ROCA-ROSELL, A. (ed.).(2012) The Circulation of Science and Technology: Proceedings of the 4th International Conference of the ESHS, Barcelona, 18-20 November 2010. Barcelona: SCHCT-IEC, p. 462.

I. M. PERES, M. E. JARDIM, F. M. COSTA: THE PHOTOGRAPHIC SELF-RECORDING OF NATURAL PHENOMENA IN THE NINETEENTH CENTURY

Isabel Marília PERES1, Maria Estela JARDIM2, Fernanda Madalena COSTA1 1Centro de Ciências Moleculares e Materiais da Universidade de Lisboa, PORTUGAL [email protected] 2Centro de Filosofia das Ciências da Universidade de Lisboa, PORTUGAL [email protected]

Abstract

From the time of its discovery, photography participated in the production of evidence in many scientific fields. In the second half of the nineteenth century the quality of the photographic images as well as the discovery of easier and more reliable photographic techniques, transformed photography in a precious tool for scientists; they were now able to register in an indirect way atmospheric and magnetic phenomena. Throughout Europe, Meteorological and Astronomical Observatories had started to be equipped with photographic self-recording instruments in order to be able to register in a continuous way temperature, pressure or atmospheric electricity variations. One of these Institutions was the Kew Observatory, considered one of the best in Europe. By the end of the nineteenth century, the Infante D. Luiz Observatory of Lisbon, the Meteorological and Magnetic Observatory of the University of Coimbra, as well as the Meteorological and Magnetic Station of Oporto, owned photographic self-recording instruments for meteorological and magnetic purposes: barographs, psychrographs, electrographs and some magnetographs. Portuguese scientists established privileged scientific contacts, namely with the Director of the Kew Observatory, Balfour Stewart (1828-1887) and with William Thomson (Lord Kelvin) (1824-1907), among others. In this paper we will present our research on the instruments, photographic processes and photographic data, as well as on the contributions of Portuguese scientists in this field focusing on the international cooperation between Portugal and other European countries.

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Introduction In 1839, the French physicist François Arago (1786-1853), presented to the Academy of Sciences in Paris the works of Louis Daguerre (1787-1851) and Joseph Niépce (1765-1833) relative to Photography. He considered with great forecast the contribution that photography would have for science and art. In his speech, Arago indicated the perspectives of use of this discovery as indispensable to the scientist in the areas of Astronomy, Archeology and Spectroscopy, among others1. Scientists quickly became aware of the capacity and importance of the photographic technique in the production of evidence in many scientific fields. In the second half of the nineteenth century the discovery of easier and more reliable photographic techniques, transformed photography in a precious tool for scientists; they were now able to register directly the image of nature captured with a photographic camera (figure 1), or in an indirect way, through the reading of data for a natural phenomenon in a photographic self-recording instrument.

Fig. 1: Stereoscopic map of Peak and great crater of Tenerife (C. Piazzi Smyth; 1858).2

Meteorological Observatories throughout Europe The Royal Observatory of Greenwich in London (figure 2) played a major role in the history of astronomy and navigation, and it is best known as the location of the prime meridian. The observatory was commissioned in 1675 by King Charles II. At this time the King also created the position of Royal Astronomer. John Flamsteed (1646-1719) was the first to be appointed as director of the observatory. The earliest known measurement of magnetic declination was made by Flamsteed in 1680. The difficult nature of magnetic and meteorological observations led to the development of automatic recording devices. Between 1846 and 1852, the English surgeon Charles Brooke (1804-1879) invented a series of self-recording instruments which used photography for the automatic registration of meteorological and magnetic data. A coal gas light- source, mirrors and optics to amplify readings and a clockwork drum covered in photographic paper to record the results were used (BROOKE; 1847; 1850; 1852). These instruments included a barometer, a thermometer, a psychrometer, and a magnetometer (figure 3)3. An example of a photographic record using these instruments is shown in figure 4. These type of self-recording instruments were adopted at the Royal Observatories of Kew and Greenwich, Paris, and other meteorological stations around the world.

1 Ŗ(…) À lřinspection de plusieurs des tableaux qui ont passé sous vos yeux, chacun songera à lřimmense parti quřon aurait tiré, pendant lřexpédition dřEgypte. (…) les réactifs découverts par M. Daguerre hâteront les progrès dřune des sciences qui honorent le plus lřesprit humain. Avec leur secours, le physicien comparera les lumières par leurs effets (…), le même tableau donnera des empreintes du soleil, des rayons des étoiles.ŗ (ARAGO; 1858). 2 In Report on the Teneriffe astronomical experiment of 1856, probably the first scientific book with stereoscopic photographs. 3 Charles Brooke's inventions were awarded by the British Government, and the jurors of the Great Exhibition in London (1851).

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Fig. 2: Royal Observatory of Greenwich (MAUNDER; 1900).

Fig. 3: Brooke’s Self-recording barometer and thermometer (GREAT EXHIBITION of the Works of Industry of All Nations London; 1851).

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Fig. 4: Photographic records (BROOKE; 1847- plate VIII).

The Kew Observatory was an astronomical and terrestrial magnetic observatory founded by King George III in Richmond, Surrey. In 1842, the Council of the Royal Society proposed to establish, in connection with the British Association, a Physics Observatory in order to improve the knowledge of meteorology and magnetism. A Committee was created to construct a self-recording meteorological apparatus to be employed at the Kew Observatory (SCOTT; 1885). A purchase order for a set of meteorological and magnetic instruments to be used for the self-registration of atmospheric data was granted to the meteorologist Francis Ronalds (1788-1873). In 1847 Ronalds presented to the Royal Society a description of the photographic self-recording instruments (RONALDS; 1847). These instruments (electrometer, thermometer, barometer, and declination magnetometer), were very similar to the instruments in use at the Royal Observatory of Greenwich. In 1859 Balfour Stewart (1828-1887), a Scottish physicist, was appointed director of the Kew Observatory. He became interested in doing research on meteorology and terrestrial magnetism. These instruments were designed by J. Wesh and constructed by the maker Patrick Adie from London (STEWART; 1859). In the following year Stewart published ―An Account of the Self-recording Magnetographs at present in operation at the Kew observatory‖ and presented a plate with its description (figure 5). The first report (1867) of the Meteorological Committee of the Royal Society imparted a considerable impetus to the manufacture and use of these instruments (HICKS; 1886). In 1885 several Observatories were supplied with Kew Pattern Magnetographs: Batavia, Coimbra, Lisbon, United States, St. Petersburg, Florence, Stonyhurst, Utrecht, Melbourne, Bombay, Mauritius, Vienna, Zi-Ka-Wei, San Fernando, Potsdam, Brussels, and Nice (SCOTT; 1885). The Kew Observatory was in the second half of the 19th century an important center of the internationalization of physics, and more specifically, of geomagnetism (MALAQUIAS; 2005).

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Fig. 5: Self-recording magnetographs (STEWART; 1860).4

Portuguese Meteorological Observatories In the 1850s, the Lisbon Polytechnic School and the University of Coimbra submitted to the Portuguese government proposals to implement their own geomagnetic observatories and to collaborate with the already existing international network. Portugal joined the Magnetic Union in the summer of 1857. Brito Capello (1841-1917), observer from the Observatory of Infante D. Luiz (figure 6), made a scientific trip to the Paris and London Observatories, to become acquainted with the instruments used in these institutions. Following Brito Capello‘s advice the Lisbon Observatory bought some instruments: magnetographs and the Thomson‘s electrograph from the maker Patrick Adie of London, and the baropsychrograph from the maker Jules Salleron of Paris (OBSERVATORIO Infante D. Luiz; 1862). In 1860, with the same purpose, Jacinto António de Sousa (1818 -1880), a physicist professor from the University of Coimbra, visited Madrid, Paris, Brussels, London, Greenwich, and Kew. In a report presented to the respective University authorities he referred the reasons to adopt the Kew model for the magnetographs, a Thomson‘s electrograph and a baro- psychrograph from Patrick Adie. The Coimbra Observatory (figure 7) acquired these instruments in 1866 (SOUZA; 1862; 1875). By the beginning of the 20th century (1903), the Directors of the Observatories of Lisbon, Coimbra, Oporto and Azores (respectively A. Pina Vidal, A. Santos Viega, F. Paula Azeredo and F. Afonso Chaves) decided to organize and distribute among their institutions the tasks of meteorological and magnetic determinations. Coimbra was responsible for the magnetic data and the Observatory of Oporto (figure 8) for the study of atmospheric electricity. Following this decision, a Kelvin-Mascart quadrant electrometer was bought in 1904 for this Observatory (MACHADO; 1949).

4 Legend: Fig. 1 and 2 - the horizontal force magnetograph; fig. 3 and 4 - the vertical force magnetograph; fig. 5, 6 and 7 - the declination magnetograph; fig. 8 and 9 - the register cylinder and the clockwork and fig. 10, 11 and 12 - the gas lamp and the lens.

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Fig. 6: Observatory of Infante D. Luiz (OBSERVATORIO Infante D. Luiz; 1862).

Fig. 7: Meteorological and Magnetic Observatory of Coimbra (SOUZA; 1875).

Fig. 8: Meteorological and Magnetic Observatory of Oporto (MACHADO; 1929).

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Photographic self-recording instruments William Thomson (Lord Kelvin) published for the first time a description of a divided-ring electrometer in the Memoirs of the Roman Academy of Sciences in 1857 (THOMSON; 1857). Later on, in 1865 the Portuguese periodical Annaes do Observatório do Infante D. Luiz reported a description of the Thomson‘s electrograph working method with the photographic register of atmospheric electricity variations in a continuously mode. The system for these measurements was composed by three units: one container full of water working as a collector (figure 9b) that was connected by a copper wire (A) to the electrometer (figure 9a); in its inside is suspended by a platinum wire an aluminum needle (a). This needle electrified by the Leyden bottle (b) becomes very sensitive and detects the variations of atmospheric electricity transmitted to the metallic semi circle (c); the air inside was dried with pieces of pumice stone imbibed with sulfuric acid in the lower part (h) of the electrometer unit . Above the needle is suspended a small round mirror (e) that reflects a beam of light to an adequate rotating cylinder unit, covered with a photographic paper able to register the needle deviations.

Fig. 9 a, b: Thomson’s electrograph (SILVEIRA; 1865).

Brito Capello observed that sulphuric acid wasn‘t strong enough to dry the air and he wrote to William Thomson asking for advice on this problem. In his letter (figure 10), Lord Kelvin explains to Capello how he used the electrometer in order to get results with more accuracy for the studies of atmospheric electricity and the technique of photographic data recording (THOMSON; 1864). Later, in 1867, Thomson presented, in a Report to the British Association of Science, an improvement to the previous design, including a light mirror which would indicate deflections of the moving body and substitution of the half rings by four quadrants5 (figure 11). Another instrument, Branly‘s electrometer, an improvement on the Thomson‘s electrometer was in use by 1877 in the Lisbon Observatory (OBSERVATORIO Infante D. Luiz; 1877)

5 This instrument used the electrical force generated between charged electrodes. A butterfly‐shaped electrode with two quadrants of a circular disk is supported by a torsion fiber inside a stationary circular box composed of four quadrants, with opposite pairs of which are electrically connected. The rotation of the suspended electrode depends on the potentials applied to the various electrodes.

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Fig. 10: William Thomson’s letter to Brito Capello: 22/12/1864 (IGIDL).

Fig. 11: Thomson’s quadrant electrometer (c.a. 1867), Fig. 12: Éleuthère Mascart’s photo (Photographie MCUL00331 (M. Peres 2008). des Grands Magasins du Louvre à Paris, c.a.1890) (IGIDL- Photographs folder).

Later on 1883 a further improvement of the Thomson‘s electrometer was described by the French physicist Éleuthère Élie Nicolas Mascart (1837 – 1908), in La Nature (MASCART; 1883). This new instrument was constructed by the French maker Carpentier.

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Fig. 13: Self-recording instruments for the electric potential, adapted from Mascart (Ph. Péllin Catalogue; n.d.).

In figure 13 Mascart‘s self-recording electrometer is shown, comprising the collector (water drop system, isolated by Mascart‘s insulators), the electrometer with a Daniell‘s battery with ten elements, and on the far-right, the lantern with a gas lamp and the box with the photographic paper. The Oporto Observatory in 1904 bought a Mascart‘s electrometer from the maker Carpentier with a Daniell‘s battery with a fifty elements. The photographic register and the lantern were bought from the maker Pellin (figure 14). However, the first experiments in atmospheric electricity started only in 1927.

Fig. 14: The photographic system from the Kelvin-Mascart Electrometer (Instituto Geofísico da Universidade do Porto – photograph, courtesy of Marisa Monteiro, MCUP).

In 1864 Fradesso da Silveira, Director of the Infante D. Luiz Observatory, reported a new instrument: the baro- psychrograph (figure 15). This was a self-recording instrument that would simultaneously register pressure and temperature (readings of dry-bulb and wet-bulb thermometers) in two photographic papers, with the same lamp (SILVEIRA, 1864).

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Fig. 15: Salleron’s baro-psychrograph (SILVEIRA, 1864).

In Coimbra a baro-psychrograph made by Patrick Adie was also acquired in 1867. According to Jacinto de Souza, the Observatory‘s director, it was a unique instrument because it has resulted from scientific discussions between the maker and himself6 (CORTE REAL; 1872). In the Observatory Infante D. Luiz under the direction of Fradesso da Silveira the magnetographs (made by Adie) were in regular operation by the beginning of July, 1863 (figure 16).

Fig. 16: Octagonal box with devices for registering the magnetographs (MCUL.00354) (Photograph by Marília Peres).

These magnetographs worked until 1902. According to Fradesso da Silveira: ŖThe three magnetographs were placed in the vault room on the first floorŗ (figure 17) (SILVEIRA; 1864).

6 The whereabouts of this instrument are unfortunately not known.

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Fig. 17: The magnetographs’ room (Archive of Ajuda Astronomical Observatory, Folder 723).7

In the context of the referred international collaboration, Brito Capello sent some copies of the Lisbon magnetic curves to Stewart, superintendent of the Kew observatory. The corresponding data (figure 18) of two observatories was discussed in a paper by Capello and Stewart published by the Royal Society (CAPELLO & STEWART; 1864).

Fig. 18: Photo-lithographic Impressions of traces produced simultaneously by the magnetographs at Kew and Lisbon (Kew and Lisbon Observatories, 1864).

The first attempt to register magnetic data in the Meteorological Observatory of Coimbra was in 1867. However, some problems were reported by Jacinto de Souza: humidity, inconstancy of the gas-lamp light and the operators inexperience (Souza; 1875). These magnetographs worked until 1930, when they were replaced by the Askania Model. The 19th-century instruments (figure 19) are now in the collection of the Instituto Geofísico da Universidade de Coimbra.

7 This photograph was found in the archive of the Ajuda Observatory, in Lisbon. An identical one taken by Francisco Rocchini, entitled. ―Astronomical Observatory at Ajuda‖, belongs to the collection of Arquivo Fotográfico da Câmara Municipal de Lisboa no. 8179‖ (PAVÃO; 1990).We think it represents the vault room referred by F. Silveira.

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Fig. 19: The declination magnetograph; IGUC (photograph, Marília Peres).

The Geophysics Institute of the University of Coimbra holds an important collection of magnetograms from the long period of studies on geomagnetism at the Coimbra Observatory, since 1867 until today. These magnetograms are an important source for the study of solar activity. In figure 20 is shown a relevant example of one of this magnetograms; the great solar storm that took place on the 24th-25th October, 1870, is registered in this magnetogram. This photographic recording was studied in 2008 by Vaquero et al (VAQUERO; 2008).

Fig. 20: Photographic recording, IGUC (Photograph: Marília Peres).

The photographic process The first known description for the photographic process, for self-recording instruments, was made in 1847 by Charles Brooke in the Philosophical Transactions (BROKE; 1847). Ŗ (…) to prepare by a ready process photographic paper sufficiently sensitive to receive the feeble impressions of artificial light, and at the same time sufficiently durable to retain those impressions during a period of at least twelve hours, as a more frequent attention to the apparatus would probably interfere with the ordinary arrangements of an observatoryŗ.

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The paper was sensitized with silver bromide and a small quantity of silver iodide, and he used isinglass8 as a catalyst in the development of the photographic image. The paper used in the photographic process was previously washed with a solution of silver nitrate. A saturated solution of Gallic acid with a very small quantity of acetic acid was used as a developing solution. The paper was then washed two or three times in water and the image was fixed with a solution of sodium thiosulphate. For the chemist and physicist William Crookes (1832-1919) the advantage of the photographic process in self- recording instruments was in the sharpness and definition of the image which made it convenient for later consultation. However, there was a problem: the shrinkage of the paper when the chemical substances were applied. Crookes made an improvement. He used the wax-paper process invented by Gustave Le Gray (1820-1884) to prevent paper shrinkage and distortion of the image during its development in baths and washing of the chemical substances. He applied successfully the process to the barograph and the thermograph of the Radcliffe Observatory (CROOKES; 1857). The crucial difference between the calotype and the wax paper process was in the preparation of the paper. In the calotype process the first step was the sensitization of a sheet of high quality paper with a combination of silver halides. After exposure in a camera the image was developed and fixed with sodium thiosulphate. The translucency of the paper negative could be increased by saturating with wax. This helped to increase the contrast and shorten printing times. In most respects, the preparation of wax paper negative parallels the preparation of the calotype, except for one important difference: in Le Gray‘s wax paper negative process, the paper was saturated with wax before the chemical sensitization. This simple reversal of one step deeply altered the quality of the photographic paper, improving its wet strength. Finally, the most practical advantage offered by the new negative process was its impressive longevity. Because of the protective qualities of wax, a week‘s supply of fully prepared paper could be stored (CROOKES; 1857). This process was used by Balfour Stewart in Kew in 1859 and in the Coimbra Observatory. To enhance stability, a gold toning bath using gold and sodium chloride was added to the positive proof, which also gave an artistic finishing to the photographic image (STEWART; 1860).

Final Notes . The use of photographic devices for meteorological and magnetic studies has been crucial for its development. . The photographic process had the advantage of improving the sharpness and sensitivity of the data record. . The wax-process prevented paper shrinkage and distortion of the image during its development in baths and washing of chemical substances. . A remarkable improvement of scientific instrumentation and data processing systems, in a short relatively period of time, was achieved by these institutions. . European Observatories exchanged a great deal of information through an intensive use of scientific correspondence and circulation of publications, books and periodicals.

Acknowledgements: We are most thankfully to the following institutions for their support during this research: . Instituto Geofísico Infante D. Luís . Instituto Geofísico da Universidade de Coimbra . FCT – Fundação para a Ciência e Tecnologia . Ministério da Educação de Portugal . Museu de Ciência da Faculdade de Ciências da Universidade do Porto . Museu de Ciência da Universidade de Lisboa . Observatório Astronómico da Ajuda.

8 A transparent, almost pure gelatin prepared from the air bladder of the sturgeon and certain other fishes and used as an adhesive and a clarifying agent.

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