Hello,I am still confused about hamilton 922 and 922MP. In my view, the difference is the marker of the bridge: masterpiece. Some one told me that, 922MP has a guillaume balance.is that true? thanks for help.

Prior to 1928 Hamilton cased some 922's in the special cases that we usually associate the Masterpieces as being cased in without Masterpiece being stamped on the center bridge. Today these are still listed as 922MP's in the Hamilton serial number records.

Some late model 922MP's used "Invar" in the balances, however I know nothing about them being called a "guillaume balance". Records show about 15,700 made as 922's, and something like 1,400 prior to 1928 were unmarked 922MP's and from 1928-1936 there were 1,200 of the 922MP's made that were marked MASTERPIECE. The "marked" examples will always be the most desirable.

regards,
bb

Thanks.Buster Beck
That means 922MP has a invar balance,922 has a bimetal balance?

Thanks Buster for your post and attached image.

From the Nobel Prize in Physics 1920: Charles Edouard Guillaume - Biographical

"A chance observation by Guillaume on the coefficient of expansion of nickel-iron alloys led to a systematic investigation of a whole series of alloys and the discovery of invar, an alloy with a very low coefficient of expansion; elinvar, for which the thermoelastic coefficient is practically zero, i.e. Young's modulus constant, over a considerable temperature range; together with other useful alloys. The applications of invar were quickly recognized and the material was used in rapid methods for the measurement of geodetic baselines. The alloy is widely used in instruments of precision, such as thermostats and pendulums of astronomic clocks. Guillaume's total compensating balance for high-grade watches and chronometers, which eliminates the secondary error, was perfected by an elinvar hair spring."
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No, it is my understanding that all used the standard bi-metallic balances (expansion cut in balance wheels to allow for temperature ranges), but after 1931 " INVAR" was used in these bi-metallic balances with the position of the "cut" on the balance wheel in a slightly different position than the earlier balances.

While I am not an expert, this is my understanding of these hi grade watches.

I am familiar with "Guillaume" and his studies and writings on alloys and expansions of different metals over a normal temperature range. As said "Invar" was used in the 922MP's after 1931 however I have not seen these particular balances ever being called"Guillaume" balances in the 922MP's.

regards,
bb

Hello,Buster

Why I can not upload the pictures? I want to show the different cut of the balance.

which one is the correct balance of hamilton 922MP

Movement Number 3008581

another picture of 922MP balance

Movement Number ________

quote:

No, it is my understanding that all used the standard bi-metallic balances (expansion cut in balance wheels to allow for temperature ranges), but after 1931 " INVAR" was used in these bi-metallic balances with the position of the "cut" on the balance wheel in a slightly different position than the earlier balances.

I believe I've already answered your question in my earlier post.

regards,
bb

Hello, Buster.
I understand what you mentioned.
But after I searched the serial number. these two movements is produced before 1931.So it confused me.My question is which balance I listed is before 1931? because they have different cut. thanks