The Poles altitude is the distance betweene the Pole and the Horizon or that portion of the Meridian which is contained betweene the Pole and the Horizon The altitude of the Sunne aboue the Horizon is that portion of the circle of Azumuth which is contained betweene the Horizon and the Sunne Latitude is that arke of the meridian which is contained betweene the parallell of any place and the Equator or that part of the Meridian which is included betweene the Zenith and the Equinoctiall Longitude is that portion of the Equator contained betweene the Meridian of S. Mihels one of the Iles of the Assones and the Meridian of the place whose longitude is desired the reason why the accompt of longitude doth begin at this I le is because that there the Compasse hath no varietie for the Meridian of this I le passeth by the Poles of the worlde and the Poles of the Magnet being a Meridian proper to both Poles The longitude betweene place and place is the portion of the Equator which is contained betweene the Meridians of the same places Declination is the distance of the Sunne Moone and Starres from the Equinoctiall or that portion of the Meridian which passeth by the Center of any celestiall body and is contained betweene the same center and the Equinoctiall Hidrographie is the description of the occean Sea with all Iles bancks rocks and sands therein contained whose limits extend to the geographicall borders of the earth the perfect notice whereof is the cheefest thing required in a sufficient Pylote in his excellent practise of sayling Geographie is the description of the earth onely whereby the terrestriall forme in his due situation is giuen whose distinction is by mountaines riuers vallies cities and places of fame without regarde of the Circles Clymates or Zones Cosmographie is the description of the heauens with all that is contained within the circute thereof but to the purpose of nauigation we must vnderstand Cosmographie to be the vniuersall description of the terrestriall Globe distinguished by all such circles by which the distinction of the celestiall Sphere is vnderstoode to be giuen with euery Countrie Coast Sea Harborow or other place seated in their true longitude latitude Zone and Clyme The Chart is a speciall instrument in Nauigation pretending the Cosmographicall description of the terrestriall Globe by all such lynes circles corses and diuisions as are required to the most exquisite skill of nauigation The end of the First Booke THE SECOND PART OF THIS TREATISE OF NAVIGATION WHERIN IS TAVGHT THE nature and most necessary vse of the Globe with the Circles Zones Climates and other distinctions to the perfect vse of Sayling By which most excellent Instrument is perfourmed all that is needfully required to the full perfection of all the three kindes of Nauigation THE SECOND BOOKE OF THE SEAMANS SECRETS What is the Sphere THe Sphere is a solide body contained vnder one superficies in the midst whereof there is a point or prick which is the Center of the Sphere from whence all right lines drawn to the circumference are equall the one to the other whereby it is to be vnderstoode that the centre of the Sphere is so euenly placed in his midst as that it hath like distance from all parts of the Circumference And forasmuch as the Sphere is an instrument demonstrating nnto us the nniuersall ingine of the world we must therfore vnderstand this Center to be this terrestrial Globe wherin we haue our being which compared to the celestial Globe or heauenly circumference doth beare propertie as the center to his circle which earthly globe by the diuine mightie workmanship of God doth admirably hang vpon his center being of equall distance from all partes of the circumference What are the distinctions of the Sphere THe Sphere is distinguished by ten circles whereof sixe are great circles and 4. are lesser circles whereof there are onely 8. described vpon the body of the Globe limiting the Zones and motion of the Planets as the Equinoctiall the Ecliptick the Equinoctiall Colure the Solsiticial Colure the Tropick of Cancer the Tropick of Capricorne the Artick Polar Circle and the Antartick Polar Circle The Horizon and Meridian are not described vpon the body of the Globe but artificially annexed thereunto for the better perfection of his vse Which are the great circles and which the lesser THe Equator the Ecliptick the 2. Colures the Meridian and the Horizon are great circles because they deuide the sphere into 2. equall parts The 2. Tropicks the 2. Polar circles are lesser circles because they deuide the Sphere into 2. vnequall partes What is the Equator or Equinoctiall THe Equinoctial is a great circle deuiding the Sphere into 2. equal parts leauing the one halfe towardes the North and the other halfe towards the South and is equally distant from both the Poles of the worlde 90. degrees placed euenly betweene them and described vpon them this line crosseth the Horizon in the true points of East and West and hath alwaies his owne halfe aboue the Horizon vnles it be vnder either of the Poles for there the Equator is in the Horizon it crosseth the Meridian at right Spherick angles and it also crosseth the Ecliptick line in the first minute of Aries and Libra diuiding the Ecliptick and Horizon and is also by them deuided into two equall partes This line is also deuided into 360. equall partes or degrees which are the degrees of Longitude beginning the account in the point of Aries reckoning twoards the East concluding the number 360. in the place where the first account began viz where the Equator doth intersecte the Ecliptick in the first minute of Aries vnder which Meridian S. Mihels one of the yles of the assores is to be placed in the geographicall description of the terrestriall Globe What is the vse of the Equator THe vse of the Equinoctiall is to know the declination of the Sunne Moone Starres wherby the latitude of places is giuen for that portion of the Meridian which is contained betweene the Equator and the Centre of the Sunne Moone or Starres is their declination also by the Equinoctiall is knowne the Longitude of places for a quarter of a great Circle being drawne from the Pole to the place whose Longitude is desired and so continued to the Equinoctiall that degree and minute in which the quarter circle dooth touch the Equator is the Longitude of the same place or if you bring any place that is described vpon the Globe whose Longitude you would know vnder the Meridian of the Globe that degree of the Equinoctiall that is then likewise directly vnder the Meridian is the Longitude desired When the sunne commeth vpon the Equator then the Daies and nights are of one length through the whole worlde and then the Sunne riseth vpon the true point of East and setteth vpon the true point of West and not els at any time This circle being fixed in the
center I. to his opposite angle h. drawe a right lyne by which lyne the quadrant o. d. n. is deuided into 2. equall partes in the point d. deuide the arke d. n. into 90. equall partes drawing from the center I. lines through euery of those diuisions touching in the line n. h. as by this figure appeareth then consider the length of your transuersary and take halfe thereof laying it vpon the lyne I. o. in the point S. from that point S. drawe a perallell to the lyne I. o. as is the lyne S. Y. and as that lyne doth intersect the diuisions of she halfe quadrant so shal be the degrees of the crosse staffe and note that the sides of the sqare mnst be as long as the staffe that is to be graduated Because the staffe should be of vnreasonable length to contain more then 60. degrees the rfore to keepe him in due forme for the ease of his vse and that the complement of 90. degrees should be contained vpon the staffe the other 30. are artificially proiected vpon the transitersary as by this demonstration appereth and in this sort consider the length of your staffe from that point S to the last intersection which endeth in 30. degrees lay downe the length vpon the line I. h. at the point v. from that point drawe a right line cutting the line I. h. to right angles as is the line v. a. being iust the length of halfe the transuersary then deuide the arke o. d. into 45. equall partes accompting from the point d. to te point o. then from the angle I. drawe right lines to the first 15. of those partes and as those lines doe cut the lyne v. a. so must the transuersary be graduated on both his partes whereunto banes being framed your staffe is finished to your vse THere is a staffe of another proiection which I finde by practise to be an instrument of very great ease and certaintie at the Sea the Sunne not being more then 45. degrees aboue the Horizon whose vse is contrary to the other before demonstrated for by this staffe the beame of the Sunne shadowing vpon the transuersary doth thereby giue the height most preciselye not regarding how to place the Center of the staffe to the eye for the correction of the parrallax of the fight and without looking vpon the Sun whose demonstration is thus Drawe 2. right lines cutting ech other at right angles as doe the lines d. v and d. s. vpon the angle d. describe a quarter circle as is the arke v. s. deuide that quadrant into 2. equall partes by the line d. n. cutting the quadrant in the point h. deuide the arke s. h. into 45. equall partes or degrees drawing lines from the center d. to euery of those diuisions then from the point I. being the third parte of the line d. s. vpon the center d. describe an ark of a circle as is the arke I. o. which is for the transuersary of this staffe and and the line d. s. is for the staffe then from the point o. where the vpper ende of the transursary toucheth the line d. n. drawe a perallell to the line d. s. as is the lyne o. y. and as that line doth cut the lines drawne from the center d. so must the staffe d. s. by graduated laying it vpon the line o. y. putting that parte of the staffe where the point I. toucheth vpon the point o. and then from the point I. lay downe the degrees as are the intersections vpon the line o. y. and so is the staffe graduated The transuersary at the point i. must haue an artificiall hole made for the staffe to runne in as other slaues haue also there must be a plate of brasse with a soccat to be set to the center of the staffe as is the figure a. in the midst whereof there must be a slitte through which the sight must be conueyed to the Horizon and this plate must receiue the shadowe of the transuersary and so the staffe is finished How is the vse of this staffe THe vse of this staffe is altogether contrary to the other for the center of this staffe where the brasse plate is fastned must be turned to that parte of the Horizon which is from the Sunne and with your backe toward the Sunne by the lower edge of the halfe crosse and through the slitte of the plate you must direct your sight onely to the Horizon and then mouing the transuersary as occasion requireth vntil the shadowe of your upper edge of the transuersary doe fall directly vpon the saide slitte or long hole and also at the same instant you see the Horizon through the slitte and then the transuersary sheweth the height desired FInding by practise the eccellencye of the Crosse staffe aboue all other instruments to satisfie the Seamans expectation and also knowing that those instruments whose degrees are of largest capacitie are instruments of most certaintie I haue very carefully laboured to search a good and demonstrable meane how a Crosse staffe might be proiected not onely to contayne large degrees but also to auoide the vncertaintie of the sight by disorderlye placing of the staffe to the eye which demonstration I haue found and haue had the instrument in practise as well vnder the Sunne as in our climates but because it hath a large demonstration with manifolde vses I heere omit to manifest the same purposing to write a perticular treatise therof notwithstanding his forme and vse by picture I haue thought good to expresse THis staffe is a yard long hauing 2. halfe crosses the one circular the other straight the longest not 14. inches yet this staffe doth contain the whole 90. degrees the shortest degree being an inch and 3 4 long wherin the minutes are perticularly and very sensibly laid downe by which staffe not regarding the parallar of your fight nor looking vpon the Sunne but onelye vpon the Horizon the Sunnes height is most precisely knowne as well and as easily in the Zenith as in any other part of the Heauen Then which instrument in my opinion the Seaman shall not finde any so good and in all Clymates of so great certaintie the inuention and demonstration whereof I may boldly chalenge to appertain vnto my selfe be as portion of the talent which God hath bestowed vpon me I hope without abuse or offence to any Of the Quadrant A Quadrant is the fourth part of a circle containing 90 degrees and representeth the distance betweene the Horizon and Zenith being an excellent instrument vpon the shore to perfourme any Astconomicall obseruations but for a Seaman it is to no purpose and although there may be very much written of the commodious and excellent vses of the Quadrant yet not being an apt instrument for Sea obseruations it shall be from my purpose to write further thereof and therefore the onelye laying downe of his forme may at this present suffise Of the Astrolabie AN Astrolabie is the representation of a great circle containing foure quadrants or 360. degrees which instrument hath been in long vse among Seamen and is an excellent instrument being rightly understoode and ordered but sith the vnlgare Astrolabie with his vse is to euery Seaman sufficiently knowne it should be vaine labour for me to lay downe his vse and demonstration therefore by his fourme it shall suffise to expresse him THere hath been great paines taken by many for the enlarging of the degrees contained in an Astrolabie among which there is a proiection to conueye the degrees of a quadrant into the concauery of a Astrolabie wherby those degrees shal be double to any other Astrolabie of the same quantitie so that the Sunne beame pearcing a hole made in the side of the Astrolabie is thereby caried to the degrees noted in the opposite concaue parte as by his forme may appere Also my selfe labouring in the same matter haue found a meane whereby an Ark of quadrant whose side is 10. foote may be conueied into an Astrolabie of 10. inches diameter whose dioptra shall cut his lymbe to right angles and shall perfourme the complement of 90 degrees as amply and as effectually as by the quadrant it may in any sort be done Whose demonstration together with the demonstration of my Staffe A purpose God willing at large to manifest But there can be no inuention that can establish the certaintie of the vse of either Quadrant or Astrolabie at the Sea for vnlesse it be in very smoothe water there can be no certaintie of any obseruation by those instruments whereby the Seaman may rest assured of the la. which he seeketh but the obseruations made by the crosse staffe are without all distrust of errour and therfore no instrument may compare with the excellencie of the crosse staffe for the Seamans vse FINIS Imprinted at London at the three Cranes in the Vintree by Thomas Dawson 1595.
that by no other meanes the like can be perfourmed in so great certaintie as that by no other meanes the like can be perfourmed it teacheth the nature of Angles and Triangles aswell Sphericall as plaine superficiall and solide Comensurations the effect of lynes straight circular and peradoxall the quantities and proportions of perallells the nature of Horizons with euery particular distinction of any alteration whatsoeuer that may in Nauigation be required to a most wonderfull precise certainty for there can nothing be required to a most wonderfull precise certainty for there can nothing be required that by this heauenly hermonye of numbers shall not bee most copiouslye manifested to the Seamans admiration and great coutent the orderlye practise whereof to the best of my poore capacitie I purpose to make knowne if I may perceiue my paines already taken to be receiued in good parte which I distrust not but all honest minded Seamen and Pylots of reputation will gratefully embrace onely in regarde of my friendly good will towards them for it is not in respect of my paines but of my loue that I would receiue fauourable curtesie How may the Poles height be knowne by the Globe THere are diuers waies to finde the Poles height by the Globe aswell from the Meridian as vpon the same but sith before I haue sufficiently taught how by the Sunnes Meridian altitude the Poles height may bee found I will therefore in this place speake no further thereof but for the other kindes it may be knowne as followeth How by the Sunnes rising or setting the Poles height may be knowne BY your Compasse of variation or some magneticall instrument obserue at the sunne rising vpon what degree of the Horizon the center toucheth according to the true horizontall position of the Magnet all variation dulye considered that being knowne searche in the tables of the Ephimerides for the Sunnes place in the Ecliptick at the time of your obseruation then bring that place or degree of the Ecliptick wherein you finde the Sunne to be to the Horizon and moue that Meridian of the Globe as occasion requireth vntill that obserued degree of the Horizon and the Sunnes place in the Ecliptick doe iustly touch together for then is the Pole in his due Eleuation as by the intersection of the Horizon and Meridian may appeare in like sorte you may finde the Poles altitude by any knowne fixed Starre in the Horizon To finde the poles height by the Sunne vpon any point of the Compasse BY the Compasse of variation rectified to the true horizontall position obserue the Sunne vntill he come to any point thereof at your pleasure and at the same instant take the sunnes height from the Horizon then bring the Quarta altitudo to that point of the Compasse vpon the Horizon of the Globe where you obserued the Sunne to be there holding the Quarta altitudo stedye moue the Globe vntill you bring the degree of the Ecliptitk wherein the Sunne is at the time of your obseruation vnto the edge of the Quarta altitudo if it fall vpon that degree of altitude as was the Sunnes obserued height then doth the Pole stand to his true Eleuation but if it agree not you must eleuate or depresse the Pole as occasion requireth rectifying the Zenith answerable thereunto And againe make triall as at the first bringing the place of the Sunne to the Quarta altitudo and setting the same vpon the obserued point of the Compasse vntill it agree in all respects with your obseruation and then the Meridian sheweth in his intersection with the Horizon the Eleuation of the Pole from the Horizon To finde the Poles height by any giuen Azumuth by the Sunne being aboue the Horizon BY your magneticall instrument or Compas of variation obserue the azumuth of the Sunne at any time in the forenoone or afternoone the neerer the Sun is to the Horizon the better shal be your obseruation and at the same instant take the height of the Sun from the Horizon keep these 2. numbers in memory and note that the Azumuth be obserued according to the true position of the Horizon by hauing good regarde to the variation of the compas then bring the Quarta altitudo to the place of the Sun in the Ecliptick and set that degree of the Sunnes place in the Ecliptick vpon the obserued degree of altitude by the graduation of the Quarta altitudo and if the end thereof at the same instant doe fall right vpon the obserued degree of Azumuth then is the Pole in his due Eleuation if not then raise or lay the Pole as occasion requireth alwaies regarding that you place the Zenith answerable to the Poles altitude and then againe bring the Sunnes place to his altitude vpon the Quarta altitudo and looke againe whether the end thereof doe touch the obserued degree of Azumuth vpon the Horizon if not you must prosecute this order vntill at one instant the place of the Sunne be vpon his true almicanter by the edge of the Quarta altitudo and that the end of the quarta altitudo doe also touch the obserued degree of Azumuth vpon the Horizon for then is the Pole in his true eleuation as by the Meridian and Horizon will appeare To finde the Poles height by the Sunne by any two giuen azumuths and altitudes not regarding the true horizontal position or nedles variations BEcause there may great errors be committed in the former obseruations vnlesse the Compasse be perfectly well rectified so as it may respect the true partes or distinctions of the Horizon it is not amisse to enforme you how without regarde of variation the Poles height may be found Therefore by your Magneticall instrument or Compasse of variation obserue the Sunnes azumuth without regarde of the true horizontall position and at the same instant obserue also his altitude from the Horizon keepe those two numbers in memory then after the Sunne hath moued a point or two points of the Compasse more lesse at your discretion obserue again his azumuth and altitude as the first then consider the arke of the Horizon through which the Sunne hath moued betweene these two obseruations for by the 2. obseruations of the Sunnes altitude and by the degrees of Azumuth through which the Sunne hath moued the Poles height is thus knowne First set the Globe to the eleuation of the place wherein you are as neere as you can gesse and bring the Zenith to the like latitude from the Equator as the Poles eleuation is from the Horizon then bring the Quarta altitudo to the place of the Sunne vpon the Ecliptick for the time of your obseruation there place the Sunne vpon the first obserued altitude by the degrees of the quarta altitudo and note the degree of the Horizon which the Quarta altitudo then toucheth this done bring the Sunnes place to the second obserued altitude by mouing the Quarta altitudo and the Globe vntill the degree of the Sunnes place in