I am confused again which is not difficult for me but perhaps I am not the only one. I believe the first 992b watches had normal hairsprings with a split balance wheel. Then somewhere after the war they started making them with solid balance wheels and elinvar hairsprings. My 1961 example is so fitted but it is still marked as a 992b. My confusion is where does the 992e fit into the scheme of things and what was different about it apart from the markings?

Stephan,
The Hamilton 992E (Elinvar) was introduced in the fall of 1931 with a monometallic (solid rim balance wheel) and the Elinvar hairspring.

In Nov. 1940, the Hamilton 992B was introduced with a nonometallic balance wheel and increased quality Elinvar (White) hairspring called "Elinvar Extra".

The new 992B was described by Hamilton as "This is a completely new movement from the winding arbor to balance wheel, and its parts are not interchangeable with those of the previous 992's"

In summation, the original lever set 992 was made from 1903 to 1914. The 2nd model 992 was produced from 1914 to 1931, when the 3rd model (992E) was introduced.

Robert

Below is a side-by-side view of the Hamilton 992 Elinvar and the 992B.

The images are excerpts from Hamilton catalogues furnished by Don. Thanks Don.

Robert

Thanks Robert. Now I have it. The 992E came between the 992 and the 992B. Learning all the time. Was there any overlap or are there definate dates when you can see the transition in the records.