Description

ENGLISH INSTRUMENTS IN ENLIGHTENMENT GENEVA: AN ILLUSTRATED MANUSCRIPT ACCOUNT BOOK WITH ASTRONOMICAL OBSERVATIONS, AS WELL AS BOTANICAL AND OTHER SCIENTIFIC CONTENT FROM THE PROMINENT GENEVA FAMILY OF PICOT, 1780–1850s

[RAMSDEN, Jesse (1735–1800); TROUGHTON, Edward (1753–1835); CAVALLO, Tiberius (1749–1809)]

PICOT, Pierre (1746–1822); PICOT, Jean Gédéon (1750–1784)

Notes on scientific instruments and astronomical observations [contained in:] a family accounts ledger dated 1780 to the title page and running to c.1800, with some later notes

Summary:

An important manuscript account of Ramsden’s achromatic eyepiece, and a transcript of a lost Edward Troughton manuscript on the reflecting circle, both contained within a large-format account book, titled ‘Grand Livre’, used by three generations of the Picot family of Geneva and extensively interspersed with scientific notes.

Physical description:

Large format ledger, bound in half-vellum with patterned paper covered boards. 370 x 242mm; 44 leaves, all but two inscribed on both sides (86 pages of writing); one slip pasted in, another larger sheet pinned into the book, and 4 pages of manuscript tipped in after the final leaf. Condition: edges worn and half the spine worn through; internally very good indeed; one small excised square (35 x 35mm) to one page of accounts, affecting text on one side only; approximately 16 leaves entirely removed near the end of the volume.

Biographical note:

The principal author of this manuscript is Pierre Picot (1746–1822), the Geneva theologian who served as Professor Theology at the Académie de Genève (from 1787), and Rector of the Académie (1790–1792). Picot was widely travelled and took an early interest in scientific matters. Around 1770 Picot met Benjamin Franklin, who unsuccessfully encouraged him to accompany Captain Cook on the of Cook’s voyages. Picot served for ten years at the church of Sattigny before returning to Geneva, where he began preaching in 1783. Picot was a close collaborator of Jacques-André Mallet (1740–1790), founder in 1772 of the Geneva observatory (which acquired its own Ramsden telescope circa 1787). In 1791 Picot wrote the éloge for Mallet, published in Lalande’s Astronomie, and it is through the Mallet family that Picot acquired his Ramsden telescope – likely also his knowledge of astronomical instruments such as the Troughton reflecting circle. We have been unable to locate any other scientific manuscripts or publications by Picot.

Contents:

The title-page reads:

Grand Livre / de / Jean Gedeon Picot / Commencé le 31 Janvier / 1780 / [in another hand] Continué par Pierre Picot

Family accounts occupy the first 34 pages, culminating in an attractive diagrammatic representation of a series of keys, surprisingly captioned in English and headed ‘Case of loss’ (‘Keys of / secretary at Front / secretary in town’ etc.).

Over the subsequent 10 or so pages the chronology is mixed, and the contents become more complex, with extensive accounts relating to the publishing firm of Barde Manget et Cie, including a transcribed legal document regarding the company’s financing. Page 21 contains a summary for 1794, including a short account of celebrations on the day of Jean-Jacques Rousseau’s birthday (28 June), and a note reading ‘Samedi 19 Juillet. Horriblé revolution à Geneve’, referring to the revolutionary uprising. Further digressive entries appear throughout the manuscript, many of them relating to the well known Genevan investment in Irish ‘Tontine’ schemes, and connecting the Picot family to many other notable Genevan scientific, religious and financial families.

The scientific contents are out of sequence, with the first chronologically being Pierre Picot’s detailed and finely illustrated account of an achromatic telescope by Jesse Ramsden, bought for him in London by ‘Dr Butini’, likely Jean-Louis Mallet-Butini (1757–1832), in June 1785. This extensive account is illustrated with numerous diagrams, explaining the construction of the telescope, including tracings made of the lenses themselves, in order to indicate exact size. Ramsden’s innovative eyepiece and micrometer was to become the standard achromatic arrangement

There are a number of later records of astronomical observations and data, including a beautifully hand-coloured illustration showing the planets Jupiter, Saturn and ‘Herschell’ (Uranus), Earth, Venus, Mars, Mercury and the Moon, with a table giving their relative sizes, and a diagram giving their inclination above the ecliptic.

Two papers relating to instruments are transcribed in full. The first (chronologically) is Tiberius Cavallo’s 1791 Philosophical Transactions paper ‘Description of a Simple Micrometer for Measuring Small Angles with the Telescope’ – notable given the account of telescope micrometry in Picot’s description of Ramsden’s telescope. The second is a translation into French of Edward Troughton’s now-lost manuscript on the use of his reflecting circle. This document is here dated 1 June 1801, though it is unclear whether this relates to the translation or the original document, which is otherwise only known through it’s later publication in John Fry Heather’s standard work A Treatise on the Principal Mathematical Instruments.

Further scientific contents include an extensive extract from a work on mammals from 1854–55, and a full-page illustrated botanical diagram dividing plants into 22 classes.

Literature:

– H.E. Dall, ‘Telescope eyepieces’, Journal of the British Astronomical Association, Vol. 79 (1969), pp. 349–356 (p. 354 for the improved Ramsden eyepiece)

– Raoul Gautier and Georges Tiercy, L’Observatoire de Genève, 1772–1830–1930 (1930)

– Anita McConnell, Jesse Ramsden (1735-1800) London’s Leading Scientific Instrument Maker (2007)

– Jennifer Powell McNutt, Calvin Meets Voltaire, The Clergy of Geneva in the Age of Enlightenment, 1685–1798 (2016)