Scientific objects

Astronomical clock

This clock recalls a short period in French clockmaking history, prompted by the new revolutionary calendar that came into force on 15 Vendémiaire Year II (6 October 1793). Like the metric system, whose standardisation in France began in 1790, this calendar stemmed from the revolutionary regime’s determination to adopt a universal system based on the decimal system. It comprised a new division of the year and new names for the months and days of the week.
One one face and six smaller dials, this clock gives the time, the quantième (day of the month) and the month according to the traditional system and according to the new revolutionary calendar. It also displays the phases of the moon.

Longcase clock

The longcase clock, as its name suggests, is a tall, freestanding clock, as opposed to a smaller clock placed on a mantelpiece, for example. Its tall case houses its weight and pendulum-driven movement. These clocks were also intended to serve as time standards.

The upper clockface indicates the hour, minutes and seconds. Between the Roman numerals there are different subdivisions: five to indicate the minutes or seconds, and eight to indicate the pendulum swing (5/8ths of a second per half-swing). The lower clockface give astronomical indications concerning the Sun and Moon. The Moon, represented by a small steel ball partially concealed by a blue steel half-shell to indicate the phases, is on a gilt hand. The Moon hand goes around the Earth in 24 hours, as indicated by its tip, which rotates around the rim graduated in twice twelve hours. This rim is also graduated in degrees (twice 180) to indicate the Moon’s position in relation to the terrestrial meridians. The second gilt hand indicates the solar time on the same graduations and the Sun’s position in degrees around the Earth. Both hands are fixed to a small sphere seen from the pole representing the terrestrial globe.