Swiss silver poor man’s tourbillon club tooth lever Circa 1900

Silver open faced lever watch by Courvoisier Frères
–
A Swiss silver open faced poor man’s tourbillon pocket watch according to Swiss Patent No. 30754 of Paul Loichot, circa 1900. Full plate movement, a club tooth lever escapement, screw compensation balance, engraved U.S. Pat. appl. for D.R.P. ang. Pat. N. 7888/1905, Brevettato R.A.208.N.232, Btè S.G.D.G. 30754.
An engine turned case. Silvered dial, small eccentric time indication in the upper half with radial Arabic hour numerals, outer minute dots and blued spade hands, an aperture for the visible tourbillon with engraved balance bridge.
–
Diameter: 53 mm
–
Weight: 99 g
–
Signed: Courvoisier Frères Mobilis La Chaux-de-Fonds
–
Courvoisier Frères 
Henri-Louis and Philippe Auguste Courvoisier traded from 1842 on under the name Courvoisier Frères. When more brothers joined the partnership in 1882, they changed the company name to “Courvoisier Fils”. Specializing in high quality watches, they were commissioned by the city of La Chaux-de-Fonds to create a watch for the Prussian King William IV; at the time, this ultra flat watch was supposedly the thinnest in the world. The tourbillon movement invented by the Swiss Paul Loichot (which he turned in the case so it would be visibly face sided) was patented for the Courvoisier brothers on July 4th, 1905, under the number 19062 and the name “Mobilis”.