Pacinotti, Antonio

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(b. Pisa, Italy, 17 June 1841; d. Pisa, 24 March 1912)


Although Pacinotti spent most of his life as a physics professor at various Italian universities, his subsequent reputation was due largely to his invention of a new form of armature used in electric motors and generators. The armature design that Pacinotti first described in a paper published in Nuovo cimento (June 1864) became a key element in the evolution from the magnetoelectric generator to the commercial selfexcited dynamo during the next decade. The Pacinotti armature consisted of an iron ring with projecting teeth interspersed with coils which formed a closed series circuit with connections to a commutator. In his paper Pacinotti pointed out that his new machine could be used as either a direct-current motor or a generator. A similar ring armature design was developed, apparently independently, by Gramme by 1869.

Pacinotti developed his armature while a student at the University of Pisa. His electrical investigations were encouraged by his father, Luigi Pacinotti, a professor of mathematics and physics at Pisa who had himself engaged in electrical studies during the 1840’s. A laboratory notebook kept by the younger Pacinotti indicates that he began his armature experiments in 1858. His work was interrupted by a year of service in the corps of engineers during the war for Italian independence. Pacinotti later claimed to have conceived the idea for radial teeth on his armature after having seen radially stacked muskets during the war. He returned to Pisa and resumed his electrical experiments, which culminated in a small test machine described in his 1864 paper. Following his graduation from Pisa in 1861, Pacinotti taught at Florence until 1864. He then taught physics at the Royal Institute of Technology in Bologna and at the University of Cagliari before returning to the University of Pisa, where he spent the rest of his life.

In the wake of the widespread publicity given the Gramme dynamo, Pacinotti called attention to his own earlier work in a note published in Comptes rendus… de L’Academie des sciences in 1871. Belated recognition followed at the Vienna Exposition of 1873 and the Paris Electrical Exhibition of 1881. From the perspective of the historian of science, Pacinotti provides an interesting example of a scientist whose contribution was not especially impressive but whose reputation ultimately derived from his recognition by the new electrical engineering profession for his invention of a device that was largely ignored until its apparently independent invention some years later.


I. Original Works. See the Royal Society Catalogue of scientific Papers, IV, 733; VIII,549; X,977–978; XII,553; of which appeared in Nuovo cimento. His paper on armature design, “Correnti elettriche generate dall’azione del calorico e della luce,” in Nuovo cimento, 19 (1864), 378–384, was reprinted as Descrizione di una macehina electiro-magnetica (Bergamo, 1912), with accompanying French, English, German, and Latin translations.

II.Secondary Literature. There is a three-part biographical essay based on original sources by Franklin L. Pope, in Electrical Engineer (New York), 14 (1892), 259–262,283–284,339–341. see s.P. Thompson,Dynamo-Electric Machinery, 3rd ed,. (London, 1888), for a detailed disussion of Pacinotti’s design and the results of thompson’s experiments comparing the electrical performance of the Pacinotti and Gramme armatures. An obituary apppeared in Electrical World, 59 (1912), 732–733. See also G.Polvani, Antonio Pacinotti: la vita, Popera(Milan, 1932).

James E. Brittain