Matteucci's Apparatus
    In his experiments in 1830 with electromagnetic induction, Michael Faraday discovered that a change in the magnetic flux produced by one coil produced an EMF in a parallel coil. In his experiments the two coils were close together and linked by a length of iron.
   The Italian experimenter, Carlo Matteucci (1811-1868), in experiments in the mid-eighteen forties, showed that the effect worked over larger distances without the presence of iron. He devised a pair of identical flat coils, with wire wound in a spiral pattern on the surface of glass disks about 30 cm in diameter. A Leiden jar was discharged through one of the coils, and an experimenter holding on to wires connected to the other coil felt a shock. The magnitude of the shock increased when the distance between the two coils decreased.

   Matteucci is also known for his work with the electrical conductivity of the earth in 1844. By demonstrating that the earth has an appreciable conductivity, he showed that it was possible to use the earth as a return conductor for telegraph signals, thus making it possible to use one metallic conductor instead of two. 


  
  Both of these sets of Matteucci coils on display at the museum at St. Patrick's College, Maynooth, County Kildare, Ireland are by Yeates of Dublin. The larger set, ca. 1860 are signed Horatio Yeates (1834-1906), and the smaller is signed Yeates & Son. 

   In 1836 Nicholas Callan, a faculty member at St. Patrick's College, described a similar apparatus in a letter to Sturgeon's Annals of Electricity.

  This pair of Matteucci's coils is in the Garland Collection of Classical Physics Apparatus at Vanderbilt University in Nashville, Tennessee. The glass plates are about 34 cm in diameter and the spiral of wire is glued to the surface of the glass. 

   If the plates are brought close enough to each other, a shock can be felt by an experimenter holding on to the ends of the secondary coil, as shown in the picture below from Ganot's Physics.

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   This single Matteucci coil is in the apparatus collection at Vassar College in Poughkeepsie, New York. The flat coil is glued to a plate of glass.

   The cast-iron base suggests that the apparatus is ca. 1900.