Biography of Antoine-Hippolyte Pixii



Hippolyte Pixii, a French instrument maker, constructed the first direct current dynamo in 1832. Antoine-Hippolyte Pixii lived a very short life – only 27 years – but he made an important contribution to the development of electrical machines. Pixii’s magneto-electric machine, developed in 1832, was the first practical mechanical generator of electrical current that used concepts demonstrated by Faraday.

In 1832, after the publication of Faraday’s experiments in his famous “Experimental Researches into Electricity”, Hippolyte Pixii, an electrical instrument maker in Paris, constructed with the aid of William Ritchie a device in which a rotating permanent magnet induced an alternating current in the field coils of a stationary horseshoe electromagnet.

The machine contained a permanent magnet which was rotated by a hand crank. The spinning magnet was positioned so that its north and southpoles passed by a piece of iron wrapped with wire. Pixii found that the spinning magnet produced a pulse of current in the wire each time a pole passed the coil. Furthermore, the north and south poles of the magnetinduced currents in opposite directions.

This was the first practical device for producing an electric current by mechanical means. Pixii called it a “magnetoelectric” machine. This machine was able to produce an “uninterrupted series of sparks by means of a magnet”.

Later that same year Pixii produced a second machine, at Ampere’s suggestion, with a commutator to rectify the alternative current currents. Pixii’s first device was improved upon in 1833 by Joseph Saxton of Philadelphia who used a rotating electromagnet, the inverse of Pixii’s design. The resulting magneto-electric “shock machine” was regarded for many years as a toy, but later found widespread use as the crank telephone bell ringer.

All DC motors and generators in the world today are direct descendants of the machinery developed by Pixii from Faraday’s first electromagnetic induction principles !!!

Antoine-Hippolyte Pixii has designed many other physical instruments and devices, two of them: a dilatation pyrometer and a vacuum pump are shown below.

Dilatation Pyrometer made by Antoine-Hippolyte Pixii in Paris, c. 1830.

Pyrometers are instruments made to measure high temperatures. They use numerous principles of physics, such as: absorption of heat by a metallic block (calorimetric pyrometers) thermoelectric effect (thermoelectric pyrometers) variations of resistance by temperature (electric resistence pyrometers) comparison of superficial brilliance of an examined body with that of another body at a well-known temperature (optical pyrometers).

The pyrometer shown here utilizes the thermal dilatation of a metallic bar. In fact, the elongation of a thin metal bar due to the variations of temperature, is amplified by a system of levers and transmitted to a mobile index along a porcelain scale in the form of a circular crown. The base has a small drawer in which small metal bars of diverse lengths are stored. Information regarding the maker is found on the porcelain frame.

A vacuum pump design by Antoine-Hippolyte Pixii.


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