ModelPlan 130

Michael Adler's



The best mechanical timekeeper known is a pendulum swinging freely under gravity, but in order to convert such a pendulum into a practical clock, the pendulum must be sustained in motion so that the oscillations do not die down, and the swings must be counted. In ordinary clocks, the sustaining and counting function are both carried out by the escapement and the clock mechanism, but the free motion of the pendulum is considerably interfered with thereby, with a consequential loss of accuracy in timekeeping. What is so special about the Shortt Free Pendulum Clock is that a free pendulum became a reality, and for a number of years, from about 1922 until it was superseded by the atomic clock, it served as the pre-eminent time-keeper, and was to be found in all the world's observatories.

To serve the master, Shortt enlisted the services of the Synchronome company, whose director was Frank Hope-Jones, whose clock was then utilised as the slave to the Shortt Clock.

When Michael Adler first saw the Shortt clock about 10 years ago, he was fascinated because of its amazing mechanism, free pendulum and excellent time keeping ability, and by the importance it had earned in the horological world. It contained no fewer than three wonderful electro-mechanical working sections, and he marvelled at the interplay between one part and the other. He wondered if it could be reproduced in Meccano. He found out about phase locked loops and synchronisation, and kept going back to examine the clock.

One day he settled down to see if he could build the gravity arm and heavier reset arm. He realised at the outset that he would have to have a fairly heavy pendulum weight, and that he would have to work out how much of an impulse it would need to keep it oscillating on its own for half a minute. 

From there he worked backwards to the reset arm and the power that it would need to operate it.

When he had completed the Shortt clock and its slave (the Hope-Jones clock), the stage was set for interlinking the two. He had an overwhelming feeling when he got his clock to hit and miss for the first time.

The clock is a fascinating mechanism, which provided endless opportunity for Meccano construction, as well as an investigation of the theory of its operation.

The introduction to the ModelPlan consists of no less than nineteen pages of information on the prototype, illustrated by ten technical diagrams.

The fully comprehensive instructions cover another twenty-nine pages, with an illustrated section which includes some forty black & white photographs together with a further seventeen diagrams.

Also included are a Preface, Glossary of Terms, Parts List, List of Contents, List of Illustrations, Acknowledgements and References.

Also available on CD.   Michael Adler's Clocks on CD.