This is a rare Charpentier Calculimetre Calculator patented in 1881 with leather pouch.  It is nickel plated and copper ring with engravings.  It is a French circular metal slide rule invented and manufactured by G. Charpentier, Brevete S.G.D.G.  Diameter is 2.25”.  The seldom found machine is documented in Thomas Russo’s book “Antique Office Machines” as Scarce.  Included are 7 pages photo copies of patent application and various 1880s offerings.  This 130+ year old scarce Calculator is in very good display and operational condition.