subject: The Marine Chronometer- What Is Its Story? [print this page] Time and space have always stirred people's imagination. The nature and origin of the two have been a source of fascination for numerous scholars, scientists or mere dilettantes. Bus, as the time passed, people's interest went beyond these initial concerns rather philosophical in nature. The new approach to time began to be o more practical one: finding ways to subdue time in order to have a better control over the world they were living in.
Clocks were humans' invention when they wanted to control time. The marine chronometer was their invention when they dreamed to conquer the world by conquering its seas. This is a type of clock accurate enough to be used to calculate longitude. A science known as celestial navigation or astronavigation is the means by which these calculations are done. When marine chronometer was invented, it was seen as a discovery of major importance. For the first time in its history, the problem of a time standard in sea navigation was provided with a solution.
Up to the 1970s, every ship had aboard a version of what is known today as H1- H4, the first sea clocks devised by John Harrison (1693-1776). Their story is closely connected to the Longitude Act which was passed in Britain in July 1714. This Act stipulated that the individual capable of coming with a method of determining longitude within an accuracy of half a degree (sixty nautical miles) was to be given a prize of 20,000. The great astronomers living in that period entered the competition with great enthusiasm, but in the end the prize was won by the very determined from Yorkshire.
Harrison devoted many years of his life for developing the H1-H4 sea-clocks were. The work on H1 began in 1730 and ended in1735 and this first version was conceived as a spring driven mechanism. Springs controlled and counter-balanced the moving parts which caused H1 not to be affected by the direction of gravity. In 1737, it was time for H2. As opposed to H1, H2 was larger and heavier, but the design and system for functioning remained basically the same. Yet, it was soon discovered that the design was not accurate enough and the bar balances were not always efficient in countering the motion of a ship. This was proof that it was highly improbable for H2 to show accuracy on sea.
When H3 took the stage, it brought along the innovative use of circular balances. Inventions such as the bi-metallic strip and caged rolled bearings were used here too, the latter two being very popular up to the present day. But in the end, the circular balances proved H3's inaccuracy and thus it was time for H4 to follow. From the beginning H4 was smaller and lighter than the other three marine chronometers. It measured just 13 cm in diameter and weighed 1.45 kg. It looked more like an unusually big pocket watch. The mechanism based on which it functioned relied on a fast-beating balance under the control of a temperature-compensated spiral string.
Marine chronometers are still very much present in the tumultuous world of today. Their modern elegant forms bear little resemblance to those of their H1-H4 ancestors though. The watch market offers a huge variety of models and top manufactures of watches don't neglect the inclusion of this special type of timekeepers among their wide range of products.
