The tangent rule

Full text article published @ Horological Science Newsletter.

The subject here is the check of the relationship between the timing of the impulse and the period duration, Airy's tangent rule.

At this youtube video you can follow the development of the actual raw data of a power pulse delay scan

• The parameters of this magnetic escapement experimental run are:

one impulse very 5 periods, the 70 ms impulse occurs at 10 set delays from 100 ms (7 mm at bob's level) before to 100 ms after the pendulum crossing of the vertical

In agreement with Airy's tangent rule, see P.Woodward, My own right time, pag.69, the period at impulse lengthens for delayed impulses and shortens for the early ones, the period variations disappear in the noise when the impulse is centered within a few mm.