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Astronomical connections: Dalrymple, Halley and Cook

It is now 250 years since James Cook and the crew and scientists on the Endeavour sighted the shoreline of the land we now call Australia. This blog explores a twist of fate and history and the possibility that Cook may not have been chosen as the commander because there were other options(1). I will provide background to the decision to choose Cook to command the Endeavour on an ambitious journey and why other influential people were keen for him to explore the possibilities of a ‘Great South Land’ after the transit of Venus was achieved. One of these people shares my name, Dalrymple.

The term ‘Terra Australis Incognita’ was used as far back as the ancient Greeks to mean the unknown Great Southern Land (2) – this was estimated to balance the land mass in the northern hemisphere. That Australia was considered to be ‘unknown’ would have been rather surprising to its inhabitants who had lived on, and in many ways mapped, the continent for over 70,000 years (3). There were reports and maps by Dutch, Portuguese and British (Dampier) mariners who had encountered Australia’s North and West coasts, calling it ‘New Holland’; Tasmania and parts of New Zealand. The map below dates back to 1616 and it is by Flemish cartographer Petrus Bertius.

Petrus Bertius

Alexander Dalrymple, not related to the author as far as is known, was a Scot and he was the principal map maker for the British East India Company. He also had the conviction that there was a great South Land. Dalrymple was an avid promoter of the idea that there must be a great land mass south of the equator, under Indonesia, to balance the mass of Europe and Asia North of the equator. He published a pamphlet about his findings from Spanish voyages new the Torres Straits (4) and communicated this with Joseph Banks (1).

Dalrymple was the candidate proposed by the Royal Society to captain the ship to make the voyage to measure the transit of Venus in Tahiti. Through family connections he had been sent out from England to India as a schoolboy, to work as a clerk. Over the years he learned map making and even Captained East India trading ships up to Canton in China. But there was a problem, Dalrymple was a civilian and the Admiralty had had an unfavourable experience with a previous civilian Captain called Edmond Halley.

Edmond Halley is best known as a comet discoverer, but in 1698 he had been sent by the Admiralty on a voyage of scientific discovery to St Helena to chart the southern stars. Aided by a naval crew, Halley had been appointed ‘Captain,’ and there were many problems with his command, furthermore his behaviour after the voyages was not favoured by the Admiralty. Even though Halley had been dead for almost thirty years when they were considering Dalrymple, they had not forgotten this.

Therefore, although Dalrymple was a contender for the position of Captain for a voyage of discovery as favoured by the Royal Society, the final appointment by the Admiralty was James Cook, a naval lieutenant. Cook was already known for his map-making and had also earned a Fellowship of the Royal Astronomical Society (F.R.A.S.) for his exacting timing of an eclipse while on station off the coast of North America. Dalrymple was offered a scientific position of astronomer, which he turned down (1). So, after the expedition had achieved the Royal Society objective of observing a Transit of Venus with Charles Green the astronomer, Cook then considered the ‘Sealed Orders’ objective of finding how far East ‘New Holland’, also known as the Great South Land, extended. This decision, weighed up against other options, the condition of the boat, the weather and their rations, was ratified by his officers and supported by Joseph Banks, the gentleman botanist.

Whilst Cook mapped much of the East coast of Australia in 1770, it was on the second voyage that he proved that there was no Great South Land of the scale previously imagined.

Interestingly, a few years later when the proposal to establish a convict colony in the area which we now call Botany Bay was being considered, Dalrymple opposed the settlement (5).

(1) Beaglehole, J.C. 1974, The Life of Captain James Cook, Stanford University press, Califormia.

(2) Oxford Companion to Ships and the Sea (2 ed), 2006.

(3) Turnbull, D 1989, Maps are territories: science is an atlas: a portfolio of exhibits with a contribution by Helen Watson with the Yolngu community at Yirrkala, University of Chicago Press, Chicago.

(4) Dalrymple, A 1767 An Account of the Discoveries Made in The South Pacifick Ocean, Previous to 1764, London.

(5) Dalrymple, A 1786 A Serious Admonition to the Public on the Intended Thief-Colony at Botany Bay, London.

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