Pocket Watch and Wristwatch Service ~~ Repair ~~ Restoration If you are an antique pocket watch or wristwatch collector, you know the importance of keeping your watches serviced.
You know that keeping it clean and lubricated will keep parts from rusting and wearing out so your watch will run correctly indefinitely.
Hamilton's experience with the original Elinvar quickly told them that they needed to find something better, and that was Elinvar Extra, introduced c.1940., initially on the all-new railroad grade 992B and special WWII timepieces, and eventually to all Hamilton domestic production.
There are no number tables that I am aware of to cross reference the date of manufacture with the serial number.
These watches were also engraved with the owners name and the date- 19 respectively.
These must have been the first years that Bulova implemented it's new dating system.
sometimes the watchmakers express this in Hz; for example 3.0Hz = 21600 VPH watch.
the AU postfix you see in the pictures is because the machine is set in Automatic Mode to Auto-Detect the VPH of the watch measured. this is basically set at about 51 to 52 degrees for the watch. if the dots spread into 2 lines, the beat error is larger. positive) the graph will incline up, rate is slow - graph inclines down.