969485r
1. Some remembrances of taking the altitude of sonne
by the Astrolabe and Sea
by the Astrolabe and Sea
There are three instruments used at sea for taking of altitude, the
Astrolabe, The ring, & the staffe. Seamen use the Astrolabe The
Astolabe hath here most ancient & is used commonly & only for the
sonne; and serveth the seamans turne most specially when the sonne is
[???] becuase then they if the find the staffe very uncertayne. And when
the sea is wrought it is very hard to make any observation by it
also; because of his agitation & unquiet
Astrolabe, The ring, & the staffe. Seamen use the Astrolabe The
Astolabe hath here most ancient & is used commonly & only for the
sonne; and serveth the seamans turne most specially when the sonne is
[???] becuase then they if the find the staffe very uncertayne. And when
the sea is wrought it is very hard to make any observation by it
also; because of his agitation & unquiet
But howsoever when there is need you must do as well as you may.
and therefore when you have your Astrolabe guaging as quietly as the time
will permit with his side toward the sonne according to the usual order,
you are to fit the Judex by moving it so long up & downe till the former
shine thourough the holes of both the sights at the same time. Or you finding by reason
of his agitation that the sonne will not passe iustly thourough the lower sights but be
[???] sometme higher & sometime lower. where you finde the lyst of the syghts
now as much over as under: then your Judex standeth as precisely as if the
Astrolabe had hong quietly; & sheweth the true altitude of the center of the
and therefore when you have your Astrolabe guaging as quietly as the time
will permit with his side toward the sonne according to the usual order,
you are to fit the Judex by moving it so long up & downe till the former
shine thourough the holes of both the sights at the same time. Or you finding by reason
of his agitation that the sonne will not passe iustly thourough the lower sights but be
[???] sometme higher & sometime lower. where you finde the lyst of the syghts
now as much over as under: then your Judex standeth as precisely as if the
Astrolabe had hong quietly; & sheweth the true altitude of the center of the
But if you doubt of the true guaging of the AStrolabe, you may move
your Judex quickly to the same signe on the other side & hold it towards the sonne.
If you find the sonne shine thourough as before your Astrolabe hangeth well.
Otherwise you are also to move your the Judex, till you have also the altitude on
that side. Which had, compare with the other & note the difference. The half of that
difference added to the lesse altitude or detract from the greater; And you have
the altitude of the sonne as exacte as if your Astrolabe had hung truly
your Judex quickly to the same signe on the other side & hold it towards the sonne.
If you find the sonne shine thourough as before your Astrolabe hangeth well.
Otherwise you are also to move your the Judex, till you have also the altitude on
that side. Which had, compare with the other & note the difference. The half of that
difference added to the lesse altitude or detract from the greater; And you have
the altitude of the sonne as exacte as if your Astrolabe had hung truly
The other instrument called Sea Ring is of late yeares in great use with the
Portingalls & Spaniards, The making whereof & use they had about 40
yeares past of a country man of their owne a learned mathematician called
Petrus Nonius who also hath written [???] of the arte of Navigating
as well in Latin as in Spanish. And is only for taking the altitude of the
sonne as the Astrolabe. but for ease & space it much excelleth it
as also for exactnesse. for the degrees are as large agayne as in an
Astrolabe of the same signes. And in the use, there is no noe troublesome
moving up & downe any Judex as in an Astrolabe; but it guaging as the
Astrolabe, the & that side which hath a small be of bing holden towards
the sonne; the light passing thh presently sheweth upon the degrees noted
within the ring the altitude of the sonne you desire. you are to note
that the middle of the light be it round or long is your true marke.
And if the light play by reason of his unquiet hanging; then the
middle of the play is the th hight. This instrument is continued
together for your use the last viadge with the Astrolabe , And upon your
returne it was geven to your servant Cap. Whidden, who now hath
also hath it redy for your use. By our last practice [???] I
found it much lighter then it ought to be, which is a fault also in all
the Astrolabes I have seene. By reason of [???] speedy setting
setting forth it cnnot more be remedied; but is to be used as
Portingalls & Spaniards, The making whereof & use they had about 40
yeares past of a country man of their owne a learned mathematician called
Petrus Nonius who also hath written [???] of the arte of Navigating
as well in Latin as in Spanish. And is only for taking the altitude of the
sonne as the Astrolabe. but for ease & space it much excelleth it
as also for exactnesse. for the degrees are as large agayne as in an
Astrolabe of the same signes. And in the use, there is no noe troublesome
moving up & downe any Judex as in an Astrolabe; but it guaging as the
Astrolabe, the & that side which hath a small be of bing holden towards
the sonne; the light passing thh presently sheweth upon the degrees noted
within the ring the altitude of the sonne you desire. you are to note
that the middle of the light be it round or long is your true marke.
And if the light play by reason of his unquiet hanging; then the
middle of the play is the th hight. This instrument is continued
together for your use the last viadge with the Astrolabe , And upon your
returne it was geven to your servant Cap. Whidden, who now hath
also hath it redy for your use. By our last practice [???] I
found it much lighter then it ought to be, which is a fault also in all
the Astrolabes I have seene. By reason of [???] speedy setting
setting forth it cnnot more be remedied; but is to be used as