A rare Vintage Chronograph Clamshell case, Brevet 189190

A rare vintage chronograph
in a patented, waterproof "Clamshell" case
Brevet 189190

This chronograph has a patented watertight case, so-called Clamshell case. The case part is fixed in the calotte with 4 worm screws / grub screws in the lugs. The Clamshell case, patented in 1937 by Schmitz Freres with patent no. 189190, consisted of a watertight compartment that held the movement secured to the case body by four screws.

Details on the watch
Dial
black
applied Arabic numerals
outer five-minute divisions
30 min. counter
auxiliary seconds
Baton hands
very good condition, slight traces of use

Movement
rhodium plated
caliber Landeron 248
17 Jewels
finely ground chronograph steel parts
ruby endstone on balance
the movement is fully functional

Case
steel case
two body
brushed band
diameter 36mm without crown
lenght 45mm
good condition

Bracelet
neutral leather bracelet
The watch is fully functional and is in a good, used total condition.