Our paper on the cover of the MDPI Applied Mechanics journal
A. S. Blumenthal and M. Nosonovsky 2020. Friction and Dynamics of Verge and Foliot: How the Invention of the Pendulum Made Clocks Much More Accurate
Appl. Mech. 2020, 1(2), 111-122; https://doi.org/10.3390/applmech1020008

Cover Story (view full-size image): Mechanical clocks built in Europe starting from the end of the 13th century employed the “verge and foliot escapement” mechanism with a relatively low accuracy of time measurement. The introduction of the pendulum into the clock mechanism by Christiaan Huygens in 1658–1673 improved accuracy by about 30 times. The improvement is attributed to the isochronicity of small linear vibrations of a mathematical pendulum. We developed a mathematical model of both mechanisms. Using scaling arguments, we show that the introduction of the pendulum resulted in accuracy improvement by approximately π/μ ≈ 30 times, where μ ≈ 0.1 is the coefficient of friction.