An attempt To prove the Motion of the Earth from Observations

I should have here described some Clocks and Time-keeppers of great use, nay absolute necessity in these and many other Astronomical observations, but that I reserve them for some attempts that are hereafter to follow, about the various wayes I have tryed, not without good success of improving Clocks and Watches, and adapting them for varius uses, as for accurating Astronomy, compleating the Tables of the fixt Stars to Seconds, discovery of Longitude, regulating Navigation and Geography, detecting the proprieties and effctes of motions for promoting secret a

Trial of H.4 to Jamaica

To qualify for the highest award of £20,000, the timekeeper would have to show that on arrival in Jamaica it had not exceeded a total loss or gain of 1 minute 54 seconds of time since it had been set by Mr Robertson at Portsmouth on 7 November, some 81 days previously. This performance would be the equivalent of a variation of under 1 1/2 seconds a day, a standard of timekeeping which, even to-day,could be achieved by very few high grade watches.