Time and Tide

Time and Tide ... Like many others I suspect, I use the since every hour of time represents 15 summer to catch up on my reading. And this degrees of longitude. The ship therefore year I finally caught up with a book I meant must carry a clock set to time in the home to read some time ago and that is now out port and kept at that time as a benchmark to in paperback (and hence good for the compare with the 'on-board' local time. In beach): Longitude by Dava Sobel (4th order to win the prize, Harrison had to Estate, London, ISBN 1 85702 571 7). It is a measure longitude to within half a degree, story of inspiring vision and small-minded and this meant bUilding a ship's clock bigotry, fashioned around a heady brew of capable of maintaining time to a precision technology, politics, money and religion. that was quite unheard of in the early 18th century. It was normal for clocks of the time to be accurate to within 15 minutes in 24 The story centres on one of the biggest hours. Harrison's challenge was to build one technological problems of the 18th century - that did not gain or lose more than 3 how to know where you are at sea. It was seconds in 24 hours. easy enough to know one's N/S position (latitude) - by reading the angle of the sun at noon; but there was no way to ascertain It is a fascinating story and Harrison's with accuracy the EIW position (longitude). technical wizardry shines through it as he Prof Richard The problem was highlighted when Admiral moved from the original prototype H1 Kimbell Sir Clowdisley Shovell (what a fabulous (1737), through a series of refinements in name) was leading his small fleet of prize H2 (1741), H3 (1759), H4 (1760) and finally Technology ships, full of captured treasure, back to H5 (1770). In the process, and in pursuit of Education Research England after a series of skirmishes in the his personal Holy Grail, Harrison tackled Unit, Goldsmiths Mediterranean. Anxious to avoid coastal and cracked innumerable technical University of London rocks, Sir Clowdisley summoned all his difficulties, for example temperature navigators - who agreed that they were regulation, lubrication and balance. safely west of the Brittany peninsula. So they continued north into a foggy night and Changes of temperature as ships sailed on October 2nd 1707 Sir Clowdisley's from the Arctic to the Tropics created flagship - the Association - struck the Scilly havoc with the precision of movement of Isles. Shortly afterwards three of the four the clock mechanisms. It was Harrison other ships also struck the rocks and sank. who developed a bi-metal strip (brass Over 2,000 men and an astronomical and iron riveted together) and used it to quantity of treasure were lost. They thought enable the clock to adjust itself for they were out in the Atlantic well to the west temperature change. of any danger, and they paid a heavy price for their miscalculation. Having started life as a carpenter, Harrison's first solution to the problem of Spurred on by a catalogue of death and bearing surfaces was to use lignum destruction, and in particular the disaster of vitae, which exudes its own grease and Sir Clowdisley's fleet, Parliament finally therefore has a self lubricating quality. established the Longitude Act of 1714, Later he develop the caged ball-bearing which offered a prize of £20,000 to any whose smooth operation is central in so person able to provide a 'Practical and much machinery to this day. Useful' means of measuring longitude. Enter one unknown and largely self-educated clockmaker from Yorkshire - John Harrison. The clocks of Harrison's day all used pendulums to regulate their movement, but the pitching and rolling of a ship Harrison was confident that he could destroys the regular swing of the provide a solution based on accurate time- pendulum. Harrison developed a series keeping. He argued that all the navigator of ever more subtle springs and needed to know was the current time on escapements to replace the pendulum, board ship (from observation of the sun), which eventually allowed the and - simultaneously - the time at one's development of the chronometer. home port. The difference between these two times provides the EIW measurement But the story is not by any means all overcome his lack of formal education but technical. It is also - in parts - hilarious and he also battled for years to overcome the sad, particularly in the context of the technical difficulties that littered his path. competing theories that existed for And then he battled for more years to gain determining longitude (of which there were acceptance for his design against sceptical many given the value of the prize). The authority. No-one succeeds at design and Wounded Dog theory for example - technology without staying power. Ask proposed by Sir Kenelm Digby - relied on Dyson. the crazy idea that the yelping of wounded dogs could be made to signify noon in And then there is the gratifying triumph of London! the innovative practical man over the 'experts', the revered and incredibly well Somewhat less ludicrously, the Lunar resourced occupants of the Greenwich Distance Method was not an 18th century observatory - the high priests of the new contraceptive plan but was rather the source science of astronomy - who failed to of Harrison's major competition. It was the provide a 'Practical and Useful' solution to theory favoured by the official astronomers the problem because they were so wrapped of the day - perhaps because it provided up in their abstruse science that they failed them with endless lucrative employment. to think about the user - and make it The idea was that the movement of the useable. How often have we seen that in moon could be mapped against the whole our classrooms? The youngsters whose field of stars and result in star tables that imagination and innovation enables them to would allow the navigator to compare the design beyond the limits of their supposedly observed position of the moon from the ship 'brighter' peers or even of their teachers. to the position that the moon would be in Design and technology is a risk environment (say) London. Some highly complex with a delightfully iconoclastic tradition. mathematics was then needed to translate the difference between the two into a But the final resonating quirk in this story longitude position. Nevil Maskelyne, the concerns what we might call Mandelson's Astronomer Royal (in residence at the newly monument to the millennium. I have established Greenwich observatory) was watched with interest (from a wonderfully determined to undermine Harrison's clocks located pub overlooking the Thames at and sell his Nautical Almanac full of tightly Greenwich) as the 'Dome' has taken shape. packed astronomical data. Between 1765 It is (I think) an innovative and beautiful and 1811 he published 49 issues, and structure. I make no comment about its sailors around the world became used to the proposed contents - about which I know as tedious task of calculating their position little as most people. using it. Those sailors that did not have a Harrison chronometer had no real alternative and interestingly, it was through At one level the Dome might be seen as a this custom and practice that Greenwich monument to Maskelyne, in the sense that became the Prime Meridian - zero degrees his essentially inadequate solution to the of longitude. But Maskelyne's solution to the longitude problem none the less resulted in longitude problem was an astronomer's the Greenwich meridian fixing London as solution. Harrison's was a practical man's the datum from which the world is solution - and sea captains were practical measured. But at a more profound level, I men (Cook loved it). So as Harrison's prefer to see the dome as a monument to - famous chronometer became more and and a celebration of - the qualities that more available, Maskelyne's almanac enabled Harrison to lay a ruler around the became increasingly redundant - for sea earth. captains at least. Several things about this fascinating story resonate with me in terms of design and technology in schools. There is for example a plentiful measure of triumph over adversity, for not only did Harrison.

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