[Rusty]

The protype of the first Hamilton electric watch was labeled 17 Jewels and it had the double-wheel indexing system which, after further research was determined to be flawed.

When some of the movements were re-built with the more superior magnetic index, some of the prototypes were engraved 12 jewels. The new system eliminated the need for 5 bearings.

Source: The Watch of the Future by Rene' Rondeau, 4th ed.

 

[mgiraz]

Here's a picture and dialog on an ACTUAL Hamilton prototype of this watch. Hamilton would develop a watch and have employees wear them for a while...They would have strict rules about wearing prototypes....read the dialog, very interesting.

http://vintagewatch.info/Detail - Electric Prototype.htm