I have one question about this watch.

Why does it have a white balance spring?

I stopped the balance to take a picture, and it appears to be a solid wheel.

Steve

What is the word inder the balance wheel? I can't make it out.

Tom

It says "Brevet."

It definitely has a mono metalic balance wheel. The screws are brass, I think.

Hi Steve.

I started seeing white hairspings on PWs built during the 2nd WW, and I have just got a Waltham Premier of ca. 1948 in that fashion. On the war-built the reason is simple, cost, they saved the blueing operation. I do not know if this applies to your nice PW, bat it's as far as I can go.

Thanks Mario. That is interesting. It probably dates to the '30s or '40s then.

Steve G.

I think this regulator spring looks like a Zenith, minus the little circular thing-a-ma-jig, but the plate design looks more like an Omega.

I don't know if this will be of any help.

In "United States Horological Trademark Index" page 416 Strasburger, Louis & Co. NYC had a patent on P.H. Doret, Locle for watches issued 06/01/1875.

There was a also a patent issued to Alfred Sandoz, Philipe Henri Matthey Doret for a solar watch 06/25/1853

There was a Paul Matthey-Doret, Locle, that made chronographs & repeaters.

Tom

That is very interesting. This watch certainly isn't that old, but the company/family name goes back a long ways. Thanks, Tom.

Steve G.

I think Marios point is well taken. At first Elinvar type hairsprings were "blued" so that watchmakers and others would accept them as hairsprings were generally blued. Once the alloy hairsprings were accepted in the 1930's the unnecessary bluing was dropped and WWII hastened it along as I understand it. Nice watch.