ought thus to be Corrected that the further you advance towards either Pole their Motion is swisaer and the further they are carryed towards the Equator their Motion is retarded c. The cause wherefore these Instruments may move swifter nigh the Poles then near the Equinoctial cannot proceed from the Oval Form of the Earth as some think the cause of their swifter Motion nigher the Poles in my Opinion is cold Weather and Frosts I believe that in England in Frosty Weather our Clocks move swifter then in Summer for in Frosty Weather Springs may contract a little and grow stiffer consequently have more force to make a swifter Motion and in Hot Weather they may extend and be a little more pliable therefore the Motion may not prove altogether so swift as in Frosts There are other Causes also that may hinder the regularity of their Motions see Ph. tr N. 47. p. 951. and 976. Some may desire to know my Reasons for Springs contracting in Frosty Weather take a piece of Cold Iron or Steel one or two Foot long about ½ or ¾ of an Inch Square heat it red hot keep heating and well Hammering it hot an Hour or two when you have done measure its length exactly before it be Cold lay it aside in the Air where the Frost may ting it a Winters Night and if you measure it in the Morning you will find it considerably shorter Experience teacheth that there are few Watches that have a regular Motion for it seems impossible that the Springs in all their parts should be so exactly Hammered as to draw always equally and by what I can learn from Watch-makers a ballsnce Watch that requireth winding up every 24 Hours keepeth time more exact than one that goeth a Week before it need winding up About Seven Years ago my curiosity carried me to Gresham Colledge when the Assembly was seated the President told me they had caused several Experiments to be made with these Instruments and thought fitting not to commend them for Common Practice at Sea for fear that the Errors that might happen in their use should prove greater then the Errors in the common Practice of Navigation but now let us handle our Subject a little more closely and suppose that three or four of the said Watches being good work well made and carryed to Sea in one Ship under the Command of Ingenious Men may prove very useful towards the keeping a true Account of a Ships way on the Sea not for finding the Longitude from our first Meridian but to help to find your difference of Longitude every 24 Hours or every two or three Days as often as you observe the Latitude provided they be not too much tampered with keeping the Indexes always moving but never move them with your Fingers except extraordinary occasion require it desire not that they should always shew you the true time of the Day you may if you please keep one for that purpose besides but learn by continuance of time to find the Motion of each Watch in a Year or in a Month or Day and Hour and having the true Theory of each Watches Motion with their equalities and inequalities you may by Calculation find at what time of the Day or Night the Indexes of each Watch for I suppose they may not all move just alike will point to such or such an Hour Degree or Minute in any Meridian keep them from being hurt by any Violent Motion as falls or knocking near them keep them from Winds from too moist Airs and stinking Fumes such as are when Salt Water Casks are emptied on Deck or in a Ships Well where Men have been Stifled keep them very clean from Salt Water or any Rust or Filth let there be a place in the Ship properly appointed for them to hang in Equilibrio I find in the Ph. trans N. 47. p. 937. Instructions concerning the use of Pendulum Watches for finding the Longitude at Sea together with a Method of a Journal for such Watches c. Brother Tar if these Automata's could speak as the Welsh Man thought they would tell thee they hate Novices and if thou art so they may not bite thee but they may happen to break thy Head or do the some other Mischief or in a more plain meaning I dare not approve of their use for the difference of Longitudes except only in an East or West Course or in Case of some unknown Currents use thy discretion The Watches that are now esteemed most useful have a Pendulum Spring to regulate the Motion of the ballance those that desire to know more of these Automata's and Mechanical Motions may read Bishop Wilkin's his Mathematical Magick Water-Glasses 24 Hour Sand-Glasses and such like Self-movers are of no use in this Science though I have mentioned them for Vulgar Satisfaction only but of what use Mercurii or Quick-silver may prove in keeping time true by the regularity of its Motion in Glasses I cannot yet inform you CHAP. V. Of or concerning Longitude by Magnetick Variation THE Variation of the Compass by which I mean the deflection of the Needle from the true Meridian is of that great concernment in the Art of Navigation that the neglect thereof does little less then render useless one of the noblest Inventions Mankind ever attain'd to I desire the Ingenious Seamen that the Knowledge of Magnetick Variation may be always in his great Esteem for without it Navigation cannot be perfect It is my Opinion that many Ships have been put by their design'd Ports and more Ships lost for want of knowing the Variation then hath been lost for want of the Longitude how many Ships in Sailing from the South-fâ—re-land to the Maese hath been put to the Northward of the Maese for want of minding the Variation for the like cause some Ships have missed the Island Barbadoes and met with other dismal Accidents Mr. Edward Wright an able Mathematician in his time in the latter end of his Correction of Errors in Navigation did write concerning the Haven finding Art by the Variation of the Marriners Compass but alas he knew nothing of the Variation of the Variation or as I call it of the Increase and Decrease of the Variation in the same place therefore that part of his Book proved very Erroneous by supposing that the Variation at any place never Altered now we know better There are many of Opinion at this present time that the Longitude may be found by the Variation of the Magnetical Horizontal Needle I doubt the possibility thereof from our first Meridian for many parts of the World will afford us no Practicable proportions for the difference of Variation between them according to their distance in Longitude nor can the quantity of the Earths Atraction be easily determin'd in all places besides the quantity of each Polar Atraction for there are four at least two of them lie in the bowels of the Earth and not in the Air as Mr. Pond saith it is
Comp. Altitude if the Quadrant be revers'd on the other side and those that please may also have either Pendulum or Indexes from the Center of the Quadrant to point either to the Degrees of Altitude or Comp. Altitude It is easily managed in blowing Weather at Sea or Ashoar and the Price not above 20 Shilling I hope for a Common one I am a little Proud of the Invention however I forbear to Applaud it too much and to Print the Figure of it till I have made further Experience of it CHAP. IV. Of Automata's or Horological Self-Movers MR. Blundeville from Gemma Frisius writes of a ready way as he calls it to find out the Longitude of any place by some true Horology or Watch to that purpose Mr. Rook writes viz Ad momenta temporis accuratissime notanda quod in hujusmodi Observationibus est palmarium perutile erit Oscillatorium ab Ingeniosissimo candidissimo Hugenio feliciter excogitatum There have been some Experiments made at Sea for finding the Longitude by Pendulum Watches as you may read in the Ph. trans N. 1. pa. 13. I know several Seamen will buy this Book that are not able to furnish themselves with a Sett of Ph. Transactions therefore it may be convenient to Insert the following Narrative A Narrative concerning the Success of Pendulum Watches at Sea for the Longitudes The Relation lately made by Major Holmes concerning the Success of Pendulum Watches at Sea two whereof were Committed to his Care and Observation in his last Voyage to Guiney by some of our Eminent Virtuosi and grand Promoters of Navigation is as followeth The said Major having left that Coast and being come to the Isle of St. Thomas under the Line accompanied with four Vessels having there adjusted his Watches put to Sea sailed Westward seven or eight Hundred Leagues without changing his Course after which finding the Wind favourable he Steered towards the Coast of Africk North North East but having Sailed upon that Line a matter of two or three Hundred Leagues the Masters of the other Ships under his Conduct apprehending that they should want Water before they could reach that Coast did propose to him to steer their Course to Barbadoes to supply themselves with Water there Whereupon the said Major having called the Master and Pilots together and caused them to produce their Journals and Calculations it was found that those Pilots did differ in their Reckonings from that of the Major one of them Eighty Leagues another about an Hundred and the third more but the Major Judging by his Pendulum Watches that they were only some thirty Leagues distant from the Isle of Fuego which is one of the Isles of Cape Verd and that they might reach it next Day and having a great Confidence in the said Watches resolv'd to Steer their Course thither and having given Order so to do they got the very next Day about Noon a sight of the Isle of Fuego finding themselves to Sail directly upon it and so arrived at it that Afternoon as he had said These Watches having been first invented by the Excellent Monsieur Christian Hugens of Zuilchem and fitted to go to Sea by the Right Honourable the Earl of Kincardin both Fellows of the Royal Society are now brought by a New Addition to a wonderful Perfection the said Monsieur Hugens having been informed of the success of the Experiment made by Major Holmes wrote to a Friend at Paris a Letter to this effect Major Holmes at his return hath made a Relation concerning the usefulness of Pendulums which surpasseth my Expectation I did not imagine that the Watches of this first Structure would succeed so well and I had reserv'd my main Hopes for the New ones but seeing those have already serv'd so successfully and that the other are yet more Just and Exact I have the more Reason to believe that the Invention of Longitudes will come to its Perfection In the mean time I shall tell you that the States did receive my Proposition when I desired of them a Patent for these New Watches and the recompence set apart for the Invention in case of Success and that without any difficulty they have granted my Request commanding me to bring one of these Watches into their Assembly to explicate unto them the Invention and Application thereof to the Longitudes which I have done to their Contentment I have this Week Published that these Watches shall be exposed to Sale together with an Information necessary to use them at Sea and thus I have broken the Ice The same Objection that hath been made in your Parts against the Exactness of these Pendulums hath also been made here to Wit that though they should agree together they might fail both of them by Reason that the Air at one time might be thicker then at another But I have answered that this difference if there be any will not at all be perceiv'd in the Penduls seeing that the continual Observations made in Winter from Day to Day until Summer have shewed me that they have always agreed with the Sun I doubt the Truth As to the Printing the Figure of my New Watch I shall defer that yet a while but it shall in time appear with all the Demonstrations thereof together with a Treatise of Pendulums written by me some Days since which is of a very subtle Speculation I have read of a Glass Globe that a King of Persia had in which he could see all the Coelestial Motions of the same kind with our Clocks and Watches though perhaps more Elaborate and Subtle was that Sphere Invented by Archimides which did represent the Heavenly Motions the Diurnal and Anual Course of the Sun the Changes and Aspects of the Moon c. This is frequently Celebrated in the writings of the Antients Jupiter in parvo cum cerneret aethera Vitro Risit ad Superos talia dict a dedit Huccine mortalis progressa potentia curae Jam meus in fragili luditur orbe labor Jurapoli rerumque fidem legesque Deorum Ecce Syracusius transtulit arte Senex Inclusus Vaaiis famulatur Spiritus astris Et Vivum certts motibus urget opus Percurrit proprium mentitus Signifer annum Et simulata novo Cynthia mense redit Jamque suum Volvens audax instria mundum Gaudet humanâ sidera mente regit Quid falso insontem tonitru Salmonea miror Aemula naturae parva reperta manus I have heard from Dutch Seamen several Stories of a wonderful Sphere or Clock at Strasburgh in Germany which as they say hath or had a regular and perpetual Motion and shewed the Coelestial Motions c. Mr. Newton in his Idea of Geography and Navigation pag. 90 and 91. writeth concerning Automata's or unerring Clocks and saith that the nearer you advance within the Artick or Antartick Circles towards either of the Poles the Motion is so much slower then at London but in his Preface to the Reader saith This Paragraph
Paw or only my labour for my Pains future Ages may be more Competent Judges but my Mind will be easier when this Book is Published because therein I have done my Duty and eased the burden of my Brain If in this Treatise have seemed to reflect on any Person it is my Dialect I desire their Excuse I Envy no Men Envy and Ingratitude is most natural to some whose Duty it is to understand these things and their Capacities cannot reach them If any Person is minded or can or will undertake to Correct or Amend what I have writ I wish them good success I desire them to own what they borrow and not to reflect without just cause it is difficult to write such a Book as this is I think it is the first of this nature without Faults it is likely I my self may find some in a Years time that if I were to write over again I could amend I dare affirm that this Book contains some estimable Expressions and Methods fit for Seamens Knowledge and Practise and such as have not been formerly Published there are some Persons in England whose Duty it is being paid for it to improve Navigation and Astronomy and from whom much is expected and little or nothing of purpose appears It is my Opinion that the appearances of Comets may be found by Calculations if any Person capable think it worthy his trouble Concerning this Book the common Vogue will be viz. but will it do is it the Longitude I say Yes it is the Longitude begun and will do with Industry and Encouragement else not for it is contrary to Seamens Vulgar sayings that when the Longitude is found then there will be abundance of Artists Navigation will be so easie No no Navigation will not be so easie at present but much more certain and true The Learned Bacon said the Longitude was worth a Kingdom to a Wise Man but before I conclude to return to my Instrument the Description I have given thereof availeth little without my further assistance till then the Reader if he pleaseth may compare to Foxes staring on Bunches of ripe Gripes and cannot get at them then they are too sowr for them for so my Dream intimateth when I was among a Crowd of Foxes aw'd at my Presence and after I had looked on them they vanished and left me other Objects The most Ingenious of Humane Inventions is far less facile then the ordinary performances of Truth and Nature I love my King the Church of England and my Country and I thank my God I know my self capable and worthy to serve them though too much debased for want of Friends in Court If this meet with its deserved Encouragement the rest may follow in good time but I must make haste and conclude my attendance and dependance being required in our Navy Royal which Duty I dare not neglect for fear of being Excommunicated or which is as bad Excluded from Preferment Quamvis bene merenti Nil tam difficile est quod non Solertia Vincat Te Deum Laudamus FINIS ERRATA PAge 2. l. 9. r. plane p. 17. l. 8. r. Zulichem p. 20. l. 6. r. cert is l. 9. r. Industria l. 19. r. an Idea p. 28. l. 3. r. Bond. p. 29 l. 5. r. the encrease p. 30. l. 3. for me r. one l. 17. for by r. with p. 31. l. 22. r. though l. 23. r. suppose p. 36. l. 12. add when Northerly p. 37. l. 10. r. preceding p. 59. l. 27. for P. M. r. A. M. add Schema Solis ad Exitum Mercurii St. Hellene Anno 1677. Octob. 28. 2 h. 4 P. M. p. 55. l. 10. r will be p. 63. l. 27. r. with p. 70 l. 2. r. Sun and Stars
Idea Longitudinis Being a brief DEFINITION Of the best known AXIOMS For finding the Longitude OR A more Rational Discovery thereof than hath been heretofore Published By Edward Harrison Lt. LONDON Printed for the Author and sold by Mr. Sellers at the Hermitage R. Mount at the Postern on Tower-Hill and P. Lea at the Atlas and Hercules in Cheap-side at the Corner of Friday-street 1696. To the Right Honourable the Commissioners for Executing the Office of Lord High Admiral of England c My Lords IT is a saying in the Navy He that knows not how to obey Command is not worthy to bear Command and another saying I have often heard in the Navy It is hard for an Officer to know when he goes too fast or too slow that is whether he is too severe in the Execution of his Duty or too dull or slow in which Cases it is somtimes difficult to please our Superiours because of their different Humours As it is the Duty of a Subject to be True and Loyal to his Prince so it is the Duty of Servants to be Faithful Humble and Submissive to their Masters I thought it my Duty my Lords Humbly to present you with this small Treatise not only as a Servant but that whereas some part of it may happen to fall under your Construction more particularly the Chapter concerning Magnetick Variation which I Humbly Commend to your Joynt Care and Consideration for the Improvement and Encouragement of Navigation and Amendment of Faults in the Navy if I may presume to say there is any Faults there an Elegant Stile cannot Reasonably be expected from Sea breeding I am not willing to seem tedious if in my Discourse in this Book you find some small Faults I hope your Wisdom will be pleased to Pardon and Excuse them I am my Lords Your most Humble and Obedient Servant EDWARD HARRISON PREFACE To the Reader AFter Columbus returned from his Discovery of the Land now called America he happened into Company with some Spaniards who had the Vanity to tell him that he had done nothing but what they could do as well as he Yes Gentlemen said he now I have shown you the way he called for a Hens Egg and desired them to make it stand on one end without leaning on a smooth and flat Table they all tryed but none of them could make it so to stand he tryed after them and made it stand c. so could they also when he had shewed them the way I doubt not but in a short time there will be many Pretenders to the Longitude and to understand it better then I be pleased to remember that I shewed the way or can if I please Mistake me not think not that I am designed in this small Treatise to Teach the whole Art of Longitude Art Mathematick is very Copious part of which is Art Longitude Ingenious and Compendious requiring much larger Volumes then this is I say I can if I will God willing shew you the true Principles the right Radix and Basis whereon this Fabrick may be built one Man might carry a Stone to St. Pauls-Church in London and lay it on the Foundation give Directions for Building the same but he alone could never have perfected as now it almost is that Stately and Glorious Edifice I may begin my work to Day but what Encouragement I may meet with in carrying it on I know not or if it may please God that I may live to see this Art brought to such Perfection as to be fit for Seamens Practise some Years ago I presented a few Lines concerning this Art to a Nobleman or Person of Quality which Lines he little understood and less regarded which one of my Friends understanding well compared to casting Pearl before 〈◊〉 I have been informed of one who pretended to find the Longitude and requiring a Gratuity was sent to Mr. to have his Approbation I think they might as well a sent him to a been Rob'd I Discoursed this Art with some Fellows of the R. S. whom I found too much aiming at their peculiar Advantage therefore I resolved to appear on the Publick Stage in Print Nevertheless the Description is a little Veiled though it is what I thought convenient to Publish As for my Stile I understand not how to Express my Sentences in Topical Syllogisms or Sophistical Rhetorick if you meet with a plain Method downright Reasoning and matter of Purpose it is what I aim at I know my Method differs much from other Writers I write the Truth to the best of my Knowledge and value not Carpels and in spite of Envie I presume to declare That I believe there are but few Marriners in England that understand how to keep an Account of a Ships way on the Sea as well as I have done or may do and if I know more than others it is by Divine Authority by Industry and Experience by an Inborn Idea and Instinct in Nature it was ordained for me by God Almighty from my Mother 's Womb. My Knowledge in the Mathematicks is but little therefore I dare not compare my self to the Learned Dr. Wallis and many others who have writ large Vollumes of Geometry Algebra and Cubick Aequations Brother Tar there have been in England many Pretenders to the Longitude and some have writ concerning it If thou hast this small Treatise by thee thou mayst find more in it fit for thy purpose and Perusal then in any former Book of this Nature there have been many Persons when they have attained some Knowledge in Cosmography and Accidentally thinking on some of the ways contained in this Book believe they have found the Longitude and trouble their Brains to little purpose Therefore this Book is very convenient to ease their Brains from such Burdens because it contains all the most noted ways and Fundamental Principles whereby the most Learned of this Age have endeavoured to find the Longitude and whereas you may think that this Book doth not wholly inform you of any Practical Method for finding the Longitude yet it is hoped that the said Science will become Practicable in few Years and already is to the Ingenious but not to the Ignorant Till then I advise you duly to consider the Fifth Chapter in this Book concerning Magnetick Variation which if you understand well you have gained a Science that for Seamen's Practice is little Inferiour to the Longitude How the World may esteem of this Book I cannot tell but I hope it will be as a Safeguard or means to save many a Ship from being Wreckt Ashoar and save many a Seamans Life Some Blockheads are apt to say the Longitude cannot be found no no it cannot Accidentally as a Sow does a T d in the Streets but by Care Diligence and Industry it may be found without which it cannot be understood Though we have been at the Dutch for Hydrographical and Geographical Draughts let us not go the to French to learn their Vse But why
Sun will be this Year 1696 March the 9th Day 3 h. 21′ 20″ P. M. it cuts the Equinoctial in two opposite points in the beginning of ♈ and ♎ it s greatest Obliquity from the Equinoctial in these our Days is 23° 29′ it ends where it begins The Theory of the Planets and Stellary Motions are accounted on the Arches of this great Circle because in their Revolution they respect the Ecliptick Poles as their Center and the Sun also and not the Equinoctial Poles except the Earth only in her Diurnal Motion Sydereal Longitude is accouted from the first Star of Aries on the Ecliptick also it begins where the Ecliptick is cut by a great Circle that passeth through the 1 ⚹ of ♈ and the Ecliptick Poles the difr Long. between the 1 point of ♈ and the 1 ⚹ of ♈ is this Year the 9th Day of March 28° 52′ 9″ which difr is the praecession of the Aequinox CHAP. III. A Definition of Time and Equation of Natural Days Atque in se sua per Vestigia Volvitur annus Virg. OLD Style or Julian Year is our English Account contains 365 d. 6 h. of Astronomical years there are divers kinds but I shall only mention two the Solar or mean Tropical Year is 365 d 5 h 49′ 1″ the Sidereal Year is 365 d 6 h 8′ 30″ the natural Day in most parts of Europe is divided into 24 h the Suns or Earth mean motion in the Ecliptick in 24 h is 59′ 8″ the longest natural Day is 361° 1′ 15″ the shortest is 360° 57′ 10″ the difr in one Day is but little but in a Months time is considerable each difference adjusted is called Aequation of natural Days the shortest natural Day will be this Year the 18th Day of June when the Sun is in 7° of Cancer or thereabouts for then the ☉ and ♠are in their Apogaeon or Auge Apoge Aphelion Absis have all one Signification in Astronomy the 17th Day of December they will be in their Perigaeon or Perihelion or nearest distance this Inequality of Natural Days seems to me to be the cause why our Summer half Year is now in our times almost Eight Days longer than our Winter half Year as also it is the cause of the Impossibility of any Clock or Watch. though they move very regularly always to shew the true time of the Day Mr. Parker in his Almanack teacheth us when to Add or Substract the Time aequated to or from the mean time to accord with the Apparent Time In most Books of Astronomy there are Tables for our purpose Vide Astr Ang. lib. 3. p. 84 and 85. Canones Aequationum Dierum Naturalium Canones Equationis dierum Naturalium duabus praecedentibus Composit nostro huic Seculo citra errorem sensibilom subservien And Ph. trans N. 214. pa. 248. Tabulas aequationis Dierum cum Solis loco adeund c. All which Tables you must well understand before you can attain to Practical Longitude except Magnetick Variation it may seem necessary here that I show how to find the time of the Day or Night by Observation there are many ways Published in several Mathematick Books but I shall reduce them to one for I think Mr. Molineux's Sciotericum Telescopium will do us little or no service right way and commend you to Colson's Callender see his Astronomical Problems Prob. 9 and 10. instead of Hours and Minutes work by Degrees and Minutes and whereas I said that 360° 59′ 8″ was equal to 24 Hours you may work only by 360° for when you observe in the Night it is supposed you take the Sun 's right Ascension exactly true at that very Time and Place of your Observation allowing for the Suns Diurnal difference of R. A. also allowing for your difference of Longitude from our first Meridian else all your trouble may prove good for nothing As yet I have never seen any Vniversal Ring-Dial or other Sun-Dial that shewed the true Time of the Day except about Noon our Dialists thinking the Suns Refraction not worth their notice but those that pretend to find the Longitude must duly consider Refractions and Parallaxes It seemeth not proper in this Chapter but I think it convenient to add something concerning Instruments common Practice and Experience teacheth that a Forestaff is a useful Instrument both for backward and forward Observations I have also had Experience of it my self and for forward Observations I like it not and for backward Davis's Quadrant is better for in its use there happen several Errors hard to Correct as the Excentricitie of the Eye and end of the Staff a true Horrizon cannot be found by it in the Night but only guessed at besides the height of the Eye above the Water and the great difficulty of seeing two Objects at once that is the Sun or Star and the Horizon for if the Star be high whilst you are a looking for it at one end of the Vane you loose the Horrizon at the other end of the Vane or a looking for one you lose the sight of the other therefore to avoid such Errors for taking Altitudes in the Night I commend you to a Quadrant with a Pendulum from its Center see the Figure of it in Moxon's Tutor to Astr Prob. 13. p. 48. This Instrument may seem very troublesome at first for want of Use and Custom use a weight of at least two or three Pound with a small Wire or Catts-Gut for taking small Heights or Distances you may use an Almicanter Staff for ordinary Uses but if your Observation requires greater exactness Vide Tichonis Brahe Astronomiae Instauratae Mechanica or John Heuelii Machinae Caelestis pars prior c. instead of Instruments that resolve Mathematical Questions as Sectors upon Quadrants Analemmas c. Stick close to the Doctrine of plain and Spherical Triangles and to Logarithmical Tables but on better Consideration the Quadrant in Moxons Tutor to Astr aforesaid is not very fitting for Sea Uses without some Alterations therefore I have contriv'd a Quadrant something like the former with weights that Commands it so that it will always continue in the same position you direct it to It may be contriv'd to hang like a pair of Scales or Ballance having an Axis in its Center of Gravity on which it is equally poised without the weight to turn round having a Swifle and Ring to hang or hook to any convenient place in the Ship or those that please may have a Stand purposely for it there must be a small Line or slippery Cord or Cords fastened somewhat slack from Corner to Corner on the Circumference of the Quadrant on which Cords hang the weights of 20 or 30 Pound or more or less as you find most convenient for the Substance or Radius of the Quadrant from the said weights or rather from that part that slides on the Cords may come two Indexes one to point to the Altitude on one side of the Quadrant and the other to the
want of understanding the Longitude or the Variation I say I believe such Accidents may have happened but very rarely for most Ships have been lost by many other Accidents as Storms or the like Example our great Loss by Storms lately in the Streights of Giblaterra and the late Hurricane at Barbadoes in which Ships I believe were some as able Seamen and Experienc'd Artists in Navigation as the World did afford The finding the Lattitude by the Inclination of the Inclinatory Needle is at present thrown out of Doors as of little or no account as well it may if we will be such Novices as to confine the Inclinatory Needle in a narrow Cycloid as commonly it is by which means it becomes useless at Sea and not manageable therefore it ought to be contriv'd to hang in Equilibiro so that it may have a free Circular Motion any way on its Center of Gravity and then it will much easier shew the Inclination and Variation also if need require it and if the Theory of its Inclination were known all the World over we might also find the Latitude by it The following words were forgot at the end of the 4th Chapter viz. Our Countryman Mr. Watson who made an Ingenious Clock for our late Queen which sheweth the Coelestial Motions and Monsieur Didiers Coelestial Globe shewing the apparent Motions from East to West and from West to East of the Sun Moon and fixed Stars see Ph. Tr N. 136. p. 895. I think a Globe may be projected and made like the later that may shew Latitude Longitude Sun or Stars Horary distance from the Meridian and Variation c. But it would be too costly for ordinary Uses and nothing hinder its Truth or equal Motion more then the different Temperatures of Air and Weather though we may attribute something to the goodness of the Springs and Oyls CHAP. VI. Longitude by the Moon 's Motion by her Conjunctions or Eclipses and Apulses to fixed Stars of her Illumination by the Sun THE Question is yet unresolv'd which time ought to be called the true Conjunction or Opposition whether when the Sun and Moon are in one Line perpendicular to the Ecliptick or perpendicular to the Orb of the Moon or when they are equally distant from the Nodes Mr. Shakerley's Tabulae Britannicae precept 15. pag. 67. Let us Correct this Learned Mistake and agree with most Astronomers that it is always New Moon when the Sun and Moon have both one Longitude from the first point of Aries The mean motion of the Moon in one Natural Day is 13° 10′ 35″ her mean motion from the Sun in one Day is 12° 11′ 27″ but in her motions she hath many inequalities for which purpose Tables of her motions may be required I refer you to Astronomia Carolina Astronomia Harmonicae Astronomica Instaurata Tabulae Britannicae Astronomia Anglicana Cursus Mathematicus Rudolphus's Tables not forgetting Mr. Newton's and Sir Jonas Moors Tables yet amongst them all the Theory of the Moon 's motion remains In perfect and not easie to Calculate many able Mathematicians have writ concerning finding the Longitude by the Moons motion Mr. Norwood writ somthing but it was never Published I have been informed his Method was by the Moons motion concerning which he writ a large Tract of her motion and contriv'd an Instrument for taking her distance from fixed Stars Mr. Streets way is unknown to me but we suppose his way by the Moons motion also by his contriving an Instrument for taking Angles by Reflection I have seen the Instrument but he could not bring it to perfection which I gather from those who have had some Cognizance thereof see his Appendix to Astr Car. I have seen a Pamphlet writ by John Herne wherein his Method for finding the Moons Southing is very Erroneous as also almost all the rest of it you may believe the like of Theakers Book and Wooden Tools these I mention that Seamen be not deluded by such Foolish Tools and Pamphlets There is a late Author saith viz. find the true Moment of time in which the Moon comes to the Meridian and thereby the Longitude of any place may be found after this manner c. in answer thereto Sir I assure you the Longitude is not to be found after your manner nor by any of your Methods till better Taught I presume I know better then your self what belongs to Meridian Altitudes especially at Sea and if you please to learn from me that when the Sun hath South Declination 20° or 23° and in North Lattitude 50 or 60° it is too difficult a matter to find Noon or Mid-day by any usual Sea Instrument within two or three Minutes of time our observers commonly begin to observe a little before the Bell strikes Seven and in the aforesaid Latitudes it is common to observe till a quarter of an Hour past 12 a Clock before they can perceive the Sun falling as they call it but when the Sun is within twelve Degrees of your Zenith then be very quick to attend or else you may lose your Observation the like of the Moon or any Star any other time of the Day is more easie and true to be found at Sea then Noon An Old Experienc'd Navigator pretended to know how to South the Moon by the North Star on the Meridian I askt him how often he hath seen the Moon and North Star on his Meridian both at one time as also how we must do in South Latitude to North the Moon and if it were possible to find the time of Moons Southing or Northing it is to no purpose to expect the Longitude thereby considering we can have but one Observation in 24 Hours besides the Error of accounting her motion in our first Meridian there is no Calculation as yet so exact in any Almanack or Ephemeris that tells us the true time of the Moons Southing in any Meridian without Error Mr. Newton writes that from the Error of one Minute of an Hour in the Moons motion from the Sun ariseth an Error of 7° 12′ in the Longitude of the place propounded and in the motion of the same Moon from any fixed Star riseth an Error of 6° 48′ and moreover he saith it is evident that if the Errors of both places be not of the same Denomination and lesser then one Minute of time the Error of Longitude cannot be less then then 13° c. The Moons mean motion being but 13° 10′ 35″ is little in proportion to 360° therefore the two Objections are very considerable however as I am a Favourer of the Longitude by the Moons motion I will undertake to solve one Objection and propose how the other may be solved then as to the first I answer that I know how to find the true time when we can have Reasonable Observations of the Day or Night to one or two seconds of time and if I Err 4 or 5 seconds it matters not others may observe as true as I if
Phlip The setting and well-manageing a Telescope is of great Consequence CHAP. VIII Conclusion OMnia probate quod bonum est tenete That which I have written in this Book I designed for the publick good of Mankind in which I hope I have not offended God If any Arts or Sciences Commerce or Trade be Good and Just in their kind then what I have writ concerning Longitude is Good and Just in its kind that is if it be not Abused Though there was an Officer in the Navy as I was informed who Cursed and Damn'd the Man that should discover the Longitude thou Old Inveterate Rusty Musty Filthy Cankered Carnal Devil for Cursing down upon thy Marrow-bones if thou hast any and ask God Almighty forgiveness for thy Sins know that it it is not in thy Power to Damn any Man but thy self God who suffered the Earth to be Inhabited by Angels for an infinite number of Ages before he Created Adam and then expelling them hence for their Wickedness and turning them to Devils gave this Globe for a dwelling place to Men grant that the enormous Crimes of Mortals may not provoke him to Exterminate our Humane Race and restore the Devils to their Antient Habitations Tur. Spy Vol. 3. Pag. 359. But as for that one Man I doubt there is more such aforesaid I believe He did not speak it then out of Ill-will to me but to some other Person or rather rashly or unawares I believe his meaning at that time was that this ungrateful World did not deserve so great a Blessing or so worthy a Science I am thinking what my Country will be pleased to say of me if they call me Astrologer I give very little Credit to Judicial Astrology nor do I profess any such deceitful lying Arts if Maggoty it s an Expression for Fools and their bolt is soon shot if Star-Gazer I answer a Star-Gazer is better then a Booby some may Envy me some Laugh and Scoff at me a common Method to solve their own Ignorance others Mock and Ridicule me so our Predecessors did at Columbus when he came hither to offer them the discovery of the World and ought not they to have been Recorded for F s as some say the Pope was that Anathematiz'd the Bishop of Scrasburg for writing of Antipodes But now I think on 't I have a reserve which they are not like to know yet a while As I have heard say the Venetians have offered Rewards the States of Holland as I was informed some Years ago took this Science so much into their Consideration that they offered Ten Thousand Pounds to any Man that was capable to discover it Thomas Axe an Englishman left a Legacy of One Thousand Pound never to be paid I think to any Person that should discover the Longitude within the space of Ten Years after his Decease if his Wife and Child died Childless in that time besides it is to be approved of by the four Professors of Geometry and Astronomy in Oxford and Cambridge for the time being and at least twenty Experienc'd Masters of Ships that shall have made several Experiments thereof in long Voyages Affidavits are to be made before the Twelve Judges of England c. He dyed in the year 1691 and I think took care enough that the said one Thousand Pound should be Irrecoverable indeed I have little better Opinion of either the Venetian or Dutch Gratuities States may be mistaken in their Policies God Almighty never ordained that this Science should be well known to the World by fraudulent means but if their designs be real as you may suppose where is the Encouragement I know not how to recover my Cost and Charges though I have laid and shall the rest by and by most of the ground work at my Charge where is the Money to raise and perfect the Work There is Pounds wanting present Pay towards the Charge of making two wonderful Instruments for the first making of the Instrument will be very Chargeable one of them may prove far more chargeable then the other and yet when it becomes common it may be sold at a low Price I Judge under fifty Shillings yet before the Instrument can be brought to such Perfection as to show two or three Examples may cost several Hundreds of Pounds and for ought I know take up most part of a Year to accomplish them it is an Instrument that must be truly Cut and Polished a small matter of a false sweep or stroke may quite spoil it and make it good for little or nothing therefore one Hundred of them may happen to be spoiled before we can get the right Art of making them neither of them will suddenly be fit for Seamens Practise because the Natural motions that one of them is to show are at this present writing I believe unknown to the World therefore reasonable time is required to Calculate the Theories of those motions I will give you a brief Description of one of the Instruments it is one or two I know not well which to call it it is round its Diameter about 8 or 10 Inches may be a good size it is not altogether flat nor Convex nor Concave nor Globular it contains several Circles exactly swept even to a Hairs breadth the Areas of each Circle must have their just proportions but have no visible point for a Center nor are the Circles Cut and raked in its Surface but ought to appear above it it hath no straight Lines save only in its Frame of which must be divided into 360 Deg. and subdivided c. it is Scioptrick Dioptrick Catoptrick P S. K. and P. H K. and whereas most Secrets seem most wonderful before they are discovered this Instrument will seem most wonderful when the best Description is given of it and when put to common use to give a true and perfect Description of its secret properties like the Loadstone may puzzle the Oxonian Sophist or Parisian Sorbonist but this I give for one Aphorism Natura nil agit frustra I hope it may answer our designs in the Longitude nisi Argentum agit frustra but all is in the Power of God it is an Emblem of Trinity Trinity in Vnity and Vnity in Trinity Indeed I have but little more Knowledge of it then is in the Idea of my Brain for the Experimental part is most wanting but the World may believe that I can produce sound Principles and Evinceing Arguments for my Opinion else I should not have made it so publick delays are dangerous Ars longa Vita brevis but if it please God I should be glad to live to see this Art come to such Perfection as to be fit for Seamens Practice during the natural Course of my Life Reader believe if you please that he that writ this could a writ more and more to the purpose if he would I think it enough for five or six Weeks Time and Study and abundance too much if for a Gratuity I may suck my