100% Original large sterling silver case measuring 47mm excluding crown, 55mm including and 55mm lug to lug. Case back is signed 6BB/ 924-3306 Arrow logo 1337/81.Case measures 40mm including crown and 45mm lug to lug.Approximate date the movement of a watch is produced.Factory records differ from year-to-year and factory-to-factory. For this reason, many factory production dates are approximate.by year Is your chance to get a fair estimate of when your Longines watch was originally produced.You simply look up your serial number and place it in the shown table.To accomplish this, Francillon built a factory on a piece of land known as "Les Longines" and the Longines brand was born.
These large watches contained high-quality pocket-watch movements for use in aircraft navigation.
System developed and agreed-upon by American watch manufacturers to determine the diameter of a watch movement.
The larger the number, the larger the diameter of the movement.
I am slowly adding serial number tables to this site. With the exception of BULOVA, the numbers on the inside and outside of the CASE ITSELF are ONLY for identification purposes - they mean nothing.
Serial number records are available for many of the old pocket watch companies like AM Waltham, Elgin, South Bend etc. The number you need is the serial number stamped on the MOVEMENT (i.e the inner workings).