|Diameter:||39.95 mm (18 ligne)|
|Hands:||Central Hour Hand, Central Minute Hand|
|Distinguishing Technical Characteristics|
Counter-Clockwise Balance Cock
|Production: 1895 – 1941|
Cal. 1 was an 18 ligne pin-set pocket watch movement produced by Robert Frères (later called Minerva) from about 1895 through the early 1940s. It was a basic movement with a cylinder escapement and was usually cased with an open face.