Early medieval texts show how the steering star has been a friend to sailors through the ages.
“…till atte last gan fall
Such a myst among hem that no man myght se other,
That wele was hym that had there the blessing of his moder.
For thre dayes dessantly the derknes among hem was
That no shipp myghte se other; wherfor ful offt ‘Alas!’ They seyd, and to the highe God they made hir preyere
That He wold of His grace hem govern and stere,
So that hir lyves myghte i-saved be.
For they were cleen in dispeyr because they myght nat se
The loder, wherby these shipmen her cours toke echon.”
Canterbury (Tales) Interlude and Merchant’s Tale of Beryn, Anon circa 1450
In this later, 15th-century, addition to Geoffrey Chaucer’s Canterbury Tales an unknown medieval scholar relates how sailors were using the ‘loder’ – the North Star or Polaris as we now know it –to navigate, and how dangerous it was to be caught in prolonged fog.
The Loder got her name by the lodestone, or magnetite, which is used to magnetise an iron needle so that it will always point to magnetic north. An iron needle was put into a piece of cork ’til it almost disappeared, then touched with the lodestone. Used by the ancient Chinese, it is referred to in Europe from the 12th century. Typically the thus-magnetised needle was then put into a cornstalk or reed and floated in a bowl of water where it oriented to the magnetic pole. Needless to say there were varying degrees of accuracy, especially on the small caravel-like ships that Beryn was described as sailing, and the text above suggests that a middle-ages seaman still trusted more to steering by the star. Shakespeare, in Much Ado About Nothing, (Act III Scene IV) writes: “There’s no more sailing by the star” – referring to the Pole Star and therefore something trusted.
There was also the known matter of variation, of which Columbus was aware. Variation is the difference between true north on the earth’s axis and the much more changing magnetic north – NE Canadian Arctic. In 1580s London for instance the compass pointed 11º15’ East of North while by 1607 it pointed True North. By 1819 variation had swung West to a maximum 24º18’W while in early 2020 it was back to True North (2º30’W) and is now moving east again – at the rate of about 8′ per year (eight minutes; there are 60 minutes in a degree). Compass Variation, and its annual change east or west locally, are to be found on the inside of the compass rose on your charts. DH
Illustration: Guy Venables
More on steering by a star: HERE