To pay tribute to Galileo Galilei’s Pendulum clock, Panerai have released the PAM00500 table clock at SIHH 2014.
In the words of Jake Ehrlich, This Pendulum Clock is mounted on a mahogany base, with a hinged plate on the front on which the name of the model is engraved; underneath the plate is a bubble level, indispensable since the clock must be perfectly horizontal to run accurately. The base is levelled by turning the four adjustable feet of the wooden base. Completing the Pendulum Clock is a glass case, with a black-lacquered aluminium frame and a door at the front enabling the clock to be wound and its hands to be set.
IN PANERAI’S WORDS
Unique edition of 30 units
The pendulum of Galileo Galilei, the “measurer of time” which marked a turning point in horology because it opened the doors of the modern era, now beats again thanks to Officine Panerai and its new Pendulum Clock. This is a faithful reproduction of the instrument designed by Galileo to demonstrate the law of isochronism of small oscillations of the pendulum. Galileo’s discovery in the 17th century represented a real revolution, because it enabled clocks to progress from an error of several minutes per day to one of just a few seconds. The escape wheel designed by the Tuscan scientist, recognised as the first free escapement in history and the Pendulum Clock, therefore represents an operation of exceptional historic importance and technical mastery, underlining once again the link between Galileo, Florence, Science and Officine Panerai.
The application of the pendulum to timekeeping is a long and painful story: Galileo could not develop his intuition of 1641 since he was by then almost blind, so its realisation was entrusted to his son Vincenzo. Galileo died in the following year and the project lay dormant for a long time until, in 1649, his son decided to complete it. A blacksmith made the iron frame and the wheels and pinions in their crude state while Vincenzo Galilei himself cut the teeth of the escapement. Unfortunately he too died a few months later and the model, still incomplete but probably operational, remained in oblivion for some time.
It was in 1659 that Vincenzo Viviani, friend and biographer of Galileo, recovered the model at the request of Leopoldo de’ Medici and brought it to the Florentine prince together with a drawing. And it is only the latter which survives, because all trace of the machine itself has been lost: the drawing now preserved in Florence illustrates the structure and the principle of operation of this instrument which gave physical form to the intuition which Galileo had had years earlier and to the formulation of the laws of isochronism.
The Pendulum Clock is based on the model made by the Florentine clockmaker Eustachio Porcellotti in 1887 from this original drawing, a model which is now preserved in the Museo Galileo in Florence.
The remarkable new Officine Panerai production interprets Porcellotti’s work almost exactly. The height of the Pendulum Clock is 35.6 cm, the width 18.5 cm and the depth 11.1 cm: the dimensions of this table clock are taken from the original drawing and they are confirmed by the few other reliable reconstructions. The frame consists of two main plates, which are made not of iron, as in the original model and Porcellotti’s, but of brass, plated with nickel-palladium, and they are joined by crosspieces at the top and the bottom fixed in the traditional way by taper pins. The upper crosspiece carries the escapement and the pendulum suspension, while the lower one connects the lower parts of the frame plates which are formed into four scrolled feet. Between the base and the dial is the spring barrel, the drum of which contains a spring 4.10 metres long which powers the clock for eight days. The clock is wound by turning the square winding arbor with a key, while a ratchet with its related spring is mounted above the centre of the spring barrel to prevent it unwinding. Higher up is the dial with Roman numerals, like that of the 1887 model, with black-lacquered hands. The wheels with their hand-finished teeth, the bezel surrounding the dial, the spring barrel and other details are all gold plated.
The fundamental part of the clock is the regulating pendulum and escapement designed by Galileo. This consists of an escape wheel with 12 pins fitted to its side and 12 teeth cut in its perimeter, and three levers, one on the left as you look at the clock and two on the right. The one on the left, the longest lever which ends with a hook, is the stopping lever; the two on the right, arranged like scissors, are the release and impulse levers. While the wheel is in its stopped phase, the pendulum is completely free from any contact with it, and for this reason the device is called a “free escapement”. The pendulum itself consists of a rod terminating with a gold plated ovoid lenticular bob, with the screw for adjusting the period of oscillation below it. On the lower crosspiece is a place for keeping the key for winding the clock.