Captain Cook and Mister Green
In the spirit of C.S. Forester and Patrick O'Brian, frequent StarDate contributor Barbara Ryden takes us to the high seas aboard the Endeavour to tell the story of renowned explorer James Cook's first voyage and its astronomical importance.
 England's rise to power in the eighteenth century would not have been
possible without its expertise on the seas and the skies. Intrepid British
explorers charted unknown continents as the astronomers back home mapped the
heavens in unprecedented detail.
In perfecting the practical art of navigation at sea, the revered British
traditions of sailing and astronomy often joined forces. Measuring the world
and finding one's place on its surface proved no match for the Royal
Navy and Royal Society.
A more purely scientific challenge also was undertaken by British astronomers
and sailors of the day. Though few citizens of the eighteenth century had a
need to know the size of their solar system or their place in it, the voyage
of Endeavour to observe the transit of Venus from the South Pacific in 1769
was undertaken to do just that.
The voyage of H.M. Bark Endeavour to the South Pacific
for the purpose of observing
the transit of Venus in 1769.
So intertwined were sailing and astronomy in British society of the 1700s
that the expedition brought together two men whose lives straddled the two
disciplines: an astronomer who would have been a sailor and a sailor who would
have been an astronomer.
The sailor was the explorer James Cook, known to history for his voyages in
the Pacific. A tireless navigator, Cook charted the coasts of Australia, New
Zealand, the Hawaiian Islands, and western North America. The astronomer who
joined Cook on the Endeavour expedition was Charles Green, assistant to the
Astronomer Royal.
Cook's life started far from the open waters of the Pacific; he was
born in 1728 in a remote Yorkshire village. Having no taste for his father's
occupation of farming, he spent a brief but boring time as a grocer's
clerk before deciding to go to sea. Joining the Navy as an able-bodied seaman,
he rose up the ladder of promotion.
By 1764, he was entrusted with the important task of charting the coasts of
Newfoundland and Labrador, a job that involved careful observations of the
Sun, Moon, and stars to determine the latitude and longitude of points along
the coast. Not all of Cook's celestial observations were dedicated to
the utilitarian purposes of cartography: He also engaged in pure astronomy.
In 1767, his report, “An Observation of An Eclipse of the Sun at the
Island of New-found-land,” was published in the Royal Society's
journal. Cook's eclipse observations made his name known among astronomers,
who regarded him as “a good mathematician and very expert in his business.” Green's
early career has curious parallels to Cook's. Like Cook, he was the son
of a Yorkshire farmer. He escaped rural tedium not by going to sea, but by
becoming an astronomer at the Royal Observatory in Greenwich. He was sadly
underpaid, receiving only £26 sterling a year for a monotonous round
of observations and calculations. “Nothing can exceed the tediousness
and ennui of the life an assistant leads in this place,” complained one
overworked assistant at Greenwich.
Given a chance to make a sea voyage, Green jumped at the chance. In 1763,
he sailed to Barbados aboard the naval vessel HMS Princess Louisa on a voyage
to test John Harrison's celebrated chronometer. Because both the Royal
Observatory and the Royal Navy were interested in using chronometers to measure
longitude, Green's inclusion on the trip required his appointment to
the rank of purser in the Royal Navy. After completing his observations in
Barbados, Green returned to the tedium of Greenwich, but the memory of his
nautical adventure remained.
The events that brought Cook and Green together aboard Endeavour actually
began half a century earlier, when Edmond Halley (of comet fame) published
a paper describing how observations of a transit of Venus could be used to
measure the distance from Earth to the Sun. To increase
the accuracy of the measurement, Halley pointed out, observations of the transit
should be made by many widely scattered observers.
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