Shortt-Synchronome clock

The Shortt clock is a precision pendulum clock, which was developed in 1921 by the English engineer William Hamilton Shortt ( 1881-1971 ).

Description

The clock has two pendant - one of which swings freely and compensates the other whose minimal friction losses - in exact harmony. Thus, the clock reached an accuracy of better than 0.01 s / day difference, and was also superior to the invented around 1935 quartz watches.

The peculiarity of the Shortt clocks is that they are almost free from interference of any kind. This is achieved by separating the main and secondary clock. In the main clock oscillates a nearly free pendulum in an evacuated housing. A second synchronized to the master clock pendulum contains all the other moving parts whose mechanical and other disturbances could affect the master clock. The transition fault this almost frictionless construction is a few milliseconds per day, which was only surpassed by temperature-stabilized quartz watches.

The time is specified in the back-up clock that has as an ordinary pendulum clock escapement wheel and escapement. A gear turns any 30.Sekunde a driving lever of the master clock that is built entirely smoothly on a located on the free shuttle role and, in the falling down the main pendulum always in the same phase of oscillation a low drive. This solves the drive lever - always in the same swing phase - a contact that synchronizes the back-up clock.

So the main pendulum swings 29 seconds completely free and then receive only the minimum energy input. Since it is nearly frictionless and except at the pin of the roller has no oil, it can run at very low air pressure of 30 millibars.

Already in the 18th century, the seconds pendulum was generally accepted as a frequency standard, as soon as you could reduce friction and keep the amplitude constant by precise mechanics of Uhrhemmung. On Observatories special astronomical clocks were used, the second hand was connected to the shaft of the escape wheel and narrowly jumped on the pendulum impact. The resulting refined timing also led the Shortt clocks to a further development of the exact time registration.