By Steven van Roode
The transit of Venus on 1761 June 6 was the first observed throughout the world. Inspired by the appeal of Edmond Halley, astronomers travelled all around the globe to measure the phenomenon in order to find the distance tot the Sun. Many other would remain home, observing from their convenient observatories. The accuracy of the measurements were flawed due to an unexpected optical effect: the black drop.
Self-made astronomer Jan de Munck constructed his own observatory next to his house De Globe at 126 Zuidsingel in Middelburg in 1736. From this observatory he observed the 1761 transit of Venus with his 10 feet refractor. He also provided a projected image of the sun for a couple of friends, who he invited to watch the phenomenon. The observatory tower was torn down in 1775, but the house is still present, with a plaque commemorating De Munck.
Location: 51°30′09″.9 N, 3°37′01″.0 E times of contact
From the residence Zorgvliet of Willem Bentinck van Rhoon astronomer Dirk Klinkenberg observed the 1761 transit of Venus. Early in the morning he watched sunrise with a gregorian telescope from a dune west of Zorgvliet. Later on he went back to Zorgvliet and observed the remaining part of the transit with a cassegrain telescope. Afterwards, Klinkenberg discovered that his time piece was in error of at least ten seconds, making his observations useless. Today, Zorgvliet is known as Catshuis and is the residence of the Dutch prime minister.
Location: 52°05′25″.1 N, 4°17′06″.1 E times of contact
In the Netherlands the 1761 transit of Venus was observed by several people. Johan Lulofs was professor of mathematics and philosophy at Leiden University and made his observations from the simple university observatory which was located on the roof of the Academy Building.
Location: 52°09′25″.5 N, 4°29′08″.1 E times of contact
In Dordrecht, on the roof of his house at Groenmarkt 2-4, Gerardus Kuypers had a small observatory, constisting of a wooden platform. On the day of the transit there was a large crowd at Kuypers’ observatory. As a result, the floor was moving all the time, making observations of any value impossible.
Location: 51°48′54″.4 N, 4°40′00″.3 E times of contact
From the College van Gedeputeerde Staten van Friesland, Wytse Foppes Dongjuma was given Camminghaburg to observe the 1761 transit of Venus. Camminghaburg was an old castle near Leeuwarden, which was then in use as for storage of ammunition. Among the nine students who shared in the observation was probably also Eise Eisinga. Camminghaburg was demolished in 1810 and nothing of the castle can be seen today.
Location: 53°12′48″.6 N, 5°48′41″.2 E times of contact
Financed by the General Assembly of Massachusetts John Winthrop packed up two young student assistants, Samuel Williams and Isaac Rand, an excellent clock, an octant and two telescopes, and embarked for St. John’s, Newfoundland to observe the transit of Venus in 1761. Winthrop’s exact position is not known, but the very top of Kenmount Hill seems to be the most propable location. His observation is commemorated with a plaque on an armillary sphere opposite the Henrietta Harvey Building on St. John’s campus of Memorial University of Newfoundland.
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Location: 47°32′01″ N, 52°47′26″ W times of contact
From Powderham Castle near Exeter, William Chapple and a friend tried to catch a glimpse of the rumoured satellite of Venus during its transit across the sun. They only found two sunspots, which were seen in a line with Venus, but did not follow the planet’s motion.
Location: 50°38′34″.4 N, 3°27′37″.1 W times of contact
From his farmhouse Underwood in Mosser near Cockermouth, West Cumberland, yeoman farmer Isaac Fletcher observed the 1761 transit of Venus, together with George Bell and Elihu Robinson. They set up a solar telescope and watched the projected image of the sun on a white cloth. During the transit, clouds sometimes interfered. Soon after the transit ended, thick clouds covered the complete sky.
Location: 54°36′36″.5 N, 3°22′54″.3 W times of contact
The president of the Royal Society, George Parker, 2nd Earl of Macclesfield, had built an observatory at his residence, Shirburn Castle near Oxford. Here Thomas Hornsby observed the 1761 transit of Venus, together with two assistants of Parker, John Bartlett and Thomas Phelps. The morning at first seemed unpromising, yet the clouds began to disperse and Hornsby made many measurements of the differences of Venus and the sun’s limb.
Location: 51°39′30″.1 N, 0°59′39″.6 W times of contact
In 1761 Samuel Dunn, master of the academy at Ormonde House in Chelsea, took advantage of the good observatory located at the school to observe the transit of Venus. For the occasion, Dunn had constructed an angular micrometer to measure the diameter of Venus and the planet’s distance to the sunspots. Today, Ormonde House has been demolished.
Location: 51°29′12″.8 N, 0°09′37″.7 W times of contact
In 1761 the Duke of York wanted to observe the rare transit of Venus and asked James Short to attend him on that occasion at his residence, Savile House in London. Short planned to measure the distance of Venus from the sun’s limb, but clouds prevented these observations at the start of the transit. However, about an hour before egress the sun was perfectly clear during the remainder of the transit and he could time both interior and exterior contact. Savile House, at 5–6 Leicester Square, was destroyed by fire in 1865.
Location: 51°30′38″.9 N, 0°07′50″.4 W times of contact
At the Royal Observatory in Greenwich the 1761 transit of Venus was observed by Nathaniel Bliss. The Astronomer Royal, James Bradley, wasn’t able to take part in the observations due to poor health. The sky was very cloudy the morning of the transit, till the end of the transit was approaching, when is was tolerable clear. Bliss timed both the interior and exterior contact at egress.
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Location: 51°28′40″.8 N, 0°00′07″.1 W times of contact
In 1761 the reverend William Hirst observed the transit of Venus on top of the colonial governor’s house in Fort St George, at Madras in India. At the terrace of the fort house Hirst, governor George Pigot and Mr. Call called at their instruments. At interior contact at ingress, Hirst noticed that the planet Venus resembled more the form of a bergamot pear instead of appearing truly circular. Today, the terrace doesn’t exist anymore.
Location: 13°04′46″.6 N, 80°17′14″.2 E times of contact
At the priory of Saint-Lô in Rouen, prior Jean Bouin had an observatory. From this observatory he watched the 1761 transit of Venus, together with brother Jarnard. At sunrise, he started with a 6-feet telescope and at egress continued with a 9-feet telescope. Vincent Dulague, professor of hydrography at Rouen, was also present. He used a 4-feet telescope at first, and changed to a 16-feet telescope at egress. Today, only a portal of the ancient church of the priory is still present as part of the Lycée Camille Saint Saëns.
Location: 49°26′32″.3 N, 1°05′37″.6 E times of contact
From the philosophical and optical chamber of King Louis XV at the Château de la Muette near Paris, Swedish astronomer Bengt Ferner observed the 1761 transit of Venus. He was accompanied by astronomer Jean-Paul Grandjean de Fouchy and the king’s chief scientist father Noël. Today, the original Château de la Muette has completely disappeared.
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Location: 48°51′31″.1 N, 2°16′17″.4 E times of contact
At the Observatoire Royal in Paris astronomer Jean-Dominique Maraldi observed the 1761 transit of Venus with a six feet telescope, equipped with a micrometer. Around the disk of Venus Maraldi discerned a reddish glow, which he attributed to the fatigueness of his eyes.
Location: 48°50’10″.8 N, 2°20′11″.4 E times of contact
During the first hours after sunrise, persistent clouds in the east permitted Joseph-Jérôme le François de Lalande to make only few observations from the Palais du Luxembourg in Paris. Only after seven het was able to measure the distances between the limbs of Venus and the sun with a heliometer. At the end of the transit, he could time the last two contacts under favourable conditions. The dome at the entrance of the Palais du Luxembourg, facing the Rue de Tournon, had been used for astronomical observations before.
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Location: 48°50′56″.9 N, 2°20′14″.3 E times of contact
From the Observatoire de la Marine at the Hôtel de Cluny in Paris, Charles-Joseph Messier observed the 1761 transit of Venus. The observatory, a wood and glass structure consisting of a pyramidal framework with opening windows, was built on top of the tower. The observatory dome was later removed from the tower.
Location: 48°51′01″.4 N, 2°20′39″.0 E times of contact
At the abbey of Saint Geneviève its librarian Alexandre-Gui Pingré had a small observatory. Pingré observing on Rodrigues Island, the observatory was used by Joseph-Nicolas Delisle to watch the 1761 transit of Venus. Delisle was a key figure in the international preparations for the transit enterprise. Today, the Lycée Henri IV occupies the abbey’s buildings.
Location: 48°50′46″.2 N, 2°20′52″.6 E times of contact
From the tower of the episcopal palace in Béziers, Jean Bouillet, his son Jean-Henri-Nicolas, Mr. De Manse and the bishop of Béziers, Joseph-Bruno de Bausset de Roquefort, observed the transit. The night before, they slept at the palace and before sunrise went to the tower. They used a telescope of 7 feet focal length and one of 24 feet.
Location: 43°20′29″.1 N, 3°12′33″.0 E times of contact
From the observatory on the Tour de la Babote in Montpellier, France, Barthélemy Tandon observed the 1761 transit of Venus. Other members of the Société Royale des Sciences de Montpellier, like Etienne-Hyacinthe de Rotte and Jean-Baptiste Romieu, were also present. Today, the Fédération d’astronomie populaire amateur du Midi makes use of the building.
Location: 43°36′23″.3 N, 3°52′38″.6 E times of contact
From the observatory of the Jesuit Collège de la Trinité in Lyon, professor of mathematics Laurent Béraud observed the two contacts at egress with a telescope of 19 feet. The observatory building consisted of an eight stories′ square tower built on top of the college’s church. It was destroyed in 1793 during the siege of Lyon.
Location: 45°45’55″.8 N, 4°50′14″.5 E times of contact
In April 1761, after a five month’s journey, the Abbé Jean-Baptiste Chappe d’Auteroche reached Tobolsk in Siberia, east of the Ural Mountains. He set up his wooden observatory on a plateau just outside the town. The observation of the transit of Venus went well, but Chappe had to take precautions to the fury of the local inhabitants, who thought he was a magician. Efforts are now being made to install a plaque on the hill to commemorate the observation.
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Location: 58°11’43″.4 N, 68°15′29″.1 E times of contact
From the observatory of the university of Lund, located on top of the round tower of the Lundagårdshuset professor of mathematics Nils Schenmark observed the 1761 transit of Venus. Due to clouds only the last stages of the external contact at egress could be seen. Schenmark observed with a refractor of 21 feet focal length, while his collegue, Johan Henrik Burmester, used a refractor of 16 feet focal length.
Location: 55°42′19″.4 N, 13°11′38″.7 E times of contact
From the observatory founded by Anders Celsius in Uppsala, Sweden, astronomer Mårten Strömer observed the 1761 transit of Venus. Strömer was assisted by Torben Bergman and Metlander Mallet. The observatory was constructed on the rooftop of a medieval building in the centre of Uppsala. Today, the building still exists, but the observatory tower was dismounted in 1857.
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Location: 59°51′35″.6 N, 17°38′13″.0 E times of contact
In Stockholm, at the Observatory of the Royal Swedish Academy of Sciences, the head of the observatory, Pehr Wilhelm Wargentin, and Samuel Klingenstierna observed the 1761 transit of Venus. Wargentin made use of a 21 feet telescope, while Klingenstierna used a 10 feet telescope by Dollond with a power of 140 times.
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Location: 59°20′29″.4 N, 18°03′16″.6 E times of contact
In 1761 the Danish Astronomer Royal, Christian Horrebow, presided the observations made at the Rundetaarn, a high observatory tower in the centre of Copenhagen. Although the weather was perfect, the results were rediculed due to the observer’s inability to keep correct track of the time.
Location: 55°40′53″.0 N, 12°34′32″.8 E times of contact
At St Petersburg Observatory, located on the roof of the Imperial Academy of Sciences (modern Kunstkamera), Russian scientist Mikhail Lomonosov did a special observation during the 1761 transit of Venus. Just before ingress and just after egress, he noticed a bright ring of light around Venus’ outline. Lomonosov correctly attributed this aureole to the planet’s atmosphere. While Lomonosov focused on the observation of physical phenomena, astronomers Andrey Krasilnikov and Nikolay Kurganov carried out the contact observations.
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Location: 59°56′29″.4 N, 30°18′16″.1 E times of contact
In spring of 1761 astronomer Christian Mayer set up three small observatory buildings in front of the orangery in the gardens of Schwetzingen Castle, Germany. One was for a quadrant, another for a telescope by Dollond and one for a clock. Together with Elector Carl Theodor, who was ill on the day of the transit, he observed the transit of Venus under rainy conditions; egress couldn’t be timed with certainty because of intervening clouds.
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Location: 49°23′07″.7 N, 8°33′56″.4 E times of contact
The first observatory of Würzburg University was established in 1757 and located on the tower of the Neubaukirche. From this observatory professor of mathematics and astronomy Franz Huberti observed the 1761 transit of Venus with a reflecting telescope. A stone marker commemorates the observatory and Huberti’s observation of the transit of Venus.
Location: 49°47′25″.6 N, 9°55′55″.8 E times of contact
From the observatory of Göttingen in Germany, astronomer Tobias Mayer observed the 1761 transit of Venus with a telescope of 12 feet focal length. The observatory was located on a medieval tower and was also furnished with a mural quadrant by Bird and a reflector. After the observatory already moved to another location in the early nineteenth century, the tower was demolished in 1897.
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Location: 51°31′49″.3 N, 9°56′06″.0 E times of contact
From the Toplerhaus in Nürnberg, physician Georg Friedrich Kordenbusch observed both contacts at egress with a Gregorian reflector. In 1945 the Toplerhaus was completely destroyed by an Allied air raid.
Location: 49°27′29″.3 N, 11°04′44″.5 E times of contact
From the observatory of the monastery Berge near Magdeburg Georg Christoph Silberschlag observed the 1761 transit of Venus together with Heinrich Wilhelm Bachmann. The atmosphere of Venus was clearly seen by the observers. The monastery was demolished in 1813 by the French.
Location: 52°06′52″ N, 11°38′01″ E times of contact
From his observatory at the Grauen Kloster in Eldena, just outside Greifswald Lambert Heinrich Röhl observed the transit of Venus, together with Andreas Mayer. By then, the monastery was already a ruin and used as a stone pit to obtain bricks.
Location: 54°05′21″.4 N, 13°27′09″.3 E times of contact
A farmer-astronomer, Johann Georg Palitzsch lived in Prohlis near Dresden. In 1761 he observed the transit of Venus with two telescopes. One was used to project the solar image and the with the other he looked at the sun directly. At egress, Palitzsch saw the blackdrop effect and the aureole. Today, only two buildings of the original farm still stand, which house the Heimat- und Palitzschmuseum. In 1877, the city of Dresden honored him with a monument at the northeast corner of Prohliser Straße and Gamigstraße, next to his former residence.
Location: 51°00′26″.4 N, 13°47′35″.8 E times of contact
In Tolkewitz near Dresden, not far from the farm of Johann Palitzsch in Prohlis, other farmer-astronomer Christian Gärtner also observed the 1761 transit of Venus. His farm stood till the 1990’s.
Location: 51°01′51″.1 N, 13°49′52″.6 E times of contact
Jesuit astronomer Franciscus Weiss observed the last contact of the 1761 transit of Venus from the mathematical tower of the Jesuit College in Tyrnau (modern Trnava in Slovakia). He used a reflector of 4 feet focal length.
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Location: 48°22′50″.4 N, 17°35′20″.0 E times of contact
From the terrace of the Zaluski Public Library in Warsaw, Jesuit father Stefan Luskina observed the 1761 transit of Venus. Luskina was trained in astronomy in Vienna and professor of mathematics and physics at the Jesuit College in Warsaw. On the day of the transit, he showed the phenomenon to a number of well-born ladies and noblemen.
Location: 52°14′43″.2 N, 21°00′27″.4 E times of contact
From the observatory of the monastery of Kremsmünster, father Eugen Dobler observed the 1761 transit of Venus. He was accompanied by prelate Bertholdi and other clergymen.
Location: 48°03′18″.6 N, 14°07′53″.8 E times of contact
In 1729 Felix Freiherr von Ehrmann zum Schlug had built an observatory tower next to his Schloß Wetzlas near Pölla in Austria to do astronomical observations. From this observatory tower he observed the 1761 transit of Venus and timed the last two contacts. He used a reflecting telescope of 4 feet focal length.
Location: 48°36′10″.7 N, 15°24′11″.0 E times of contact
In 1761 the director of the Imperial Observatory in Vienna, Jesuit father Maximilian Hell, observed the transit of Venus. The Vienna observatory had been constructed just a few years earlier on the roof of the university building, which today houses the Österreichischen Akademie der Wissenschaften.
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Location: 48°12′32″.0 N, 16°22′37″.2 E times of contact
Located close to the Imperial Observatory, the Jesuit College in Vienna possesed an observatory tower of 45 meters hight. From this tower father Joseph Xavier Liesganig observed the 1761 transit of Venus. He was accompanied by César-François Cassini de Thury, director of the Royal Observatory in Paris.
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Location: 48°12′30″.1 N, 16°22′41″.7 E times of contact
In the Giardini Reali in Turin, Giovanni Battista Beccaria set up a quadrant of 3 feet focal length on a tripod to observe the 1761 transit of Venus. Beccaria was assisted by Canonica, who wrote down the times and the measured distances, and Revelli, who observed with a refractor of 40 feet focal length. Beccaria also had an observatory tower nearby at 1 Via Po (which still exists), but most likely he didn’t use it on this occasion.
Location: 45°04′21 N, 7°41′21 E times of contact
From his small observatory established on the upper grounds of the convent of San Giovanni in Florence, Jesuit father Leonardo Ximenes observed the 1761 transit of Venus. He used a Newtonian reflector of 4 Parisian feet.
Location: 43°46′27″.8 N, 11°15′18″.5 E times of contact
From the upper room of the observatory tower of the University of Bologna, Eustachio Zanotti observed the 1761 transit of Venus together with two assistants. In a lower chamber was father Frisi, accompanied by two other colleagues. In the logbook, Zanotti’s observations are dated June 5 instead of June 6. That’s because at Bologna observatory the sunset time was assumed as the beginning of the astronomical day.
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Location: 44°29′48″.5 N, 11°21′07″.8 E times of contact
From his home in Padova Giovanni Poleni observed the 1761 transit of Venus. His home was located at 5 Via Beato Pellegrino and contained a physics laboratory on the ground floor and a library on the first floor. Unfortunately, Poleni was clouded out.
Location: 45°24′49″.2 N, 11°52′19″.4 E times of contact
From his small observatory at the novitiate’s loggia at the convent of Santa Maria sopra Minerva in Rome, Giovanni Battista Audiffredi observed the transit of Venus with a refractor of about 2 metres focal length, equipped with a micrometer, and a refractor of 4.25 metres focal length by Eustachio Divini. The first was used to observe Venus during the transit and the latter to observe the egress.
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Location: 41°53′56″.1 N, 12°28′42″.9 E times of contact
A few days before the transit, on 1761 June 3, there was a lecture at the Seminario Romano on the transit of Venus. The history of the phenomenon, the observing methods and the use of the results were spoken of. On June 6, the transit was observed by Agostino Salluzzo with an excellent Newtonian telescope.
Location: 41°53′57″.2 N, 12°28′44″.2 E times of contact
From the observatory of the Collegio Romano, of which he was director, Giuseppe Maria Asclepi observed the transit of Venus. He used a 5-Roman palms quadrant, a 12-Roman palms refractor by Eustachio Divini and an 8-Roman palms refractor. Asclepi was assisted by Andrea Spagni, who observed with a 20-Roman palms Huygens refractor. The Collegio Romano didn’t have a permanent observatory building at the time, so the exact location of the observation remains unclear.
Location: 41°53′53″.2 N, 12°28′48″.3 E times of contact
Probably from a terrace François Jacquier observed the transit of Venus at the convent of Trinità dei Monti in Rome. Together with Thomas Le Seur he used instruments of which the dimensions are not mentioned.
Location: 41°54′22″.3 N, 12°29′00″.3 E times of contact
The Colégio dos Nobres was founded in Lisbon in March 1761. From the grounds of the new college Miguel António Ciera observed the transit of Venus. Today, the building houses the Museo de Ciência.
Location: 38°43′03″.8 N, 9°09′02″.8 W times of contact
In the grounds of the convent which was once located on the same block as the modern Igreja dos Congregados in Porto, Teodoro de Almeida observed the 1761 transit of Venus. He used a two feet Gregorian reflector, fitted with a green and a smoked glass, and managed to time both interior and exterior contact at egress. He also measured the diameter of Venus. De Almeida had to do the observation in cognita because he was being pursued by the Marquis of Pombal.
Location: 41°08′46″.7 N, 8°36′39″.2 W times of contact
At the observatory of the abbey of Saint Geneviève in Paris José Joaquim Soares de Barros e Vasconcelos watched the 1761 transit of Venus together with Jospeh-Nicolas Delisle. Soares de Barros had just been appointed secretary of the Portuguese embassy. He was educated in astronomy by Delisle a few years earlier when they observed the 1753 transit of Mercury together.
Location: 48°50′46″.2 N, 2°20′52″.6 E times of contact
At the Colegio Imperial de la Compañía de Jesús in Madrid, German Jesuit Father Christian Rieger observed the 1761 transit of Venus. Today, the building still exists but is called Iglesia Colegiata de San Isidoro.
Location: 40°24′46″.6 N, 3°42′26″.2 W times of contact