TitleGregorian telescope Datec 1733-1755About this objectThis reflecting telescope follows the design proposed by Scottish mathematician and astronomer James Gregory in his 1663 treatise Optica Promota. It features two concave mirrors: a primary paraboloid that gathers and focuses light, and a secondary ellipsoid that reflects the image back through a central aperture in the primary mirror. The eyepiece, positioned at the rear of the instrument, allows the observer to view an upright image – an advantage for astronomical and terrestrial use.
Although Gregory’s concept predated Isaac Newton’s reflecting telescope, it was not successfully constructed until 1673, when Robert Hooke built the first model. The Gregorian design offered several improvements over earlier reflectors, including a shorter tube relative to its focal length and the ability to observe from behind the primary mirror. These features made it particularly suitable for fieldwork and navigation.
This object is an example of the type of telescope used by mariners in the 18th century, when precise optical instruments were essential for surveying, charting and celestial navigation. Its design reflects the intersection of theoretical innovation and practical application during a period of rapid advancement in optics and exploration. Object No.88.58Inscriptions & marksParis à Paris'DimensionsH: 415mm
W: 420
D: 200mmPlace madeFranceMaterialBrassGlassSharkskinSourceLa Perouse MuseumCredit lineGift of Secretariat d'État au Pacifique Sud, 1988On displayYesTypeMuseum objectsOrganisations (Detailed entries)La Perouse Museum (La Perouse, N.S.W.)ThemesEuropean arrivalsScience and communication
