Before leaving St Helena, Halley sent a letter to the Admiralty – there’s no addressee but it’s presumably the Secretary, Josiah Burchett. He tells Burchett about the great danger they encountered among the “Islands of Ice” and also that he has “noe reason to doubt” that he will be able to derive a general theory of compass variation from his observations that will help mariners find their longitude at sea.
The letter isn’t in Halley’s handwriting, and I’ve made some minor changes to the punctuation and split it into two paragraphs to make it easier to read, but left the spelling as written.
(Halley to ?Burchett, dated 30 March 1700 from St Helena, National Archives ADM 1/1871)
I must Intreat You to lay before the Lords of the Admty this account of what I have done in execution of the Orders I Received from them. Since my last from St. Iago, which I hope came long since to Your hands, haveing not been able to fetch Madera by reason of the winds shifting upon me, I was Obleged to putt into Ryo Jennero in Brasile to gett some Rumm for my ships company, from whence I wrote you a letter which I suppose will not be in Engl[and] soe soon as this. I left Ryo Jennero on the 29° of December last and stood to the Southward till the 1st of February, when being gotten into my Station Vizt in Lattd: 52°½ and 35° west Longitude from London, we fell in with great Islands of Ice, of soe Incredible a hight and Magnitude, that I scarce dare write my thoughts of it. At first we took it for land with chaulky clifts, and the topp all covered with snow, but we soon found our mistake by standing in with it, and that it was nothing but Ice, though it could not be less then ?200 foot high, and one Island at least 5 mile in front. We could not get ground in 140 fadtham, Yet I conceive it was a ground, Ice being very little lighter then water and not above an Eight part above the Surface when it swims. It was then the hight of Summer, but we had noe other singe of it but long Days; it froze both night and day, whence it may be Understood how these bodies of Ice are generated being allways increased and never thawing.
The next day February the 2d. we were in Imminent Danger to looss our ship and lives, being Invironed with Ice on all sides in a fogg soe thick, that we could not see it till was ready to strike against it, and had it blowne hard it had scarce been possible to escape it: Soe I stood to the Northward to get clear of it, which in the Lattd. of 50° I did, and their Saw the last Ice. In my way hither I Discoverd* the Isles of Tristan da Cunha, and in Eleaven Weeks from Ryo Jennero I arrived at this Island, to fill my Water and refrezen my men, and in this whole course I have found noe reason to doubt of an exact conformity in the variations of the compass to a generall Theory, which I am in great hopes to settle effectually
Your most Obedt Servt
* “Discoverd” here simply means ‘saw’