Grignion Clock

The prototype can be seen at the Worshipful Company of Clockmakers Museum at the Guildhall in the City of London.  Almost nothing is known about it, except that it was designed in the mid 18th century, and was donated to the museum in 1850.  

The clock has a most unique escapement.  Impulse is given on one stroke of the pendulum only and it returns to the beginning of the cycle under its own inertia.  Before the impulse is given, the pendulum unlocks the escapement, and the escape wheel then impulses the pendulum through the pallet.    The effect is to give the escapement an almost dead beat appearance, to which a seconds hand can be easily attached.   The effect is an attractive and interesting mechanism. 

The Meccano Grignion is built entirely from standard Meccano parts and the power to the escapement is delivered through the weight of a small 6 or 12 volt electric motor which rotates in an epicyclic manner around one of the driving gears, activated by a mercury tilt switch.  Recycling occurs about every 40 seconds and the  power required to drive the clock is very small indeed, so that it can operate unattended for months.   The  clock also keeps very good time, and being only 18 inches tall, can easily be accommodated on a table or shelf.   Perhaps not much to look at, but a very interesting clock.