Second Trial of John Harrison’s H.4 to the West Indies – Barbados
Chapter 13, Second Trial of John Harrison’s H.4 to the West Indies – Barbados, pp. 134-135.
Harrison’s homeward journey was made in the merchantman New Elisabeth (Captain Robert Manley), which sailed from Barbados on 4 June, 1764, but Maskelyne remained behind to continue making observations of Jupiter’s satellites from which the longitude of the island could be determined afresh. According to the results published later, nine observations of the first satellites made at Barbados when compared with five similar observations made by Mr John Bradley at Portsmouth, gave the longitude of the island to within a distance of 8.77 miles of what it is now known to be. (Note: The observations gave the difference in time between Portsmouth and Barbados as being 3 hours 54 minutes and 2 seconds, which works out as being 8.77 miles.) The accuracy of this result was exceptional,... It will be noticed that no official precautions were taken to prevent interference with the watch during the return voyage from Barbados to England. Unofficially however, it was claimed on behalf of Harrison that from the beginning to the end of the double journey to and from Barbados, the watch had gained only 54 seconds in 156 days!
John Harrison, The Man who found Longitude, Dublin: Made and Printed in the Republic of Irland by Hely Thom Ltd.
"This book tells the story of how Harrison succeeded in doing the near-impossible by designing and constructing a marine time-keeper that met the onerous conditions laid down; and then how he had to contend with a series of official investigations, interminable delays and frustrations before he received his deserved reward"
- An account of the Going of Mr. John Harrison’s Watch…, by the Rev. N. Maskelyne, London, 1767, p. lvi.
- The Annual Register for 1765, p. 121.
- The Longitude Found, D.H. Sadler, Reviews no 3, Vol 20, pp. 358-360. (journals.cambridge. org)