Would anyone have an idea as to when balance shock proofing began.. Here is picture of an upper balance jewel that "floats' in its setting.. The Swiss bar movement is key wind and set..It has a lever escapement...

Here are the dust cover inscriptions

Actually the shockproof mechanism pictured is a French invention by Abraham Louis Breguet. It is most often found with a compensation curb for temperature compensation as in your example.

Thanks Tom...Would you have any thoughts on the date of this movement.. Balance also has timing screws..I have "improved" the photo..

The movement is typical of the 1840's but I think Sandoz fils may be a little later. Pritchard says they were active from the early 19th Century.

Breguet introduced the parachute around 1810. The compensation curb was invented by Harrison and used extensively by Earnshaw and the French makers from about 1795.