I haven't stumbled across this before, and was wondering....with the war years going on during WW2, did Hamilton still have the Elivar hairspring installed in the 4992B's during war production, considering the difficulty in accessing materials during the war...or were they one of the receivers OF that war material so they COULD continue to make and install the Elivar hairspring in the 4992B?

Just a random question that rattled through my brain this morning.

Regards! Mark

Thank you, Lindell. I, too, have often wondered about that, and suspected with the amount of electronic gear that these watches had to function beside, they HAD to have that type hairspring...but to date do not recall ever reading anything about it..

I appreciate the response.

Regards! Mark

Actually the 59% iron, 36% nickel, 5% chromium nonmagnetic and corrosion resistant Elinvar material was pretty easy to make and was also used widely (without the Chromium) as "Invar" and "Kovar" for Glass to metal sealing leads coming out of Radio Tubes. I know because I used it for its inherent stability on some of my "inventions".

The "Special" formulation with Chromium added that Hamilton used was (reportedly) made by Hamilton to their own spec's. Ten (10) pounds of finished spring was probably enough for the entire "War Effort".

Interesting! Thanks David!

Regard !Mark

I understand that Hamilton developed and probably patented the "Elvinar" hairspring.

Did Hamilton license the "Elvinar" hairspring to other watch manufacturers?