Paper, account of Signor Campani's new optick glasses [telescopes] and their effects by unknown author

Description

Paper concerning optic glasses, or telescopes, including a scale for Roman palms. This account is most likely related to the ‘competition’ between telescopes made by Eustachio Divini (1635-1715) and Giuseppi Campani (1610-1685), held in Rome in 1664 at the behest of the Grand Duke Ferdinand II and Prince Leopold. Lorenzo Magalotti (1637-1712), secretary of the Accademia del Cimento in Florence, instructed Paolo Falconieri (1638-1704), a courtier at the Medici court and member of the Accademia, to compare the effectiveness of the telescopes by using two printed sheets with eleven lines of decreasingly small fonts. Sheet ‘A’ contained meaningless words made up of random letters, and the second sheet, ‘B’, contained individual letters without ascenders or descenders, and flattened out to eliminate possible shadow effects created by the grooves made by the type-face. These were to be read with a telescope from a distance, in a darkened room with two lights. Three Campani telescopes and five Divini telescopes were tested in this way in December 1664 in the Panfilio palace on the Piazza Navona. Because Matteo Campani (Giuseppe’s brother) recorded the lengths of the telescopes systematically shorter, and because Divini added a candle to the lighting, the results were not conclusive.

Henry Oldenburg reported on Campani’s telescopes to Robert Boyle in 9 October 1664. Oldenburg may have acquired an account of this contest either by Magalotti or Falconieri, who visited England in 1668. They were present at the meeting of 27 February 1668, when Francis Smethwick produced some telescopic glasses.

English translation found at CLP/2/8.

Subject: Astronomy

Reference number

CLP/2/7

Earliest possible date

1664

Physical description

Ink on paper

Page extent

2 pages

Format

Manuscript