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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Peter Fogg
Date: 2009 Oct 15, 20:45 +1100
Brad, is it possible to distribute this file with an older version of MS Word?
William Bourne
A Regiment for the Sea
1574
The sixt Chapter or rule she-
weth, how to take the heigth of the Sun
with the crosse staffe or with the Astro-
lobe, and also how to find the true
Meridian, with other neces-
sarie matters.
To take the true heigth of the Sunne at the Sea, beste way is,
to doe it with the crosse staffe: for that the Sea is moueable, and
causeth the Shippe to heaue, and sette little or much: and also
vpon the scrosse staffe the degrees be larger marked than the
Ring or Astrolobe: and in a large instrument an errour is seene
sooner and better than it is in a small instrument.
Nowe to take the heigth of the Sunne, to knowe they Alti-
tude of the Pole aboue the Horizon, doe this: Firste set the
Sunne with a compasse, to knowe when that the Sunne com-
meth near vnto the Meridian: as soone as you see that the
Sunne is come vnto the South and by East, then beginne to take
the heigth of the Sunne with the crosse staffe in this manner:
Put the Transitorie vpon the long staffe, then set the end of the
long staffe close at the corner of your eye, winking with your
other eye, and remouing the Transitorie forwardes or back-
wardes, vntill you doe see the lower end of if (being iust with
the Horizon_ and the vpper ende of it, (being iust with the
middle of the Sunne) both to agree with the Sunne and the
Horizon at one time: and so haue you the true heigth of the
Sunne: this doe, stil ovserue ye same, vntil you see the Sunne
at the highest and beginning to descende, and they haue you
finished. Yest notwithstanding this is to be noted: that it is beste
to take the heigth of the Sunne with the crosse staffe, when then
Sunne is vnder 50. degrees in heigthe aboue the Horizon,for
two causes. The one is this: till the Sunne be .50. degrees in
heigthe the degrees be largely marked vppon the crosse staffe,
but after (the Sune being aboue .50. degrees high) they be
lesser marked. The other is, for that the Sunne being vnder 50.
degrees in heigth, you may easily take the height, bycause you
may easily see or viewe the vpper end and nether end of the
crossstaffe bothe at one time: but if it dothe exceede .50. degrees,
then by the meanes of casting your eye vpwardes and down-
wardes so much, you may soone commit error, and then in
like manner the degrees be so small marked, that if the Sunne
dothe passe .50. or .60 degrees in heigth, you must leaue the
crosse staffe and vse the Mariners Ring, called by them the
Astralaby, which they ought to call the Astrolobe. Nowe to
take the heigth of the Sunne with the common Ring or Astro-
love, doe thus: The Sunne being (as before is declared) neare
the Meridian or South, ovserue it (vntill you haue the greatest
heygth thereof) in this manner: Holde the Ring of the Astro-
lobe vpon one of youre fingers, and turne the Alhidada vppe
and downe, vntil you see the shadowe of the Sunne pearse or
passe thorough bothe the sightes thereof, being sure that the
Astrolobe dothe hang vpright, whiche you may proue in this
manner: Looke at mowe many degrees and minutes the Alhi-
dada dothe stande vppon the Astrolobe, then turne the Alhidada
vnto the same number of degrees and minutes on the other
sode of the Astrolobe, then taking the heigth of the Sunne
againe, if it doe agree as it did before, then the Astrolobe dothe
hang vpright. but if it doe not, then it dothe not hang vpright.
For knowledge of the true heigth of the Sun (the Astrolobe not
hanging vpright) do thus: if the Astrolobe be truely marked,
marke the diuersitie, that being knowne, rebate from the
greatest heigth halfe the diuersitie, or else adde vnto the lesser
heigth halfe the diuersitie, and that shall be the true heigth of
the Sunne, although that the Astrolobe doth not hang vpright.
The Astrolobe is best to take the height of the Sun, if the
Sunne be very high at .60.70. or 80. degrees, and the cause is
this: the Sunne coming so neere vnto your Zenith, hathe great
power of light, for to pearce the .2. sights of the Alhidada of the
Astrolobe, and then it is not good to vse the crosse staffe, for
that the Sunne hurteth the eyes of a man, and besides that it is to
high to occupy the crosse staffe, (as before is declared) so that
this way you may very much preserue your eyes. If you haue
not glasses vpon your staffe (to saue your eyes in taking the
heigth of the Sunne) but be vnprouided of them, to thus: take
and couer the Sunne with the end of the transitorie of the crosse
staffe, unto the very vpper edge or brinke of the Sunne (so shall
you not neede to heholde the brightnesse of it) and with the
other end of the transitorie to take the horizon truely, and that
being done, for that the Sunne is .30. or .31. minuts in diameter
or bredth, therefore you shall rebate .15. minutes from the
altitude or beigthe of the Sunne, and then that whiche shall
remaine shall be the true heigth of the Sunne from the center or
middle of the Sunne. And furthermore there is some error in
the taking Sunne or Starre with the Ballastel or crosse staffe,
and that groweth by this meanes: for that the true center
(which is the sight of the eye) is within the middle of the eye,
and not in the outside of the eye, so that the end of the long
staffe in the setting of it vnto the corner of your eye, dothe
stande somewhat further out than the sight of your eye, that is
to saye, that the sighte of the eye is somewhat further into the
head, than the ende of the staffe dothe come: wherefore you
must pare away a little of the ended of the staffe, for some mens
vses more, and some mens vses lesse, for that it is according as
you may set the staffe vnto your eye, for some men neede pare
away little or nothing, and some men must pare away .14. or
.15. minutes as you may set the staffe: bycause some mens eyes
be further into their head than other some mens are, and the
bones of some mens face stand further out than other some do.
It is moreouer conuenient to know the true meridian, or South,
whiche you must do, either with a good compasse or with a
perfyte diall or Needel: but if you be on the land this you may
do: on a peece of timber, or any other thing that standeth fast,
with a paire of compasses make a circle, then in the midle or
center where the foote of the compasse did stand set a wire
vprigth (as circumspectly as you can) and then you may do this:
looke in the morning (so it be on plaine ground that you may
see the horizon circle, without any let) a the sunne rising, for
the shadow of the wier, and ther set a pricke: then at the
setting of the Sunne you shall set another pricke: euen at the
circumference of the circle, then diuide that with our com-
passes euen in .2. peeces, and strike a straight line for the wier
or center of the circle, to the middle or deuided prick, & that
shal be the true meridian. Or else (the wier standing vprigth) first
in the fore noone when the top of the wier doth touch, or is
ready to come into the circumference or edge of the circle, there
make a pricke: then in the after noone in like manner, at the
very comming out or touching of the wyer, of the edge of the
circle, there make an other pricke euen with the comming out
of the shadow: this done (as circumspectly as you can) deuide
these 2. prickes in the midle, then as before is said, drawe a line
from the center or wier, to the midle prick, and that shadow shal
be your true meridian. After another manner you may doe
this: looke and watch when the wyer giueth the shortest
shadowe, and there make a pricke: then draw a line from that
prick to the wyer, which shadow shall be the true meridian.
And yet furthermore, for yt it is most conuenient to know ye
true Meridian at the Sea, bicause in long viages going far vnto
the Westware or Eastward, the compasse doth varie: to find the
true Meridian do this. Set the Sunne with your compasse is hir
rising or appearing aboue ye horizon, & then (knowing what
point and part the Sune doth rise at) set the Sun with your
compas at hir setting or departing vnder ye horizon & (that
being known) you shal perfitly know, whether the compas be
varied & how much: for ensample this, I doe set the Sun at hir
rising with the compas & she doth rise vpon the East point: in
like maner also I do set the Sun with hir compas at hir setting, &
do find hir to set West Northwest: so I do see the compass to be varied one pointe, thst is to say, the North point doth stand
North and by East, &c. And furthermore (for that seldome
times the Sun dothe rise and set cleere by the meanes of the
cloudes, and other impediments neere the horizon) you may
get the true Meridian thus: at any time in the fore noone, first
set the Sunne with your compas, and then take the true heigth
of the Sunne. Now you (knowing how many degress ye Sun
was high at that point of the compas) may in like maner obserue
the Sunne in the afternoon, untill you do find the Sun iust at
that heigth that it was in the forenoone, marking at what point
of the compas the Sunne is, and so shall you see perfitely
whether the compas be varied or no, and also howe much: for
ensample thus: I take the Sun upon the Southest poynt .20.
degrees aboue the horizon, & then in the after noone I do ob-
serue the Sun vntil such time as I do find the Sunne iust .20.
degrees aboue the horizon again, & then I set ye Sun with the
compas and do find ye compas to be varied one point, yt is
to say the North point doth stand North & by East. &c.
Another way also to know ye true meridian, is by the Sun: that
is, to set ye Sun with ye compas at hir greatest heigth aboue the
horizon, & so you shall know whither ye compas be varied, &
how much: & looke what is spoken of ye Sun by day, you may
do the like by night by any of the Starres yt you perfectly do
know, doing as you do by ye Sun in all points: but you cannot
do it so well and truly by the Moone, by the meanes of the
swiftness of ye moones motion in the Zodiack, you may also
find the variation of ye compas by the North Starre, as thus: set ye
North Star with the compas, if the North point do stande right
with the Starre, then it is not varied: and that must be done
when the .2. Starres of Charles Waine called the pointes be
right vnder, or right ouer the North Star, but if that the Starres
be West from the North Starre, then the North Starre is the
third part of a point vnto the Eastward of the North pole. If the
.2. Starres of Charles Wayne called the poynters be due east
from the North Starre, then the North Starre is the third part
of a point vnot the westwarde of the North pole .&c. This
haue I saide bycause that sometine in sundry places, the com-
passe doth varie, & especially in the sayling of long viages run-
ning East and West, (called the Northeasting or Northwesting
of the compasse) therefore I would not wish them to meddle
with the mending of their compasse or whetting of the side of
the needell to the end to make it stand due North, but cir-
cumspectly to awaite the altering of the compasse, and what
quantitie it doth alter: as you may do very well, by the order
before rehersed, and then let your compasse alone: for although
that it dothe varie .2. or .3. poynts, you may make account
according to the variation as thus: I admit the Northwest point
standeth due North, and my course is to go due West, I will
occupy the Southwest pointe in this case for the west poynte.
And thus ( by oberuation and trying of my compass) I care not
what point standeth due North, for it is all one, so that you
consider what poynt standeth North. And now furthermore,
come are of that opinion, that (by the Northeasting or North-
westing of the compasse) you may knowe the Longitude: but I
am not of the opinion, for I admit that it be so (as some do
affirme) that the compasse doth varie, (as some haue said) that
is, that you being .90. degrees vnot the Westwarde (from the
place youre compasse was made at) youre North poynt should
stand Northeast: and in like maner you being .90. degrees East,
your North poynt shoudl stand Northwest: then by that order
the compasse should vary one poynt at .22. degrees and a halfe,
and that cometh vnto .450. english leagues (if you be neere
vnto the equinoctial:) wherfore no master or pilotte of a
shippe, doth keepe so simple account fo the shippes way, but
that he may knowe what distance he hath vnto any place better
than he shal know by the variing of the compas: & also
whether it be so or not yt the compas doth keepe any such pro-
portion in the variation, I do refer that vnto them that haue tried
the experience thereof: for I for my part can say nothing in that
matter. Wherfore I cease from writing muche thereof, al-
thoughe the Sea men by very desirous to haue some way to get
the Longitude. But if it be true that the compasse doth verie by
that proportion, then it were very good for them to practise
that matter, that shoulde make any discoury vnto the North-
wardes, for that the degrees be so short in those Paralels.
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