Guinand, Pierre Louis

SUBJECT AREA: Photography, film and optics

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b. 20 April 1748 Brenets, Neuchâtel, Switzerland

d. 13 February 1824 Brenets, Neuchâtel, Switzerland

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Swiss optical glassmaker.

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Guinand received little formal education and followed his father's trade of joiner. He specialized in making clock cases, but after learning how to cast metals he took up the more lucrative work of making watch cases. When he was about 20 years old, in a customer's house he caught sight of an English telescope, a rarity in a Swiss mountain village. Intrigued, he obtained permission to examine it. This aroused his interest in optical matters and he began making spectacles and small telescopes.

Achromatic lenses were becoming known, their use being to remove the defect of chromatic aberration or coloured optical images, but there remained defects due to imperfections in the glass itself. Stimulated by offers of prizes by scientific bodies, including the Royal Society of London, for removing these defects, Guinand set out to remedy them. He embarked in 1784 on a long and arduous series of experiments, varying the materials and techniques for making glass. The even more lucrative trade of making bells for repeaters provided the funds for a furnace capable of holding 2 cwt (102 kg) of molten glass. By 1798 or so he had succeeded in making discs of homogeneous glass. He impressed the famous Parisian astronomer de Lalande with them and his glass became well enough known for scientists to visit him. In 1805 Fraunhofer persuaded Guinand to join his optical-instrument works at Benediktheurn, in Bavaria, to make lenses. After nine years, Guinand returned to Brenets with a pension, on condition he made no more glass and disclosed no details of his methods. After two years these conditions had become irksome and he relinquished the pension. On 19 February 1823 Guinand described his discoveries in his classic "Memoir on the making of optical glass, more particularly of glass of high refractive index for use in the production of achromatic lenses", presented to the Société de Physique et d'Histoire Naturelle de Genève. This gives details of his experiments and investigations and discusses a suitable pot-clay stirrer and stirring mechanism for the molten glass, with temperature control, to overcome optical-glass defects such as bubbles, seeds, cords and colours. Guinand was hailed as the man in Europe who had achieved this and has thus rightly been called the founder of the era of optical glassmaking.

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Further Reading

The fullest account in English of Guinand's life and work is 'Some account of the late M. Guinand and of the discovery made by him in the manufacture of flint glass for large telescopes by F.R., extracted from the Bibliothèque Universelle des Sciences, trans.

C.F.de B.', Quart.J.Sci.Roy.Instn.Lond. (1825) 19: 244–58.

M.von Rohr, 1924, "Pierre Louis Guinand", Zeitschrift für Instr., 46:121, 139, with an English summary in J.Glass. Tech., (1926) 10: abs. 150–1.

LRD