Verney-Carron. In the 1890's he invented a top lever closing system that had four locks and never needed to be adjusted. He patented it under several names for 30 years. It has a stop on the left side of the top lever...no threaded nut on the top of the lever because he inverted it. A lot of French firms copied it for years...or they put "Helice" on their top levers hoping that the V-C reputation would leak onto their guns.
It's been discussed here for years - See these lines:
https://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=561538https://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=514455&page=allhttps://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=480839https://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=541475This gun however, does not use the V-C patent; It's a Scott Spindle: see the slot in the top lever:
