secure it, 2) vertical swing hinged in the middle of the rear standard, and 3) lacquered, draw-filed brass hardware.

Flammang's Revolving-Back View Camera Back Focus Variation 2.1:  same as Variation 2.0 (push-pull focus, swing hinged in the middle), except having a device at the rear standard that, when pushed, allows horizontal swing.  The example is also later than the Variation 2 examples, in that it was made when American Optical was owned by The Scovill & Adams Co. (after 1889)

Flammang's Revolving-Back View Camera Back Focus Variation 2.2:  same as Variation 2.0 (push-pull focus, swing hinged in the middle), except for 3) nickel-plated, polished brass hardware.

Flammang's Revolving-Back View Camera Back Focus Variation 3.0:  1) rack and pinion focus, 2) vertical swing hinged in the middle, and 3) lacquered, draw-filed brass hardware.

Another camera of interest to Flammang's Revolving Back Camera design:
Counterfeit Flammang's Revolving-Back View Camera Back Focus Variation 3.0: a camera which superficially looks like the genuine American Optical Flammang's Revolving Back View Camera Back Focus Variation 3.0, but, in detail, can be seen to have almost every detail and measurement slightly different than a genuine Variation 3.0.