(b. San Severino delle Marche [near Ancona], Italy, 4 October 1610; d. Rome, Italy, 1685)
Divini was among the first to develop technology for the production of scientifically designed optical instruments. He established himself in Rome about 1646 as a maker of clocks and lenses. In 1648 he constructed an innovative compound microscope with cardboard sliding tubes and convex lenses for the objective and the eyepiece; several years later he developed the doublet lens for microscopes. During the same period he experimented with the construction of telescopes of long focus. It was at this time that Giuseppe Campani of Castel San Felice came to Rome and learned the art of lensmaking. His lenses and instruments were competitive with Divini’s, and a bitter rivalry between the two artisans developed into a lasting feud that involved Pope Alexander VII.
Divini constructed long telescopes consisting of wooden tubes with four lenses, of a focal length of seventy-two Roman palms (633 inches). He experimented with the elimination of achromatic aberration in his lenses with some success. He had received some scientific training from Benedetto Castelli, one of Galileo’s disciples.
In 1649 Divini published a copper engraving of a map of the moon, based upon his own observations of 1647, 1648, and early 1649, which were made with instruments of his own construction. These instruments incorporated a micrometer of a gridiron design of his own invention.
Divini made a number of astronomical observations, utilizing his instruments. He made observations of the rings of Saturn and the spots and satellites of the planet Jupiter. In his observations he became involved in a controversy with Huygens, in the course of which he published several tracts.
Significant examples of Divini’s microscopes and telescopes have survived in such important public collections as those of the Istituto e Museo di Storia della Scienza in Florence, the Osservatorio Astronomico e Museo Copernicano in Rome, the Museo di Fisica in Padua, and the British Museum in London.
I. Original Works. Divini published Eustachii de Divinis Septempedani brevis adnotatio in systema Saturnium Christiani Hugenii ad Serenissimum Principem Leopoldum Magni Ducis Etruriae fratrem una cum Christiani Hugenii responso ad eumdem Principem (Rome, 1660); Eustachius de Divinis Septemedanus pro sua adnotatione in systema Saturnium Christiani Hugenii adversus ejusdem assertionem (Rome, 1661); Lettera di Eustachio Divini al conte Carlo Antonio Manzini Si ragguaglia di un nuovo lavoro e compimento di lenti, che servono a occhialoni o simplici o composti (Rome, 1663); Lettera di Eustachio Divini con altra del P. Egidio Francesco Gottignes intorno alle macchie nuovamente scoperte nel mese di Luglio 1665, con suoi cannochiali nel pianeta di Giove (Rome, 1665); and Lettera sulle ombre delle stelle Medicee nel volto di Giove (Bologna,1666).
II. Secondary Literature. On Divini and his work see also Silvio A. Bedini, “Seventeenth Century Italian Compound Microscopes,” in Physis, 5 (1963), 383–397; Giovanni-Carlo Gentili, Elogio storico di Monsignor Angelo Massarelli di Sanseverino (Macerata, 1837), pp. 60–86; and Carlo Antonio Manzini, L’occhiale all’occhio, dioptrica practica (Bologna, 1660).
Silvio A. Bedini