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Description

For its first voyage to Australia, the ROYAL CHARTER became a large practical experiment for one of its passengers, Rev William Scoresby.

Scoresby was an Arctic explorer, a natural scientist and a clergyman. He was an active member of the British Association for the Advancement of Science and had a passion for developing a better understanding of the working of the earth's magnetic fields.

By 1855, it had become widely recognized that the increased use of iron in the construction of ships had made the compass, one of the mariner's primary navigation aids, increasingly unreliable.The simple acts of working iron with heat and hammering, and any vibrations during construction or repairs whilst a ship was sitting in the Earth's magnetic field, caused vessels to become permanently magnetized. The ship itself behaves like a big bar magnet and causes the arrow of the compass to drawn away from pointing towards the earth's magnetic north and south poles.

Iron was introduced into ships to replace parts or strength the framework of the hull. It began to be used to make chain cable replacing natural materials for anchor cables and hawsers, and twisted in to wire rope, began replace to the hemp used standing rigging. The first all-iron ship to make sea voyages was a paddle steamer called the AARON MANBY which was prefabricated near Birmingham in 1821, reassembled in the Surrey Docks in London, and steamed across the Channel. The first all iron-ship classified by Lloyds and placed on Lloyds Register was the GOLIATH, a sailing ketch, built at Liverpool in 1836. Ongoing experimentation by naval architects and engineers gradually began to improve performance and lower costs. By 1853, Lloyds register confirms that at least 62 iron sailing vessel were in service and, in 1855, Lloyds published the first set of guidelines for marine surveyors to judge the fitness of the iron, the size and quality to used for many of the component parts of ships, such as the the ribs, plates, beams, etc.

The practice of mounting compass on wooden poles on deck to try and isolate them from some of the effects of a ship's magnetism became widespread. However, Victorian scientists, such as the Rev William Scoresby worked to better understand the phenomenon so that a better permanent solutions could be found.

The Rev Scoresby was in disagreement with a paper published by the British Astronomer Royal, Geogre Biddel Airy, in 1839, entitled 'Experiments on Iron-built Ships, instituted for the purpose of discovering a correction for the deviation of the Compass produced-by the Iron of the Ships - a method for correcting deviation had become widely accepted by the mercantile navy', but Rev Scoresby considered it 'not only erroneous in principle but dangerous in practice'.

Scoresby had commanded whaling ships in the Arctic noting large compass deviations. He had published his observations in 1819 and his conclusions very nearly confirmed the true scientific law of magnetism - that deviation is caused not only increased local attraction but in the diminution of the directive force of the earth's magnetic field.

In the intervening years other learned papers were published, but Scoresby was still very concerned. In 1854, he read a paper at the British Association in Liverpool entitled 'On the loss of the TAYLEUR, and the changes in the compasses in Iron Ships'. The TAYLEUR had been a new iron ship with a recorded compass deviation of 60 degrees (corrected by magnets), but which Scoresby contended had been given a new magnetism by the shaking it received during a storm. The TAYLEUR's compass had been so altered that vessel had ended up being wrecked on the Irish coast. In 1854, a new type of binnacle was patented by John Gray of Liverpool which directly incorporated adjustable correcting magnets on screws or rack and pinions. But the debate between Airy and Scoresby continued hotly into 1855 with Scoresby strongly contending that a ship is most liable to undergo a change of magnetism at any time and the percussion shock of the sea on the iron plates of the ship were sufficient to render a change. Scoresby was also much concerned with observing the changes which took place in the magnetic state of an iron ship proceeding from the northern hemispheres to a southern magnetic hemisphere. In order to investigate these important questions, on which lives and valuable ships and cargoes might rest, Dr Scoresby and his wife set sail to Australia on the ROYAL CHARTER.

To prevent disaster, a ship would be 'swung' through all the points of the compass before it left port. The deviation of the compass was recorded and used to create a chart. This provided the helmsman with the precise adjustment needed for each heading. The compasses of the ROYAL CHARTER were swung in 4 January 1856. Scorebsy wrote detailed description of how this was done and the results for each of the ROYAL CHARTER's compasses:

'These results indicated a maximum error in each of the three fixed compasses of about half a point, and in standard, not being adjusted or compensated, of nearly two points. Inspection of the table (of observations), moreover, shows that in all directions of the ship's head, from N., east about S, or S.W., the compass aloft and the companion compass were, as to the every practical purpose correct. The extent of disturbance in the elevated compass, in the north-easterly quarter, were probably due to some local influence from the ironwork about the masts.'

Scoresby made observations of deviations nearly every day. He also used an additional delicate pocket-compass, held two or three inches from the plating of the ship's deck, to assess what effect mounting a compass at different parts of the ship might have. He found that the iron work around the stern of the vessel showed 'a decided and vigorous polarity' to the rest of the ship (Voyage Diary, Wednesday 2 July 1855, pg 241).

His voyage journal was not published until after his death (in the same year that the Royal Charter was lost), but it provides wonderful insights into a Victorian gentlemen's pursuit of scientific knowledge and life on board the ROYAL CHARTER during its voyage to Australia.


To make a compass of your own, you will need the following:
1) Sewing needle about one to two inches long
2) Small bar magnet or refrigerator magnet
3) A small piece of cork (corks from wine bottles work well, but not the plastic stoppers)
4) A small glass or cup of water to float the cork and needle
5) Pair of pliers

You can follow the instructions contained in this illustrated handout from the United States National Oceanic and Atmospheric Administration:

http://oceanservice.noaa.gov/education/for_fun/MakeyourownCompass.pdf.

Alternatively, there is also a useful video provided by the Children Learning Online organisation:

http://www.youtube.com/watch?v=VobcByagbPU

Placing a magnet near your compass and moving it, will change the direction that the compass needle points - this represents deviation or the influence of iron in close proximity to the compass that Scoresby was determined to better understand.

These links provide more about these prominent Victorians, Rev Scoresby and the Astronomer Royal George Airy.

http://www.whitbymuseum.org.uk/collection
s/scoresby1.htm

http://www.rmg.co.uk/explore/astronomy-and-time/astronomy-facts/history

The full text of Rev William Scoresby's Journal of a Voyage to Australia and around the World for Magnetical Research published in 1859, is available online from Google Books.

http://books.google.co.uk/books/about/Journal_of_a_voyage_to_Australia_a...

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