There is likely no better place in the world to ponder time and place than in the courtyard of the Royal Observatory in Greenwich, which is divided by a line marking the Prime Meridian – Longitude O.
I well recall, as a child, having to go to bed after the 9 o’clock news – usually read then by Boris Moiseiwitsch. The news bulletin was preceded by 9 pips to mark the hour precisely with reference to Greenwich Mean Time. At that age I had no idea where Greenwich was, nor did I understand why time could be so mean!
It took over half a century for me to visit Greenwich. It is easy to reach by rail from the centre of London as a result of network developments built for the 2012 Olympic Games.
In Greenwich the visitor can walk under and over the Cutty Sark, visit the National Maritime Museum, admire the paintings in the Painted Hall, and enjoy the quiet sobriety of the Old Royal Naval College chapel.
But the highlight of my day in Greenwich was the Royal Observatory. This building was constructed in 1675; it originally served astronomical purposes, but is now a museum which houses, among other objects, John Harrison’s clocks and watches. These number among the greatest human artefacts, and I was awed when I found them all in their glass case, in particular by the watch known now as H4.
The calculation of longitude at sea had become such a difficulty that in 1714 the British Parliament passed a Longitude Act offering a handsome reward to any person who could come up with a solution. A critical factor in accurate navigation was a reliable timepiece. A clockmaker, John Harrison, arrived in London in 1728 and devoted the remainder of his life to constructing accurate and usable chronometers. Between 1728 and 1759 he built three timepieces, large pendulum clocks which advanced the art of clockmaking, but were not practical on pitching rolling ships.
In 1759 he produced a pocket watch, H4. The object itself is stunningly beautiful: it can be held in the palm of a large hand, it has a look of burnished gold, it is beautifully decorated and bejeweled. And it was eventually to win Harrison the Longitude prize of £20,000, over $2m in present day currency.
H4 was trialled on a voyage to the West Indies in 1762. The watch ran just five seconds slow – the equivalent of one nautical mile – after 117 days at sea.
The voyages of Captain Cook became testing grounds for the new timepiece. A copy of H4 accompanied Cook on his second voyage to New Zealand on the Resolution from 1772-1775. This timepiece enabled Cook to correct some longitude errors on the famous chart he made of New Zealand during his first voyage in 1769.
Harrison died a wealthy man in 1776. It took some time for navigation by chronometer to become established; only by the 1830s had the production of sea clocks become more accurate, more reliable, and above all cheaper, so that all ships could carry them.
H4, so central to the longitude story, is not just a remarkable invention, it also represents one the great leaps forward in human technological history. I felt a strong sense of awe and gravity standing in that room in the Royal Observatory, an experience that I will not forget.
30 July 2016
