Carlo Croce, Cogorno, Italy. 1999. 12"h x
8.5"w x 8.5"d, without dome. 15"h x 11"diameter with dome. Tourbillon regulator with Mudge type lever escapement, one second balance wheel period,
eight minute tourbillon rotational period. Movement is fully jeweled up to the motion
works (excluding escape pallets).
Click on the
individual pictures to see more detail.
The tourbillon, (French for 'whirlwind') is recognized as one of the more difficult
complications to make. It was invented by Abraham-Louis Breguet in 1795 to compensate for
positional errors in watches. This is accomplished by mounting the escapement in a
rotating frame, so that the effect of gravity cancels out when the escapement is rotated
180°. By encasing the entire escapement within a rotating frame (the tourbillon), the
frame, as it rotates, constantly varies the position of the balance wheel in
relation to its environment. The effects of gravity were particularly problematic when
pocket watches were carried in the same pocketed position for most of the day. In a
tourbillon, the entire escapement assembly rotates, including balance wheel, escapement
wheel, and pallet fork.
Of course, this is entirely superfluous in a stationary table top clock. This fact
coupled with the difficulty of fabrication, results in few such examples having been made in the larger versions
necessary for a table top skeleton clock. This clock was the featured cover article of Clocks
Magazine, January 2000.
This clock is a custom, one off design. Movement plates are extremely pierced to a
delicate degree. The clock frame pillars as well as those supporting the tourbillon cage
are intricately turned. An outstanding feature of this design are the subsystems
containing the wheels, arbors and plates that intersect on different planes. The
section containing the fusee and mainspring are in a separate filigreed frame
perpendicular to the rest of the movement. This is an example of a 'tour de force'
in specialty clock making.
Below is an animation of the tourbillon escapement. It is enclosed in a cage (often
referred to as a carrousel) which supports the escapement and rotates along with it. A
close up of the cage is seen in the last photograph above. The entire assembly resides in
the center of the clock and rotates once every eight minutes. A rather slow moving version
compared to the typical watch tourbillon which does the same in one minute. At the same
time, the mass of this system is at least 100 times that found in a watch.