The growing number of lights being built on the coasts meant that it became necessary to distinguish these from the lights of dwellings. From this requirement came the idea of using revolving lights capable of producing flashes of light. The beacon was distinguished by its rhythm and became identifiable by the number of flashes and duration of its rotation..
The rotation machines used for Fresnel’s optics were designed following the principle of a weighted watch which drives a turning support on bronze rollers.
These machines are distinguished by three main elements:
. the blade regulator, with a friction disk or ball with inertial system which governed the speed of descent of the motor weight,
.gearwheels which reduce movement according to the speed of rotation required by the device,
. drum which winds or unwinds the cable of the counterweight.
In order to eliminate the jerks in release, Augustin Fresnel modified the blade regulator around 1826 with the aid of the clockmaker Lepaute, by incorporating a ball regulator.
Three companies have manufactured this type of equipment in France:
1) F. Barbier et Fenestre (Barbier-Bénard et Turenne),
2) Sautter-Harlé (Sautter et Lemonier),
3) Lepaute - Henry-Lepaute.
The replacement of supports which turn on rollers by the use of mercury tanks from 1890 onwards did not affect rotation machines which continued to be utilised and were only slightly modified upon the complete electrification of the system. From then on, a new generation of so-called “universal” machine functioning with a mechanical or electrical winding action would be installed.