Anchor escapement the anchor is aligned with the bending point of the spring. This arrangement results in a more stable pendulum support than simply suspending the pendulum directly from the anchor. The anchor is very tolerant of variations in its geometry, so its shape varied widely. In late 19th century, in Britain, the usual design was a 90° angle between the pallets, which meant locating the anchor pivot a distance of ≈ 1.4 times the escape wheel radius from the escape wheel pivot. In a grandfather clock, which had a pendulum which swung once per second, the escape wheel often had 30
Escapement is made from a special steel alloy with 36% nickel called Invar whose length changes very little with temperature, swings as free of external influence as possible sealed in a vacuum chamber and does no work. It is in mechanical contact with its escapement for only a fraction of a second every 30 seconds. A secondary "slave" pendulum turns a ratchet, which triggers an electromagnet slightly less than every thirty seconds. This electromagnet releases a gravity lever onto the escapement above the master pendulum. A fraction of a second later (but exactly every 30 seconds), the motion of the master