Stevin | Havenvinding | Haven-finding art (transl. Edward Wright)

Title , dedication , preface , Stevin , table , definitions , variation , instrument


[ A1 ]

T H E   H A V E N-

F I N D I N G   A R T,

Or

T H E    W A Y    T O    F I N D
any Haven or place at sea by

the Latitude and variation.

Lately   published   in   the   Dutch,   French,

and Latine tongues, by commandement of the
right honourable  Count Mauritz of Nassau,  Lord
high Admiral of the united Provinces of the
Low countries, enioyning all Seamen that
take charge of ships under his iurisdi-
ction, to make diligent observati-
on, in all their voyages, ac-
cording to the directions
prescribed herein:


And now translated into English, for the common benefite
of the Seamen of England.



mark   Imprinted at London by
G. B. R. N. and R. B.

1599.




[ A2 ]
T O   T H E   R I G H T
Honorable  Charles  Earle  of  No-
tingham, Baron Howard of Effingham, knight
of the noble Order of the Garter. Lord high
Admiral of England, Ireland, Wales, &c. And her
Maiesties Lieutenant, and Captaine general over
all her subiects, levied in the South
parts of this Realme, &c.


RIght Honourable, being informed by my learned friend and most earnest and effectuall furtherer of Navigation for the common good of his countrey M. Richard Hackluit, upon the dedication of his first volume of discoveries unto your Lor. about a yeere since, of the singular affection your Lor. beareth towardes the advancement of knowledge and skill among our seamen in marine causes; so farre foorth that to the end they might be the more stirred up and holpen this way, your Lor. would not onely be a meane unto her Majestie for the establishing of an ordinary Lecture to be read for their instruction, but also rather then so good a purpose should fall to the ground would be at some charges your selfe for the bringing of it to effect: I conceived no smal comfort upon this report,
[ A2v ]
considering that now of late, the right honorable Count Maurice of Nassaw, L. high Admirall of the united Provinces of the low countries hath shewed himselfe wholly to be of your Lor. minde, thinking it a most principal point for the welfare of their estate to have their mariners now entring into long voyages to be better informed in matters concerning their faculty, then heretofore they have bene. To which end he hath lately caused a certaine exhortatory iniunction to be published, and hath also given commandement that the same should be diligently observed by all masters of ships and their companies within the same Provinces. By observation wherof they may have a more certaine and compendious way, whereby they may guide themselves to come to any place they shall desire at sea, with a streighter course, and in shorter time then hath bin commonly accustomed: Which way is to be found by knowledge of the latitude and variation of the place wherto they purpose to go. For seeing one and the same place hath alwaies the same latitude and variation, whereof the one sheweth what situation the place hath between North and South, the other between East and West, it cannot be but that the master of the ship bringing himselfe to the latitude
[ A3 ]
and variation of the place to which he purposeth to go, must needs bring himselfe to the same place also.
    Considering therefore howe great profit might hereby redound to seamen if the variations of all places were truely known, the said
Count Maurice hath given commandement to all that shall take charge of ships, that before they set forth, they should provide themselves meete instruments for that purpose, that into what place soever they shall come, they may diligently search out the declination of the magneticall needle from the true North (which they commonly cal the variation of the Compasse) and that after their returne into their owne countrey they should give a true certificate of those observations to the rest of their collegues and companies of the Admiralty, that by them they may be brought into some good order and method, and so be published for their common good. Desiring also as it may appeare to stirre up other nations to the same care and diligence in observing the variation, he hath caused the said iniunction to be published, not only in his native tongue, but in the French and Latine also: intending (as it may seeme hereby) to make not only it, but also his honorable desire in furthering this observation commonly known to
[ A3v ]
all Christendome. Desiring therefore, according to the measure of my small abilitie, to be a furtherer of so good a purpose of so famous a personage, I have done mine indevour to make the same knowen to all English mariners, by publishing the foresaid Iniunction in their mother tongue: nothing doubting, but as they have not bene inferiour to any nation, either for excellency of skill, or felicitie in performance of their most wonderfull Navigations, and that principally in this most happy time of your Lor. enioying your most honorable office of high Admiralty: So, if it might please your Lor. to give them to understand that your Lor. would be very loth that English mariners (whom I have knowen to have had the skill, to finde out places at sea by the latitude & variation, after the same maner that is perscribed in this booke, more then ten yeres since) should now (either for too much sparingnes in not preparing, or for want of diligence in heedful using meete instruments for that purpose) cast themselves behinde the Netherlanders; there may assured hope be conceived, that they wil not only not come behind, but farre exceed, and go beyond them, or any other nation. And so much the rather there is reason to induce us to be of this opinion,
[ A4 ]
because there hath bene a secret of the magneticall needle first revealed by our countriman M. Rob. Norman, wherof other nations as yet seeme to be ignorant, I meane the falling of the North end of the needle touched with the loadstone under the horizon. Of which new-found propertie if there shal be diligent and continuall observation made, especially in long voyages, there may in all likelihood no lesse profit arise thereby then by the variation.
    Considering therefore how greatly your Lor. authority, yea inclination or beck onely mought prevaile to move the minds of all English mariners to the diligent, heedfull, and continual observation of these so rare and wonderful properties of the magneticall needle, at all places wheresoever they shall come, wherby so great profit may assuredly redound not onely to seamen, but even to the whole body of the Christian commonwealth: I was emboldened, recounting with my selfe your Lor. exceeding clemencie conioyned with so high authority to bring before your most honorable presence this Dutch Pilot (as it were, for so I may not unfitly call this booke) whom since his arrivall here I have onely taught to speake English that so he might be the more serviceable unto your Lor. and to all English
[ A4v ]
seamen in that he professeth, which is to bring them to any place in the main Ocean, by a shorter course, then hath bene accustomed. Wherein because the renowned Count Maurice his master hath given him so great credit, as to command him to be imploied by al that take charge of ships under his office of admiralty, may it therfore please your L. to affoord him the favour as to commend him to all English maisters to be thorowly examined by due triall of exact observation in al places at sea; to the end that if he shall be found indeed to performe so much as he promiseth (wherof there is given exceeding great hope by proofe already made by some of our skilfullest English navigators) he may for ever after be received with enterteinment worthy so notable service.
    Thus nothing doubting that this Dutch Pilot so highly commended by so worthy a personage, shall find such favourable acceptation at your L. hands, as in your Lor. high wisedom to him duely appertaineth: I most humbly beseech the Lord of all Lords to increase your Lor. with all true honour in this life, and with endlesse blisse in that life which shal last for ever.
  23. Aug. 1599.

Your Lordships most humble            
to be commanded.        

E. Wright.    

[ B1 ]
T O     T H E     W O R S H I P-
full M. Richard Poulter the Maister, and
brotherhood of Trinitie house, and to all
English mariners and sea-men in ge-
nerall  that  love  the  perfection  of  their
owne profession, health and happines.


HAving dedicated this litle Booke to the Right Hon. the Lord high Admirall of England, to whom the governement of sea causes next under her Maiestie chiefly appertaineth (with whom also it hath found such favourable acceptation as of so honorable a personage might be iustly espected) I thought it meete in the next place to commend the same to your Wor. societie also, as to them who have best occasion in your so manifold navigations to make most plentifull and sufficient triall thereof, and to whom it may assuredly doe most necessary and profitable service. But least you should stand in doubt of this my commendation, the Right Honourable Count Maurice, Lord high Admirall of the united Provinces of the Low Countries, hath not only commended the same to all Masters of ships and their companies (or brotherhoods as we may call them) that are under his iurisdiction; but hath also commanded them to make diligent and continuall observation in all their voyages, according to the directions prescribed herein. He also, as not content that the fruit which may spring hereof should be conteined within the narrow boundes and compasse of the Lowe Countries, hath caused this booke to be translated into the
[ B1v ]
French and Latine tongues: endevouring as it may seeme hereby to make the same knowen to all nations in Christendome. Amongst whom as the Latine translatour M. Hugo de Groot hath chosen the Venetians for their excellencie in Navigation (as he conceiveth) to whom he might especially dedicate this small Volume togither with his owne labour in translating the same: So I thought it meete to make choise of your worshipfull society, whom I take to be nothing at all inferiour to the Venetians either for excellencie of skill, or for use and experience in that facultie: and to whom I may more iustly commend this little Booke, even almost with the same words which Hugo de Groot useth to the Venetians [<] as followeth.
    Therefore that we may enter a little more deepely into the matter, Aristotle the wittiest of all philosophers and the most famous Lawyers doe witnesse that all arts were founde, out of the necessitie of mans nature, that what is wanting in one, might be supplied by that which is abounding in another: and that because every countrey yeeldeth not all things, there might be a mutual exchange of one thing for another by way of merchandise. But now because diverse countries are very far distant each from other, that there can be no carriage of any wares or marchandise from the one to the other, either on beasts backs or in cartes: the art of Navigation was therefore invented, that the sea might supply the want of dry land. Yet surely skilfull nature hath done all this in vaine, if a certaine way how to sayle cannot in some sort be found, but that mariners must be constrained to make their voyages doubtfully not knowing what course to keepe. Therefore
[ B2 ]
the ancient navigators (thinking not without cause that there was great affinitie betweene Astronomie and Navigation) directed all their course by the starres, the Sidonians by the lesser beare which is the certainer, the Grecians by the greater which is the clearer. But because neither star truely shewed the North part of the world, they were oftentimes deceived in their coniectures: and because the night is not alwayes so cleare that those starres may be seene, if the skie were at any time overcast they had no meanes wherby they might know which way they ought to guide themselves. Hereof it commeth that in ancient authors oftentimes, & in many places we see the mariners complaining of the darknesse of the nights, and that the greatest and most famous navies have beene dispersed and discomfited, by reason of the uncertaintie of these things.
    But assuredly it seemeth to be so ordeined by nature, that all things should not be brought to light at one time: but that after a long continuance of times the certaintie of things should be knowen. There is a stone which for the exceeding great strength thereof is called
Herculeus, that is the stone of Hercules, & because it draweth iron unto it, is by the Grecians called σιδηριτις, commonly it is called by the name of him that first found it, Magnes, that is the Magnete or Load-stone. For it appeareth out of Nicander and Plinie, that one Magnes found it sticking to a sharpe pointed piece of yron. After a great number of yeeres a new propertie of that stone was reveiled, that being rubbed upon yron, or rather upon steele, it would make the same point to the Northe. Therefore when by this marveilous pointing the mariners knew the North,
[ B2v ]
and over against it the South, and making account by the elevation of the pole they learned also the latitude: then they had (as it was thought) means sufficient of infallible direction how to guide themselves at all times. But neither did this ioy (as many times it commeth to passe) continue long. For when they sayled from the East westwards, the Loadstone was found by litle and litle to decline from the North; which thing strooke no small doubtfulnesse and uncertaintie into the mariners mindes. Yet nowe at the length, by long observation of the declinations of the loadstone that have bene diligently sought out in diverse places and times, the matter is brought to that issue, that they which are most skilfull in the Mathematicks, and amongst them the said Count Maurice of Nassau, have supposed that this declination of the Loadstone happeneth not by chance, but is caused by some certaine reason in nature, that according to the varietie of places the pointing of the needle should also varie.
    Wherefore the said Count
Maurice sent this exhortatorie iniunction (for so I may call this litle booke written by his Mathematician Stevinus ) to them that take charge of ships, that if these things were not found in all points to be so as his observation importeth, they should do so much as in them lay, that out of diverse experiments some certaine reason and rule of the variation might be gathered: which if it may by diligent observation be obteined, then there shall not onely be a more certaine way to knowe the course from place to place by the instrument made to finde the variation (of which way more shall be spoken in the booke it selfe) but the longitude also, or rather the effect of the longitude shall be given by the variation;
[ B3 ]
which thing also shalbe shewed more at large in the Treatise it selfe following. Because therefore it is certaine that this knowledge cannot otherwise be found but by the experiments of divers men compared togither, and that by divers observations a more easie way may be prepared for science (which from the particulars ariseth up unto the universall) I thought good to present unto you this iniunction of the worthy Count Maurice, that if you (which are most expert in Navigation) be of opinion that there may be so great profite of this matter as we (which thinke it to appertaine to the principall state of the common-wealth) you might doe your best endevour unto what place soever you shall come (taking with you needfull instruments for that purpose) to observe diligently the variation of the magneticall needle, that at length we may come to that certaintie, that they which take charge of ships may know in their navigations to what latitude and to what variation (which shall serve in stead of the longitude not yet found) they ought to bring themselves, that by this meanes they may assuredly finde what place soever they will in the midst of the maine Ocean sea. And although this bee the end for which principally this Booke was made, notwithstanding we make no doubt that there may many more be found no lesse profitable then this; of which sort is that which wee of late have found, which may also be of very great profit unto us: To wit, that when any navie (for which cause our common-wealth hath obteyned exceeding renowne) is prepared against the enemie, a certaine place may be appointed in the midst of the sea, into which (if perchance too great a force should come upon them unlooked for) all the ships
[ B3v ]
after a certaine time might assemble themselves.
Whereto I may also adioyne a third use of the variation, that is, the reforming of many errors which must needes be in the ordinarie sea-charts, because the coasts of all countries and the courses from place to place, have beene set downe in them by direction of the varying compasse, without abatement or allowance answerable to the variation; wherof there must needes follow much deformitie and confusion in many parts of the chart, especially where the variation is great, as it is upon the coast of Newfoundland; where the variation being two whole points of the compasse (as is reported) there must needes be so much error also in laying out all the sea coast of that countrey, and in the courses of all places neere adioyning in the ordinarie sea charts. All which errors may be amended, if the variations be first truely observed, and then abated from, or allowed to the courses of all places, as neede shall require.
    But the variation cannot serve to so great use as otherwise it might, except other errors also aswell in the chart, as in other instruments and meanes of navigation be also avoyded. For the chart as it hath beene hitherto generally made with right-lined rumbes and degrees of latitude every where equall, must needes be very erroneous, especially in the Northerne parts thereof, that although all the foresaid errors arising by the variation were corrected, yet for this cause onely you may bee deceived one, two, yea three whole points of the compasse, in the courses of many places: and in measuring the distance you may erre one halfe, yea three quarters and more sometimes, accounting the same to be twise, yea thrise greater then
[ B4 ]
indeede it is, especially in farre Northerly navigations. If therefore these so notorious errors be not also amended, the correction of the errors arising by the variation, cannot be to so great purpose as otherwise it might.
    Neither can that be so fully performed which in the Treatise following is chiefly intended (that is, to find any place at sea by the variation and latitude) except the meanes that have beene used for finding the latitude be also amended. For in observing the heigth of the sunne and starres, with the small crosse-staves which are most usuall for that purpose, there may be error of halfe a degree, and more sometimes by neglect of the parallax or eccentricity of the observers eye. The Regiments or Tables of declination of the sunne that have bene most commonly used by English mariners doe erre oft times ten, eleven, or twelve minutes. The rule of allowances and abatements to be added to, or subtracted from the heigth of the pole-starre for finding the heigth of the pole (being grounded upon a false position, to wit, that the pole-starre is three degrees and an halfe distant from the pole, when indeede it its almost 40 minutes lesse) must needes be false many times more then halfe a degree.
    The declinations of the principall fixed starres as they are set downe in the bookes of Navigation, that have bene heretofore published, are for the most part erroneous; many of them differing from trueth above halfe a degree, & some of them an whole degree, yea two whole degrees and more. All which imperfections of so excellent an art, I have since the time of my first employment at sea (now more then tenne yeeres since) by diligent search with no small labour discovered and amended, not onely by tenne
[ B4v ]
whole moneths experience at sea, but also by often and diligent observation on land, as it may more at large appeare in my booke of errors in Navigation (which at mine own charges is also published for the common good of you all) wherein the way is shewed how your charts and crosse-staves may be freed from the errors aforesaid; and the declinations of the sunne and fixed starres are set foorth unto you, agreeably to the trueth of the heavens found out by often and exact observations, whereby the latitudes of places may be found much more truely then hath beene accustomed. This Booke therefore, because it may affoord needfull ayd for accomplishing the sayd renowned Count Maurice his desire in finding the latitude more exactly, and may also deliver you from much inconvenience and daunger, which may necessarily be expected to follow out of so many and notable errors as hitherto have beene in the usuall meanes of Navigation alreadie mentioned: I commend the same togither with this small Treatise now following unto you all, to be dayly tried and examined by the touchstone of your long and skilfull experience at sea: nothing doubting but as they have endured the more exquisite triall of exact observation, and Geometricall demonstration both by seamen and landmen on shore, so they shall be found agreeable to the heedefull experiments of all skilfull Navigators at sea. And so with my whole heart commending you all to him whose worde both seas and windes obey, I end.

Edw. Wright.        


[ 1 ] [ Ned. ]
border

mark   The Haven-finding Art,
Or
The way to finde any Haven or

place appoynted at sea.


THere is no man, I suppose, that knoweth not with howe great diligence now of a long time (especially since men leaving no part of the world unattempted, have sayled into America, and to the utmost Indies) the searchers out of excellent things have sought some certaine way, whereby they which take charge of ships might know assuredly the situation and longitude of what place soever they would goe unto, and so come to any Haven or place appointed at sea. But I know not how it hath comme to passe, that there could not hitherto any certaine knowledge of that matter be attayned unto. For some when they indevoured to find this thing by the magneticall needle gave the Load-stone it selfe a Pole, which of the Load-Stone (called also the Magnete) they named the magnetical Pole, or Pole of the Load-stone. But that this is otherwise, the thing it selfe hath
[ 2 ]
taught us, because the variation of the needle is found not to follow the rule of that Pole. Yet in the meane time this continuall searching gave occasion of another meane whereby a ship might certainly direct her course unto any haven or place at sea whereto you would desire to go, although the true Longitude both of the place wherein the ship is, as also of the place where the haven is, were both unknowen. Which that it may in some sort be rudely shewed, and that the circumstances hereof maay more clearely be set foorth before your eyes, whereby there may ensue a more certaine and general use of the same, first of all it must be knowen that wee are taught by dayly experience, that the magnetical needle touched with the Load-stone or Magnete (which therefore we call the magneticall needle) doth not alwayes point out the same part of the world, but without any respect of that magnetical Pole, (whereof we made mention before) sometimes indeed it sheweth the true place of the North: but for the most part it declineth either towards the East or West: which variation, yea even in a small distance of places, hath most manifestly appeared to them which have directed their course from the easterne parts towards the West: For examples sake at Amsterdam the variation is 9 degrees and 30 min. towards the East. In the foreland of England 11 deg. At London 11 deg. 30 min. Neare Tinmouth in the sea 12 deg. 40 min. and so forth.
[ 3 ]
How any Haven or place at sea may be found,
the latitude and variation of the same
place only being knowen.

T
He variation of the magnetical needle, and the latitude of the place being knowen, the same place may be found, although the longitude be unknown & that dayly experience plentifully teacheth. For (that we may make this matter plain by examples especially) if the mariner know that the latitude of the citie of Amsterdam is 52 deg. and 20 min. and that the variation of the compasse in the same place is 9 deg. & 30 min. he must needs not be ignorant, that when he hath brought himselfe to that latitude and variation he is not farre from Amsterdam, what longitude soever that citie have. But some man may obiect, that there are many places which have the same latitude and variation that the citie of Amsterdam hath: whereto we may readily answere that indeed there be such places: but very farre distant from thence, and such as may easily bee knowen by other circumstances, whereof we shall speake hereafter. And although the mariners may find Amsterdam otherwise, as by the places neere adioning, by coniectures, by the soundings, by the sands, & many other signes without any regard of the variation: yet I thought good to propound a knowen place for example, that the universality of the same rule might be knowen in long navigations, wherein no land appeareth. As for example if the master of a ship desire to sayle from hence to Cape S. Augustine in Brasile, and know that the variation there (as it is reported) is 3 deg.
[ 4 ]
and 10 min. & the latitude 8 deg. 30 min. towards the South, when in going thitherwards he shall come to that latitude, and variation, he shall then know that he is come to the Cape of S. Augustine: and although he thinke otherwise by his coniecture, and reckoning, yet not regarding that coniecture he shall confesse himselfe either to have gessed ill, or els to have beene deceived with some easterne, or westerne currents: For reason will not suffer us to thinke that that variation which before was found at the Cape of S. Augustine is changed, that he should need to yeeld himselfe to that opinion. So also who will not esteeme it to bee absurd, and altogether against reason, that hee which knoweth very well that he findeth at sea another variation then that which is at Cape S. Augustine, of 3. degr. 10 min. should notwithstanding, neglecting the experience of the variation, and resting upon coniecture only, affirme that he is neere the Cape S. Augustine? Because he speaketh contrary things, when he sayth that the variation there is 3 degrees 10 minutes, and againe avoucheth that it is not.

    Neither is this unworthy the marking, which hath often happened, that he which should have sayled to the Isle of S Helena, when he was come to the latitude of the same Iland, & saw not there the Iland, & was also ignorant whether he were to the eastwards or westward from the same, by coniectures sought that place towards the East, which indeed lay from him towardes the west, & so the further he sayles the further alwaies he went from that Iland. Now I leave it to thy consideration, if he (whosoever he were that was master of that ship, which diligently sought that Iland for the
[ 5 ]
space of certaine weekes, tacking about also divers times before he could find any place to abide in) if he I say had not bene ignorant what the variation of the compasse was at S. Helens Iland, and what the use of the variation is at sea, and how to find it out: I leave it, I say, to thy consideration, whether he would willingly have floated doubtfully to and fro following a greater variation, knowing assuredly that the variation there was lesser.

    Hereby it may easily be conceived how great use there is of the variation, when they especially which in sayling folow the lines shewing the courses (which lines because now they have found this name among the Portugales we cal Rumbs, the ignorance of which (lines) can hardly be permitted in them which attempt long voiages upon the huge ocean) ought every where to know certainly the place of the true North, which is commonly found by the knowledge of the variation.

    If any man likewise consider the uncertaine situation of those places which are set into Globes or sea Charts by the mariners relation, which uncertaintie taketh his beginning from hence, because every man thinketh that to be the true place of the North which is shewed by the Flower de luce (as they call it) of the compasse which they brought with them from home, (which thing also bringeth no lesse doutfulnes to the mariners themselves) hee will thinke (and that not without cause) that the observation of the variation is a very needfull thing even for this cause also: Because it is an easie matter to place the Flower de luce in such sort that it shal not misse any thing in shewing the true North part of the world, to wit, if one move
[ 6 ]
the magneticall needle, or points of the wires in the Compasse from the Flower de luce so much as neede shall require.

    These things therefore having bene observed and granted, and this especially that the variation altereth according to the variety of countries, (as by the common testimony af al men it is proved) it is in some sort manifest that they which denie this varying property to be of very great use for navigation, are either wiser then the common sort, and have some hidden secrets which are not reveiled to every man, or els are notable fooles and mad men.

    Therefore when the most excellent Prince Maurice, having throughly considered hereof, thought that it might assuredly brought to that passe that mariners might receive great profit by this meanes; he (the high Admirall) gave commaundement to all the companies of the Admiralty (adioining also thereto a certaine introduction) that they should doe their best indevour, that all masters of ships should provide themselves for this purpose: that is to say, that to what place soever they should come, they should seeke out the declination of the magneticall needle from the North, or the variation of the Compasse, not lightly, running over the matter as it were by the way, and for fashions sake onely; but with great carefulnes and diligence, taking with them meete and needfull instruments for that purpose: and that after their returne into their countrie they should truely and faithfully certifie their companies or brotherhoods of the Admiralty, of that matter: that the selfe same experiments being by them brought into good order,
[ 7 ]
might be published for the common good.
    But that every man may more perfectly learne the circumstances of this matter, I thought it meete here to set downe certaine principles of this thing, which is yet notwithstanding to be further searched into by more experiments, in which shall be shewed a generall view or table of those places, whose variations have already bene observed by the learned Geographer Petrus Plancius, with continuall labour, and not without great charges, from divers corners of the earth neere and farre off: whom for honours sake I therefore name, that as well they that shall hereafter finde out places or havens after this manner, as also they have already found, may know that they are bound to give thankes to Plancius alone, as to him that is the chiefe cause of this observation. But that table or generall viewe of variations, whereof there shall hereafter followe a plainer declaration is this.
[ 8 ]

A Table or View of Variation.

North-
easting.
Latitude
 
Longi-
tude.
Deg. Mi. Deg. Mi. Deg. Mi.
The North-
easting, or the
East variation
of the first part
or space to-
wards the
North
brace increasing brace In the Flemish Iland Corvo  0  N 37  0
In the Flemish Iland Saint
    Mary
 3 20   N 37  8 20 
Neere the Iland Maio  4 55   N 15  11 20 
At Palma one of the Canarie
    Ilands
 6 10   N 28 30   16 20 
At the Rocke neere Lisbon  10  N 38 55   24 30 
In the Westermost part of
    Ireland
 11  N 52  24 12 
In the West part of England  12 40   N 50 21   28
 
decreasing brace About one mile Eastward
    from Plimmouth
 13 24   N 50 18   30
By Tinmouth in the Sea  12 40   N 55  33
At London in England  11 30   N 51 24   34
In the foreland of England  11  N 51  35 40 
In Amsterdam  9 30   N 52 20   39 30 

North-
westing
The North-
westing, or the
West variati-
on of the se-
cond part or
space towards
the North
brace increasing brace At Helmshade to the West-
   ward from the North
    Cape of Finmarke
 0  60
At the North Cape of Fin-
   marke
 0 55   N 71 25   61 30 
At Norquinda  2  N 71 10   63 30 
At S. Michael or Archangel
   in Russia
 12 30   N 64 54   83 30 
In the South streight of
    Vaigatz
 24 30   N 69 30   103
At Langenes in Nova Zembla  25  N 73 20   100 30 
 
decreasing brace In Williams
    Iland
closing brace In Nova
Zembla
 33  N 75 35   110
At Yshouck  27  N 77 12   120 30 
At Winter-
    house
 26  N 76  120 30 

[ 9 ]

A table of variations.

North-
easting.
Latitude
 
Longi-
tude.
Deg. Mi. Deg. Mi. Deg. Mi.
The
Northea-
sting of the
first part
or space
towards
the South.
brace increasing brace 105 Spanish leagues Westwards from
    Cape S. Augustine in Brasile
 0  S  0
At Cape S. Augustine in Brasile  3 10   S 8 30   6
North and South with Cape das Almas
    in Guinea
 12 15   S 0  29
Towards the Northwest, Northerly frõ
    the Ilands of Tristan da Cuncha
 19  S 31 30   30
 
decreasing brace Towards the Northwest, Westerly frõ 
    the same Ilands
 15  S 31 30   36
North & South with the Cape of Good
    Hope
 2 30   S 35 30   57

North-
westing
The
Northwe-
sting of the
second
part or
space to-
wards the
South, ex-
cept Goa,
Cochin
, and
Cantan.
brace increasing brace 17 Germane miles from Cape das A-
    guillas
Eastwards
 0  S  60
5 miles in the Sea frõ Terra de Natal  4 30   S 33  66
At the shoulds of Indie  11  S 22  79 30 
In Mosambique  11  S 14 50   81 40 
In the Baie of S. Augustine in Mada-
    gascar
 13  S 23 30   83
Southwards from Cape S. Romane  16  S 28  86 20 
In Anthonie Gills Baie in Madagascar  15  S 16 20   91
 
decreasing brace 34 Germane miles Southeast from
    Brandaon
 22  S 19 20   110
In Goa a famous Mart towne in Indie  15 10   N 15 30   120
In Cochin  15  N 9 45   120
25 Germane miles West, a little Nor-
    therly from the Southwest corner
    of Sumatra
 6  S 5 28   147
In Bantam a Mart towne of Iava  4 45   S 6  150
In the Iland Lubocqua  2 25   S 6 10   155
In the Southwest corner from the Ile
    of Balij
 1 30   S 8 40   157
In the mouth of the river Cantan in
    China
 0  N 23  160
In Bunam 46 Dutch miles Eastwards
    from the East part of Iava
 0  S  160

[ 10 ]

A declaration of the former Table or view of
variations.

B
Efore we come to the declaration of this Table, this first of al we would not have unknowen, namely, that if perchance hereafter by more diligent and more exact experience, any other variation, longitude, or latitude of places can be found, then that which is set downe in this Table, so as it should be needfull to change the definitions and expositions of some things and wordes here set downe: yet we ought not therefore to be scarred from this purpose; but much rather ought we to strive with al our strength to attain thereto, that by litle and litle we may come to a more certaine knowledge of things, building upon these as upon foundations: we therefore following this opinion will prosecute that as true, which at this time is most like to be true; that if others also doe the same when occasion is given, we may alwaies come neerer to that which is most true in the nature of things.

    Which things being omitted, that we may come to the declaration of the former Table, first of all we say, that the first of the three columnes which thou seest in the table, sheweth the variation op the place, the second, the latitude, to which the third is adioyned conteyning the longitudes, as we could by coniecture attaine unto them, that the places might so much the more easily be found in the globe, and the manner of the variations might more plainely be shewed in that which followeth hereafter. The marke of the letter N in the second colume, signifieth North latitude, and S South.
    Then, because in them mention is made of the variation,
[ 11 ]
of the Northeasting, of the Northwesting increasing or decreasing, all which (as proper words of Art) have neede of their severall definitions: first of all we must know that the Magnetical needle in one and the same place, doth alwayes shewe the same part of heaven, but not the same part in all places: for in some places it pointeth due North, in other places it declineth more or lesse to the East or West. Therefore in manner of a definition, we will say thus:

The first definition.

T
He declination of the Magneticall needle from the North towardes the East, is called the Northeasting, towards the West, Northwesting; and with a generall name it is called the variation: but the variation and the North-pointing of the needle (that is the pointing of the needle due North) may by a generall name bee called the needle-pointing, or pointing of the needle.

    As concerning those words of increasing and decreasing, as also of the first and second part or space, before we come to the definitions of them, they have neede of some precedent declaration. It may be seene in the Table of variations, that in Corvo the Magneticall needle pointeth due North: but after that, the more a man shal goe towards the East, so much the more also shall he see the needle varie towards the East, till he come one mile to the Eastward from Plimouth, where the variation comming to the greatest is 13 degr. 24 min. From hence the Northeasting beginneth to decrease, til you come to Helmshude (which place is Westwards from the North Cape of Finmark) where againe
[ 12 ]
the needle pointeth due North. Now the longitude from Corvo to Helmshude is 60 degr. Which things being well weighed, it appeareth that the greatest variation 13 degr. 24 minutes at Plimmouth (the longitude whereof is 30 degr.) is in the midst betweene the places where the needle pointeth due North. For 30 degrees is the midst betweene the beginning and 60 degrees. And what is here said of the North part, experience teacheth that the same taketh place in the south part also, for 105 Spanish miles from Cape S. Augustine at the beginning of longitude, againe it pointeth due North, as it doth 17 Germaine miles form Cape das Aguillas (as it appeareth by the table of variations) which place is in the longitude of 60 degrees, and in the middest betwixt both at 30 degr. (as in the North part) again there is the greatest Northeasting; of which place there was this mention made in the Table or view of variations: towards the Northwest northerly from the Ilands of Tristan da Cuncha, where the variation is 19 degrees.

    Out of these we may conclude, that the Magnetical needle doth point due North in every place situate in two meridian halfe-circles drawen from the one pole to the other by Corvo and Helmshude. And that the greatest Northeasting is in all places situate in the meridian semicircle drawen by that place, which we said was distant one mile from Plimmouth towards the East. So as that part of the earth which is conteyned betweene two Meridian semicircles, distant each from other 60. degrees in longitude, is the space wherein the Magneticall needle, alwayes declineth from the North towards the East. And the halfe of that part, that is, that
[ 13 ]
portion of the earth which is included betweene two Meridian semicircles, the first of which is drawen by the beginning, the other by the 30 degr. of longitude, is every where the place of the Northeasting increasing: but the other halfe is the place of the Northeasting decreasing, to wit, when one goeth from the West Eastwards, following the order of the degrees of longitude.

    By this that hath beene spoken of the first Segment, with the Northeasting and his parts (in one of which parts the Northeasting is increasing, in the other decreasing) it may easily be understood what the manner of the second Segment is with the Northwesting, and what is the manner of the partes thereof, whereof one is the part of the Northwesting increasing, the other is the part of the Northwesting decreasing, for in the mouth of the river Cantan in China, at the longitude of 160 degrees distant from Corvo, the needle pointeth due North the third time: there therfore drawing the third Meridian semicircle, the portion of the earth betweene the foresaid second Meridian semicircle, and this third (distant each from other 100 degrees in longitude) shalbe the space wherein the Magneticall needle declineth from the North towards the West: and in the middle of both in the Meridian semicircle 50 degrees distant from the second, and as much from the third, (or otherwise 110 degres remooved from the first Meridian drawen by Corvo) shall be the greatest variation of the Magneticall needle, as it appeareth out of the Table of variations in two places, whereof one is Williams Iland at Nova Zembla, where the greatest Northwesting is found to be 33 degrees. The
[ 14 ]
other is distant 34 dutch miles to the Southeast from Brandaon, where the greatest variation is found to be 22 degrees, and the longitude of each of those places is 110 degrees. So as in the halfe of the second space (which portion of the earth is conteyned betweene the Meridian semicircles of 60 degrees longitude, and of 110 degr.) the Northwesting is every where increasing; in the other halfe decreasing.

    Of these 160 degrees of Longitude (which arch wanteth but 20 degrees of halfe the compasse of the earth) Plancius hath attained to the knowledge of the variation, in such sort as now we have shewed. As concerning the other parts of the world, distant either towards the West from Corvo, or towards the East from Cantan, the experiments which hitherto hee hath gotten from the Spaniards, the Englishmen, & our countriemen (the Netherlanders) doe not well agree. Neither is it any marvell, seeing they had neither perfect knowledge, nor needfull instruments for that purpose: yet he expecteth other experiments from the ships which have now beene abroad 14 moneths and more. In the meane time we will bring forth that to publique view, which a man may without absurditie imagine.

    If so be that the propertie of pointing due North, take place not onely in the three foresaid Semicircles (which we coniecture to be Meridian semicircles drawn from the one pole to the other) but in the whole circles also; there should then be six such semicircles upon the earth, conteyning also betweene them six partes of spaces of the upper face of the earth.
    The first with the Northeasting 60 degrees long.
    The second with the Northwesting 100 degr. long.
[ 15 ]
    The third with the Norteasting 20 degr. long.
    The fourth with the Northwesting 60 degr. long.
    The fifth with the Northeasting 100 degr. long.
    The sixth with the Northwesting 20 degr. long.

    That those things which have beene spoken may by certaine geometricall figures be more clearly concieved, let ABCDEFGHIKLM, be the aequinoctiall of the earth: let N be the pole: then let NA bee the halfe of the first Meridian semicircle drawen by Corvo: NC, halfe of the second semicircle: NE, of the third: NG, of the fourth: NI, of the fifth: NL, of the sixth. So as the arch AC, may make 60 degrees: CE, 100 degr. and so AE, 160 degr. EG, 20 degr. and so AG, 180 degr. GI, 60 degr. and so AI, 240. IL, 100 degrees, and so AL, 340 degr. LA, 20 degr. and so the whole circle 360 degrees. Then let the sixe pointes BDFHKM be the middles between AC, CE, EG, GI, IL, LA. Which being supposed,
ANC shall signifie the first space with the Northeasting.
ANB the Northeasting of the first space increasing.
BNC the Northeasting of the first space decreasing.
CNE the second space with the Northwesting.
CND the Northwesting of the second space increasing.
DNE the Northwesting of the second space decreasing.
ENG the third space with the Northeasting.
ENF the Northeasting of the third space increasing.
FNG the Northeasting of the third space decreasing.
GNI the fourth space with the Northwesting.
GNH the Northwesting of the 4 space increasing.
HNI the Northwesting of the 4 space decreasing.
[ 16 ] [ image from Ned. ]
spaces
INL the fift space with the Northeasting.
INK the Northeasting of the fift space increasing.
KNL the Northeasting of the fift space decreasing.
LNA the sixt space with the Northwesting.
LNM the Northwesting of the 6 space increasing.
MNA the Northwesting of the 6 space decreasing.

    Note. Though a man may not without cause stand in doubt that the three last semicircles shall not bee found in the same sort, which the former coniecture hath imagined, but peradventure in a quantitie eyther greater or lesser, and in another forme: neverthelesse, here the maner is rudely shewed how the whole world
[ 17 ]
may be divided into certaine portions by such semicircles as shall hereafter bee found by observation. Moreover, by that which hath beene spoken, it may easily be understood what be the Northeastings or northwestings increasing or decreasing, what is the first and second Meridian semicircle, together with the parts or spaces. Which, that we may comprehend in forme of definitions, I thought good in few words thus to pronounce.

The second definition.

    The Northeasting or Northwesting increasing is that whereby the variation increaseth, the Magneticall needle being caried from the West Eastwards: and the Northeasting or the Northwesting decreasing is that whereby it decreaseth.

The third definition.

    The Semicircles of the Meridian, in which the needle pointeth due North, wee call the first and second Meridian Semicircles, and so forwards according to the order of the degrees of longitude, how many soever such Semicircles there shalbe, beginning at the Semicircle drawen by Corvo.

The fourth definition.

    The portion of the Sphaericall superficies, or round upperface of the earth conteyned by the first and second Meridian Semicircles, is called the first part or space, and the rest in order, the second, the third, and so foorth unto the end.

    Having thus set downe the maner of the variation, it remayneth that we shew by examples (that which before we promised) that although in divers places having the same latitude there be the same variation also, yet nevertheles the master of the ship may know in what part of the world, and in what place he is. Let
[ 18 ]
us therefore againe suppose that a ship had appointed to goe from Amsterdam to Cape S. Augustine, in Brasile, thelatitude whereof in the table of variations is set downe to bee 8 degrees 30 minutes, and the variation northeasting increasing of the first space 3 degr. 10 minutes. The same shippe sayling along by the coast of England, the variation shall be found to northeast or varie towards the East dayly more and more untill you come to Plimmouth, where it commeth to the greatest, and is 13 deg. 24 min. Therefore the master of the ship shall know assuredly that hitherto hee hath sayled in the Northeasting of the first space decreasing, and that after this he shall have the northeasting increasing, which when he shall find to be 10 degrees in the latitude of 38 deg. 55 min. then hee may assure himselfe that hee is come to the Rocke neere Lisbone. Going forwards again from thence as it were towards the Southwest, he shal dayly find the latitude to be diminished, and the magneticall needle declining towards the North. Or otherwise if the magneticall needle recline not towards the North, but either stand stil, or els decline more towards the East, then he may assure himselfe that hee is caried Eastwards by some secret current not perceived: which notwithstanding he may remedy, if he goe so much the more towards the West, untill the magneticall needle recover his due variation. But if hee should come to the northeasting of 3 degrees 10 minutes, before he have his Southerly latitude to be 8 deg. 30 min. he shall then indevour as much as in him lieth to keepe that variation, and so sayle on towards the South part of the world guiding his ship so much the more towards
[ 19 ]
the West or East as occasion shall require. And although he may deeme otherwise by coniecture, yet he shal not follow that coniecture, for the reasons before shewed: for so comming to the southerly latitude of 8 deg. 30 min. with the northeasting increasing 3 deg. 10 min. he may assuredly perswade hinselfe that he is neere Cape S. Augustine, whereas otherwise trusting to coniectures he may very easily misse an hundreth leagues of the place to which he had appointed to goe, not knowing in the meane time, whether he be to the eastwards, or to the westwards from thence; which experience it selfe hath taught too much in such navigations. And therefore the latitude and variation in all places of the earth being observed, and the knowledge thereof published, there shall be a much more easie way of sayling about the worlde, then ever hath bene heretofore.

    Hitherto we have described the kindes of the variation, which are afterwards declared out of those things which were set downe in the table of variations. If the mistris of things (experience) shal hereafter teach that any thing is otherwise, that thing may also out of the same experience be otherwise defined, that the masters of ships in their navigations may follow that only which sall bee best and most profitable.

How the North point, and the variation
may be found.

A
Lthough the finding of the variation, (whereof hitherto often mention hath bene made) is known to very many: yet we will in fewe wordes shew this thing to them which as yet peradventure know not
[ 20 ]
the manner thereof. For here is a question or demand how to find the declination of the magnetical needle. First therfore the north point must be sought out, that the pointing of the needle may bee compared therewith. The finding thereof in a movable ship hath no small affinitie with the finding of the north point or meridian line on land, and may thus be shortly dispatched. In the Instrument which some call the sea-directorie, some the nauticall box, and we for avoyding ambiguity name the sea-compasse, in that instrument I say, the Floure de luce ought to agree with the north point of the needle, or wires lying underneath: or (that which is farre more commodious) in stead of the Floure de luce the magneticall needle may be fastened above upon the paper or pastboord, and the limbe or circumference of the pastboord must be devided into 360 degrees, beginning at the north poynt of the needle as you may see hereafter in the circle A.B.C.D, wherein the magneticall needle is signified by A.C. which is fastned above upon the paper or pasteboord. E is the center. The use thereof is this. As the master of the shippe in seeking the latitude is wont to tary for the noone-tide, that is to say, untill the shadow of the perpendicular stile, or the plumbline agree with the meridian line in his instrument: so all things also do here proceed, but that he beginneth three or foure houres before noone, marking diligently into which degree of the compasse, or into what division, the shadow of the perpendicular stile, or plumbline falleth. Let us suppose therefore that he find it in the 40 deg. which we have noted with the letter F, so as G.E.F. may signifie the whole shadow: then hee
[ 21 ]
compass

shall seeke the height of the sunne, which for examples sake admit hee find to bee 25 degrees: which together with the 40 degrees above named, he shal note down for helping his memory: After this he shall attend till
[ 22 ]
the sunne descending after noone come to the same height of 25 degrees, and he shall then also diligently marke what place the shadow of the perpendicular stile poynteth in the paper, which againe let us take to be 40 deg. to wit, the other way as at the letter H, so as nowe IEH may represent the whole shadowe. Which being done, the midst of the arch FH (that is A) is the north point: and because the magneticall needle directly pointeth the same, it hath no variation in that place, because it sheweth due north. But if in the same experiment after noone the shadow had not shewed the 40 degr. on the other side beyond A, but (for examples sake) the 20 degr. onely unto K, in that case the arke FK making 60 degr. ought by imagination to be devided into two parts at L, so as LF and LK may make either of them 30 degrees and the variation sought for may be from L to A eastwardes 10 degrees.

    But if in the same afternoone experiment, the shadow of the perpendicular stile L had shewed 30 degr. from F, the arke FL (conteining 30 deg.) must by imagination be devided at M, so as MF, ML may either of them conteine 15 degrees; which being thus performed, M shalbe the North point, and A the point of variation sought for, northeasting from M to A 25 degr. and so in the rest.

    But if the needle onely were turned about and not fastned to the paper or pastborde (as before) and the degrees were marked in the margine or limbe of the box, or case of the instrument as is sometimes used, there is the same manner of using it, that was before rehearsed: saving that in the beginning of the observation,
[ 23 ]
the box must bee turned about so farre till the Magneticall needle shewe the beginning of the degrees.

    Others take an Azimuthal or verticall quadrant, whose Horizontall plaine (whereupon it standeth upright) without any impediment received from the motion of the ship alwayes remayneth parallel to the Horizon in such manner as we shall shew. Thus the heigth of the sunne is found, togither with the azimuth.

    The fashion of this instrument may be described after this manner, ABC signifieth a quadrant of a circle standing at right angles. Upon the circle BDCE devided into 360 degrees, whereby the plaine of the Horizon is signified. The center thereof is F upon which the quadrant may be turned about: and that it alwayes remaine at right angles upon the circle BDCE it is under-propped on both sides from G to D and E, and those props are fastned to the same quadrant, that they may be turned about togither with it. Moreover in the circle BDCE there is a glasse, and under the glasse a magneticall needle, which must be so long as the box may suffer it. And the box or case hath within it 360. degrees, which the magneticall needle may precisely poynt unto, which likewise doe agree with as many other degrees inscribed into the horizontall plaine.

    This instrument was made according to the invention of Reginaldus Petraeus [<], hanging upon two axtrees like the sea-compasse that so the circle BDCE notwithstanding the motion of the ship may alwayes bee equally distant from the Horizon. And that this may
[ 24 ]
instrument
[ 25 ]
be done with the greater securitie, the weight marked with the letter H is adioyned underneath, conteyning 25. or 30. pounds, or so many as the greatnesse of the instrument shall require. But this also is worthy to be noted, to wit, that the quadrant perpendicularly erect in his place is of the same weight on both sides of the center: that is to say, the side from F to C counterpoyseth the side from F to B which may be knowen if a man taking up the quadrant, hang it with G downewards, the threed being fastned in the middest of BC at F and then cut off so much of the heavier part, as may suffice, that the line BC may hang levell. But because some man may obiect that the ruler or index which the Barbarians call the Alhidada, may bring a great varietie in the weight as it shall be turned higher or lower: wee must know that any such thing need not to bee greatly feared, because of the great weight H and the lightnesse of the ruler.

    The use of this instrument in finding the North point and variation is this: you must begin to observe (as in the former kind) certaine houres before noone, and the instrument must be turned untill the magneticall needle point to the beginning of the circle: then the quadrant must be turned this way or that way, and the sight-ruler of the quadrant must be lifted up, or put downe till the sunne shine through the sight. All which being done, suppose it bee found (for examples sake) that the utmost margine or index of the quadrant shew in the Horizontall plaine 40. degr. and admit the heigth of the sunne be also found to be 25. degrees, which togither with the 40. degrees he shall for memorie sake have need to note. And when he hath expected after
[ 26 ]
noone till the sunne descending by the same instrument be found placed in the same 25. degr. of altitude, then the box it selfe must againe be turned this way or that way, untill (the sunne againe shining through the sights) the magneticall needle doe point to the beginning of the circle. Which things being thus dispatched, the middle point of the arch in the horizontall plaine betweene the first and second experiment is the North point, and how much the needle declineth from that point, so much is the variation sought for, as before wee have shewed in the first example more at large.

    Whatsoever we have affirmed to be availeable in the day time, in these experiments of the sunne, the same may bee understood and done in like manner in the night, by any of the fixed starres, whereof there is the same use in this matter that there is of the sunne. But there is not the same reason of the moone, aswell because of the swiftnesse of her proper motion; as also because of the greatnesse of her parallax (as they call it) which the overmuch neerenesse of the moone to the globe of the earth bringeth forth. But this also is to be noted that two, three, or foure, yea and more observations may be made in the fore-noone. As for example let the first bee when the sunne is 10. degrees above the horizon, the second when it is 15. degr. the third when it is 20. degr. and if any man will make triall as often after noone, hee shall see how every experiment agreeth with other: and when at every moment the same North point is found, that thing shall give the master of the ship no small courage, and more certaine confidence of his worke.
[ 27 ]
    But notwithstanding, when the mariner sayleth from the East Westwards, or contrariwise from the West Eastwards, it may be that in the space of 10 or 12 houres between the first and second experiment, there may be difference of one degree or more in the variation, whereof may follow that the North poynt found by the first forenoone observation, and the last in the afternoone, shall not agree with that which was found by the first in the afternoone and the last in the forenoone: when notwithstanding the mariner hath not erred in observing.

Which  if  it  shall  happen  often,  the  skilfull  mariner
may  iudge  thereby  what  difference  of  variation  is
answerable to any determinate time of sayling, and so
finde a way whereby the North poynt may bee
found with more certaintie and securitie:
which thing may thus also be done, if
a man diligently compare the
variation found in the for-
mer dayes with the
variation which
he presently
seeth.



F I N I S.






Introduction in 'Principal Works' (^) III, 363-417:
363: § 1. Introduction and general remarks
365: § 2. The place of The Haven-finding art among 16th century textbooks on navigation
367: § 3. The contents ... of 1599   a. Stevin's "conjecture" about terrestrial magnetism
372: § 3 b. The measurement of the variation of the compass according to Stevin
375: § 3 c. The Latin translation       376: § 3 d. The English translation
378: § 3 e. The French translation   f. Stevins's view ... in 1608
380: § 4. The measurement of the variation of the compass   a. Before Stevin's day
388: § 4 b. Reynier Pietersz and his "golden compass"
392: § 5. ... longitude by means of the variation of the compass.   a. The earliest views
397: § 5 b. Mercator (1512 - 1594)       398: § 5 c. Plancius (1552 - 1622)       404: § 5 d. Stevin
411: § 5 e. The evolution of the subject in the 17th and 18th centuries
413: § 6. Appendix   a. The construction and the use of the astrolabium catholicum
415: § 6 b. ... the longitude-finder of Plancius.

Reinier Pietersz's instrument (p. 24) also in: Edward Wright, Certain errors in navigation, 1657 (IMSS: ill. 12).


Simon Stevin | The Haven-finding art (top) | Havenvinding