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Other Astronomy on the First Voyage
During the first voyage, other astronomical objects and events were observed in order to accurately determine longitude. Among these were the Moon and Jovian satellite phenomena, a total lunar eclipse on 18 June 1769, the 9 November 1769 transit of Mercury, and a partial solar eclipse on 15 May 1771. The transit of Mercury was observed from Mercury Bay in New Zealand, and this was the first shore-based scientific astronomical observation made from that country.
Astronomical observations of a non-nautical nature were of Comet C/1769 P1 Messier. Between 27 August and 4 September 1769 it was readily visible to the naked eye and at its best displayed a tail fully 42 degrees in length.
Another phenomenon which created a good deal of interest was an Aurora Australis. The aurora seen on Cook’s first voyage occurred at a time close to a sunspot maximum.
"About 10 O’Clock a Phenomenon appeared in the heavens in many things resembling the Aurora Borealis but differing materially in others: it consisted of a dull reddish light reaching in height about 20 degrees above the Horizon."
The Discovery of Australia
After completing his observations of the transit of Venus at Tahiti, Cook tore open a secret letter which had been given to him by the British government at the start of his voyage. This letter gave him instructions to search for a ‘southern continent’ and he sailed westwards to New Zealand and Australia. On 19 April 1770 he sighted Cape Everard near the south-east extremity of the Australian mainland.
For the next several months Cook explored and mapped the eastern mainland coast. He carried out nautical astronomy along the coast to determine latitude and longitude, and before returning to England he laid claim to the land in the name of George III.
Thus a voyage of scientific discovery, organised by the learned society of London for the purpose of determining the distance of the Earth from the sun, first brought the British into contact with the eastern coast of Australia.
Cook’s Second Voyage
Two Royal Greenwich Observatory astronomers were assigned to the Second Voyage. William Wales (1734-1799) was the astronomer on Cook’s ship, the Resolution. The other astronomer was William Bayly (1737-1810) on HMS Adventure. The astronomical instruments provided for the astronomers were similar to those on Cook’s first voyage, but with three important exceptions. In addition to the mandatory reflecting telescopes, there were two refracting telescopes, a transit telescope, and four chronometers. All of the chronometers were modelled on Harrison’s successful ‘clock machine’; one was the so-called “K1’. Two tent observatories were provided.
<- London watchmaker Larcum Kendall’s chronometer known as K1. This chronometer accompanied Cook on his second voyage. K1 was also brought to Australia by Governor Phillip as part of the First Fleet.
The observing equipment was for the lunar eclipses on 12 September 1772 and 7 April 1773 and a partial solar eclipse on 7 September 1774. The only other celestial phenomenon of interest during the voyage was the Aurora Australia. The aurorae were observed on a number of occasions in February and March 1773 which is a little surprising given that the Sun was nearing a sunspot minimum at this time.
Wales and Bayly determined the value derived for the longitude at Queen Charlotte Sound in New Zealand and found that it differed by nearly one-and-a-half degrees from the first voyage figure, demonstrating the merits of shore-based observations (in 1770 the observations were made from the Endeavour). The chronometer K1 was to prove by far the most accurate of the four chronometers. Wales and Bayly worked together on the official astronomical account, and this was published in 1777.
Cook’s Third Voyage
The two vessels used on the third voyage were the Resolution, and the Discovery under Captain Charles Clerke. Bayly again served as astronomer, this time on the Discovery. No full-time astronomer was assigned to the Resolution; Cook and King were expected to share the associated duties. King (1750-84) was a naval officer who had studied science in France before moving to Oxford.
The astronomical instruments consigned to the third voyage were very similar to those taken on the previous voyage. Significant astronomical events which attracted the astronomers on the third voyage were lunar eclipses on 30 July 1776, 21 July 1777 and 4 November 1778, and partial solar eclipses on 5 July and 30 December 1777. Anderson, the surgeon on the resolution, noted that for several days before the 5 July 1777 solar eclipse:
"A great many spots were seen in that body (the Sun) which changed daily their number, magnitude and situation, but amongst others there was one place which had a group exactly like a cluster of nine islands."
Queen Charlotte Sound once more served as a vital stopover centre. By the end of the voyage, the co-ordinates of Ship Cove were known with greater accuracy than almost any other place on Earth!
After the voyage, King and Bayly worked on the official astronomical volume. The resulting volume was eventually published in 1782, and included the late James Cook as an author. However, his surname was somehow spelt incorrectly!
