In December 1770, at the end of Endeavour’s stay at Batavia for repairs, Captain Cook gave a short description of the place in his journal. He noted that Batavia “lies in latitude 6° 10′ South Latitude and 106° 50′ East Longitude from the Meridian of Greenwich, settled by Astronomical observations made on the spot by the Reverend Mr Mohr, who has built a very Elegant Observatory which is as well furnished with Instruments as most in Europe”.
After sailing for England, Endeavour passed through Sunda Strait. On 16 January, 1771, Cook wrote, “Java Head, from which I take my Departure Lies in the Latitude of 6 ° 49′ S and Longitude 255° 12′ West from the Meridion of Greenwich, deduced from Several Astronomical Observations made at Batavia by the Reverd Mr Mohr”.
In a letter to the Secretary of the Royal Society, dated 11 July, 1771, Cook wrote of “a paper on the [Transit of Venus] given to Mr Green by the Revd Mr Mohr at Batavia”.
Joseph Banks does not mention in his journal the Reverend Mohr. However, shortly after Banks and Solander arrived in London in July 1771, the Dutchman John Loten, a London neighbour and friend, met them. He related in a letter to his brother Arnout, “They speak excitedly of the magnificent observatory near Batavia; it was built by the Reverend Mohr, and valued at least £20,000 sterling. This is a noble enterprise”.
The London Evening Post for 27-29 August, 1771, printed a letter from “a gentleman on board the Endeavour” saying, in part, that “Great respect was paid here to Mr. Green, by the principal people of Batavia, but no particular notice was taken of the rest of us by the Dutch”.
I am left wondering who visited Reverend Mohr, under what circumstances, and what was discussed?
Born in Eppingen (now part of Germany), Johan Maurits Mohr (1716-1775) studied theology at the University of Groningen. He moved to Batavia in 1737, where he became minister for the Dutch East India Church. In 1743 he became rector of the Theological Seminary. In 1761 he took part in the observations of the Transit of Venus, which were held at his residence. In 1763 he built a new house, with an astronomical observatory. He used it to observe the Transit of Venus in 1769, which Cook and Green observed at Tahiti. Mohr also observed the Transit of Mercury later that year.
When Louis-Antoine de Bougainville stopped at Batavia, in October 1768, after his Pacific voyage, he wrote, “Mr. Mohr, the first clergyman at Batavia, a man of immense riches, but more valuable on account of his knowledge and taste for the sciences, has built an observatory, in a garden belonging to one of his country-houses, which would be an ornament to any royal palace. This building, which is scarce completed, has cost prodigious sums. Its owner now does something still better, he makes observations in it. He has got the best instruments of all kinds from Europe, necessary for the nicest observations, and he is capable of making use of them”.
Sadly, after Mohr’s death, his observatory was damaged by an earthquake in 1780, and demolished.
Originally published in Cook's Log, page 19, volume 43, number 4 (2020).
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