Reference numberCLP/2/8
TitlePaper, 'An account off some of Signor Campani his new optick glasses [telescopes], and their effects, in reference to some characters, they were imployed upon' by unknown author
DescriptionAccount translated from the original Italian (found at CLP/2/7) into English by Henry Oldenburg.

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.

Subject: Astronomy
Physical descriptionInk on paper
Access statusOpen
Related materialFor Italian version see CLP/2/7
Related records in the catalogueCLP/2/7
Fellows associated with this archive
NA8001Oldenburg; Henry (c1619 - 1677); scientific correspondentc1619 - 1677
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