Louis-Francois-Clement Breguet was a watchmaker and physicist who invented some electrical instruments, e.g. first induction coils, and particularly contributed to the development of electrical telegraphy. Louis-Francois-Clement Breguet was a watchmaker and the owner of the famous watchmaking company. In 1856 he made important work on electric clocks, particularly on the municipal clocks in Lyon. A number of patents registered in the following years. On 26 October 1866 he patented the tuning-fork clock.
A tuning fork is a U-shaped two pronged steel bar. It can be tuned to an exact frequency.
However, Breguet was passionately interested in electrical applications. In 1840 he published an important paper on electrical induction. Working in colaboration with two physicists, Masson and Savart, he developed first prototypes of induction coils that now are usually called Ruhmkorff induction coils.
Ten years later, Ruhmkorff just made them more practical, but Ruhmkorff name is remembered in the connection to the coils. Breguet also built the Jamin’s magnet in 1847, then about 1850 he used this magnet in an electrical generator. Breguet was studying the transformation of dynamic electricity into static electricity. Louis Breguet working together with Masson contributed to the work of the Delezenne’s hoop (1840).
This magnet was created on the demand of Jamin, lecturer in physics at the Ecole polytechnique between 1851 and 1880. An indepth study of the distribution of magnetism in bar magnets, lead Jamin to make horse-shoe magnets composed of a number of wet thin steel strips are first magnetised separately.
They are then placed face-to-face to one another, forming the shape of a horse-shoe. The strips at each end are secured by screws to the two soft iron armatures. These are kept at a constant distance from each other by brass straps. The inner steel strips are held against themselves by their elasticity. Their lengths are fixed, in that the outer strips are exactly restyed on the two armatures. These magnets have a considerably larger force, than any others made up until then.
Delzenne’s Hoop is a device which shows the presence of induction currents evolving from the earth (telluric induction). Taking up the work of Ampere and Faraday, on the influence of the earth’s magnetism on moving metallic circuits, Delezenne showed the existence of telluric induction with the aid of a type of induction machine, Delezenne’s Hoop. This consists of a circle of wood, fixed on an axis.
A conducting wire is wrapped around this, fitted into a groove on the circle’s circumference. It is propelled by a rotation on it’s axis, by way of a pulley turned by a crank. The whole apparatus is supported on a double wooden stand. This enables the part supporting the moving components to be joined at an angle to the rest of the device. The two extremes of the conductor wire both end at a cylindrical commutator, separated and placed on the axis of the hoop which two small metal springs rub against, thus forming a collector.
If the hoop’s axis is placed in the magnetic meridian and turned by the crank, a cuirrent starts to flow. This gathers in the collector, having passed through a galvanometer. This current changes direction with every half rotation of the hoop. The cylindrical collector enables a current of the same direction to be maintained.
In 1870 Louis-Clement Breguet decided to devote himself entirely to the applications of electricity, particularly to electrical telegraphs and the nascent field of telecommunications. He selled the watchmaking firm to workshop manager Edward Brown, in whose family it would remain for one hundreds years until 1970.
Member of the Commission of Telegraphy in 1845, he created the mobile telegraph and the telegraph with dial. In France, the Breguet dial telegraph was used by stationmasters to regulate the traffic between their stations.
Breguet’s telegraph, consisting of a transmitter and a receiver supplied by an electric battery, is one example of the new technology. Both transmitter and receiver have a round face on which appear the letters of the alphabet. In the centre of the transmitter’s dial is a wavy-edged brass disc. When this disc is turned it activates a metal tongue which alternately closes and opens the electric circuit formed by the transmitter, receiver and electric battery.
The receiver has an electromagnet which acts on an armature, attracting it when the transmitter’s tongue closes the electrical circuit and releasing it when the circuit is open. The shuttle movement of the armature is transmitted to a toothed wheel; this turns in unison with a pointer whose tip thereby indicates the letters of the alphabet on the receiver dial. At the beginning of the message, the pointers of the transmitter and receiver point to a cross on the respective dials.
When the person using the transmitter turns the pointer, the electrical circuit opens and closes successively, and the pointer on the receiver advances to the letter corresponding to the position where the transmitter pointer stops. Once the first letter is received, the operators of the receiver and the transmitter should put the pointers back to the initial position. This process is repeated for each letter of the message.
A complete Breguet (TX-RX-bell) set ca 1860, the bell is extremely rare
The pointer indicates the letters of the alphabet on the receiver dial. Messages were sent letter by letter. This was already an advantage in comparison with the earlier system of Foy & Breguet.
The needle could adopt one of eight positions simulating the signal arm of the (optical) Chappe system. Two consecutive signals represented a figure between 1 and 64. Consecutive figures referred to a word or an expression.
Internal view of the mechanism of the Brequet telegraph
The Breguet telegraph key is somewhat special in that it has a second, smaller key on the same board. It may have been used to ring a signal bell at the opposite end of the circuit, however, that would require a seperate wire.
Louis-Clement Breguet together with his son, Antoine Breguet (1851-1882), was also the manufacturer of the Bell telephone in France.
In 1843 Louis-Clement Breguet was appointed to the Board of Longitude. In 1845 Louis Clement Breguet was awarded the Legion d’Honneur. He became member of the Office of Longitudes in 1862. Breguet became a member of the French Academy of Science in 1874.
Louis-Francois-Clement Breguet died in 1883.