Vintage Brass Lens by Darlot Paris Opticien Vis a Portrait Paysage

Vintage early brass lens ca. 19 century, nice patina
height ca. 13 cm
Diameter front ca. 6 till 8cm
Diameter rear ca. 8cm
Vintage lens w. small separations
Lens engraving is:
"Darlot Opticien Paris" 28.516
"Vis a Portrait" and "Vis a Paysage"
Brass lens with the puff of history