Eustachio Divini

Eustachio Divini (4 October 1610–22 February 1685) was an Italian manufacturer and experimenter of optical instruments for scientific use in Rome.

Eustachio was born on 4 October 1610 in San Severino Marche, from the illustrious Divini's family. At the age of 4 his mother, Virginia Saracini, died and 7 years later his father, Tardozzo Divini, also died, so his brothers Vincenzo and Cipriano looked after him and his basic education before moving to Rome. At that time Divini was initiated into the military career but after a severe disease in 1629 he had to give up. After that he joined again his brothers.

His brother Vincenzo, who frequented the literary and scientific circle in Rome, incited him to follow the lessons of monk Benedetto Castelli, disciple of Galilei. So Eustachio began his new fertile formative experience with people of his same generation such as Evangelista Torricelli, Alfonso Borelli, Bonaventura Cavalieri and Michelangelo Ricci. In the early 1640s Divini practiced as a clock-maker. Subsequently his good relationship and friendship with Torricelli led him to cultivate a shared interest, the construction of optical instruments, microscopes and telescopes and their improvement. Divini's factory of instruments was located in the area of Navona square in Rome, and it is very probable that quite a high number of artisans (mechanics, glassmakers, tanners etc.) where working under Divini's direction. Since 1646 to about mid-century his lenses and glasses spread all over Europe granting him the role of Italy's foremost optician.

Many types of telescopes of various lengths were owned by prominent secular and ecclesiastic authorities in Rome. Divini's reputation and earnings were obtained not only thanks to the manufacture of optical instruments, but also thanks to the frequenting of a circle of scholars of the Roman College, where the astronomical research and the quality of the instruments of observation were both important. Differently from Francini, Galilei’s artisan, this group produced new working methods and new optical systems. These discoveries were published and spread all over Europe. The Court of Medici in Florence bought many Divini's telescopes and was not only a test bench for him, but also a spreading engine for the notoriety of the optician, because of the role of the associated Accademia del Cimento in triggering astronomical research in all Europe. So it isn’t a surprise that the prestigious Science Academy of London dedicated to Divini with the inscription: "Divinus Eustachius De Sancto Severini, Insignis Mathematicus". It should be noted, however, that the astronomers of the Accademia del Cimento substituted several Divini's objectives for Torricelli's lenses, obtaining a perfect combination with Divini's convex oculars and composed eyepieces. Recent tests and analysis of telescopes conserved in Florence Science Museum confirm these changes on Divini's telescopes and the better quality of Torricelli's objective lenses.

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