Dear Hans Georg.
Yes Layies watches are much underestimated. In the 1930's it was the aim to
build the smallest accurate (+/-) well running movement.
The watchmaker realy needed ultra fine tolls and hand feeling to build such
movements. These tiny watchs; you can buy them now for few bucks.
I sometimes think, today the size and glamour is more important than the
heart of the watches. When you compare a modern wrist movement with a tiny
lady wrist watch, you compare a bulldozer with filigran watch technology.
(Sorry to all movement developer, they have other aims today: Reliability,
fast and
easy assembly of the movement. Manufacturing time is now the most expensiv
part of a movement. In the early time it was 1/3 for the material, 1/3 for the
machining of the parts and 1/3 for the assembly and adjustment for the
movement. Maybe the cost distribution for a simple movement is today not much
differernt, and the price for a movement is 10 times higher than 100 years
ago. The cost for labour I think is now 1000 times higher than 100 years ago,
so what is to do....)
Sorry this was not the question....
I grabbed in my documents. For the the 2nd version of the c.64 (ver. 1904) a
height of 4mm
(4.1mm Fournitures #7) and a diameter of 27 mm (26.5mm Fournitures #7) are
indicated. (Diameter = 12 lin.)
For the earler versions (1890/1894), I could not find a height indication.
Measuring makes it to
H=5mm (4.9mm) and a diameter of 12 1/2 lin. (28.2mm). For 1890 and 1894 I
could not find a difference with my rough tools
Digging in my garbage bin I even found ot the bottom some the c.63/64
movements and watches, ready to go.

A funny thing is: Most of them do not have a seconds hand. So if c.63 or c.64
is not important for the position of the seconds indicator, only for the
mechanism to set the time: "push button" or "lever".
A mor philosophic question is, why there are no seconds hands: Because the
watch was not accurate enough or that the wearer did not realy care about
seconds (nor the time)
regards
Ralph