any land This Horizon is of two sorts namely right and oblique The right Horizon is that which they have that live under the Equinoctial which passeth by their Zenith and therefore the Equinoctial line or circle falleth perpendicularly and right acrosse with their Horizon and both the South and the North Poles are in their Horizon The oblique Horizon is that which they have that live not directly under the Equinoctial for unto them the Equinoctial divideth the Horizon obliquely and not right acrosse and one Pole is alwayes above their Horizon and the other is beneath their Horizon and cannot be seen This Horizon is represented in the Sea-Chart by a certain imagined circle whose center is the point where our ship is From which center are imagined to proceed unto the said circle 32 lines which represent the 32 winds or rumbs which alwayes are drawn in our Sea-Compasse which likewise in a little peece of paper doth continually represent unto us both by day and night the whole Horizon with his 32 divisions CHAP. XVI Of the 32 Winds THis right or oblique Horizon is divided into 32 equal parts by 16 lines which they call Rumbs and they cut themselves in the point where we stand of which rumbs that which passeth by the points where the Equinoctial beginneth and endeth which are where the Sun riseth and setteth the 11 of March and the 13 of September is called East and West and that which cutteth it right acrosse is named North and South And the four extreams or ends of these two lines are distant upon the Horizon one fourth part of a circle and they make four quarters Every one of which quarters being divided in the midst do make four other points and that which falleth between the North and the East is called North-east and that between the North and the West North-west that between the South and the East South-east and that between the South and the West South-west And so the Horizon is divided by four lines or numbs into eight principal winds noted in the Sea-Chart with black lines And if you divide every one of those eight parts in the midst you shall have other eight lines and other four rumbs which in all are 16 winds And each one of these hath his name compounded of the names of those principal winds which are on either side thereof As for example that half winde which is between the North and the North-east is called North-north-east and that which bloweth between the East and the North-east is called East-north-east and that between the East and the South-east East-south-east and that between the South and the South-east South-south-east and that between the South-west and the VVest VVest-south-west and that between the VVest and North-west West-north-west and that between the North-west and the North North-north-west And these are noted in the Chart with green lines Finally if you divide every one of these sixteen winds in the midst they will yield you other 16 winds and will amount to 32 winds in all Which 16 last mentioned are drawn in the Sea-Chart with red lines and are by the Spaniards called quarters of the eighth first and principal winds and every one of these is called by the name of that principal wind which is next it together with an addition of the word By and the name of another principal wind which is next unto it As for example of the two quarter-winds which fall next the rumb of the North that which lieth towards the North-east is called North and by East and that which falleth towards the North-west is called North by West So likewise of those two winds which blow next the North-east that towards the North is called North-east and by North and that towards the East North-east and by East And after the same manner you may name all the rest The Figure of the Sea-Compasse and of the Horizon divided into 32 Winds by 16 Rumbs But here is to be noted that there is difference between the Rumb and the Wind because a Rumb is one direct line continued with two contrary winds as the Rumb of North South and the Rumb of East and West And so when we will name the lying of any Coast we will say that it lieth North and South or North and by East and South and by West But the wind is one line of those 32 into which the Horizon is divided and it is one part of those two which together are called the Rumb And so we say that Land lieth from us towards the South and towards the South and by West or towards the South-south-west c. CHAP. XVII Of the two Tropicks BEsides the six Circles above-mentioned which are drawn upon the superficies of the Sphere of the World there are other two which the Sun describeth with the motion of the Primum Mobile about the 12 day of June and of December of which two Circles that which the Sun describeth the 12 of June from the time of his rising till the time that he riseth the day following is called the Tropick of the Summer Sun-standing or the Tropick of Cancer for the Sun having departed from the Equinoctial and increasing his Declination towards the North when he cometh to describe that Circle for two or three dayes it semeth that he cometh no neerer to our Zenith nor departeth from the Equinoctial one day more then another but from thence forward he goeth back diminishing his Declination till he come to the Equinoctial and crossing the same he goeth on the other side increasing his Declination until the 12 of December upon which day from the time of his rising till he be come about to rise again the next morning he describeth another Circle called the Tropick of the Winter Sun-standing or the Tropick of Capricorn for the Sun being departed from the Equinoctial and increasing his Declination towards the South when he cometh to describe that Circle it seemeth for two or three dayes that he returneth not one whit towards the Equinoctial nor goeth further from our Zenith one day more then other but from thence forwards he commeth back again diminishing his Declination till he be returned to the Equinoctial and from thence towards our Zenith These two Circles in Sea-Charts are marked with two great red lines drawn from East to West which lie on either side of the Equinoctial being distant from thence about 23 deg and an half And wheresoever our ship be in any place between these two Circles or lines we may in some time of the year take the Sun in our Zenith at which time it maketh no shadow at all being then just 90 degr high above our Horizon But they which are without the said two Circles or lines shall never have the Sun in their Zenith because it cannot come to the height of 90 degr above their Horizon CHAP. XVIII Of the Parallels THe parallel Circles are those which are in all parts equally distant from the
an half being deducted out of the heighth of the North Star the remainder is the just heighth of the Pole The sixth Rule When the guards are in the South-west one beareth from another East and West and the former lieth from the North Star North-east and South-west and then the North Star is above the Pole three degrees and an half which three degrees and an half being deducted out of the heighth of the Star that which remaineth shall be the heighth of the Pole The seventh Rule When the guards are at the lowest the former guard beareth with the North Star North and South and then the North Star is above the Pole three degrees which being deducted the remainder is the heighth of the Pole The eight Rule When the guards are in the South-east one beareth from another North and South and the former beareth from the North Star North-west and South-east and the North Star is above the Pole half a degree which half degree being deducted from the heighth of the Star the remainder is the heighth of the Pole above our Horizon and just so much are we distant from the Equinoctial towards the North. This is the account which alwaies hath bin made of the North Star from the time that it hath had three degrees and an half distance from the Pole unto this present But because at this time by reason of the compound motion of the 8 and 9 heavens the fixed Stars have notably varied from their places the Pole Star hath also approched neerer the Pole being now distant therefrom not above three degrees and eight minutes And so I think it convenient to set down the account which ought now to be made thereof according to the foresaid distance to the end that from henceforth the heighth of the Pole taken by the Star may agree justly with the distance from the Equinoctial taken by the Sun Which two things have hitherto disagreed and caused no small confusion unto the Pilots and some error in Navigation The guards being in the East you shall adde unto the heighth taken by the Crosse-staffe 1 degree 20 minutes North-east 3 degrees 8 minutes North 2 degrees 41 minutes Northwest 0 degree 27 minutes In the contrary Rumbs to these you must deduct these degrees from the heighth of the Star which you take with your Crosse-staffe and then you shall have the heighth of the Pole above the Horizon CHAP. XV. Other things to be noted in Observing the heighth of the Pole NEXT unto the constellation of the Horn here is a Star which is called by the Spaniards el Guion signified before by the letter D which standing East and West from the North-star giveth you to understand that it and the North Star and the very Pole are East and West And so taking the heighth of the North Star when it is thus situate in regard of the Guion with out making any other account you have the just heighth of the Pole and the distance from the Equinoctial Here followeth the Table The guards being in the East The third star is in the Southeast The sixt star in the South The 9 th star in the Southwest Northeast East Southeast South North Northeast East Southeast Northwest North Northeast East West Northwest North Northeast Southwest West Northwest North South Southwest West Northwest Southeast South Southwest West In this Table the first column serveth for the guards the second for the third star the third column for the sixth star and the fourth for the ninth star Insomuch as if you seek the rumb seeing any of these four stars in this Table right against the same do answer those rumbs where the other three are although we cannot see them in the Heavens CHAP. XVI Of the Crosiers WHen the Mariners pass the Equinoctial line towards the South so that they cannot see the North-star they make use of another staâ— which is in the Constellation called by the Astronomers the Centaur which star with other three notable stars which are in the same Constellation maketh the figure of a Crosse for which cause they call it the Crosier And it is holden for certain that when the star A which of all four commeth neerest to the South Pole is North and South with the star B that then it is rightly situate to take the heighth by And because this star A which they call the Cocks foot is thirty degrees from the South Pole it cometh to passe that if being situate as is aforesaid we take the heighth thereof which is then the greatest that it can have this heighth will truly shew how far we are distant from the Equinoctial For if the said heighth be thirty degrees then we are in the very Equinoctial and if it be more then thirty degrees then are we by so much past the Equinoctial towards the South And if it be lesse then 30 degrees so much as it wanteth are we to the North of the Equinoctial And here it is to be noted that when the guards are in the North-east then are the stars in the Crosier fitly situate for observation because then they are in the Meridian CHAP. XVII Of the Sea-Compass THe Sea-Compass is one of the most necessary Instruments which are used in Navigation for day and night in clear and dark weather it sheweth always the right way through the Sea And therefore it is meet that this Instrument be made with much care to the end that it may be most certain and true And the manner of making it is that upon a piece of pastboard you draw a circle so big as you will have your Compasse to be which being divided into 32 equal parts as we have already shewed in the Chapter of the winds with sixteen lines crossing one another in the center then you shall adorn the eight principal winds as is to be seen in the figure following ending in the North with a Flower deluis and you shall paint the North and South and East and West with blew and the North-east and South-west and the North-west and South-east with red And then taking two steel wires which are to be placed like the head of a launce you must fasten them on the back side of the said circle in such sort that one meeting of the points of those steel wires be right under the North allowing half a point towards the North-east in regard of the North-easting of the needle at Sevil and the other meeting at the opposite point which is South and half a point towards the south-South-west and touching or rubbing those two points of the wires with the ends of the Load-stone which look to the North and to the South to wit the North points of the wires with the South of the stone the South point of the wires with the North of the stone This being done you must place upon the center of the said circle a Capitel which must be very well bored in from off a round pyramis to the end that
cast his point in manner following and he shall errer as little as is possible Let him examine according to the ordinary running of his ship how much way she might make every day that he hath sailed and the leagues that shall amount in all the dayes let him take between the points of one compass and let him place one point thereof upon the place from whence he departed and taking another compass let him set one point thereof upon the graduation according to the heighth which he hath taken and the other point upon the next East and West Rumb Now let this compass run by his East and West rumb till the point coming from the graduation meet with the second point of the other Compass which he holdeth not upon the Chart and in the place where they meet he may say that there is his point and his ship And because in this case all Pilots do not use this point of imagination and heighth there grow great diversities among them concerning their distance from land when as in long voyages they confer and communicate their opinions one with another insomuch that one according to his conjecture judgeth himself to be 50 leagues from land another 100 another 200 and another thinketh he is hard by the land The reason is because some of them cast their point by traversing others by imagination onely and others by imagination and heighth who are alwayes more certain then the rest CHAP. XXIV What it is to increase or diminish in heighth THe Mariners call it increasing in heighth when they go further and further from the Equinoctial and diminishing in height when they approach neerer to the Equinoctial So that in our Navigation we either sail from a greater to a less altitude of the pole and then we go towards the Equinoctial and then the height is said to be diminished or we sail from a less to a greater height of the pole and then we go from the Equinoctial and are said to increase our heighth And hence it is that casting our point by imagination and afterwards having taken the heigth amending it by traversing either the heighth wherein we find our selves being taken by the Sun or star is greater or else it is less then that which we made account of by imagination And hence do arise four rules The first is that when in sailing we do increase the heighth if the point amended by traversing be of greater heighth then the point of imagination the ship hath gone more then the point of imagination shewed us The second when we increase our heighth if the point amended by traversing be in lesse height then the point found by imagination then hath the ship gone less way then we imagined The third is when we diminish our height in sailing if the point amended by traversing be in a greater heighth then the point found by imagination then hath the ship made less way then we ghessed by our imagination The fourth is when we diminish our heighth if the point amended by traverse be in less heighth then the point found by imagination then hath the ship made more way then we imagined CHAP. XXV How you may cast a traverse point without Compasses IF a Mariner chance to lose his Compasses he may cast his point of traverse after this manner Let him take two slender threds and putting the end of one of them upon the place from whence he departed let him stretch it in equal distance from the Rumb by which he hath sailed and putting another thred in equall distance from the next East and West rumb let him make it to pass by the degrees of heighth in which he findeth himself and where the two threds cross one another there is the point of the ship and alwayes the first thred if it hath not changed the course sheweth the way which the ship hath gone and the second the parallel wherein the ship is CHAP. XXVI Of another kind of casting a point by traverse EXamine the difference of the degrees of distance from the Equinoctial which are between the place from whence the ship set forth and the place where the ship is Then taking the heighths of both places very precisely and subtracting the lesser out of the greater that which remaineth is the difference which difference you must multiply by the leagues which answer to one degree in the rumb by which you have sailed and those leagues which the degrees and minutes of difference shall make you shall take between the points of a pair of compasses out of your scale of leagues and holding the said compass so open set one foot thereof upon the point from whence the ship departed and the other foot stretching towards the place whithre the ship hath sailed you must hold up a little from the Chart and you must set one foot of the other Compasse at the degree of the distance wherein your ship is from the Equinoctial when the said point is sought for and the other point you must place upon the next East and West Parallel And let this second Compasse run by his next East and West Rumb untill the point of the first Compasse lifted up being set downe that point of the second Compasse which came from the said degree doth meete therewithal and where those two points shall meet there is the true point of the ship CHAP. XXVII Of the leagues which in Navigation answer to each degree of Latitude in every Rumb IF we suppose as we have before said in the chap. of the quantity of the earth that the greatest circle thereof conaineth in compasse 6300 common Spanish leagues then unto every degree of the Meridian which is the greatest circle doe answer 17 Spanish leagus and an half so that sailing North and South if your heighth of the Pole or your distance from the Equinoctial be varied one degree you may say that you have gone seventeen leagues and an half but if you varie one degree and hold your course upon the first point then have you sailed 17 leagues and ⅙ And you have declined from the Meridian or right line which passeth by the place from which you departed three leagus and an half And if you sail upon the second point from the North or South till your heighth of the Pole be changed one degree you have then gone 19 leagues and ⅜ and are distant from your right line 7 leagues and ¼ And varying a degree upon the third point of the Compasse from North or South you have gone 21 leagues and are departed from your right line 11 leagues and ⅔ Sailing upon the fourth point of the Compasse there doe answer unto every degree 24 leagues and three fourths and you are distant from the right line or Meridian 17 leagues and an half Upon the fifth point you must allow for one degree 31 leagues and an half and then are you distant from your right line 26 leagues and ⅕ Upon the sixth point doe
themselves doe often find the imperfections of their Charts in shewing the courses and distances of many places each from other wherto we may adjoyne the experience of the best Hydrographers of our time who daily making their Charts after the accustomed manner with straight lined rumbes and degrees of Latitude every where equal have found such difficulties in labouring to bring their Marine descriptions to some due correspondence of truth in the courses heights and distances that tired herewith in the end they have holden it impossible to make the Chart agree in all these with the Globe Wherein notwithstanding they erre by making too generall a conclusion in holding that to be simplie impossible which cannot be done by such a way and meanes as they know and use 3 The Crosse-staffe the principall Instrument that hath at Sea been most generally used for observing the Altitudes of the Sunne or Starres thereby to know more assuredly the Latitude and so to examine and rectifie the account of the course kept by direction of the Compasse upon the Chart if there be not abatement made answerable to the eccentricitie of the eye that is to the distance wherewith the center or point wherein the sight beams concurre within the eye is further backward then the end of the staffe may through neglect of this abatement cause error in taking the height observed to be greater then indeed it is by 10 20 30 minutes yea an whole degree and more sometimes if the height be much the staffe small and the eccentricitie of the eye great 4 But both this staffe and all other Instruments though never so well made and used can do us but small pleasure for finding the Latitude at Sea if the declination of the Sunne and Starres which wee observe be not also known To this end therefore there have been made tables of the Declinations both of the Sun and fixed Starres yet such as even that which hath been publikely commended as not differing from truth in any place above one minute I mean the Regiment of the Sun set forth by R. N. doth notwithstanding differ from truth in many places eleven twelve or thirteen minutes And as for the fixed Starres scarce one of them hath his declination truly set down and agreeable to observation Yea even the Pole-starre it selfe though it be better known and more observed by the most part of Seamen then all the rest and indeed as it might be used being to be observed at any time of the night all the yeere long might stand them in as much stead for finding the Latitude as all of the rest almost yet in the bookes of Navigation that are most common amongst English Mariners the distance thereof from the Pole is made to be in our time above 40 minutes more then it should be No marvell therefore if the Mariners complain as I have heard them sometimes that they cannot make their observations of the Latitude by the Sunne and this Starre to agree Neither is there more truth to be looked for in the declination of many other principall fixed Starâ—s published in those bookes divers of them erring from truth one two yea some of them three whole degrees and more as in the treatise following shall be shewed And these errors in the declination of the Sunne and fixed Starres not only I but also the right worshipfull Sir Christopher Heydon Knight and the noble Lord of Knudstrupp Tycho Brahe founder of Vraniburg with the gratious Prince William Landtgrave of Hassia father of him that now is have often found by many and most diligent observations with large and exact Instruments wherein both minutes and halfe minutes might be easily discerned Notwithstanding if any stand in doubt hereof I wish that he himselfe also would bestow no lesse cost time and diligence to make often heedfull and exact observations then either the Prince of Hassia or Tycho Brahe or at least as I my selfe have done and then let him beleeve that which he shall see to be true with his own eyes These errors therefore in the Chart Compasse Crosse-staffe and declinations of the Sun and Starrs I have in the treatise following laboured to reforme to the utmost yea rather beyond the utmost of my poore abilitie neglecting in the meane time other studies and courses that might have been more beneficiall to me which may argue my good will to have proceeded further to the amendment of such other faults and imperfections as yet remain besides those that are alreadie specified and that especially in two points that is in the courses and Longitudes of places The reforming of the Chart in reducing all places from those varying courses wherein now they are set down to the true positions they have each from other by separating the variation wherewith they are in the ordinary Charts for the most part intermingled were a busie peece of work yet as were most worthie and necessarie to be laboured in as without which the Charts Maps and Globes or any other Hydrographicall or Geographical descriptions cannot be freed from many intricate absurdities wherewith now they must needes in many parts be pestered because the courses and positions of places are in them set down as they were observed by the varying Compasse without separating the variation afterwards that so the true courses and positions of places might be known The Longitude also would well deserve both labour and cost to be both skilfully and liberally bestowed for the finding thereof whereby it were possible to bring it to that passe the motions of the Sunne and Moone and places of the fixed Starres being verified whereof that noble Tycho Brahe hath afforded great hope that the industrious and willing minded Mariner might be capable thereof in such sort that for the most part when the Moone and fixed Starres appeare he might be able hereby to know what Longitude he is in yea even at Sea more truly then many have done by their dead reckonings in sailing out of the bay of Mexico to the Azores or from New-found-land to England or almost from the Azores to England But on land the Longitude might by this meanes be found exactly as the Latitude hath been by many observers at Sea And so opportunities of observation with meet Instruments on shoar not being neglected especially in long Voyages farr Eastward or Westward many most notorious errors in the Longitudes of places would in short time be corrected wherewith the most excellent arts of Geographie and Navigation are very much blemished For who that loveth truth can patiently endure to heare the Mariners common and constant complaint of 150 or 200 leagues error in the distance between the bay of Mexico and the Azores or that which is yet most intollerable and monstrous of 600 leagues difference in the distance between Cape Mendosino and Cape California some making that distance to be twelve or thirteene hundred leagues where others will have it and that more probably to be no more then six or
after it is touched with the Loadstone by means whereof it seemeth something probable that Seamen may have some help to know their height or Latitude in dark and cloudie weather when neither Sun nor Stars for many daies appear to be observed I thought it should not be impertinent to this place to set down the Theorick that hath been devised of this magnetical inclination together with a demonstration for the making of a Table thereof to every degree of Latitude according to that Theorick to the end that such of our Sea-men as mean to be diligent observers hereof may make heedfull trial of that inclining propertie and compare the same with this Table in all parts of the world where they shall travell especially in those long Voyages to the East and West Indies and in their Northeast or Northwest discoveries The third part may be called Geometrical intreating of the Crosse-staffe and shewing how such errors may be avoided as have been commonly committed in the use thereof either by reason of the parallax or eccentricitie of the eye or by the height of the eye above the water or by the parallax or refraction of the Sun And because for finding the quantitie of the angle that is to be abated out of the apparent altitude of the Sunne or starres observed by this staff for any height of the ey above the water it was needfull to know the quantitie of the earths semidiameter concerning which there is great varietie of opinions amongst learned authors I have therefore in this part of this treatise now shewed divers waies for the more certain finding thereof one of which waies I have also for my more assurance exemplified by observation as meanes and opertunitie served me neere Plimmouth sound anno 1589. The fourth and last part may be called Astronomical wherein my chief intent was to correct the errors that are in the ordinary Tables of declination of the Sunne and fixed starres To which end there is first set down a table of the declination of every minute of the Ecliptick in degrees minutes and seconds calculated for the greatest obliquitie of the Zodiack as it is found by observation in this age 23 degrees 21 minutes and an half Whereto is adjoyned the use thereof for the readie finding of the place of the Sun by his declination given or contrariwise for finding the Suns declination his place being first known After this is shewed the way and means I used for exact observation of the Suns Meridian altitudes with a table of those observations for four yeeres together that so the more certaintie might be had of the declinations and places and consequently of the whole course and motion of the Sunne and that by comparing together so many observations the Sunnes Eccentricitie and Apogaeum might the more assuredly be known By knowledge whereof the way was laid open for the correcting and true making of the Tables of the Suns middle motions and Prosthaphaereses which were necessarie helps and means for calculating the Ephemerides of the Sun there set down without which the regiment or table of declination of the Sunne next following which I may commend as free from error observable at sea and seldome differing one minute from observation on land and for which principally all the former pains were undertaken could not so easily have been made Now if any shall think that most of this fourth part going before this regiment might have been omitted as being impertinent to the use of Mariners and exceeding their capacitie I answer that it was not my purpose neither could I in all places apply my self to the most part of sea-mens capacitie knowing many that would not be content with this regiment alone but that desired more to know the ground and root from whence this fruit grew whose desire I was also willing to satisfie as I could for the present having seldome had a more inconvenient season for such a purpose Then after some caution given concerning the use of this table of Declination and the Equation thereof in places farre differing in longitude from hence there followeth a Table of 32 principall fixed starres about the Aequinoctiall that have been most commonly known and observed by Seamen with their Declinations corrected and another Table of as many more of the notablest starrs about the North Pole is thereto annexed with their distances from the Pole corrected also and verified by diligent Observation on land To these is added a Table of the Suns Right Ascensions resolved into hours and minutes for every day of the year with the use thereof for finding at what houre any of those stars commeth to the Meridian at any time of the year that hereby the Mariner might find at all times when they come to the Meridian and so the easilier learn to know and observe them Hereunto I have newly adjoyned the description and use of an Instrument which way not unfitly be called a Sea-quadrant whereby is shewed how the height of the Sun at sea may by two observers be much more exctly observed then by any other means before published and how the height of the Pole may readily be found at any time of the night by observation of the Pole-star and Guard without making any abatement or allowance as the manner hath been in regard of the point of the compasse whereupon the Guard is situate But now for further satisfaction in every one of these particulars I refer the friendly Reader to the Treatise it self here following which Simon Stevins inconsiderate desire of finding fault with my Tables of Rumbs hath caused me to conclude with an Answer to him plainly shewing himself and not me to be in the same fault that he would find with me To this Treatise for the benefit of the younger and unskilfuller sort of Seamen it was thought not unmeet to adjoyn the short Treatise following containing the sum of the whole Art of Navigation first set forth in Spanish by Roderigo Samorano and since translated into English by a friend of mine for the benefit of our Nation which Treatise I would wish all them that are but New beginners in that Art first to peruse and understand well before they come to the reading of the former which for the reading thereof with the greater profit requireth such a one as is alreadie reasonably well acquainted with the rules and principles of that Art which I have not hitherto known to be more briefly and plainly nor yet more fully set down and published in any other book then they are in that little Treatise This notwithstanding I must admonish the Reader that in stead of the Sea-Chart therein described according to the common error with equal degrees of Latitude he follow that manner of making the same which I have in the former Treatise set down Chap. 3 4 5 and 6. And that in stead of the rules and allowances for finding the Latitude by the height of the Pole-star which are many waies and much
24 47 69 17 77 86 48 18 34 0 48 70 9 78 87 8 19 35 36 49 70 59 79 87 26 20 37 9 50 71 48 â—0 87 44 21 38 41 51 72 36 81 88 1 22 40 11 52 73 23 82 88 17 23 41 39 53 74 8 83 88 33 24 43 6 54 74 52 84 88 47 25 44 30 55 75 35 85 89 1 26 45 54 56 76 17 86 89 14 27 47 15 57 76 57 87 89 27 28 48 36 58 77 37 88 89 39 29 49 54 59 78 15 89 89 50 30 51 11 60 78 53 90 90 0 whose complement to a quadrant is the angle sought for ARZ According to this Diagram and demonstration was calculated the Table here following the first column whereof containeth the height of the Pole for every whole degree the second column sheweth the Inclination or Dipping of the Magnetical Needle answerable thereto in degrees and minutes CHAP. XV. Error in using the Crosse-staffe and how they may be avoided AFter the Chart and Compasse the Crosse-staffe may with good reason succeed as in the use whereof more error is committed then in any other Instrument of Navigation the two former excepted and that four severall waies First in neglecting the Paralax or Eccentricitie of the eye Secondly in not considering the height of the eye above the Water Thirdly and Fourthly in not regarding the Paralax and Refraction of the Sun For the first they count the height of the Sun and Stars in such sort as if the center of the eye or vertex of the visual cone in using the Staffe were even with the end thereof that is set to the eye Therefore how much the center of the sight is distant from the end of the Staffe so much are they deceived But how much the Eccentricitie or Paralax of the eye is it may be known after this manner Make two Transversaries the one twice so long as the other The longest of these two set fast at the further end of the Index the other of them move up or down upon the Index untill such time that your eye placed at the end of the Index in such sort as you use to place it when you observe you may see both ends of both Transversaries lie even together For then look how much the segment of the Index betwixt the two Transversaries exceedeth the segment from the shorter Transversarie unto the eye so much is the Parallax or Eccentricitie of your sight or the point wherein your eye wherein the visual beams concur is so much distant from the end of the Index As for example in this figure let the Transversarie HEI placed at E the end of the Index be double to the Transversarie FDG which is placed in such sort upon the Index that the visual lines AFH AGI of the eye placed at the end of the Index do passe straight on by FH and GI the ends of the Transversaries For in this figure A is the center of the sight or eye wherein the visual lines AFH AGI doe concurre B representeth the end of the Index placed at the corner of the eye and then AB is the Eccentricitie C signifieth the end of the Index set against the bone underneath the eye for observing of distances and then AC is the Eccentricitie which is thus demonstrated Secondly they increase the former error by not regarding the height of the eye above the Water Which although it be not so great a fault as the other yet it may deceive them by increasing the former error five or six minutes or more in a tall Ship For the higher the eye is above the water the greater is the angle contained betwixt the two visual lines whereof one toucheth the convex superficies of the Sea the other passeth on to the Sun or Stars And the lower the eye is the lesse is the foresaid angle and then onely it sheweth the true Altitude when the center of the sight is in the same line of levell with the superficies of the Water But if the eye be higher then the Water that angle is greater then the true Altitude and therefore subtraction must be made accordingly that you may have the true Altitude Now to find how much it is that should be subtracted at any height of the eye above the Water there be two waies the one without knowledge of the Earths semidiameter the other with knowledge of the same For the first you must have some such convenient place at the Water side where you may have a free and cleere prospect unto the Sea without impediment and where you may also have such provision made that you may place both your self and also an exact and large Water Levell in convenient manner to make exact observation at what height soever you desire above the superficies of the Sea till you come to the height of the tallest Ships that go upon the Seas that levell having the sight that you must look through at the end thereof next the eye so fitted that you may both easily and steadily set it higher then the fore sight that is the sight that is at the fore-end of the Levell so much as shall be needfull to lay the fore-sight precisely to the touching of the Sea and that you may also perfectly know how much the back-sight or sight at your eye is higher then the fore-sight above the line of Levell For by the difference of the heights of those sights above the line of Levell and the distance between them it may easily be found how much the visual line touching the roundnes of the Sea Dippeth under the line of levell or true Horizon from whence the height of the Sun and Stars is to be accounted thus As the distance betwixt the sights is to the difference of their heights above the line of levell so is the whole sine to the Tangent of the angle of Dipping which we desired to know This angle may otherwise be found the quantitie of the Earth semidiameter being first known which is to be done divers waies but they may be all reduced to two heads or kinds whereof the first requireth the certain measure of some arch of the Meridian to be first given which is also divers waies to be performed But the best and perfectest way of all others is to observe so axactly as is possible the Summer solstitiall Altitude of the Sun at two places so farr distant asunder and lying so neer North and South each from other with so direct and faire a way betweene them as conveniently may be chosen Suppose for example Portsmouth and Barwick or some other place in the furthest parts of Scotland for the further these places are each from other the more perfectly may this businesse be performed Then measure and plat down so truly as is possible all the way betweene those two places with all the turnings and windings ascents and descents that are therein out of which the arch of the great circle
with the Regiment of the Sun and of the star the rules of the Moon and of the Tides the declaration of the Sea-chart and other things appertaining hereunto CHAP. I. The Definition of the Sphere A Sphere is a solid or massie body without hollownesse and perfectly round in the midst whereof there is a prick called the center by which there passeth a right line named the Axtree and the points where this line endeth upon the superficies of the whole body are called Poles because upon them the Sphere is moved CHAP. II. That the whole World is a Sphere AND so it is evident that the whole frame of the World wherein we live is a Sphere being as it is solid so that in the whole World there is no empty place also it is perfectly round upon the upper Superficies of the highest heaven and it hath in the very midst a certain point to wit the center of the earth by which we do imagine a right line or Axtree to passe from one pole to another upon which the World is moved about from East to West CHAP. III. Of the division of the Sphere THE whole Sphere of the World is divided into two parts or Regions the Elementary and Celestial The Elementary part or Region hath four parts the first whereof is the earth which together with the element of water which is the second maketh one perfect Globe and round about both these are two other elements namely the Air and above that the fire which filleth the space between the Air and the Sphere of the Moon of which Elements by vertue of the heat of the Heavens are made and compounded all corruptible things in the world The celestial Region consisteth of other ten parts the first whereof is the Sphere of the Moon the second the Sphere of Mercury the third of Venus the fourth is the Sphere of the Sun the fifth of Mars the sixth of Jupiter the seventh of Saturn the eighth is the Sphere of the fixed stars which is called the Firmament the ninth is the Crystalline heaven and lastly the tenth and highest is the Sphere called the Primum mobile that is the first or highest moveable heaven That which remaineth called the Empyreal heaven because it hath no motion cometh not to be considered on in the Art of Navigation A Figure wherein may be seen the Composition of the whole Sphere of the World CHAP. IV. Of the motion of the Heavens THe number of the Heavens is known by the motions observed in them which are ten distinct one from another For the Moon moveth her proper and peculiar motion in 27 dayes and 8 hours which is one Revolution Mercury Venus and the Sun finish their motion in one year which conteineth 365 dayes and almost a quarter of a day Mars runneth his course in two years Jupiter in twelve years Saturn in thirty years the eight Sphere according to the opinion of some in seven thousand years the ninth in five and twenty thousand and eight hundred years and the tenth in four and twenty hours almost Which ten motions are reduced unto three principal the first is that of the first moveable upon the two ends of the Axletree which are called the Poles of the World from East to West turning about again unto the East in 24 hours and this Sphere by the force of his motion carrieth about with it all the other lower Spheres in the space of 24 hours Howbeit they move also the contrary way with a second motion which is from West to East upon two other poles distant from the first about three and twenty and an half such parts whereof the whole compasse of heaven conteineth three hundred and sixty And this second motion is accomplished in each of the lower Heavens in divers spaces of time as is before said The third motion is proper to the eighth Heaven wherein the fixed stars are placed which motion is the cause that the distance of the poles of the first motion from them of the second motion doth vary being sometimes greater and sometimes lesse CHAP. V. Of the Figure of the Heavens THat the Heavens are round it is proved because roundnesse is the most perfect Figure of all others being whole and intire having no need of any joynts being also of the greatest capacity of all figures that have the same compasse and in that respect most fit to contain all other things Also the principal bodies of the World as the Sun the Moon and the stars are of this Figure and we see the same likewise in those things which are bounded by themselves as it is manifest in drops of water and all other liquid things CHAP. VI. That the Earth and Water make one perfect Globe THere is nothing that sheweth more cleerly that the earth and water make one round Globe then the shadow which they make in the Eclipses of the Moon which shadow we alwayes see to be a part of a circle For if the body which is the cause of the same shadow were three-square or four-square the shadow it self also would appear in the same fashion Wherefore the shadow of these two bodies together being round it is manifest that they are round also CHAP. VII That the Earth is in the center of the World ONe sign we have to be assured that the Earth is in the midst and center of the World namely that wheresoever we are upon the face of the earth we alwayes see one half of the Heavens the other half being hidden out of our sight Moreover the stars in what part of the Heavens soever they be either in the East West or South we see that they are alwayes of the very same bignesse Whereby we may easily perceive that they are alwayes equally distant from our sight and whereas they move round about it it followeth that we are upon the center of that body on whose superficies the said stars describe their circles CHAP. VIII The whole quantity of the Earth ANd albeit the Globe of the Earth and Water compared with the Spheres of the Stars is as it were a center or prick yet being considered by it self it conteineth in the greatest circle thereof 6300 common Spanish leagues Which a man may easily perceive by taking two such points or head-lands of the earth as are under the same Meridian and which differ in distance one from another so much as one of those parts is whereof the compasse of the whole world conteineth 360 and it is found both by Navigation at Sea and also by travel on land that the two foresaid points are distant each from other 17 leagues and an half of which leagues each one conteineth 4000 paces every pace 5 foot every foot 16 fingers and every finger 4 grains of barley CHAP. IX Of the Equinoctial Circle BEing to treat of the Circles of the Sphere of the World the first which offereth it self to be spoken of is the Equinoctial Circle by means whereof we do know in
because they are equal This heighth of the Pole is known by the help of four things which are the Ballâ—stilla or Crosse-staffe the position of the North-star the heighth of the said star and certain Rules CHAP. XI The making of the Cross-staff THe Mariners Crosse-staff is that which by the Astronomers is called Radius Astronomicus and the manner how to make it is as followeth First upon a very plain and broad table you may draw a semicircle which from the center to the circumference must contain at the least four hand breadths And having drawn thorow the center thereof the line ABC divide the circumference into two equal parts in the point E as likewise you must divide the quadrant EC in the very midst by the point F. Then must you divide the arch EF into 90 equal parts dividing it first into three and every of these three into other three and every of those nine into two and each of those two into five which you must do with much precisenesse and care Then laying your Ruler to the point B which is the center through every one those 90 divisions of the half quadrant you must draw 90 lines And keeping this quadrant so divided it will serve you for a pattern to make us many Crosse-staves as you think good of what bignesse soever you will But to make the Crosse-staff you must take a piece of wood of some three foot in length and a finger thick four square and very even and fitting a transversary thereto which may with facility slide up and down upon the staff alwayes right acrosse take with your compasses half the length of the transversary and placing one foot of the compasses upon the point B make with the other a mark in the line BC which may serve for the point G and draw thorow the point G the line GI which may run equally distant from the line EB Finally laying one end of the staff upon the point G let it lie all along just upon the line GI and make your marks upon the edges of the staff by which you may draw 90 lines putting the number of every line upon the said edge begining to place 90 where the line BE doth crosse the staff and from thence descending unto one or two which may be put down according to the length of the staffe and the largenesse of the transversary CHAP. XII Of the position of the North-star and the Guards AMongst the 48 Constellations which the Astronomers place in the Heavens the neerest unto the pole of the World is that which they call the lesser Bear and the Mariners Bozina or the horn in regard of the fashion thereof which Constellation consisteth of 7 stars which are placed after this manner And of these stars the three greatest marked with the letters ABC do serve especially for our purpose And so A is called the North-star B the the formost guard C the other guard behind And they are so called because that by force of the motion of the first moveable Heaven the star B goeth alwayes before and the star C behind Every of these three stars as well as all others in the Heavens besides describe thâ—â— circles round about the pole with the motion of the first or highest moveable Heaven 〈◊〉 which motion sometimes the 〈◊〉 stars AB are just of 〈…〉 above the Horizon 〈…〉 they are said to be East and West one from another Sometimes they are in a perpendicular line to the Horizon according to our sight and then they are said to be North and South and sometimes also the two guards BC are East and West one from another and then the former guard beareth from the North-star North-east and South-west And when these two guards be in a perpendicular line one above another the former guard beareth from the North star North-east and South-west Insomuch that from these four positions do arise eight rules for the eight Rumbs wherein the former guard may stand being considered in respect of the North star And so presupposing that the North star is distant from the Pole three degrees and an half according to the opinion of some Mariners who love numbers that have not any fractions sometime the North star shall be as high as the Pole it self sometime three degrees and an half lower or higher then the Pole and sometime three degrees and sometimes one and an half and sometimes half a degree CHAP. XIII Of the heighth of the Star taken with the Crosse-staffe TO know how much the North Star is elevated above the Horizon you must take the heighth thereof onely at such times when as in respect of the former guard it is in some one of these four Rumbs that is to say North and South East and West North-east and South-west and North-west and South-east Wherefore seeing it placed in any of the foresaid Rumbs you shall put that end of the Crosse-staffe which is next 90 degrees upon your cheek-bone at the utter corner of your eye and holding it there stedfast you must move the transversarie till you see the Horizon joyned with the lower end thereof and the North Star with the higher end Then mark the degree and part of the degree which the transuersarie sheweth upon the staffe for that is the heighth of the Star CHAP. XIIII The regiment or Rules of the North Star The first Rules WHEN the guards are in the East the former guard beareth with the North Star East and West and then the North Star is a degree and half under the Pole let us add this degree and half to the height which we Observed with the Crosse-staffe and the whole product sheweth the number of degrees which the Pole is elevated above our Horizon And so much are we distant from the Equinoctial toward the North. The second Rule When the guards are in the North-east one guard beareth from another East and West and the former guard standeth from the North Star North-east and South-west and then the North Star is under the Pole three degrees and one half which being added to the height of the Star will shew you the height of the Pole The third Rule When the guards be at the highest then the former guard beareth from the North Star North and South the North Star being then three degrees under the Pole which three degrees being added to the height of the Star do shew the true height of the Pole The fourth Rule When the guards are in the North-west they bear one from another North and South and the former guard lieth from the North Star North-east and South-west and then the North Star is under the Pole half a degree which half degree being added to the heighth of the Star giveth you the heighth of the Pole The fifth Rule When the guards are in the East the former guard lieth from the North Star East and West and then the North Star is a degree and an half above the Pole which degree and
the rose or fly may play more nimbly upon the pin This pin must be made of lattin with a very sharp point and is to be fastned upright in a round box of wood which must be of the fashion of a great cup-dish containing the rose within it being covered above with a clear round glasse and the joynts thereof must be stopped with wax to the end that no wind may enter into the rose to disturb it There must be great care had that this rose with the wires placed upon the pin may go nimbly and may not swerve more to the one side then to the other but may stand even and level And when it inclineth towards either part you must put on the contrary part a little wax or a thin plate of lead fastened under the pastboard which covereth the wires This box wherein the rose plaieth up and down hangeth within two hoops of lattin which are two round circles inclosed one within another and distant asunder by the space of half a fingers breadth with two nails of lattin which are diametrally opposite And the box being fitly placed within these hoops you must make in the outward hoop two holes which must be distant from the foresaid two nails a quarter of a Circle both wayes And by these two holes must the outward hoop or circle be fastened within a square box or a round so as although that uttermost box be tossed up and down every way with the motion of the ship yet alwayes the superficies and glasse of the inner box may lie level with the Horizon And this being done with care the instrument which they call the Sea-Compasse is fully finished The manner of using the same is when being placed with the box in the midst of the poop of the ship where the bittacle standeth in a right line which passeth from the bolt-sprit by the midst of the main mast to the poop it serveth continually to govern the ship by moving of the Rudder till the winde or the line of your Compass towards which we desire to shape our course stand directly towards the prow or bolt-sprit of the ship They use also for the night to mark a point within the inner part of the inner box which in respect of the capitel of the Compasse may stand directly towards the prow of the ship And alwayes in guiding the ship you must take heed that the said point be continually joyned with the winde of the rose towards which you intend your course CHAP. XVIII How the Variation of the Compasse may be found THe Mariners use to examine whether their Compass North-easteth or South-westeth watching for that purpose when the former guard beareth with the North star North-east and South-west taking a little of the point of North and South And placing their Compasse in an open place where the North star may be seen if the flowerdeluis of the Rose looketh directly towards the star their Compasse varieth nothing at all but if the star be to the North-east so much as it varieth from the point of the flowerdeluis so much the Compass North-westeth and if it varieth to the North-west of the Compass how much the star swerveth from the point of the flowerdeluis so much the Compasse North-easteth And in regard of this variation of the Compasse there must alwayes allowance be made in the course which is holden This manner of finding out the variation I do account to be somewhat subject unto errour but at land there is another more certain way by the Meridian line which is to be taken in manner following The finding of the Meridian-line In a superficies which is plain and level every where and in a place where the Sun shineth at his rising and setting you must draw certain circles upon one center and having pitched a stile upright in the same center the head whereof must be approved with a pair of compasses to be equally distant from all parts of one of those circles observe you in the morning two or three hours before noon when the point of the shadow of the stile toucheth the circumference of any of those circles and having made a mark in the touches take diligent heed in the afternoon also when the same point of the shadow turneth about to touch in the same circle and making another mark in that second touch divide in the midst that part of the circle which is between those two marks Then laying your Ruler upon the point of the division and upon the center of those circles draw a line which shall be your Meridian and the true North and South Rumb upon which setting your compasse and laying your Ruler over the glasse that it may passe along over the Meridian and over the center or capitel of the rose or flie eithe said Ruler lieth over the North and South of the Compasse and then is the Compasse without variation or the Ruler declineth toward the North-east or South-west and how much it declineth that way so much the Compasse North-westeth or else it declineth towards the North-west and then it North-easteth so much as the Ruler declineth that way But to know the variation of the Compasse both at land and sea we will deliver another far more easie and certain way when we come to intreat of the universal Dial. CHAP. XIX Of the Sea-chart THe Sea-chart is nothing else but a lively picture of the earth and water And it containeth five notable things which do concern as well the true making of the Chart as also the inabling of the Mariner to know the way which he maketh the place where he is and the end of his journey The first is the laying out of the Coasts of the Land which that it may be truly done it is meet that every thing be set down in the Chart in the same course distance and heighth that shall be found in Navigation The second is that it containeth not onely the coast of the firm land but also all other particularities which do occur in sailing as namely Islands Iselets Banks or Bars Shoalds Rocks and Flats The third is the lines which signifie the 32 winds by the help whereof we may see whether the parts of the land be well laid out and in their true courses one from another And of these winds the black are the eight principal which are called whole winds The green be half winds or half parted winds and the red be the quarters of the winds You may know in your Chart whether these winds be well drawn if you trie with your compasses that all points of them be equally distant one from another and that all winds representing the same Rumb be parallels As namely that one Northeast and Southwest Rumb be parallel to another Northeast and Southwest Rumb The fourth is the graduation in all parts whereof it is meet that the degrees be equal one to another and that the parts of the land do directly lie East
5 I divide these 24 by 5 and I find the quotient to be four and the remainder four And so I say that the Moon commeth to the North-east four hours and ⅘ later then the Sun And because the Sun commeth to the North-east at three a clock in the morning I add those 4 hours and ⅘ unto the 3 hours last mentioned and they make seven hours and ⅘ which is the hour of the morning wherein the Tide or full Sea happeneth And adding unto these seven hours and ⅘ other six hours and ⅕ they make in all fourteene hours which falleth out at two a clock in the afternoon which is the hour of the first low water or ebb And adding unto the said hour of the full Sea twelve hours and ⅖ it will amount unto eight of the clock and ⅕ part of an hour which is the hour of the night wherein the second Tide or high water was And add unto this second Tide other six hours and ⅕ and they make two of the clock in the morning and ⅕ at which time there commeth the second ebb or low Sea CHAP. XXXIII Of a certain Instrument whereby you may in generall judge of the Tides BEcause the Tides it being supposed that in all places they proceed from the motion of the Moon run not in every part of the world by one and the same Rumb as it is manifest in the channell of Flanders and in all the coasts of the Northern Sea which is a matter of great confusion and difficulty to Mariners I thought good here to set down an Instrument whereby the daies of the Moon and the Rumb whereupon the Moon causeth the Tide in every part being known they may judge of the ebb and flood with great facility Draw upon a sheet of paper or upon a plate of tinn or any other matter a circle as bigg as the palm of a mans hand and half a fingers bredth within that circle draw another circle and having divided them both into 32 equall parts with lines drawn from the center to the circumference of the greater circle upon the upper end of one of those lines place a flower-deluis and the number of 12 and in the next line thereunto toward the left hand set down 12 and ¾ and in the third line 1 ½ and so proceed forwards putting down upon every line following ¾ of an hour more untill you come again to the number of 12 in the lowest line And from thence forwards set down the same numbers that you did at the first These 32 lines so drawn doe represent the 32 winds whereby the Sun and Moon pass every day And so you may set down the names of the principal Winds to the end that you may know them and those that are next them And then in like manner make another round and slender Table as bigg as the innermost circle of those two which you drew in the first Table and dividing it into thirty equal parts first into two by a line dividing it in the midst and then either of those two into three and every of those three into five these divisions will represent the days of the Moon And leaving upon 1 of those parts an Index or small point which may reach without the circle set down the numbers thereof beginning with 30 in that part where that point endeth and the number of 1 in the line following towards the left hand and then 2 c. till you end at the same point with 30 This being done fasten with a thred or nail the second Table or Circle upon the center of the first so that it may freely without impediment turne round about The use of this Instrument The use of this Instrument is that knowing in every Port or part of any coast the Rumb or quarter on which the Moon maketh full Sea or high water you must note upon the outward Circle of the Winds that quarter or Rumb and placing the tooth or point of the inner Circle were the number of 30 is upon that quarter or Rumb make it there fast puting a litle wax underneath that it may not move Then account the days of the Moons age in the inner Circle and over against the end of your account you shall see in the uttermost Circle the hour of the full Sea of that day together with the Rumb where the Sun is at that hour And at the same hour when it is in the contrary part it will make a full Sea The place of the moon at the hour of the tide is alwaies either where the point is or at the point right over against it and hence you may easily find both ebbes also This little Instrument although it be but of small Invention is of great use and profit for the Navigations of Flanders France England Ireland and all the Northern regions where you have much variety in the tides CHAP. XXXIIII Of the making of an universall Diall which may serve Generally all the World over DRaw upon a Table or pastboord the Circle ABCD upon the center E and half a fingers breadth within that Circle upon the same center draw another Circle and about the breadth of a wheat corn within the second Circle draw a third and placing your Ruler upon the center E by the right line AC divide the two inner Circles in the midst ABC and CDA in the points BD upon which and upon the center E the Ruler being placed you may draw the line BD whereby every one of the foresaid Circles shall be divided into four equal parts And dividing every one of those four Quadrants of the inner Circle to wit AB BC CD DA into 90 parts as the manner is in the making of an Astrolabe set numbers thereto from 5 to 5. begining your account from the two points AC and so proceding both ways till you end your account in 90 at the points BD and this inner Circle thus divided representeth the Meridian And the point C is the North A the South and the points B D are those where the Equinoctial cutteth the Meridian Then count 23 degres and an half from the point B to F and to G on both sides And so much account also from the point D to H and to I. And then drawing two right lines FH and GI the line FH shall represent the Tropick of Cancer and GI the Tropick of Capricorn And those two lines shall cut the line CA which is the Axtree of the World and the Circle of six of the clock in the morning and evening upon the points LM Then count fifteene degrees from C towards B and other fifteeen from A towards B and placing your Ruler on either side upon the end of your account you shall cut the Equinoctial BD upon a certain point which shall represent unto you seven a clock in the morning and five of the clock at evening And counting other fifteen degrees on both sides more towards the point B and placing
the Ruler as before you shall cut the line BD in another point which shall represent eight of the clock in the morning and four in the afternoon And accounting higher fifteen degrees more one both sides and placing your Ruler upon the end of your account it will divide the line BD at another point which shall be nine a clock in the morning and three in the afternoon and so you shall proceed from fifteen to fifteen degrees till you come to eleven of the clock in the morning and one in the afternoon And if you will have the half hours also you must account from seven degrees and an half to seven and an half and doing as you did with the fifteenth degrees you shall have the half hours also Then placing your compasses upon the center E and upon every division of the line EB you shall draw the same divisions likewise upon the line ED which being done draw certain obscure lines from the point A to the divisions of the line EB and drawing the right line GF see where GF is cut at the highest of the obscure lines which must be at the point N from whence the line NO is to be drawn equally distant from the line BE. And this line NO shall be divided proportionally by the obscure lines even as the line BE. Then let the divisions of the line NO be transferred into the lines MG MI LF LH and then the Tropicks also shall be divided Then by every three points answerable in the Equinoctial and the two Tropicks you shall draw certain parts of Circles seeking the center of those three points in the Equinoctial line extended forth on either side and these parts of Circles represent the hours then make an account of the degr of Declination from the point B and from D on both sides by every 2 degr and draw lines Parallel to the Equinoctiall from one to another and those shall be the Parallels of the Suns Declination Moreover you shall make an Horizon as large as the Diameter of the inner Circle which shall be divided after this manner Count from the points AC towards B five degrees and putting your Ruler upon the end of the account of both parts see where it cutteth the line EB and there make a mark and then counting on both sides other five degrees and putting the Ruler once again at the end of your account make another mark where it cutteth the line EB And so the line EB must be divided from five to five degrees which divisions shall be removed into the said Horizon fastning it to the Center and laying it to the line BD and dividing it both ways as the line EB is divided and set numbers thereinto from 5 to 5 which may begin in the midst and end with 90 at the ends of the Horizon and let every one of these parts be divided into five other parts or degrees Then accounting from the Center E in the Horizon eleven degrees and ¼ you shall set there a mark which shall be the seventh point from North and South that is it shall represent the points which are next to the East and West in the Compasse And accounting another eleven degrees and a quarter and making there a mark it shall represent the sixth point from North and South And so you must doe with the other points and then your Instrument is finished CHAP. XXXV Of the parts of this Instrument IN this Instrument the first thing is a Circle divided into 360 degrees which is the Meridian and the line of twelve a clock The second are the right lines of which that in the midst is the Equinoctial and the two others are the Tropicks of Cancer and Capricorn And the other lines between those are the Parallels of the Suns Declination which have their numbers agreeable to them And those that are between the Equinoctial and the Tropick of Cancer doe serve from the 11 of March to the 13 of September and the others for the residue of the year The crooked lines which cross those Parallels are the hour lines And the point of the Meridian which in 90 degrees distant from the Equinoctial towards the left hand is the North Pole and the point opposite to that is the South Pole In the Horizon there are first the degrees and then the points of the Compass distinguished by the small pricked lines CHAP. XXXVI How you may know what a clock it is by this Instrument AT any time of the day when you would know what a clock it is take the heighth of the Sun with your Astrolabe and seeking the Table of the Suns Declination what Declination it hath the same day and the height of the Pole which a good Mariner knoweth at all times because he must direct his course thereby This being known place the Horizon Instrument on the one side under the North and on the other side above the South so many degrees as his distance from the Equinoctial is the same day and fasten it there with a little wax that it may not move Then count in the Meridian on either side from the Horizon which now standeth firm the height of the Sun above the Horizon take with your Astrolabe and by the end of the account draw a line or thred overthwart which shall be equally distant from the Horizon Then reckon the Suns Declination in the parallels beginning from the Equinoctial of the Instrument that way which the Sun Declineth and mark the line or Parallel at which the account of the Declination endeth where and at what hour it is crossed by the thred for that hour is the hour of the day But note this that if the crossing of the thred and Parallel doe fall upon the division of the Parallel and of the hour it is a just hour but if it fall beside the common meeting of the Parallel and of the hour-line upon that side where it falleth see how much more there is then an hour whether ¼ or 1 ◠or ½ c. Now although every hour line hath two numbers one of the morning and another of the afternoon yet it is an easie matter to distinguish which of them will serve your turn if you know whether your Observation be before high noon or after which is to be known by your Astrolabe for if the Sun ascend it is before noon but if it descend it is afternoon CHAP. XXXVII Of the Variation of the Compasse by this Instrument IF you would know by this Instrument the Variation of the Compasse you must doe thus When the Sun riseth or goeth down at the Horizon Observe him with your Compasse noting very diligently upon what Rumb and part of the Rumb he riseth or falleth And if the compasse be divided into 360 parts beginning to reckon them from the East and from the West on either side and ending in the North and South with 90 degrees it shall be the fitter for this purpose because then you shall see