Flinders and Bungaree - How did they navigate?
Matthew Flinders, and his young brother Samuel, did most of the important astronomical observations on the voyage. John Crosley was the original astronomer but he got sick on the way from England to Australia. He was left behind at the Cape of Good Hope in South Africa.
Flinders was a gifted navigator, cartographer and scientist. He drew and wrote his observations at the end of each day before going to bed. His maps were so accurate they were still used in the 20th century.
Vessels
HMS Investigator was the flagship for the circumnavigation of Australia.
HMS Investigator was a collier (carried coal) like James Cook’s original HMB Endeavour. It was built in the north Country of England, was 8 metres wide, 33 metres long, and weighed 334 tons. It had previously been called the Xenophon. It was freshly coppered and repaired for the voyage and there were 88 people on board when the ship left Portsmouth on the 18th of July in 1801.
Navigation instruments
Flinders used different instruments to determine his ship’s location, the direction he was sailing, and to make charts of the coastline. These included a sextant, chronometer, astronomical clock and a theodolite.
A sextant is used to determine the latitude by measuring the angles between the sun or moon or star and the horizon. This allowed Samuel and Matthew to determine how far north or south they were from the equator. Three large sextants with stands were made for the voyage.
Sextant made by Spencer, Browning and Rust, 1784-1840.
ANMM Collection Purchased with USA Bicentennial Gift funds
H3940 Box chronometer, serial No 520, brass / wood / steel / glass, made by Thomas Earnshaw, London, England, 1801, used by Captain Matthew Flinders, 1801-1803
Powerhouse Collection. Purchased 1937. Photograph Sotha Bourn.
A chronometer is a very precise clock which can keep time accurately. Historically, they were used by sailors to calculate longitude at sea. It was invented by John Harrison in the 18th century. Marine chronometers are not affected by changes in temperature or the motion of a ship. This makes them ideal pieces of equipment for long sea voyages.
There were four chronometers on HMS Investigator, but two of them stopped working early in the voyage! This box chronometer kept working and was used throughput the trip. It was made of brass, wood, steel and glass.
Flinders logged his time and longitude every day to keep track of the distance he’d travelled and his location.
To calculate longitude, you need to wait until the sun is at its zenith or highest point in the sky. That’s midday! Then, you need to check the time on the chronometer which was set to Greenwich Mean Time (GMT). The difference in time between the ship (midday) and the marine chronometer, helps you to determine the longitude.
1 hour difference = 15° of longitude.
Thomas Earnshaw made this Long case clock [metal / mahogany] London, England
Powerhouse Collection. Purchased 1994. Photograph Marinco Kojdanovski.
An astronomical clock isn’t like a clock on the wall that tells you the time of day. It is a special time keeping device that measures the rotation of Earth relative to stars. It looked a bit like a grandfather clock and was as tall as a person! During his circumnavigation of Australia, Flinders would set it up on shore in an observatory tent to help find celestial objects in the night sky and used it to check the accuracy of his chronometer.
Flinders’ chronometer and astronomical clock were both made by Thomas Earnshaw in London.
Theodolite circa 1795 designed by Dudley Adams. Used to measure horizontal and vertical angles.
Reproduced courtesy of National Maritime Museum, Greenwich, London. CC-BY-NC-ND
A theodolite is an instrument used to measure angles between two points. A Ramsden Universal Theodolite was used on the HMS Investigator voyage. It was set up on a tripod stand on the shore in a tent observatory. The measurements were used to make charts of the coastline.