isochronism

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

From Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 4 "G" to "Gaskell, Elizabeth" by Various

Dr. Hooke, the inventor of the balance spring, soon discovered it could be manipulated to isochronism, i.e., so arcs of different extent would be formed in equal time.

From Watch and Clock Escapements A Complete Study in Theory and Practice of the Lever, Cylinder and Chronometer Escapements, Together with a Brief Account of the Origin and Evolution of the Escapement in Horology by Anonymous

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

From Rules and Practice for Adjusting Watches by Walter J. Kleinlein

And it was not until the close of the year 1750 that Pierre Le Roy and Ferdinand Berthoud studied the conditions of isochronism pertaining to the spiral.

From Watch and Clock Escapements A Complete Study in Theory and Practice of the Lever, Cylinder and Chronometer Escapements, Together with a Brief Account of the Origin and Evolution of the Escapement in Horology by Anonymous

Thus, in 1720, Julien Leroy occupied himself working out the proper shapes for the inclines to produce this desired isochronism.

From Watch and Clock Escapements A Complete Study in Theory and Practice of the Lever, Cylinder and Chronometer Escapements, Together with a Brief Account of the Origin and Evolution of the Escapement in Horology by Anonymous