Captain James Cook – Part Two

In the navy, the commander of a ship is always referred to as Captain, regardless of his/her actual rank. Captain Cook, after his first world voyage, was promoted from lieutenant to commander. On his first voyage, Cook had shown that New Zealand was an island and, by charting the east coastline of Australia, he had shown that Australia was continent sized. However, the Royal Society did not believe that Australia was the fabled Terra Australis. The scientists at the time believed that the landmasses in the northern hemisphere were countered by landmasses of equal mass in the south. This was the Royal Society’s basis for believing that Terra Australis existed. Finding this fabled continent was the reason for Cook’s first voyage, and the reason the Royal Society and His Majesty’s Navy sent Cook on his second voyage (1772-1775).

Cook set sail in command of the HMS Resolution, with Tobias Furneaux commanding the HMS Adventure. This voyage he circumnavigated the world at a higher southern latitude. Cook also became the first man to sail below the Antarctic Circle, reaching 71 degrees and 10 minutes South. Cook turned back before reaching the Antarctic mainland, and became separated in fog from the HMS Adventure. Furneaux then sailed the HMS Adventure back to England.

Before leaving the Pacific, Cook visited Easter Island, Norfolk Island, and several other islands. Then he sailed round Cape Horn and across the South Atlantic, claiming islands (for Britain) while exploring, surveying, and mapping; before turning north for South Africa and England.

Cook’s reports in England put to rest the belief in the fabled Terra Australis, he was made a fellow of the Royal Society, promoted to post-captain and retired. Once again, Cook was honored and praised upon his return, painted by noted portrait artist Nathaniel Dance-Holland, awarded medals, and praised by Parliament. Cook resisted retirement, but had little choice.

Cook’s greatest accomplishment, for the seafaring community at least, was his use of Larcum Kendall’s copy of a John Harrison marine chronometer. In Cook’s day, finding a ship’s latitude, north or south, was a simple act of taking a sighting on the sun (daytime) or star (at night) and performing the mathematical calculations to arrive at your ship’s north or south position. East and west longitude was not so easy to calculate. The common way mariners navigated was to steer a course for an island with a known longitude and latitude, upon sighting the island they would sail for another known island. This way the navigator could do a fair job of plotting his ship’s progress. This method caused ship’s captains to sail much longer routes. What navigators needed was an extremely accurate timepiece, a chronometer. Many kingdoms around the world were offering prizes for the first person to create just such a marine chronometer, one that was portable and would stand up to the rigors of life at sea.

The way a marine chronometer is used to find the ship’s longitude is a simple matter. The chronometer is set to the time at a known place, on English ships this was Greenwich, England (known as Greenwich Mean Time or GMT). The ship would sight the sun with a sextant at the local noontime for the position they were in, this is the time when the sun is at its highest peak in the sky. The time for local noon would be noted, and the ships clocks would be reset to local noon, all clocks except the marine chronometer that is. Then the difference between local noon and Greenwich noon would be noted and the difference would be the difference in longitude.

If the local noon happened when it was 1 PM in Greenwich, then the ship was 60 minutes west of Greenwich, which is also 1 degree west of Greenwich or at a longitude of 179⁰ W. Latitude and longitude are divided into degrees, 180⁰ of west and 180⁰ of east longitude. Latitude is divided into 90⁰ north and south latitude. Time on a clock and position in latitude and longitude is directly proportional. One hour in time equals one degree in distance, minute for minute, and second for second. Each degree is divided into 60 minutes, and each minute is divided into 60 seconds; so that 23⁰ 45’ 8” N 119⁰ 17’ 11” W is read, “23 degrees 45 minutes 8 seconds north 119 degrees 17 minutes 11 seconds west.” What the marine chronometer did was to free ships to sail the most direct route from any point on the earth to any point on the earth, in some cases shortening sea voyages by months. This was a huge savings in supplies a ship would have to carry, and for the merchant marine, less travel time meant more voyages and more income. This also meant that ships could now sail anywhere in the world, and know precisely where they were, something never possible before.

A year later, a voyage was planned to find the fabled Northwest Passage. Cook, chafing in retirement, volunteered to lead the expedition. This was Cook’s third and last expedition, one from which he would never return. But, oh what an expedition it was. For now though, we will leave Cook in his unwanted retirement.

Have a great week and take care of yourself,