isochronism

The phrase "Adjusted to Isochronism and Positions" does not always indicate the same high quality or the expense assumed in obtaining close rating in different kinds of watches.

This may be further explained as creating an error in a spring which is supposed to be theoretically isochronous, with the idea of making it act in opposition to the position error and the combination thus obtained produces practical isochronism as well as a corrected position rate.

Adjusted to isochronism indicates that the watch functions uniformly during the entire twenty-four hours running.

When the balance is slightly out of poise and the motion is exactly one and one-fourth turn during the twenty-four hours, this out of poise will not affect the isochronism.

The experimental verification of this fact led him to the important discovery of the isochronism of the pendulum.