Amplitude: Maximum displacement of any point from the dead point.
Vibration: Maximum displacement to maximum displacement, passing through the dead point.
Oscillation: One complete cycle of the escapement (2 vibrations).
The name of the rectangular slot in the mainspring (inner end) is the eye or eyelet and the bit attached to the outer end (it looks a bit like a spot-welded tail) is called the (slipping) bridle or hook.
A Mathematical Pendulum is a theoretical construct which imagines a weight (the pendulum) swinging as if it were attached by an arm, or bar, which is assumed not to exist. It is therefore a physical impossibility but a useful concept for the analysis of a pendulum’s theoretical effectiveness.
In other words: a theoretical or simple pendulum consisting of a mass suspended from a fixed point by a fine thread without mass, which is rigid and non-extendable. For experimentation only.
Recoil is not only a type of escapement, but also an action that occurs during the operation of the escapement.
Recoil is the slight backwards motion of the escape wheel just after the escape wheel tooth hits the locking face of either pallet.
If an escapement releases excessive energy to the balance, the impact can be reduced by using a weaker mainspring. If a weaker mainspring is unavailable, it would be acceptable to increase the depth of lock.
In really exceptional cases, you could try using a thicker oil on the escapement to reduce the amplitude (but this is unadvisable).
In a standard watch the balance spring is roughly 50% of the diameter of the balance wheel. Having fitted and timed a spring of known CGS (centimetre, gram, seconds system) one can calculate the correct spring for the given balance.
If you are working with a screw balance (that’s a balance wheel that has little screws sticking out of the sides for the purpose of poising and regulation), there are a few cheeky ways that you can speed the balance up if it not running at a sufficient tempo without changing the position of the pinning point. You could either move the screws in (imagine a spinning Ice Skater, drawing their arms into their chest to increase the speed of the spin), remove material (making the wheel lighter), or regulate it using the curb pins to make the active length of the hairspring shorter.
To establish the maximum variation, the watch must be tested in all five positions when fully wound and then again after 24 hours. The results are pooled and the maximum variation is the difference between the biggest gain and the biggest loss (effectively a ‘super-delta).
To check the isochronism of a watch, you must test the watch in all five positions when fully wound, and then again when half wound (often 24 hours later). The readings are then totalled (separately) and an average rate is found. The difference between those rates is then referred to as the isochronous error.
