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SHAKSPER 1991: Astral Navigation & Sonnet 166
From: Ken Steele (ksteele@epas.utoronto.ca) Date: 12/22/91
Shakespeare Electronic Conference, Vol. 2, No. 332. Sunday, 22 Dec 1991.
(1) Date: Sat, 21 Dec 91 11:11:22 EST
From: Ronald Dwelle <dweller@GVSU.EDU>
Subj: SHK 2.0331 Q: Sonnet 166 & Astral Navigation?
(2) Date: Sat, 21 Dec 91 16:40:48 PST
From: kay.stockholder@mtsg.ubc.ca
Subj: SHK 2.0331 Q: Sonnet 166 & Astral Navigation?
(1)----------------------------------------------------------------------
Date: Sat, 21 Dec 91 11:11:22 EST
From: Ronald Dwelle <dweller@GVSU.EDU>
Subject: Q: Sonnet 166 & Astral Navigation?
Comment: SHK 2.0331 Q: Sonnet 166 & Astral Navigation?
A most interesting question, Geoff, on 116, and one that
I've contemplated frequently. Most memorable for me was six
hours I spent reading and re-reading the sonnet, while
becalmed in the Atlantic ocean about 200 miles from Bermuda.
I frequently had to interrupt my reading to grab the sextant
and shoot the sun through breaks in the overcast.
To a contemporary celestial navigator, the lines can make
sense in this way: a good star sight is always difficult,
since in order to get the "height" or elevation of the star,
you need to see the horizon and the star at the same time.
The "height" is, by definition, the angle between the
horizon and the star. The difficulty comes because at night
it's often hard to identify the horizon accurately enough to
get a precise angle--or, occasionally because of overcast or
ship motion, it's hard to identify which star you're
shooting.
It is not unusual for a navigator (in poor conditions) to
"shoot" any star he can. When you do that, you have a height
(read off the sextant, or astrolabe), but you don't have a
"worth"--that is, the navigator still has to calculate his
position, to "reduce" the sight and convert it into a
geographical position on the globe. Or simply guess which
star he's working with.
This is pretty sophisticated navigating for 1594, unless the
star referred to is the North star or Pole star. By
measuring the angle between the horizon and the North star,
the navigator can make a fairly easy reduction to determine
his latitude. Think of it this way: If the North Star were
dead overhead, the height (angle) between the horizon and
the star would be 90 degrees. And the ship would be at
90-degrees north latitude (or the North Pole). If the North
Star were dead on the horizon, the height (angle) would be
0, and the ship would be located at 0-degrees latitude (or
the equator). If the height (angle) were 45-degrees, the
ship would be at latitude 45 degrees. Etcetera. This is a
bit oversimplified, because several corrections have to made
to the raw sight (defraction in the atmosphere, sextant
mirror error, the fact that the pole star is not exactly
over the pole, etc.) before the "worth" (accurate latitude)
is known.
This is all sensible in Shakespeare's time, since "latitude
sailing" was the common way to traverse the ocean.
(Longitude couldn't be easily determined until Captain
Cook's time, since an accurate timepiece is required for
that.) What the shipmaster did was sail "up" or "down" to
the latitude of the home port or landfall (for example, the
southern tip of Ireland), and then sail due east by compass
until landfall was made. Frequent checks of the height of
the north star had to be made, of course, to be sure the
ship was not being set off course by currents or steered off
course by poor helmsmanship, or forced away by contrary
winds.
So the sonnet's lines seem to be to be good navigation, or
good navigational terminology. Love is like the North Star
to every wandering bark, but it's not a sure simple easy
thing, because you have to work at it, taking heights and
calculating worths, and you're always in the sort of medial
stage that the navigator finds himself in--confident yet
anxious--between the taking of the sight and its reduction.
When you do finally get the reduction right (when you know
the star's worth), it is heaven, man. (Don't take my
word--ask any navigator at sea!)
It does seem a little surprising that Shakespeare understood
navigation that well, though perhaps he just picked up the
concept and the language, as he did with so many other areas
of knowledge and experience.
Ron Dwelle (dweller@gvsu.edu) (Sorry the preceding is a
little incoherent--my local e-mail system has an unusable
text editor, so what you get is my rough draft.)
(2)--------------------------------------------------------------------------
Date: Sat, 21 Dec 91 16:40:48 PST
From: kay.stockholder@mtsg.ubc.ca
Subject: Q: Sonnet 166 & Astral Navigation?
Comment: SHK 2.0331 Q: Sonnet 166 & Astral Navigation?
I thought that was the point, that is, that the worth
of a star is beyond navigational knowledge, as the value
of love is beyond calculation. No?
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