H-3: Harrison’s “curious third machine”.

The Copley Medal is awarded by the Royal Society for outstanding achievement in research.   It was originally funded by a bequest from Sir Godfrey Copley in 1709, and then another from Sir Joseph William Copley in 1881.   It is awarded annually, alternating between physical and biological sciences.   Today, the medal is silver gilt, and comes with a cheque for £5,000.   Most recently, the medal was awarded to Martin Evans (2009, embryonic stem cells), Roger Penrose (2008, mathematical physics), Robert May (2007, biological populations) and Stephen Hawking (2006, theoretical cosmology).

Caged ball bearings don’t rub against each other, so friction and wear is reduced.   Moreover they can’t jam.   Because of these benefits, most rolling-element bearings use cages.  

Because different metals expand at different rates when heated, if two strips of different metals (usually steel and copper) are welded or riveted together, the combined strip will bend as it warms.   A coiled bimetallic strip is the fundamental mechanism in thermostats.  

The memorial plaque to John Harrison in Westminster Abbey incorporates a meridian line formed from two metals to represent this essential invention.

John Jefferys (1701-1754) came from a Quaker family in Midgham, Berkshire.   Little else is known about him.

 

H-4.  At last.

Sobel is perhaps a little unkind to Nevil Maskelyne (1732-1811).   He is the villain of this piece, but in life he played other, happier roles.   The single act of instituting the Nautical Almanac should make him a hero to mariners the world over, and his aggressive advocacy of the lunar distance method of calculating longitude was not unreasonable given the constancy of the heavens and the low cost of a set of lunar distance tables as compared to a chronometer.   Indeed his method was preferred by seamen for several decades, until reliable chronometers became more affordable.   He was awarded the Copley Medal 26 years after Harrison (for “curious and laborious Observations on the Attraction of Mountains” – an experiment to measure the density of the Earth) , and his lunar distance work almost certainly kept safe many ships and their crews throughout the late-18 ^th and early-19 ^th centuries.

For those who care about such things, we also have Maskelyne to thank for the primacy of the Greenwich Meridian.   Perhaps the irritation this caused the French is the Reverend’s most endearing achievement…

 Every 243 years, Venus twice passes between the Sun and Earth.   The two transits are eight years apart.   The event is regular, predictable and very rare, and so is of great interest to astronomers.   For a few hours, a black disc is visible passing across the face of the sun.   By recording the exact time of the transit start from widespread points on Earth, it was possible to calculate by triangulation the distance to Venus and the Sun.   Expeditions were sent all over the world to time the transits in 1761 and 1769, and from the combined data a close approximation of the distance to the sun (150m km) was achieved by Jérôme Lalande.

We are currently between two transits: the last was in 2004; the next will take place on 6 June 2012.

 

The 1761 transit was only observable from places fairly remote from Europe.   Despite the complications of the Seven Years War, enemies Britain and France both sent their best astronomers to the far corners of the globe.   Astonishingly, they were armed with letters of transit which allowed them to cross enemy lines and shipping lanes unharmed in the name of science.   British teams were sent to St Helena (Maskelyne), Sumatra (Mason and Dixon – diverted to South Africa) and Newfoundland (John Winthrop). French observers voyaged to Madagascar, Siberia and Pondicherry.  

The Mason-Dixon line separates the U.S. states (then colonies) of Pennsylvania and Maryland, as well as West Virginia and Delaware.   It is marked by boundary stones at every mile.   Surveyed between 1763 and 1767 to resolve a border dispute (known as Cresap’s War), it has come to symbolize the divide between the northern and southern states of the USA.  

In 1766, the Royal Society commissioned James Cook to sail to the Pacific to record the second transit of Venus in 1769.   He made the observations from Tahiti, but they were not sufficiently accurate to be of great use.   Much more valuable was his subsequent mapping of the entire New Zealand coastline, and it was on this first voyage that he “discovered” Australia, as the first recorded European to reach its eastern coast.   He claimed the whole eastern coastline, from Botany Bay to the Torres Strait, for Britain.

Britain and France had been fighting in North America for two years before the official start of the Seven Years War in 1756, marked by the Prussian invasion of Saxony.   During the subsequent seven years, more than one million people were killed on three continents, including soldiers from a neutral Dutch force in India.   Prussia sided with Britain and Portugal against France, Sweden, Austria, Spain and Russia.   In Europe, the war was effectively a stalemate, but across the Atlantic British forces captured most of France’s colonies in North America and several of their Caribbean islands.   Britain also took French possessions in India, and Spanish possessions in Cuba, Florida and the Philippines.   This first “world war” established Great Britain as the dominant colonial master, and Prussia as an important new European power.

Jamaica became an English colony in 1661, and soon developed into a prized agricultural possession, with sugar and coffee grown by African slaves bringing great riches to British landowners.   Sea traffic between Britain and Jamaica was regular and frequent.

 Madeira Island is the largest in a volcanic archipelago in the Atlantic, 230 miles north of the Canaries.   The islands were settled by the Portuguese from 1420, and remain under Portuguese control as an “autonomous region”.   Today Madeira is a popular tourism destination, famous for its wine and gardens, as well as the largest firework display in the world on New Year’s Eve.

 

Kingston Harbour is a vast natural haven in Jamaica.   The original commercial centre was Port Royal, located on the tip of the thin sand spit called Palisadoes that forms the breakwater for the Harbour.   It was an important base for privateers and pirates operating against Spanish and French treasure ships during the 17 ^th century, and with the resulting debauchery was called the “Sodom of the New World” – it had one tavern for every 10 residents.   In 1692, an earthquake destroyed most of the city and submerged much of it beneath the sea, an event seen by many as God’s retribution against a sinful population.   As a result, it is known as “the City that Sank”.  

After the earthquake, the refugees moved to the mainland side of the Harbour and founded Kingston, although the new town did not replace Port Royal as commercial centre until the latter was further destroyed by fire in 1703.   Following the earthquake, the capital was moved to Spanish Town, but frequent attempts were made to rebuild Port Royal, each of them frustrated by hurricanes, fire or flooding.   Another earthquake in 1907 finished off the city, and today just 2,000 people live in Port Royal, while across the water Kingston is the capital with a population of 650,000.   Port Royal features in the Pirates of the Caribbean films, as well as James Michener’s book, Caribbean.

 

 

The Commemorative Octant.

This fairly barbaric tradition is particularly associated with bullfighting, where the successful matador is awarded his victim’s ears and tail.

The original guide is available online.

 Nathaniel Bliss (1700-1764) was Astronomer Royal for just the last two years of his life.  

Like Jamaica, Barbados was at the time an important commercial colony to Britain, with a major sugar cane industry built on slave labour.   It is a non-volcanic coral island, extremely popular with tourists and cricketers.   As the easternmost Caribbean island, it still has particular maritime significance, for example as the finishing point in trans-Atlantic rowing contests.  

A clip of this scene from the TV movie is available on YouTube.