Halted Coriolis

Andrew Wyeth - Wind from the Sea (1947)

«In 1851 Foucault carried out his famous experiment in which he observed a slow rotation of the vertical plane of the pendulum’s oscillation. This effect is due to the terms I (a southward force) and III (an eastward force); to a first approximation, the frequency of the plane’s rotation is given by Ωsin(Φ). Soon after, many such experiments were carried out at different places by other experimentalists. They not only confirmed the original experiment but also testified to the great appeal a direct mechanical proof of the Earth’s rotation had to many, even if few would by then have doubted its reality. 

There is an ironical twist here, for in fact the experiment had already been inadvertently done at a time when the Earth’s rotation itself was still under debate. In notes from the 1660s, members of the Accademia del Cimento mention their experiments on pendulums and report a clockwise rotation of the vertical plane. They did not realize that the Earth’s rotation may have something to do with it. For them, it was a nuisance; and afterwards they fixed the pendulum at two ropes to preclude this annoying perturbation!

The four terms (I) to (IV), first derived by Laplace, are none other than what we now know as the “Coriolis force”. In 1835, Coriolis derived ‘his’ force in a theoretical treatise on the forces acting in rotating devices [2]. He called it the “force centrifuge composée”; the association with the name of Coriolis became common only by the late 19th century. In fact, his paper past unnoticed in the first few decades after its publication. Notably, Poisson in his papers on the deflection of projectiles in 1837/1838 drew on Laplace’s Mécanique Céleste and shows no awareness of Coriolis’ paper. The same is true for early theoretical explanations of Foucault’s pendulum (such as by Binet in 1851). Ferrel’s work, too, is a case in point. 

It is only natural that Laplace was much more influential than Coriolis. Firstly, because Laplace’s work concerned the Earth’s rotation, which, ever since Borelli, was the primary object of study in effects of deflection (the cases discussed above testify to that). By contrast, Coriolis’ work was more abstract and the applications he envisaged were rooted in the industrial revolution, with rotating devices such as waterwheels – a wholly different context. Secondly, Laplace’s derivation of the deflecting force preceded that by Coriolis by four decades. Historically, it would certainly be more accurate to speak of the “Laplace force”. But, then, Laplace has already got so many things named after him, that it should be considered a matter of fairness to speak of the “Coriolis force”!»

A brief history of the Coriolis Force - Theo Gerkema & Louis Gostiaux

Europhysics News Volume 43, Number 2, March-April 2012