Going Dutch_ How England Plundered Holland's Glory - Lisa Jardine [126]
At precisely the same time that they were dealing ‘in secret’ with Hooke’s proposed revolutionary designs for longitude timekeepers, Brouncker and Moray had taken it upon themselves to move the Bruce–Huygens clock trials onto a more systematic footing, with the Royal Society’s official backing. They arranged for Robert Holmes, captain of the Jersey, to carry the two pendulum clocks to and from Lisbon in 1663, and then on a longer voyage to Guinea and back in 1663–64.72
For the history of development of longitude timekeepers these trials were a turning point. By contrast with Bruce’s trials, those conducted during Holmes’s voyages, particularly on the voyage to Guinea, were spectacularly successful. The clocks ran well throughout the journey, Holmes set them regularly and kept them running, and crucially, the clocks allowed Holmes to make a calculation of his position at a key moment in the Guinea voyage which revealed the inadequacy of traditional longitude- finding methods.
On the return journey, Holmes had been obliged to sail several hundred nautical miles westwards in order to pick up a favourable wind. Having done so, the Jersey and the three ships accompanying her sailed several hundred more miles north-eastwards, at which point the four captains found that water was running worryingly low on board. Holmes’s three fellow captains produced three conflicting calculations of their current position based on traditional dead-reckoning, but all agreed that they were dangerously far from any potential source of water. Not so, declared Holmes. According to his calculations – based on the pendulum clocks – they were a mere ninety miles west of Fuego, one of the Cape Verde islands. He persuaded the party to set their course due east, and the very next day, around noon, they indeed made landfall on Fuego, exactly as predicted.73 Huygens’s clocks had saved the day.
This was exactly the kind of publicity the pendulum timekeepers needed in order to capture the public imagination. Moray’s report of this dramatic success, in a letter to Huygens dated 23 January 1665, is clear as to its impact: ‘At last Captain Holmes has returned, and the account he has given us of the experiment with the pendulum clocks leaves us in absolutely no doubt as to their success.’74
The following day Huygens replied. He was delighted to hear of Holmes’s triumph with the clocks; every line of the account gave him the greatest pleasure, and he thanked Moray for being the bearer of such good tidings.75 Holmes’s report was published verbatim in the Royal Society’s Philosophical Transactions and in French in the Journal des sçavans, and eventually featured as the unique account of a sea trial of pendulum clocks to be included in Huygens’s landmark book the Horologium Oscillatorium, published in 1673.76 Right down to the present day, the spectacular success of these trials is invoked as the crucial evidence on the basis of which Huygens’s pendulum-clock timekeepers take their place as a significant step in the progression from the theoretical aspiration to determine longitude at sea using a precision clock, to the realisation of that dream with John Harrison’s longitude timekeeper in the following century.
The success of the Holmes trials probably led directly to Moray and Brouncker abandoning attempts to agree a patent document with Hooke. By this time too, ironically, Moray had given up hope of getting Bruce and Huygens to agree a fair distribution of financial reward, and abandoned their patent bid also.77
So it might appear that there is some justice in the fact that Huygens has continued to receive most of the credit for early longitude clock trials, and developments culminating in the balance-spring-regulated pocket watch,