If you’ve been following this blog, you’ll know I’m an admirer of Halley and expect that I side with him in his difficulties with his lieutenant – yet when I first read about Edward Harrison and his book, I did have some sympathy and respect for the lieutenant.
Harrison described himself as “sea-bred”, indicating he’d been at sea from an early age, but he was evidently a man of some, if limited, education. These facts suggest someone of modest background and resources, and so it seemed to me rather impressive that he had written a book, got it printed, and circulated it to the Royal Society and the Admiralty – and I could feel some sympathy for his dismay when Halley then dismissed his enterprising efforts.
But then I read his book and that sympathy disappeared. The book, Idea Longitudinis, was published by Harrison in 1696; he’d submitted a paper of his ideas to the Royal Society about 2 years earlier but received no encouragement and so he decided to “appear on the Publick Stage”. 
The book includes a dedication to the Lords of the Admiralty, a preface, and 8 chapters including a conclusion, the whole about 97 pages long. The first 3 chapters cover: where to set a first meridian, a definition of longitude, a definition of time (solar, sidereal year), and chapters 4-7 consider the different methods of finding longitude: horological, magnetic variation, lunar, and Jovian.
The book seems not without merit as a handbook for his “Brother Tar”, and some of his remarks about the problems that would be encountered (refraction, parallax, impossibility of using a long telescope (for the Jovian method) on a rolling ship) are helpful – but this was all commonplace to the fellows of the Royal Society, and I would guess that that was the opinion Halley gave to their Lordships.
What Halley actually said about the book doesn’t seem to be extant, but a slightly later review of another paper of Harrison’s may give us some indication. While Halley was away on his second voyage, Harrison submitted another paper to the Royal Society on tides and winds, and this was reviewed by Richard Waller, who ends his 2-page review with “between you and me [he’s writing to Hans Sloane] I see nothing in the Paper but what is better explained in the places I have above quoted”. 
Perhaps Halley gave a similar assessment – that it contained nothing new – an opinion that would be reinforced when he found that the opening lines of Harrison’s chapter on magnetic variation (see image) were copied almost verbatim from his 1683 paper on the same subject (there’s at least one other section copied directly from Halley’s paper).
Alan Cook describes Harrison’s book as “[s]cientifically and technically… poor, second-hand, and ill-digested. It is shot through with aspersions on mathematicians, the manner is aggressive, and it shows a deep inferiority complex”, and possibly the most interesting aspect of the book is what it reveals about Harrison himself, giving us some idea of what Halley had to deal with on board his ship. 
Harrison comes across as having a rather inflated view of himself. He twice compares himself to Columbus as being someone who “shewed the way”, and warns us that some “ordinary Mathematicians may hate to be out-done by a Tarpolin, if they have ought to say against him, its because his Practice and Experience may prove him to be a more Competent Artist in Navigation then [sic] themselves”. 
Hindsight makes the opening lines of the dedication seem ironic: “It is a saying in the Navy, He that knows not how to obey Command, is not worthy to bear Command”. As, too, does this sentence, given he’d lifted passages from Halley and then gone on to despise him for dismissing his book: “If any Envious Person pretend I have borrowed most of my Book, may he be obliged to Quote the Authors, where I have not”. 
The passages that revealed most about his personality were also the most unexpected:
“…if I know more than others, it is by Divine Authority, by Industry and Experience, by an Inborn Idea, and Instinct in Nature; it was ordained for me by God Almighty, from my Mother’s Womb.” 
And when considering the location of a first meridian:
“I could Bafle and Impose on the World as our Predecessors have, false Arguments for other places, from whence they might account their first Meridian. God forbid I should be so wicked, Honour and Glory, and beginning of Good, belongs to God; a first Meridian may be represented, and if the Heads of our Church and State, think it good, let there be made a Figure, representing a first Meridian, and Erected over St. Pauls Church in London, with this Inscription, Glory be to God, good Will towards Men…” 
Blimey. These passages took me by surprise, as it had never occurred to me that Harrison might be religious, and they perhaps provide another reason why Harrison was so hostile towards Halley, as Halley had something of a reputation for being irreligious. I think Halley must have had a hard time dealing with Lieutenant Harrison, and yet, as he tells us, he “endeavoured all I could to oblige him”. 
My feeling is that Halley gave an honest critique of Harrison’s book, but that Harrison was not the type of person who could accept criticism and so nursed a grievance towards Halley (whom perhaps he had once admired, given his imitation of his works) and seized the opportunity to wreak his revenge when chance put them together on board the same ship.
I suspect that Harrison was rather fortunate in the court’s verdict…
This post was originally published on 10 July 2013 and revised in July 2017.
 Edward Harrison, Idea Longitudinis (London, 1696), preface
 Richard Waller to Hans Sloane, dated 4 Dec 1699, Royal Society, EL/W3/68
 Alan Cook, Edmond Halley: Charting the Heavens and the Seas (Oxford, 1998) p 264
 Harrison, preface
 Harrison, preface
 Harrison, preface
 Harrison, pp 3-4
 Captains’ Letter Book, National Archives, ADM 1/1871