A Rare Telescope Objective Lens by Antonio Degola
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40 Bulletin of the Scientific Instrument Society No. 111 (2011) A rare objective lens, signed by the Italian optician Antonio Degola (fl. 1680-1710), was recently ‘discovered’ in the Physics Cabinet of the Science Museum of the Uni- versity of Coimbra.The gray-green lens was discovered by Ermelinda Antunes after the removal of a thick layer of dust. This short note aims at describing its main physical features in the light of a preliminary ongo- ing research. The convergent gray-green lens (Fig. 1) is biconvex or plano-convex with a consider- ably large radius of curvature. Its diameter is 77 mm and thickness 5 mm.The lens’ most remarkable feature is the existence of two inscriptions on both sides of its surface, along the rim, revealing information about its origin and history. The inscriptions read as follows: Joannes Antonius Degola fecit Genuæ anno 1716 Pal. 60 Rom. and: Pro Ill o et [?] R mo D. Fran co Blanchino S a M a M y Can co ac [?] D [?] Papa Clem. XII Cubic.º Onory This was the objective lens of a long tube refracting telescope or an aerial telescope – devoid of a tube with the optics of the lens and the eyepiece connected together and kept aligned by a thread. According to the inscription, the lens was manufactured in Genoa in 1716 and offered by instrument maker Antonio Degola to the astronomer, antiquarian and leading member of the papal court Francesco Bianchini (1662- 1729). 2 Apparently, reference to Clement XII is a mistake, since the Pope in 1716 was Clement XI. The focal length was measured by one of the authors (G. Pereira), in collaboration with Francisco Gil, from the University of Coimbra. They reached a value of ~ 13.45 m, consistent with the 60 roman feet (13.40 m) inscribed on the lens. Significantly, a previous survey of Italian in- strument makers gave no results for surviv- ing instruments signed by Degola. 3 The lens probably came to Portugal via the Jesuits or through the direct relationship Francesco Bianchini had with his patron King John V of Portugal. In 1726, John V offered Bianchini a Newtonian telescope commissioned to Samuel Molyneux (1689- 1728) – presumably one of the first reflec- tors to reach continental Europe. 4 Two years later Bianchini dedicated his most influential astronomical book, Hesperi et phosphori nova phaenomena sive Obser- vationes circa planetam Veneris, to John V. It was a sumptuous volume containing a cartography of the planet Venus honouring Portuguese historical figures. 5 These hypotheses are currently being ex- amined and we would be grateful for any information that could contribute to the research on the history of this remarkable and rare lens. Acknowledgments This research is being conducted in the framework of the research project ‘On the Instruments Trail’ (PTDC/HIS- HCT/098970/2008), funded by the Portu- guese Foundation for Science and Technol- ogy. We are also grateful to Francisco Gil, from the Physics Department of the Faculty of Sciences and Technology of the Univer- sity of Coimbra, to Ermelinda Antunes and to the Science Museum of the University of Coimbra. References and Notes 1. See C. M. da Silva,‘Note on the Mafra Meridi- ana’, SIS Bulletin, No. 110 (September 2011), p. 43. 2. On Francesco Bianchini see: J. L. Heilbron, The Sun in the Church, Cathedrals as solar observatories (Cambridge, 1999), pp. 148- 155. 3. A. Lualdi,‘Repertorio dei costruttori italiani di strumenti scientifici’, Nuncius, 15/1 (2000), pp 169-234. 4. For details on the reflecting telescope pre- sented to Bianchini see: R. de Carvalho, A Astronomia em Portugal no Século XVIII (Lisbon, 1985), pp. 50-51, and L. Tirapicos, O telescópio astronómico em Portugal no sé- culo XVIII [masters dissertation, University of Lisbon, 2010], pp. 30-32, 128. 5.An english translation of Bianchini’s Hesperi et phosphori can be found in: F. Bianchini, Ob- servations Concerning the Planet Venus (London, 1996). Authors’ addresses: Luís Tirapicos CIUHCT/MNHNC Rua da Escola Politécnica, 58 1250-102 Lisboa, Portugal e-mail: [email protected] Gilberto Pereira Museu da Ciência da Universidade de Coimbra Largo Marquês de Pombal 3000-272 Coimbra, Portugal e-mail: [email protected] A Rare Telescope Objective Lens by Antonio Degola Luís Tirapicos and Gilberto Pereira Fig. 1 A rare objective lens, 77 mm x 5 mm, signed by the Italian optician Antonio Degola. Inventory No. FIS.1983. Photograph by Gilberto Pereira.
Transcript of A Rare Telescope Objective Lens by Antonio Degola
40 Bulletin of the Scientific Instrument Society No. 111 (2011)
A rare objective lens, signed by the Italian optician Antonio Degola (fl. 1680-1710), was recently ‘discovered’ in the Physics Cabinet of the Science Museum of the Uni-versity of Coimbra. The gray-green lens was discovered by Ermelinda Antunes after the removal of a thick layer of dust. This short note aims at describing its main physical features in the light of a preliminary ongo-ing research.
The convergent gray-green lens (Fig. 1) is biconvex or plano-convex with a consider-ably large radius of curvature. Its diameter is 77 mm and thickness 5 mm. The lens’ most remarkable feature is the existence of two inscriptions on both sides of its surface, along the rim, revealing information about its origin and history. The inscriptions read as follows:
Joannes Antonius Degola fecit Genuæ anno 1716 Pal. 60 Rom.
and:
Pro Illo et [?] Rmo D. Fran co Blanchino Sa Ma My Can co ac [?] D [?] Papa Clem. XII Cubic.º Onory
This was the objective lens of a long tube refracting telescope or an aerial telescope – devoid of a tube with the optics of the lens and the eyepiece connected together and kept aligned by a thread. According to the inscription, the lens was manufactured in Genoa in 1716 and offered by instrument maker Antonio Degola to the astronomer, antiquarian and leading member of the papal court Francesco Bianchini (1662-1729).2 Apparently, reference to Clement XII is a mistake, since the Pope in 1716 was Clement XI.
The focal length was measured by one of the authors (G. Pereira), in collaboration with Francisco Gil, from the University of Coimbra. They reached a value of ~ 13.45 m, consistent with the 60 roman feet (13.40 m) inscribed on the lens.
Significantly, a previous survey of Italian in-strument makers gave no results for surviv-ing instruments signed by Degola.3
The lens probably came to Portugal via the Jesuits or through the direct relationship Francesco Bianchini had with his patron King John V of Portugal. In 1726, John V offered Bianchini a Newtonian telescope commissioned to Samuel Molyneux (1689-1728) – presumably one of the first reflec-tors to reach continental Europe.4 Two years later Bianchini dedicated his most influential astronomical book, Hesperi et phosphori nova phaenomena sive Obser-
vationes circa planetam Veneris, to John V. It was a sumptuous volume containing a cartography of the planet Venus honouring Portuguese historical figures.5
These hypotheses are currently being ex-amined and we would be grateful for any information that could contribute to the research on the history of this remarkable and rare lens.
Acknowledgments
This research is being conducted in the framework of the research project ‘On the Instruments Trail’ (PTDC/HIS-HCT/098970/2008), funded by the Portu-guese Foundation for Science and Technol-ogy. We are also grateful to Francisco Gil, from the Physics Department of the Faculty of Sciences and Technology of the Univer-sity of Coimbra, to Ermelinda Antunes and to the Science Museum of the University of Coimbra.
References and Notes1. See C. M. da Silva, ‘Note on the Mafra Meridi-ana’, SIS Bulletin, No. 110 (September 2011), p. 43.
2. On Francesco Bianchini see: J. L. Heilbron,
The Sun in the Church, Cathedrals as solar observatories (Cambridge, 1999), pp. 148-155.
3. A. Lualdi, ‘Repertorio dei costruttori italiani di strumenti scientifici’, Nuncius, 15/1 (2000), pp 169-234.
4. For details on the reflecting telescope pre-sented to Bianchini see: R. de Carvalho, A Astronomia em Portugal no Século XVIII (Lisbon, 1985), pp. 50-51, and L. Tirapicos, O telescópio astronómico em Portugal no sé-culo XVIII [masters dissertation, University of Lisbon, 2010], pp. 30-32, 128.
5. An english translation of Bianchini’s Hesperi et phosphori can be found in: F. Bianchini, Ob-servations Concerning the Planet Venus (London, 1996).
Authors’ addresses:Luís Tirapicos CIUHCT/MNHNC
Rua da Escola Politécnica, 581250-102 Lisboa, Portugal
e-mail: [email protected]
Gilberto PereiraMuseu da Ciência da Universidade de
CoimbraLargo Marquês de Pombal
3000-272 Coimbra, Portugal e-mail: [email protected]
A Rare Telescope Objective Lens by Antonio Degola
Luís Tirapicos and Gilberto Pereira
Fig. 1 A rare objective lens, 77 mm x 5 mm, signed by the Italian optician Antonio Degola. Inventory No. FIS.1983. Photograph by Gilberto Pereira.
