The transit of Venus

The forthcoming transit of Venus (on 5-6 June 2012) is an opportunity to remind ourselves how the needs of society determine the development of science. Venus passes in front of the Sun on two occasions about 8 years apart about once in every century. Soon after Johannes Kepler had formulated his third law - that a planet's distance is proportional to the time to complete on orbit - in 1609, it was realized that the transit of Venus can be used to determine the distance between the Earth and the Sun, which in turn can be used to determine longitude, a task of vital importance to open ocean navigation. It was the time of and colonial acquisition, and imperial powers had a great interest in this. Their interest was so great indeed that Britain, France and Austria cooperated in sending science parties out to Siberia, Norway, Newfoundland and Madagascar to observe the transit of Venus of 1761. Unfortunately clouds prevented most observers from getting good data, but a second chance came 8 years later. So in 1768 Britain sent Captain James Cook to Tahiti to observe Venus' second transit in 1769.

Today most people know about James Cook as the discoverer of New Zealand and the east coast of Australia but are not aware of the public reason for his voyage. The instructions from the Admiralty concerning investigations of the postulated continent of the south were in fact given in a sealed envelope, not to be opened before departure from port, so that the official motivation for Cook's voyage would be known to the competing imperial powers as the observation of the transit of Venus.

The cost of Cook's voyage for the British state budget was comparable in relative terms to the cost incurred bu the USA to send a man to the moon. May the other powers marvel at Britain's generosity to support a scientific endevour of benefit to all; the real value of the financial outlay becomes clear to those who could access the secret orders.

The role of profit in scientific exploration during the "Age of Discovery"

The early European ocean voyages of the Age of Discovery did not always lead to the discovery of unknown lands. Their main objective was to obtain as much profit as could be made. Exploration of new coasts, with the associated benefits for science, was a secondary consideration, performed only to the degree necessary to bring success to the economic purpose of the voyage.

The early Portuguese and Spanish sea captains were true explorers, in the sense that their contract with the crown (four fifth of the profit to the explorer, one fifth to the crown) was based on voyages to unknown destinations and therefore carried great risk. The British crown found it more profitable to raid the Spanish outposts in regions already discovered. It financed Francis Drake, Thomas Cavendish and other "privateers" to sack Spanish settlements and capture Spain's ships.

The profitability of marauding voyages was beyond doubt. When Drake captured a Spanish galleon in 1579 he obtained 13 chests of silver coin, 26 tons of silver bullion, 80 pounds of gold, and uncounted jewellery. Cavendish sacked Puna Island off Peru, slaughtering its Indian inhabitants, in 1587; he returned from his two year marauding voyage with a booty worth 125,000 pounds, nearly half of the Crown's annual revenue. Such adventurism did not contribute much to science.