Louis Thouverez, Paris.

A very rare and important French skeleton clock with full perpetual calendars including both year and leap year, equation of time, 1/4 striking on 2 bells and phases of the moon by the noted French maker Louis Thouverez.

The complex 14-day mechanism has finely spoked and finished wheelwork, brass end-caps, several positioning cocks that keep the wheels on the front end in alignment, simple 5mm. thick polished brass frames unified by six shaped pillars screwed front and back and is supported by a ‘Verde Antico’ architectural marble case with detailed ormolu mounts and feet. The spring barrel, located in the center, has the click mechanism carried on the barrel cap in front and a Geneva Stop mechanism on the back. The pinwheel escapement has brass pins, is mounted on the back plate and has steel caliber-style adjustable pallets.  It is regulated by an ormolu compensating nine-rod bimetallic grid-iron pendulum that is suspended by reverse knife-edge and engages the screwed beat adjustment on the crutch by steel pin.

The calendar mechanism is fully perpetual and not only adjusts for months with differing total days, but also adjusts for leap year. The years are indicated 0-9 so it continues to be relevant for successive decades. Each of the calendar wheels is held in position by a spring loaded shaped brass arm with either a steel or brass roller and are advanced once per day by a long rectangular arm that is tripped by the striking movement.

The engraved silvered equation of time annular wheel has a steel indicator hand, is driven by the motion work off the minute wheel, is mounted to the back plate, signed by the maker, ‘Thouverez Junior’, oriented toward the front and carries a kidney shaped cam. Riding along the edge of the cam is an arm with a roller that moves, by rack and pinion, an engraved ormolu hand that is counterbalanced by a small brass weight and indicates the equation of time on the main dial.

The quarter-striking movement is housed in the base while the largest bell and the striking arm mechanism remain visible between the marble pedestals. The movement has twin going barrels that are wound out the front and a large countwheel on the back that carries a separate indexing wheel. Riding on the indexing wheel and counterbalanced by a weighted arm is the lifting platform for the hammer. The hammer itself strikes by torsion and rides along the platform on a large brass wheel. This set-up allows the countwheel movement with a single hammer to strike the proper sequence of bells for the different quarters.

The striking sequence is as follows:

1^st  quarter – high bell

2^nd quarter – high bell, middle bell.

3^rd quarter – high bell, middle bell, high bell.

4^th quarter – high bell, middle bell, high bell, middle bell, dummy blow and largest and lowest bell to count hours.

The dummy blow is added to separate the quarters from the hour. It eliminates any confusion and allows the countwheel to dictate all the needed striking.

A thin steel rod activates the striking mechanism when tripped from above by a pin in the clock’s motion work.

The records of the 1823 Industrial Exposition at the Louvre contain an entry indicating that M. Thouverez exhibited “une pendule a equation”.

There are also several other references to M. Thouverez having an “equation and calendar clock”

One of the springs in the striking mechanism is dated 1820.

The back of the calendar dial has some indistinguishable lettering.

Tardy lists Louis Thouverez as becoming a master in 1788.

Britten’s list Louis Thouverot (Thouverez) as ‘working 1788-1825. Equation and calendar clock (Clu)’.

For a similar clock by Berthoud see: ‘Continental and American Skeleton Clocks’ by Roberts, pg. 23.

For the Berthoud clock at auction see: Christies, London, 7/95, Lot 338.

For a similar clock by Thouverez see ‘Continental and American Skeleton Clocks’ by Roberts, pg. 31 and ‘Skeleton Clocks’ by Collard, pg. 87.