The principles of astronomy and navigation, or, A clear, short, yet full explanation of all circles of the celestial and terrestrial globes and of their uses : being the whole doctrine of the sphere and hypotheses to the phenomena of the primum mobile : to which is added a discovery of the secrets of nature which are found in the mercurial-weather-glass &c. : as also a new proposal for buoying of a ship of any burden from the bottom of the sea / by George Sinclair. Sinclair, George, d. 1696. 1688 Approx. 146 KB of XML-encoded text transcribed from 82 1-bit group-IV TIFF page images. Text Creation Partnership, Ann Arbor, MI ; Oxford (UK) : 2003-11 (EEBO-TCP Phase 1). A60283 Wing S3857 ESTC R26242 09398782 ocm 09398782 42972 This keyboarded and encoded edition of the work described above is co-owned by the institutions providing financial support to the Early English Books Online Text Creation Partnership. This Phase I text is available for reuse, according to the terms of Creative Commons 0 1.0 Universal . The text can be copied, modified, distributed and performed, even for commercial purposes, all without asking permission. Early English books online. (EEBO-TCP ; phase 1, no. A60283) Transcribed from: (Early English Books Online ; image set 42972) Images scanned from microfilm: (Early English books, 1641-1700 ; 1315:23) The principles of astronomy and navigation, or, A clear, short, yet full explanation of all circles of the celestial and terrestrial globes and of their uses : being the whole doctrine of the sphere and hypotheses to the phenomena of the primum mobile : to which is added a discovery of the secrets of nature which are found in the mercurial-weather-glass &c. : as also a new proposal for buoying of a ship of any burden from the bottom of the sea / by George Sinclair. Sinclair, George, d. 1696. Sinclair, George, d. 1696. Proteus bound with chains, or, A discovery of the secrets of nature which are found in the mercurial-weather-glass. [6], 85, 49, 14 p. Printed by the heir of Andrew Anderson, Edinburgh : 1688. "Proteus bound with chains, or, A discovery of the secrets of nature which are found in the mercurial-weather-glass" has special t.p. and separate pagination. Reproduction of original in the Cambridge University Library. Created by converting TCP files to TEI P5 using tcp2tei.xsl, TEI @ Oxford. Re-processed by University of Nebraska-Lincoln and Northwestern, with changes to facilitate morpho-syntactic tagging. Gap elements of known extent have been transformed into placeholder characters or elements to simplify the filling in of gaps by user contributors. 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Copies of the texts have been issued variously as SGML (TCP schema; ASCII text with mnemonic sdata character entities); displayable XML (TCP schema; characters represented either as UTF-8 Unicode or text strings within braces); or lossless XML (TEI P5, characters represented either as UTF-8 Unicode or TEI g elements). Keying and markup guidelines are available at the Text Creation Partnership web site . eng Astronomy -- Early works to 1800. Navigation -- Early works to 1800. 2003-07 TCP Assigned for keying and markup 2003-07 Apex CoVantage Keyed and coded from ProQuest page images 2003-09 Mona Logarbo Sampled and proofread 2003-09 Mona Logarbo Text and markup reviewed and edited 2003-10 pfs Batch review (QC) and XML conversion THE PRINCIPLES OF Astronomy and Navigation : OR , A Clear , Short , yet Full Explanation , of all Circles of the Celestial , and Terrestrial Globes , and of their Uses , being the whole Doctrine of the Sphere , and Hypotheses to the Phenomena of the Primum Mobile . To which is Added A Discovery of the Secrets of Nature , which are found in the Mercurial-Weather-Glass , &c. AS ALSO A New Proposal for Buoying up a Ship of any Burden from the Bottom of the Sea. By GEORGE SINCLAR , sometime Professor of Philosophy in the Colledge of GLASGOW . Edinburgh , Printed by the Heir of Andrew Anderson , Printer to His most Sccred Majesty , Anno d 〈…〉 Academiae Cantabrigiensis Liber . To the Right Honourable MAGNUS PRINCE , Lord Provost ; Alexander Brand , Alexander Simpson , Iohn Morray , and William Montgomery , Baillies ; Iames Nicolson Dean of Gild , Edward Marjorebanks Thesaurer ; and remanent Members of the Honourable Senate , of the Antient City of Edinburgh . May it please your Lordship , and the Honourable Senate , IT is neither Ambition , nor Ignorance of your Worth and Merit , which have inclin'd me , to prefix your Names to the Frontispiece of this mean Pamphlet , but the sure experience I have of your encouraging all vertuous Actions and Learning . What I have now in Equity and Reason presented , I humbly desire the Honourable Senate , may accept favourably . I owe all I have , and my Self too , to your Devotion and Service . I chuse rather to be doing somewhat Amiss , than doing Nothing . 'T is the Widows Mite , which I have shelter'd under the Wings of your Protection . If I should endeavour , but to recapitulat , what Sentiments of your Kindness I have found , both Time , and my Memory would fail me . None can think , that there is any Deserving in me , which can be proportionable to those unvaluable Acts of your Bounty . If there be any , I am confident , it is too too scanty to Oblige . When I was able to do more , none were found more willing . I endeavoured indeed , according to my Capacity , to contribute my Assistance for promoving that great and noble Design , which was accomplish'd ; for which the Generations to come , shall call you Happy , whom you have Enriched , with Refreshing-Streams of Cooling-Waters , more Advantagious and Useful to the City , than the Fruit of the Vine . I cannot satisfie all the Obligations to Duty , which ly upon me . The more I was inclin'd to offer this Trifle , the more I was overcome with Reasons perswading to the contrary . But the uprightness of my Intention , to beautify this trivial Subject , with the Splendor , and Glory of your Names , will excuse the faillings of my Understanding . I cannot remunerat the Kindness of the Honourable Senate , better , than by Hearty Prayer , that the LORD may give you , the Spirit of Wisdom , and Government , to Manage the Weighty Affairs of the City , and His Conduct , not only to Guide each one of you , in his particular Calling , but all of you , to the endless Fruition of Immortal Life . This I fervently wish , while I am Your Lordships and the Councils , much Obliged Servant , GEORGE SINCLAR . TO THE READER . I Iudge it altogether needless to Preface any thing by way of Commendation to the following Tracts . They will ( I hope ) commend themselves , to the intelligent Reader . There is first , The Doctrine of the Sphere , so compendiously set down , that nothing can either be Added , or Subtracted . It is the very Rudiments of Astronomy and Navigation , and of many other Mathematical Sciences . By the use of the Globes , the whole Doctrine of the Sphere may be easily comprehended , even by the meanest Capacity . The second Tract , is not so evident , because more Physical , and less Mathematical , but perhaps as sure . I have set down my own Thoughts only , If any Man shall offer to salve the Phenomena better , I shall be glad . The third Tract is , a new Invention for Buoying up of Ships from the Ground of the Sea. This Proposal was made some few Years ago , to try the Invention and Wit of some Notional Men , but though they have plowed with my Heifer , yet were they not able , to find out my Riddle : Nay some of them were so confident to aver , that when this Proposal was made to them , How to make a Vessel Sail below the Water ; they Replyed , it might be easily resolved by their Analyticks . ERRATA . IN the second Tract , Page 28. line 13. for earthly read earthy . pag. 33. lin . ult . for Idaea read Idea . THE PRINCIPLES OF Astronomy and Navigation . CHAP. I. Of the Circles of the Sphere in general . THE material Sphere , is an Instrument , whereby all the Phenomena of the Primum Mobile , are most easily known . It is composed of Ten Circles chiefly , which are , the Equinoctial , the Zodiack , the two Colures , the Horizon , the Meridian , the two Tropicks , and the two Polars . Those Circles , are three manner of ways distinguished among themselves . First , Some of them are called Circuli Maximi , the Greatest Circles ; others are called Circuli Minores , the lesser Circles . The Greatest are , the Equinoctial , the Zodiak , the two Colures , the Horizon , and the Meridian ; because there cannot be greater Circles in the Sphere , than they are . The lesser Circles are , the two Tropicks , and the two Polars . They are so called , because there are found in the Sphere greater ones . Secondly , The Circles of the Material Sphere , while the Primum Mobile is turning about , are either Parallel one to another , Right , or Oblique , that is , to ly crosly . The Parallel Circles , are the two Polars , the two Tropicks , and the Equinoctial , which ly middle between them , together with their Equinoctial , who live under the Poles . The Oblique Circles are , the Zodiack , and the Oblique Horizon . For this cutteth the Equinoctial , at Oblique Angles ; the other by reason of its Situation doth the same to the rest of the Circles . The Circles called Right Circles , are the two Colures , the Meridian , and the Right Horizon , because they cut the Equinoctial at Right Angles . Thirdly , The Circles of the Sphere , are either Moveable , or Immoveable . The Moveable Circles , are these which are turned about with the Sphere , being eight in number , to wit , the Equinoctial , the Zodiack , the Equinoctial Colure , the Solstice Colure , the Tropick of Cancer , the Tropick of Capricorn , the Polar Artick , and the Polar Antartick . The Circles Immoveable , are the Meridian , and the Horizon ; so called , because while the Sphere is carried about , they stand stedfast , and unmoveable . CHAP. II. Of the Equinoctial . THe Equinoctial , is one of the greatest Circles , of the Sphere Moveable , and equally distant from the Poles of the World. It is called one of the greatest , that it may be distinguished from the lesser , as well from those , which are fixed in the Sphere , as from others , which we must imagine to be in it . It is called Movable , that it may be distinguished , from the Horizon of those , who live under the Poles , which coinciding with the Equinoctial , must differ from it in this , that the one is Movable , the other Immovable . Lastly , by reason of the third difference ( equally distant from the Poles of the Sphere ) it is distinguished from the Oblique , and Right Circles of the Sphere . It is called by divers Names . For sometimes it is called the Equator , sometimes the Equinoctial , and sometimes the Middle , and greatest of the Parallels . The Uses and Offices of the Equinoctial are these . 1. It measureth the first Motion . For this Circle , of all the Circles of the Sphere , under any Position whatsoever , moveth equally ; and therefore , it ought to be also the Measure of Time , it being most fit for determining the quantity of the Artificial , and Natural Days . For this cause , it is , that the Degrees of the Equinoctial , are called by some , Tempora , Times . 2. It pointeth forth to us in the Ecliptick , the two Equinoctial Points ; those Points , in which the Equinoctial , and Ecliptick cut one another , in the beginning of Aries and Libra . For when the Sun cometh to these Points , the Day and the Night are of equal length over all the Earth , which falleth out on the 10 or 11 of March , and on the 13 or 14 of September . 3. That which is Anomolous , and Irregular in the Oblique Motion of the Zodiack , is reduced to a sure Rule , by the help of the Equinoctial . 4. It divideth the Sphere into two equal parts ; the one called the North part , in which is the Pole , named Polus Septentrionalis , Boreus , or Articus : the other called the South part , in which is the Pole , named Polus Australis , Meridionalis , or Antarticus . 5. By this means , it divideth the Zodiack into six Signs , called Northern Signs , and into other six called Southern Signs . 6. From the Equinoctial are numbred the Declinations of all , and whatsoever Points in Heaven , as well South as North. The Declination of any Point , or Star , is an Arch of a Circle of Declination , measured between the Equinoctial , and the said Point , or Center of the said Star. Circles of Declinations , are of the Greatest Circles in the Sphere Movable , passing thorow the Poles of the World , and any point given . 7. Upon the Equinoctial , we reckon the Right Ascension of any , or whatsoever Point in Heaven . Right Ascension , is nothing else , but an Arch of the Equinoctial , measured between the first Point of Aries , and that Circle of Declination , which passes thorow the point given . 8. Upon the same Equinoctial , we measure the Oblique Ascension , and Descension of any point in Heaven whatsoever . Oblique Ascension , is an Arch of the Equinoctial , measured between the first Point of Aries , and that Point of the Equinoctial , which riseth in the same Moment of Time , with the Point given . Oblique Descension , is an Arch of the Equinoctial measured between the Point foresaid , and that Point of the Equinoctial , which sets in the same Moment of Time , with the Point given . 9. Upon the Equinoctial , we count and reckon the Ascensional Difference , which is nothing else , but an Arch of the Equinoctial , by which Right Ascension differs from Oblique . 10. Upon the Equinoctial , we measure the Rising and Setting Amplitude . This Rising and Setting Amplitude , is nothing else , but an Arch of the Horizon , measured between the Rising , or Setting of the Equinoctial , and the Rising or Setting of any Star , or Point given . 11. Upon the Equinoctial , we number the Longitudes of Places , and upon the same , we reckon the Latitudes of Places . The Longitude of a place , is an Arch of the Equinoctial , measured between the first Meridian , and the Meridian of the Place . The Latitude of a Place , is an Arch of the Meridian measured between the Equinoctial , and Zenith of the Place . 12. The Equinoctial is most useful for making of Sun-Dials : for there must be as many Hours upon the Plain , as there are 15 Degrees in the Equinoctial , four and twenty times numbred . CHAP. III. Of the Zodiack . THe Zodiack , is one of the Greatest Circles of the Sphere , Movable , under which the Planets perpetually haunt . The first and second Difference are added , as in the Definition of the Equinoctial . The third , which is in these words ( under which the Planets perpetually haunt ) do distinguish the Zodiack from all other Circles . For it may come to pass , that , this or that Planet , by his proper motion , may be under the Meridian , may be under some Horary Circle , may touch lightly the Horizon , but that is not always , nor do they always abide in the same Situation : but their stay is perpetual under the Zodiack . And because the Planets wander in the Heavens , viâ obliquâ , therefore this Circle is made oblique , and seing in this obliquity , they make digression , from this side , to that side , and from that to this , therefore Astronomers have granted to this Circle Latitude , whereby also it may be differenced from all other Circles , none of which ever claimed Latitude . The Zodiack is divided , first in relation to its Latitude , into North Latitude , and South Latitude . North Latitude , is that half part of the Zodiack , which from the Ecliptick ( the middle Line of it ) declines toward the North. South Latitude is opposite to this . Each one of them contains Eight Degrees , whereof the Equinoctial contains 360. The Ecliptick , or middle Line of the Zodiack , is one of the Greatest Circles of the Sphere , Moveable , under which , the Sun from West to East moves perpetually . This Line , as likewise the Zodiack , is divided according to Longitude into twelve Parts , which are called in Greek 〈◊〉 . Every one of these twelve , are subdivided into 30 parts , so that the whole Zodiack contains 360 Degrees . These twelve Divisions are called Aries , Taurus , Gemini , Cancer , Leo , Virgo , Libra , Scorpius , Sagittarius , Cap●…s , Aquarius , Pisces . But seing there are four Cardinal Points , two of the Equinoctial , and two Solstice Points , it hath pleased Astronome●… , to make the beginning of their reckoning , from the Vernal Equinoctial Point ; because the Sun being there , he not only begins the Spring , but openeth the Earth , and giveth life to all Vegetables , and things which grow ; which cannot be done , either in any of the Solstices , or when he is in the Autumnal Equinoctial Point . Next , the distinction of the Signs is manifold . For some of them are called Northern Signs , and others are called Southern . The Northern , decline from the Equinoctial towards the North , which are Aries , Taurus , Gemini , Cancer , Leo , Virgo . The Southern decline from the Equinoctial towards the South , which are Libra , Scorpius , Sagittarius , Capricornus , Aquarius , Pisces . Secondly , Some of them are called , Signs Ascending , others are called Signs Descending . The first sort , are these , wherein the Sun , and the rest of the Planets do ascend from the South towards our Zenith , which are Capricornus , Aquarius , Pisces , Aries , Taurus , Gemini . The Descending are these , wherein the Sun , and the rest of the Planets , do move from our Zenith towards the South , which are Cancer , Leo , Virgo , Libra , Scorpius , Sagittarius . Thirdly , The Signs of the Zodiack , are either Vernal , Estival , Autumnal , or Hybernal . The Vernal , are Aries , Taurus , Gemini . The Estival , are Cancer , Leo , Virgo . Autumnal , are Libra , Scorpius , Sagittarius . And the Hibernal , are Capricornus , Aquarius , Pisces . Fourthly , The Signs are either Cardinal , Middle , or Fixed , or Common , or Two-bodied . The Cardinal Signs , are Aries , Cancer , Libra , Capricornus : so called , because their beginnings are the very Cardinal Points . The Middle or Fixed Signs , are Taurus , Leo , Scorpius , Aquarius . They are called Middle or Fixed , because they keep the Middle place between the Cardinal and Common Signs . They are Fixed , because when the Sun is in them , we have a perfect temperament of the Air , agreeing to the given Quadrant of the Heavens . As when the Sun is in Taurus , we have a perfect Spring ; in Leo , a perfect Summer ; in Scorpius , a perfect Harvest ; and in Aquarius , we have a perfect Winter . They are called Common , or Two ▪ bodied , as Gemini , Virgo , Sagittarius , and Pisces ; because each one of them , hath two Bodies indeed . For Gemini are two Twins . Virgo hath an Ear of Corn in her Hand . Sagittarius is made up of a Man , and a Horse . And lastly , The Fishes are double . They are called Common , because Astrologers find , that they participate of the Nature , both of the Fixed Signs , and the Cardinal which follow . Fifthly , The Signs are divided into four Triplicities , which are called by Astrologers Trigons . The first is called the Fiery Trigon , which contains Aries , Leo , and Sagittarius . The second is the Earthy , which contains , Taurus , Virgo , and Capricorn . The third is the Aerial , which contains , Gemini , Libra , and Aquarius . The fourth is the Watery , which contains , Cancer , Scorpius , and Pisces . If it happen , that Saturn , and Iupiter be in Conjunction this year in Leo , their next Conjunction will happen 20 years after , or truly 19 years , 315 days , and 19 hours , after in Sagittarius . From Sagittarius to Aries , from Aries to Leo , and so in round till 198 years and 236 days passing , they make a Transit into a new Trigon ; so that the Revolution of one Trigon , consumes almost 200 year . The uses of the Zodiack and Ecliptick are these . 1. As the Equinoctial , is the Measure of the Pri●… Mobile , so is the Zodiack and Ecliptick , the Square and Rule of the second Movables . For as the Sun is always , in or under the Ecliptick ; so are the rest of the Planets always , in or under the Zodiack . Therefore as in the Celestial Globe , the Zodiack hath the chief place , so in the Terrestrial Globe the Equinoctial . 2. Upon the Ecliptick we reckon the Longitude of Stars , and from the same Ecliptick , we count their Latitude . The Longitude of a Star , is an Arch of the Ecliptick , measured between ●●e true Equinoctial Point , or begin●ing of Aries , and the Circle of Lati●●de passing thorow the Center of that ●tar . Circles of Latitude , are great Movable Circles , passing thorow the Poles of the Ecliptick , and the Center ●f the Star given . They are of that ●umber of Circles , which cannot be ●●aced Artificially in the Sphere . Ne●ertheless , of that same Number , is the ●olurus Solstitiorum fixed in the Sphere . The Latitude of a Star , is an Arch of a Circle of Latitude , measured between ●he Ecliptick , and the Center of the ●tar . 3. According to the Degrees , and ●arts of the Zodiack and Ecliptick , the whole Heavens , and the whole Universe 〈◊〉 divided into twelve Signs ; nay eve●y Point contain'd in the Sphere of the Fixed Stars , is said to be in this or that Sign ; tho , to be in a Sign , is said many ways . For first , To be in a Sign , is nothing else , but to be under any ●welfth part of the Zodiack . In this ●ense , the Sun is said to ●e in a Sign , because he is always under the Ecliptick . Then the Stars are said to be in a Sign , which are indeed out of the Ecliptick , nevertheless are under the Zodiack . In this sense , the Planets , which wander from the Ecliptick , are said to be in the Sign of Aries , and Taurus , &c. Thirdly , Any thing is said to be in a Sign , which is included , in any of the twelve parts , which arise from the division of the whole Heavens , passing thorow the beginnings of the Dodekatemoria , or the Poles of the Ecliptick ; they being six great Circles , which mutually cut one another , in the same Poles . In this sense , any Star , as well fixed , as wandring , or new appearing , as a Comet , are said to be in the Sign of Aries , Taurus , &c. 4. The obliquity of the Ecliptick , is the cause of the inequality of days : for seing it moves unequally , and not evenly , the Sun , which is the true Parent of Time , must of necessity make the days unequal . 5. The Year , the Month , and the four Seasons of the Year , are determined by the Ecliptick . 6. When the Sun and Moon , are both of them in the Ecliptick , of necessity there must be Eclipses ; and for this cause , it is called the Ecliptick . 7. How much is the obliquity of the Ecliptick , so much is the distance , between the Poles of the World , and the Poles of the Ecliptick : so much also is the distance , between the Equinoctial , and either of the Tropicks . CHAP. IV. Of the Colures . THe Colures are nothing else , but Circles of Declination , defined above , in the second Chapter of the Equinoctial . They are called Colures from two Greek words , Kolos , or Kolobos , Mancus , maimed or defective , and Oura , Cauda , a Tail , because in an oblique Sphere , they have some part unseen , as if they were maimed , or wantting . But all the rest of the Circles of the Sphere , while it is going about , may be seen : but the Colures , have always some of their parts towards either of the two Poles , lying hid , and unseen . There are only two of them , which use to be placed in the Sphere , one whereof is called the Solstice Colure , the other the Equinoctial Colure . The Equinoctial Colure , is one of the greatest Circles of the Sphere , Movable , passing thorow the Poles of the Sphere , and the Equinoctial Points , the first of Aries , and the first of Libra , which are called Cardinal . By the word movable , the Colures are differenced ; First , From the Meridian ; Secondly , From the Right Horizon ; And thirdly , From the Horary Circles , with all which , by one turning about of the Sphere , they are twice united . But in this they differ , that those do not move , but these follow the motion of the Primum Mobile . The Solstice Colure , is one of the greatest Circles of the Sphere , movable , drawn thorow the Poles of the Sphere , and the two Solstice Points , by which difference , they are distinguished from other Colures . The uses of all the Colures in common are these . First , We reckon upon them , the Declinations of all the Points of the Heavens whatsoever . 2. They terminate and bound the Right Ascensions . 3. They are like unto a Right Horizon , and a Meridian in any Sphere , whether Right , Oblique , or Parallel . The Uses of the Colures , which are set down in the Sphere , are these in common , 1. Without them , the Parallel Circles in the Material Sphere cannot stand , 2. By their mutual cutting one another , they shew the Poles of the Sphere . 3. They divide the Ecliptick into four Quadrants . The peculiar Uses of the Equinoctial Colure are these . 1. It demonstrats to us the Equinoctial Points , by its mutual Section , with the Ecliptick ; in which Points when the Sun is existing , there is an Universal Equinox over the whole Earth . 2. It is divides the Ecliptick into two halfs , the one called the North part , the other the South part . 3. It distinguishes the Signs , in which when the Sun is existing , the Days are longer than the Nights , from those Signs , in which when the Sun is existing , the Nights are longer than the Days . The proper Uses of the Solstice Colure are , 1. It demonstrats to us the two Solstice Points , in which when the Sun is existing , he is either nearest to our Zenith , or furthest removed from it . 2. Upon this Colure , we reckon the Suns greatest Declination , or the greatest Obliquity of the Ecliptick , which is found to be this day twenty three Degrees , and thirty Minuts . 3. It divides the Zodiack into two halfs ; the one called Ascending , the other Descending . 4. It distinguisheth the Signs , in which when the Sun is existing , the Days become longer , and the Nights become shorter , from those Signs , in which when the Sun is existing , the Nights become longer , and the Days become shorter . 5. In this Circle , are the two Poles of the Ecliptick , as many Degrees , distant from the Poles of the World , as the greatest obliquity of the Ecliptick contains . 6. Upon this Colure , the Latitudes of the Zones are determined . For between the Tropicks , is contained the breadth of the Torrid Zone , between the Tropicks , and the nearest Polar Circles , are contained the two Temperate Zones , and the other two remaining Arches of this Circle , contain the breadth of the two Frigid , or Cold Zones . CHAP. V. Of the Horizon . THe Horizon , is one of the greatest Circles of the Sphere , Immovable , and equally distant from the Vertical Point . It is called Immovable , that it may be differenced from the rest of the Movable Circles ; but especially , First , From their Equinoctial , who live under the Poles . Secondly , From their Ecliptick , whose Zenith is placed in the Polar Circles : for their Ecliptick every day is twice united with their Horizon , but without delay . Thirdly , From their Circles of Declination , or their Colures , who live under the Line : for there , the forementioned Circles , and the Horizon , are twice , by every Revolution of the Sphere , united : but the Circles of Declination follow the Motion of the Primum Mobile , but the Horizon stands Immovable . The Horizon is said indeed to be Immovable , but not Unchangable , for there are as many Horizons , as there are Vertical Points ; and while we change our Vertical Point , of necessity we change our Horizon also . Two ways is the Horizon divided . First , In relation to the Equinoctial , which is called a Right Horizon , an Oblique Horizon , and a Parallel Horizon . The Right Horizon , is so called , because it cuts the Equinoctial at Right Angles . It is called Oblique , because it cuts the Equinoctial at Oblique Angles . And it is called a Parallel Horizon , when it lies Parallel to the Plain of the Equinoctial , or rather when it is united , with the Equinoctial . And according to this Relation , it hath to the Equinoctial , the Sphere it self , hath obtained the same Division . Secondly , The Horizon is either Rational , or Sensible . The Rational Horizon , is defi●…ed above , and is understood to divide the whole World , or Sphere of the World into two equal parts , the first whereof is called the uppermost Hemisphere , the second the nethermost Hemisphere . It is called Rational , because tho we cannot see the whole World , or the exact half of it , yet Reason tell us , by the Rising and Setting of the Sun , Moon , and Stars , that the inferior part of the World , is equal to the superior part . The Sensible Horizon , is nothing else , but so much of the Earth , as a man , by turning his eye once , doth behold round about him . The Uses of the Horizon are these . First , it divides that part of the Heavens , which is seen , from the other which is not seen , the Superior part from the Inferior part . 2. Thorow the Poles of the Horizon the Meridian ought to pass : therefore the Description of the Meridians depend from the Horizon . 3. By the Situation of the Horizon , we know whether it be a Right Sphere ▪ Oblique Sphere , or a Parallel Sphere . 4. In the Horizon , the Rising or Setting of the Stars are observed 5. The Horizon sheweth , what Degree of the Ecliptick , what part also of the Equinoctial , or what Degree , with any given point of the Heaven riseth or setteth . 6. It boundeth and terminats the Ascensional Difference . 7. Upon the Horizon is numbred , the Rising or Setting Amplitude , of any point in the Heaven . 8. It demonstrats , and sheweth the Cause and Reason of the equality of Days and Nights in a Right Sphere , and of the unequality of the same in an Oblique Sphere . For the Horizon in a Right Sphere cutteth all the Circles of the Natural Day equally , but unequally in an Oblique Sphere . 9. From the Horizon we number the Morning-Twilight : for when the Sun ●…s distant , in some Vertical Circle 18 or 19 Degreees from the Horizon , so that ●…rom that Moment , he approach nearer ●…nd nearer unto it , then begins the Morning-Twilight . But the Evening-Twilight ends , when the Sun after his Set●…ing comes to that 18 or 19 Degree ●…oresaid ; for then doth the Light turn ●…nto Darkness . 10. From the Horizon , we number the Elevation of the Pole , ●…nd Equinoctial . 11. From the Hori●…on are numbred various and divers ●…inds of Hours , as the Italick , and Iewish Nocturnal Hours from the West part of the Horizon : but the Babylonish Hours , ●…nd the Iewish unequal Diurnal Hours , ●…rom the East part . CHAP. VI. Of the Meridian . THe Meridian is one of the greatest Circles in the Sphere , passing thorow the Poles of the World , and the Poles of the Horizon . By the words , thorow the Poles of the Horizon , it is distinguished from the Horary Circles , of which none but it self , passes thorow the Poles of the Horizon . It has acquired divers and sundry Names , by reason of its manifold uses , by Astrologers , which are not fit to repeat now . What was said above concerning the Colures , and Circles of Declination , to wit , that they are in number equal to the Vertical Points , the same may be said of the Meridian , for as many of them may be imagined , as there are Vertical Points , which are infinite , providing a man travel from East to West : for if a man go from North to South , or from South to North , he travels round about the World , without variation of his Meridian . The Brasen Meridian in the Celestial , or Terrestrial Globe , supplyes the office of them all , which are innumerable . But in Geographical Tables , and Mapps , Geographers use to extend one Meridian , thorow two , and two opposite Degrees of the Equinoctial , for finding out , the more easily the Latitudes of Places . Of all these Meridians there is a common beginning se●…led in the Fortunate , or Canary Islands , because the Antient Geographers deemed those Islands to be the Westmost part of the World , and therefore they fixed their first March-stone there , whence they begin to reckon . But the later Geographers , have removed this March-stone 10 Degrees more Westerly , and have made the common beginning of the Meridian to pass thorow one of the Islands called Osores , whence they begin to reckon from West to East , imita●…ing the order of the 12 Signs . The uses of the Meridian are these , 1. It distinguisheth the Eastern part , of the World , from the Western part , the Anterior part , from the Posterior part . 2. It lets us know the South part of the World , and the North part . For when the Sun is in the Meridian , ●…en is Mid-day , and when the Sun is in the Northern part , of the Meridian , then is Mid-night . 3. It divides the Nocturnal and Diurnal Time into two halfs : that is , when the Sun is come to the Meridian in our Hemisphere , as much of the day is past , as what is to come : and when the Sun is come to the Northern part of the Meridian , as much of the Night is past , as what is to come . 4. The Meridian supplies in every Oblique Sphere the place of the Right Horizon : therefore , as the Stars do ascend above the Right Horizon , so they pass over the Meridian , and those ●…ransitions are called the Right Ascensions of the Middle Heaven . 5. From the Meridian , Astronomers begin their Time. 6. In the Meridian , we find out the Zenith ; therefore when the Stars come to it , they are either highest above the Horizon , and are said by Astrologers to culminate , or they are in the lowest , and opposite part of it , which is the Nadir . 7. In the Meridian , we find out the distances between the Tropicks , and the whole Obliquity of the Ecliptick . 8. Upon the Meridian , we number the Latitude of Places upon the Earth , and likewise the Elevation of the Pole , and Equinoctial . The Elevation of the Pole , is defined , an Arch of the Meridian , measured between the Horizon , and the apparent Pole of the World , which may be found out , after the following manner . Observe the greatest and least Altitude of any of the Stars , which do not set . Subtract the least Altitude from the greatest , and divide the difference . This difference being subtracted from the greatest Elevation , or added to the least , gives the true height of the Pole. December 17. 1669 , I observed with a large Quadrant , half 9 a Clock at night , the foremost Guard-star , when it was in the Meridian , and lowest , to have 41 Degrees , 22 Minuts of Altitude . And on Ianuary 7. 1670 , at 7 a Clock in the Morning , I found it , when it was in the Meridian , and heighest , to have 70 Degrees , 27 Minuts . I subtract 41 Degrees , 22 Minuts , from 70 Degrees , 27 Minuts , and the difference is 29 Degrees , 5 Minuts . Divide this , and you have 14 Degrees , 32 Minuts , and 30 Seconds . This being added to 41 Degrees , 22 Minuts , gives you 55 Degrees , 54 Minuts , 30 Seconds . Or subtract 14 Degrees , 32 Minuts , and 30 Seconds , from 70 Degrees , 27 Minuts , and there remains 55 Degrees , 54 Minuts , and 30 Seconds , for our height of the Pole at Edinburgh . 9. The Meridians do terminate , and bound the Longitudes of Places , as well in the Terrestrial Globe , as in the Mapps , and Cards projected in Plano . 10. The Meridians do terminate , and bound the Breadths and Latitudes of the Zones , and also of the Climats . 11. We find out in the Meridian , the Antipodes , the Anteci , and Perieci . CHAP. VII . Of the Tropicks . THe Tropicks are lesser Movable Circles of the Sphere , described from the Solsticial Points , by the mo●…ion of the Primum Mobile . They are called Lesser , because there are in the Sphere Greater Circles , than they are . They are called Movable , that they may be distinguished chiefly , from the Paral●…els of their Horizon ( called Almican●…ars ) , who live under the Poles ; and ●…rom the antient Polars of those , who ●…ive under the Polars , with whom the Tropicks are equal to those Circles , which comprehend the Stars , which never come above the Horizon , nor ever go under it . They are two in number , to wit , the Tropick of Cancer , and the Tropick of Capricorn . The Tropick of Cancer , is a lesser movable Circle , described from the Summer-Solstitial-Point of the Ecliptick , by the motion of the Primum Mobile . The Tropick of Capricorn , is lesser movable Circle , described fro●… the Winter-Solstitial-Point of the Ecliptick , by the motion of the Primum Mobile . The uses of the Tropicks are these 1. They demonstrate to us , in the Ecliptick , the two Tropical or Solstic Points , to wit , the beginning of Cancer , and the beginning of Capricorn 2. They terminate and bound , the Sun greatest Declination , and consequently the greatest Obliquity of the Ecliptick 3. When the Sun comes to either of th●… two Tropicks , he is either nearest t●… our Vertical-Point , or furthest removed from it . 4. In an Oblique Sphere , they ly Parallel to the longest , and shortes●… Day . 5. Between the Tropicks , i●… comprehended the Torrid Zone , as well in the Heavens , as in the Earth : and by the same Tropicks , the Torrid Zone is divided from the Temperate Zones . CHAP. VIII . Of the Polars . THe Polars are lesser Circles of the Sphere , movable , described from the Poles of the Ecliptick , by the motion of the Primum Mobile . For this cause , they are called the Polar Circles . They are two in number , the Polar Artick , and the Polar Antartick . The Polar Artick is a lesser Circle of the Sphere , movable , described from the North Pole of the Ecliptick , by the Motion of the Primum Mobile . The Polar Antartick , is a lesser Circle of the Sphere , movable , described from the South Pole of the Ecliptick , by the motion of the Primum Mobile . They let us see first , the Poles of the Zodiack , and they measure their distance from the Poles of the World. 2. They bound the Temperat Zones , and separats them from the Cold Zones , which are bounded and inclosed by their circumferences . It is to be observed , that the antient Astronomers , Proclus , Cleomedes , and the rest , had not the same description of the Polars , which we have . For the Antients , did not describe them , as passing thorow the Poles of the Ecliptick , but thorow the common Sections of the Meridian , and Horizon , equidistant to the Equinoctial ▪ and therefore , so much was their distance from the Poles of the World , a●… the height of the Pole was above the Horizon . And by this means , where there is no Elevation of the Pole , as in a Right Sphere , there are no Polars . But from thence , they are more , and more gradually augmented , and enlarged , according to the increment of the Poles Elevation . The uses of the Polars , according to the Antients , are these , 1. They comprehend the Arch of the Elevation of the Pole. 2. Of all the Parallels of the Equinoctial , which are always seen above the Horizon , they are the greatest and of all the Parallels of the Equinoctial , which ly hid under the Horizon , they are the greatest also . But contra●…iwise , of all the Parallels of the Equinoctial , which arise and set in twenty four Hours , they are the least . Therefore ( 3. ) the foresaid Polars , comprehend within their Compass , and Circle , ●…he whole Stars and Points of Heaven , which are always in sight , and do not ●…et . Hence , there ariseth a threefold ●…istinction of the Stars . 1. There are ●…ome , which have a perpetual Day , and ●…ever set , or fall under the Horizon , to ●…it , those which are comprehended within the Circle of the Polar Artick . 2. There are others , which have a perpetual Night , which never rise , or come ●…p above the Horizon , to wit all those , which are included within the Circle of ●…he Polar Antartick . There are ( 3. ) others which both rise and set in four ●…nd twenty Hours , to wit those , which ●…ither on this side , or that side of the Equinoctial , tend towards and come nearest to the foresaid Polars . CHAP. IX . Concerning other Circles of the Sphere , both greater and lesser , which cannot be conveniently drawn upon it . BEside the Circles of the Sphere hitherto explained , there are yet innumerable more , both of the greatest and lesser sort , which Astronomers have excogitated for attaining a more perfec● knowledge of the Heavenly Motions ▪ 1. There are of the greatest sort Verticals , which pass thorow every point o● the Horizon , cutting one another there which by the Arabians are called Azimuths . 2. There are the Horary Circles , which divide the Heavens , into four and twenty parts , which are o● three sorts . For either they have the beginning in the Meridian , and pa●● thorow the Poles of the World , or the have their beginning in the East , o● West-part of the Horizon , by whic● means they touch lightly , the two Circles lying parallel to the Equinoctial , of which one is the greatest of all , which are always seen above the Horizon , the other the greatest of all , which are not seen above the Horizon : or lastly , they have their beginning in the Horizon , but neither go thorow the Poles , of the World , nor go near to the foresaid Parallels , but divide all the Segments of the Parallels , which are above or below the Horizon , into twelve equal parts . 3. There are Circles of Declination , which pass thorow the Poles of the World , and every point of the Equinoctial . There are 4. Circles of Latitude , which pass thorow the Poles of the Ecliptick , and every one of his Degrees . The lesser Circles are infinite also ; for there is no great Circle , which hath not his own Parallels . As first the Horizon , which hath Circles of Altitude , called by the Arabians Almicanthars . The Equinoctial , hath its own Parallels , to wit , described by the Primum Mobile , from all , and whatsoever Points are in the Heavens . So hath the Zodiack his Parallels , described about the Poles of the Ecliptick , which Parallels every Star , or point of the Heavens , according to the proper motion of the eight Sphere , do describe , and many more are there invented by Astronomers for Astronomical uses . CHAP. X. Of the Zones . TO the Doctrine of the Sphere , is commonly annexed the Geographical Tractat of the Zones . The Zones therefore are nothing else , but as much bounds , of the Heaven , or of the Earth , as is comprehended between both the Tropicks , or between either of the two Tropicks , and the next Polar , or between either of the two Polars , and the neighbouring Pole. Therefore the Zones , are either Celestial , or Terrestrial . The Celestial Zones , are bounded by themselves , and their own Circles in the Heavens . The Terrestrial Zones , ly directly under the same places of the Heavens . They are five in number , one Torrid , two Temperate , and two Frigid . The Torrid Zone , is that space of the Heavens , or the Earth , comprehended between the two Tropicks . This is divided into two parts , of which one is called the Northern , the other the Southern part . It is called Torrid , because here , the Rays of the Sun are more perpendicular , and so hotter , that the Inhabitants are in a manner scorched , and burnt up with Heat . The Temperate Zones , are that space of the Heavens , or of the Earth , comprehended between either of the two Tropicks , and the neighbouring Polars : and that which is included , between the Tropick of Cancer , and the Polar Artick , is called the Temperate Northern Zone , wherein are contained , all Europe almost , and a great part of Asia , and also a part of America . But that which is included between the Tropick of Capricorn , and the Antartick Polar , is called the Southern Temperate Zone . This contains more Sea , and less Land. They are called Temperate , because the Rays of the Sun , being more oblique , there is not such a reflection of Heat , but offer a most commodious Dwelling to the Inhabitants . The Frigid Zones , are that space of the Heavens , and of the Earth , comprehended between either of the Polars , and the neighbouring Pole of the World. And that bounds , which is included between the Polar Artick , and the North Pole , is called the Northern Frigid Zone : and that bounds which is included , between the Polar Antartick , and the South Pole , is called , the Southern Frigid Zone . They are called Frigid , because the Rays of the Sun are most Oblique , and are absent almost half a Year ; so that all things become rigid and stiff , with Frost , Yce , and Snow . In this Zone , lyes Island and Greenland , but in the Southern cold Zone , the parts are unknown to us . The Inhabitants of the five Zones , have obtained divers names . For those , who inhabite the Torrid Zone , are called Amphiscii , as having a shadow on both sides . I say on both sides , in respect of the Vertical Point . For the Sun with them , is sometimes on this side , and sometimes on that side of their Vertical Point : sometimes the shadow of their Dials is projected from South to North , and sometimes from North to South , when he is in the Meridian . The Inhabitants of the Temperate Zones , are called Heteroscii , as having but one shadow . For at 12 a Clock in the Day , the shadow is either casten towards the North , as with us , or towards the South , as with those , who dwell in the Southern Temperate Zone . But those , who live in the Frigid Zones , are called Periscii , as having a shadow , which goes round about them ; because they have the Sun for several Months of the Year , above their Horizon , and the Heavens there , like a Milstone , is whirled about , so that the Sun and Stars describe Parallels to the Horizon , and therefore in four and twenty Hours , he runs about without rising and setting , and projects his shadow into an Orb , or Circle . There are likewise , the Antipodes , Anteci , and Perieci . Antipodes , are those , who have the same Meridian , but dwell in points of it , diametraliter opposite , and are under opposite Parallels , ( to wit in an oblique Sphere , ) of which the one is Southern , the other Northern . These following Phenomena , are proper to them . 1. Though they have the same Rational Horizon , yet beholding the opposite Faces , all things fall out to them contrariwise . For when we have Day and Mid-day , our Antipodes have Night and Mid-night . When we have Summer , they have Winter . When the Sun rises to us , he sets to them . We have North Latitude , they have South Latitude . The Anteci are those , who dwell under opposite Parallels , equally distant from the Equator , towards both the Poles , under the same Meridian , but not in Points diametraliter opposed , but in a Semi circle of the Meridian intercepted between the Poles . They have these Phenomena proper to them . First , They agree in the same Longitude , and Latitude ; for how much is the South Pole elevated to those , so much is the North Pole elevated to these . 2. In the same Moment of Time , both of them have the Sun in their Meridian . But in this they differ ; while the Sun is coming to the Tropick of Cancer , those have Summer and longer Days , but these have Winter , and shorter Days . Again , when the Sun is returning , those have Harvest , the Days Decreasing , but these have the Spring , the Days Increasing . Hence it is , that the Sun doth not rise , and set to both , at the same time . The Perieci are those , who dwell under the same Parallel and Meridian , but in Points of the same Parallel diametraliter opposite ; so that both of them behold the same Pole , with equal height above the Horizon . First , They dwell in the same Zone . Secondly , They have the same Elevation of the same Pole. They have the same Winter , the same Summer , the same longest Day , and the same increment , and decrement of the Natural Days . But here they differ ; those having the Sun rising , these have it setting ; those having the Sun in the Meridian , these have it at our Mid-night : and contrariwise , when to those the Sun is setting , to these he is rising , when to those it is Mid-night , to these it is the Meridian . CHAP. XI . Of the Rising and Setting of the Stars according to the Poets . HItherto we have treated of the Hypotheses , to wit , the Circles of the Sphere , which so much conduce for explaining the Phenomena of the Primum Mobile . It now remaineth , that we speak and treat of the thing it self , to wit , the Phenomena themselves . And in the entry , we ought to have spoken of the rising and setting of the Stars , called Ortus & occasus stellarum Astronomicus ; but the knowledge of those things , cannot be taught here compendiously , nor without the Science of Spherical Trigonometry ; therefore passing this , we come to explain the rising and setting of the Stars , called Ortus & occasus Poeticus , which is the second Phenomenon of the Primum Mobile . This rising and setting of the Stars according to the Poets , is nothing else , but the rising of a Star above the Horizon , and the setting of a Star under it , in relation to the various Position of it , with the Sun. It is called Poetical , not because it doth not belong to Astronomers ; for it is a part of their Science to determine those Risings and Settings , but because the Poets in describing certain Seasons of the Year , use this method , as will be seen afterward . Of this Poetical Rising and Setting , there are three forms . First , That which is called the Rising and Setting of a Star Cosmice . Secondly , That which is called the Rising and Setting of a Star , Acronyce . Thirdly , That which is called the Rising and Setting of a Star Heliace . Each one of those hath a double signification ; one general , the other special . The Rising of a Star Cosmice generally taken , is the Rising of a Star above the Horizon , falling out from the Rising of the Sun to his Setting . The Setting of a Star Cosmice , generally taken , is the Setting of a Star , falling out from his Rising to his Setting . The Rising of a Star Acronyce , generally taken , is the Rising of a Star above the Horizon , falling out the whole time , the Sun is under the Horizon . The Setting of a Star Acronyce generally taken , is the Setting of a Star under the Horizon , falling out all the time the Sun is under the Horizon . The Rising of a Star Heliace generally taken , is the appearing of a Star after the Sun is Risen . The Setting of a Star Heliace generally taken , is the disappearing of a Star , after the Sun is set . But their special signification denotes , and determines , a certain , and definite time . Therefore , the Rising of a Star Cosmice , is the ascending of a Star above the Horizon , in the same moment , wherein the Sun Rises . The Setting of a Star Cosmice , is when a Star goes down , while the Sun is Rising . The Rising of a Star Acronyce , is when a Star comes above the Horizon , the Sun going down under the Horizon that same moment . The Setting of a Star Acronyce , is when a Star Sets with the Sun , that same moment . The Rising of a Star Heliace , is when a Star , which could not be seen , by reason of its nearness to the Sun , is now seen in the night time . The Setting of a Star Heliace , is when a Star , by reason of the Suns great distance from it , might have been seen in the night time , but the Sun coming nearer to it , it disappears out of our sight . We have an Example of the Rising of a Star Cosmice , in the first Book of the Georgicks . Vere fabis satio : tunc te quoque Medica putres Accipiunt sulci , & Milio venit annua cura Candidus auratis aperit , cum Cornibus annum Taurus , & adverso cedens Canis occidit Astro. When Taurus with his gilded Horns , Begins the Year , then Sowe your Corns Sowe Millet-seed , an yearly toil , Sowe Claver-grass , in putrid soil , Sowe yearly Pulse , and what you please Sowe in the Spring , both Beans and Pease . Virgil doth express here the Spring time , when the Millet-seed is to be sown●… which is in the beginning of April : An●… seing the Sun at that time , is about th●… end of Aries , it must be understood of the Rising of Taurus , which at that time riseth with the Sun Cosmice . At this time the Romans used to sowe their Beans , their Claver-grass , and their Millet , which every year must be renewed ; whereas the Claver-grass is to be sown but once in ten years . We have likewise an Example of the Setting of a Star Cosmice , from that same place in Virgil. Ante tibi Eoae Atlantides abseondantur Gnosiaque ardentis decedat stella Coronae Debita quam sulcis committas semina . When Pleiades , the Maidens seven , Are set into the Western-Heaven , When Ariadnes Crown full bright Before the Sun comes in our sight , Then sowe your Ground with Wheat and Rye 'T is of October eighteen day . Before you sowe your Ground ( says he ) let the Pleiades , or Seven-stars be set , which about October 18 , go down in the West , in the same Moment of Time , while the Sun is Rising in the East , which is called Occasus Cosmicus . We have an Example of the Rising of a Star Acronyce , from Ovid , in his first Book de Ponto . Quatuor autumnos Pleias orta facit . Four Harvests surely there have been , For Pleias four times have been seen . Ovid is here speaking of the Harvest time , when the Sun is in Scorpio , therefore when the Sun is Setting , Taurus or the Bull , and the Pleiades are Rising Acronyce . We have also an Example of the Setting of a Star Acronyce , from the same Ovid , in his second Book of his Fasts . Illa nocte aliquis tollens ad sidera vultus Dicet ubi est hodie , quae Lyra fulsit heri . Last Night when I surveyed the Sky , saw the Harp , 't is gone away This Night . This time , is the second day of Fe●…uary , at which time the Constellation ●…lled the Harp , sets Acronyce , with the ●…u . We have likewise an Example of the Rising of a Star Heliace , from the first Book of the Georgicks . Gnosiaque ardentis decedat stella Coronae . When Ariadnes Crown full bright Before the Sun comes in our sight . 'T is eviden●… that Virgil speaks here of the Rising of this Constellation Heliace , called Aridnes Crown , when the Sun is in the beginning of Scorpio . For seing this Constellation rises at Rome , where Virgil lived , with the 27 Degree of Virgo , it is needful to conceive this Crown to be seen in the Morning , the Sun being yet under the Horizon . Note , That there is a Figure called Hypallage in the word Decedat : for the Crown doth not recede from the Sun , but the Sun from it . And lastly , We have an Example of the Setting of a Star Heliace , from the same place of Virgil. Taurus , & adverso cedens Canis occidit Astro. And when the Dog shall disappear , By Phebus Beams him coming near . The Poet is here speaking of the Suns ingress into Taurus , which fell out in Virgils time on the 1●… of April . But seing the Dog-star sets at Rome with the 22 Degree of Taurus , therefore , the Sun setting in the Evening , the Dog-star setteth Heliace , or disappears out of our sight , by reason of the Suns Rays , which now are nearer him . Observe , That what Stars do arise Cosmice , which is also called Ortus Matutinus , they set Acronyce , which is called Occasus Vespertinus : and what Stars do arise Acronyce , which is called Ortus Vespertinus , they set Cosmice , which is called Occasus Matutinus , according to the following Rhyme . Cosmice descendit signum , quod Chronice surgit , Chronice descendit signum , quod Cosmice surgit . Aliter . Mane vehit supra terram tibi Cosmicus ortus Sidera , sed Phoebi lumine tecta latent . Mane dat Heliacus quaedam subvecta videre Astra , sed Achronycus nocte videnda trahit . Note secondly , That the word Cosmicus , comes from Kosmos , the World. That the word Chronicus , comes from the Greek word Chronos , Time. But Acronycus comes from Acra & Nux , which is the first part of the Night , or the Evening ▪ Twilight . That Heliacus comes from Helios , the Sun. Lastly , That Chronice , and Acronyce have the same signification . CHAP. XII . Concerning the Natural , and Artificial Days . NOw follows another Phenomenon of the Primum Mobile , to wit , the Doctrine of Days Natural and Artificial . Days are twofold , Astronomical , and Civil . Astronomical Days , are such as are measured , by the Revolutions of the Equinoctial , and determined by a certain quantity . Days Civil , are such as every Nation , according to their own Custom make use of . The Astronomical Day , is either Natural , or Artificial . The Natural Astronomical Day , is a space of time , wherein the Sun , by the Motion of the Primum Mobile , being carried about , from whatsoever immovable point of the Heavens , returns to that same point again . These Astronomical Days have their beginning in the Meridian , as was insinuate before . The Artificial Astronomical Day , is a Space of Time , wherein the Center of the Sun remains above the Horizon . And the Artificial Night , is as much Time , as the Center of the Sun remains under the Horizon . The Doctrine of the Artificial Days and Nights , is contained in the following Theorems . 1. The Artificial Days and Nights , with the Amphiscii , Heteroscii , and partly with the Periscii , are parts of the Natural Day : but with the Periscii , in those parts of the Earth , wherein the Sun , by the going about of the Primum Mobile , perfects some Circumgyrations , either above the Horizon , without setting , or under the Horizon , without rising , one Artificial Day , or one Artificial Night , doth excresce into many Natural Days ; so that indeed under the Poles , the Artificial Day contains half a Year , and the Artificial Night as much ; and so to speak properly , the whole Year consists but of one Day , men looking to the Analogy of the Natural Day . 2. Under a Right Sphere , the Artificial Day , is equal to the Night : for the Horizon , in this Position of the Sphere , cuts the Circuli Dierum , the Day-Circles , into two equal parts . The Day-Circles , are called those Parallels of the Equator which the Sun doth dayly describe , by the Motion of the Primum Mobile . 3. In an Oblique Sphere , there are only twice a Year , two Equinoxes , when the Sun is in the beginning of Aries and Libra . The Reason of this appears , from the mutual Section of the Horizon , with the Circuli Dierum , or Day-Circles , which is indeed unequal , except when the Sun is in the Equinoctial . 4. In an Oblique Sphere , which hath the vicissitude of the Artificial , and Natural Day , by one Revolution of the Equator , the Sun being in the. Tropick of Cancer ( we are now speaking of this uppermost part of the Sphere ) we have the longest Day in all the Year , and the shortest Night : but the Sun being in the Winter Solstice , the Day is shortest , and the Night longest . 5. In the same Position of the Sphere , thorow the whole half of the Ecliptick descending , the Sun maketh the following Days shorter , than the Days going before , but the Nights longer . But in the half of the Ecliptick ascending , the Sun maketh the Days following longer , than the Days going before , but the Nights shorter . 6. When the Sun is existing , in places of the Ecliptick , equally distant , from the same Solstitial Point , Days are equal to Days , and Nights to Nights . 7. When the Sun is existing in places of the Ecliptick equally distant , from the same Equinoctial Point , the Day of one Place , is equal to the Night of another . 8. In an Oblique Position of the Sphere , the greater the Elevation of the Pole is , the greater are the increments of the longest Day , and shortest Night , until coming under the Polars , the longest Day contains twenty and four Hours . 9. In an Oblique Sphere , of such as dwell between the Polar , and next Pole , the longest Day excresceth into many Natural Days , as also the longest Night . But there are certain intermediat Horary Circles , a part of which is above the Horizon , and a part under , in which , when the Sun is existing , the Artificial Days , as also the Nights , are ▪ parts of the Natural Day . 10. In a Parallel Sphere , such as they have , who live under the Poles , the whole Year , is divided into one Artificial Day , and one Artificial Night . The length of every Artificial Day , is known by the Diurnal , and Nocturnal Arch. First , find the Oblique Ascension or Point of the Equinoctial , which riseth with the Sun , and Oblique Descension , or Point of the Equinoctial , which setteth with the Sun. Subtract the lesser from the greater , and half the difference , is the Ascensional difference , which added to six Hours in the Summer half Year , but subtracted therefrom in the Winter half Year , gives half the Diurnal Arch , whose double is the whole Diurnal Arch , and the Complement of the Diurnal Arch to 24 Hours , is the Nocturnal Arch. For Example , The tenth day of April 1687 , the Oblique Ascension of the Sun ( being in the first Degree of Taurus ) is 10 deg . 21. m. the Oblique Descension is 45 deg . 27 m. whose difference is 35 deg . 6. m. whose half is 17 deg . 33 m. the Ascensional difference , which being added to 90 deg . or 6 Hours , is 107 deg . 33 m. which make 7 hours , 10 m. fere , for the time of the Suns setting , which is always half the Diurnal Arch. Therefore the Diurnal Arch is 14 hours , 20 m. Which taken from 24 hours , there remains 9 hours , 40 m. for the Nocturnal Arch required . Note , That the Ascensional difference added to the Oblique Ascension in the Summer half Year , but subtracted from it , in the Winter half Year , gives the right Ascension of the Sun , or any of the Stars . What is said of the Day in respect of the Sun , may be most commodiously applyed to the Stars . For the Day of a Star , is rightly called the space of Time , wherein it is above the Horizon : and the Night of a Star , the space of Time , wherein it is below the Horizon . Concerning the days of the fixed Stars , let the following Theorems be observed . 1. In a Right Sphere , the Stars have a perpetual Equinox . 2. But in an Oblique Sphere , the fixed Stars , whose North Declination , is greater than the Complement of the Altitude of the Pole , are said to have an Eternal Day : but those Stars , whose South Declination , exceeds the Complement of the Altitude of the Pole , are said to have an Eternal Night . The intermediate Stars , have the course of rising and setting . 3. In a Parallel Sphere , the fixed Stars are said to have Eternal Days , and Eternal Nights . Days Civil , are called the space of Time , of one Revolution of the Equinoctial , which according to every Nation , or Countrey , is divers ways begun , and made use of . For as there are various and divers Nations in the World , so each one hath a different way of beginning their Hours . For the Iews , by Divine Institution , began their Day , from the setting of the Sun , which custom the Italians do observe . The Babylonians began their Day from Sun rising , whose practice , the Norinbergers , the People called the Umbri , and the Egyptians do imitate . The Arabians as the Astronomers , begin their Day from the Meridian . The Romans from Midnight . The Germans , the Frenches , and Spainards begin their Day from the Meridian , and Mid-night . For their Clocks , and Watches are so contrived , that they return from one a Clock in the Night-time , to twelve a Clock in the Day-time , and from one a Clock in the Day-time , to twelve a Clock at Night-time . Their Days are divided , as the Astronomical Days , into one Artificial Day , and likewise into Forenoon , and Afternoon . And because Hours are parts of the Days , therefore we must speak a little of them . The Hour is the twentieth and fourth part of the Natural Day , or the space of Time , wherein the twentieth and fourth part of the Equinoctial , or 15 Degrees thereof , riseth above the Horizon . But this Definition is not sufficient , because it doth not agree to all Hours : for every twelfth part of every Day , and every Night whatsoever , was called by the Iews , and the Antients an Hour . But 15 Degrees of the Equinoctial , do not always ascend above the Horizon , every one of these Hours ; but sometimes more , and sometimes fewer , as will appear afterward . Therefore , an Hour may rather be defined thus , a certain part of the Artificial Day , and Night , made use of by divers Nations , after a divers manner , that it may be known generally , what the Hour is . For in effect , that definition agrees only to to those Hours , which are called Hor●… Aequales , equal Hours . The Hours then , which are called unequal , ought to be defined thus . The twelfth part of every Artificial Day and Night : therefore according to the divers Seasons of the Year , the Hours are sometimes shorter , and sometimes longer : in Summer longer , and in Winter shorter , as are th●… Iewish Hours : for they divide both the Day , and the Night into twelve parts , both in Summer and in Winter , calling the rising of the Sun , the beginning of the first Hour , and consequently nine their third Hour ; twelve their sixth Hour , three a Clock in the Afternoon their ninth Hour , and the setting of the Sun , the end of their twelfth Hour , by which means , their Hours must be far longer in Summer , than in Winter . The equal Hours are of three sorts : for some take their beginning from the setting of the Sun , as the Italian Hours . Others take their beginning from the rising of the Sun , as are the Babylonish Hours , and the Hours of the City of Norimberg , who from the rising of the Sun begin the number of the Hours of the Day ; the Circles of which Hours do lightly touch the greatest Parallels , of all , which do appear above the Horizon , and of all which do not appear . Lastly , Others do take their beginning from the Meridian , which Astronomers make use of , and these Nations , which either take their beginning of Hours from the superior part of the same Circle , or from the inferior part . CHAP. XIII . Concerning Years . AS Hours make up Days , so Days make up Years , therefore we must speak somewhat of Years . The Year then is twofold , Astronomical , and Political . The Astronomical Year , is the space of Time , wherein the Sun returns , either to the same Point of the Ecliptick , or to the same fixed Star. And this is twofold , the Tropical Year , called Annus Vertens , or the Syderial Year . Annus Vertens , is a space of Time , wherein the Sun leaving some Point of the Ecliptick , returns again to the same Point . The quantity of this Year is changeable ; for sometimes it is more , and sometimes it is less . Between these two extreams , the middle Year contains 365 days , hours 5 , m. 49 , sec. 15. thirds 46. But the true or apparent Year is sometimes 365 days ▪ hours 5 , min. 56. sec. 53 , thirds 1. Sometime it is 365 days , hours 5 , min. 42 , sec. 28 , thirds 27. The Syderial Year , is a space of Time , wherein the Sun under the Starry Sky , returns to the same fixed Star. The quantity of this Year is 365 days , hours 6 , min. 6 , sec. 39. It is always equal to it self , and therefore the measure of the Year called Annus Vertens . The beginning of this Annus Vertens , is taken from the Vernal Equinox , but the beginning of the Syderial Year , from the first Star of Aries . The Political Year , is an Annual space of Time , which is either accommodated to the course of the Sun , or the Moon , or to both , according to the common reckoning of several Countries and Nations . This Political Year is manifold ; for it is either Iulian , which contains 365 days , hours 6 , which six Hours , if they were reckoned every Year , would make confusion : therefore the Masters of Astronomy have appointed , they should be omitted , till the fourth Year , and then four times six , make 24 , which make up a full and compleat Day , which being inter caled , that is , interlaced , or put between , as in Leap Year there is a Day put between the 28 of February , and the first of March , the Year is called Annus Intercalaris , or Bissextile Year . It is to be adverted , that the cause of correcting the Iulian Calendar , by Pope Gregory the 13 , in the year 1582 , was the unjust quantity of it . For by this , it came to pass , that after some Ages , the four Cardinal Points did anticipate and prevent their Seats ; and so at length the four Seasons of the Year , might be interchanged . From this it is evident this Day , that according to these times , the Equinoctial , and the Ingress of the Sun into the 12 Signs have anticipated almost 13 Degrees . That is , the entering of the Sun , into Aries , Taurus , &c. falleth out sooner by 13 Degrees , than to the Romans : which comes to pass , because more , than what is just , is given to the space of the Year . For there were given to the Year , by the correction of Iulius Cesar , 365 days , and six hours : for which hours , every fourth year , one day is added , and so the common Iulian year contains 365 days , but the Bissextile 366. But seing the Solar year , in which the Sun runs thorow the whole Ecliptick , is less than this space , by almost eleven Minuts of Time every Year ; it comes to pass , that in 50 year , and a half , one hour remains , and in the space of 130 years , a whole day remains . I said the Political Year , was manifold , either Iulian , of which hitherto , or Egyptian , or Iudaical . The Egyptian year contains always 365 days . This Year was esteemed most useful by the antient Astronomers , for the Art of reckoning the Celestial Motions . The Iudaical Year is accommodated and fitted to the Motion of the Moon , and contains , for the greatest part , twelve , and sometimes thirteen Lunations . This Year did the Astronomers use , before the reformation of the Calendar , instituted by Iulius Cesar , by the help of one Sosigenes , a famous and learned Mathematician . The beginning of these Years is divers also . For the antient Romans , began their Year from March : the later Romans from the midst of Winter , called Bruma . The Iews , by Divine Institution , began their Year from the New Moon , which was next after to the Vernal Equinox . That we this day begin our Year from the first of Ianuary , it is for this , because we following the custom of the late Romans , beginning their Year from the midst of Winter , which was nearest to the first of Ianuary , by little and little the Winter Solstice did prevent , and anticipat its Seat , and Place . The Egyptian year , hath not a sure beginning , by reason that six hours are omitted . Hence is it , that every fourth Year it anticipats one Day : and therefore within 365 Years , four times numbered , or 1460 Iulian Years , the beginning of the Egyptian Year , wanders over all the Days of the Iulian Year . CHAP. XIV . Concerning the divers Phenomena , which are to be seen in the various Positions of the Sphere . THe last part of this little Tractat , shall be in examining the Phenomena , which are proper to the various Situations , and Positions of the Sphere . The Sphere may have seven different Positions , 1. When both the Poles of the World do rest in the Horizon , which is called a Right Sphere . The second Position is Oblique , when our Vertical Point , is terminated between the Equinoctial , and either of the Tropicks . The third Position is , when our Zenith is under either of the Tropicks . The fourth is , when our Zenith is between either of the Tropicks , and the neighbouring Polar . The fifth is , when our Zenith is in the very Polar itself . The sixth is , when our Zenith is between either of the Polars , and the neighbouring Pole of the World. And lastly , when the Poles of the World , do fall in with the Poles of the Horizon , which is called a Parallel Sphere . CHAP. XV. Concerning the Phenomena of the first Position . 1. EVery Star in the Heavens riseth and setteth , neither is there one of them , without this property : and therefore in this Position , there is neither Polar Artick , nor Antartick , according to the Antients . 2. There is here a perpetual Equinox . 3. The Sun every Year passing twice over their Heads , is to them twice Vertical , to wit , when he is in the Equinoctial Points . 4. As much , as the Sun declines from their Vertical Point , towards the North , as much also doth he decline from their Vertical Point , towards the South . 5. They have four Solstices , two when the Sun is highest in their Vertical Point , and two , when he is lowest , in Cancer , and Capricorn . 6. They have two Summers and two Winters , but only Analogically : for even in Winter , their Bodies are scorched with heat . 7. There are here in this Position , five different Shadows , the Meridional , or South Shadow , the North Shadow , a Shadow from the East , a Shadow from the West , and a perpendicular Shadow , which falls out only , when the Sun is in the Equinoctial Points . 8. The end or extremity of their Gnomons , upon their Horizontal Dialls , which are our Polar Dialls , describe the whole Year , the Figure called Hyperbole , except when the Sun , is in the beginning of Aries and Libra , where he describes a straight and right Line . CHAP. XVI . Of the Phenomena of the second Position ▪ 1. SOme Northern Stars tarrying always above our Horizon , have Eternal Days ; and contrariwise , there are some about the South Pole , which never come above the Horizon , but have Eternal Nights . 2. The Artick , and Antartick Circles , according to the Antients , are not as yet equal to our Polars . 3. The Artificial Day is not equal to its own Night , two Days only excepted , when the Sun is in the Equinoctial Points , at which time , there is thorow the whole World an Equinox . 4. The longest Day there , doth not exceed thirteen Hours and a half . 5. The Sun is to them , twice Vertical every Year , to wit , when he comes to those Degrees of the Ecliptick , whose Declination , is equal to the Latitude of the Place ; for he describes then , a Parallel thorow the Zenith . 6. The Sun in the Meridian , goeth further towards the South , than towards the North. Note , That we are now speaking , and in the following Discourse , of those seven Positions , which are in the Northern Sphere . 7. There are here , four Solstices , two high , and two low . The two highest fall out , when the Sun is in that Parallel , which passeth thorow the Zenith . The two lowest are , when the Sun is in the Tropicks . Yet that which falls out in the Tropick of Capricorn , is lower , than that which falls out in the Tropick of Cancer . 8. They have two Summers , and two Winters , but unequal , as appears from the various Situation of the Parallels . 9. The longest Day is not , when the Sun is in the highest Solstices , but in the Tropick of Cancer . 10. There are five different Shadows , as we observed in the first Position . 11. The end or extremity of the Gnomon , by its Shadow , when the Sun is out of the Equinoctial , describes ( as in the first Position ) the Figure called Hyperbole , but the opposite sides are not equal as there , but unequal . 12. In any part of this Position , where the Elevation of the Pole , is less , than the Declination of the Sun , the Shadow of a Style perpendicularly erected upon a Plain , may have a natural , visible , Retrocession . In the matter of Ahaz his Dial , the Retrogradation of the Shadow was miraculous , because it was done without , and not within the Tropicks , neither is it possible in nature , it can happen , but where the Elevation of the Pole , is less than the Suns Declination , which is only within the Tropicks . But the foresaid Dial was placed far without , to wit , under the Latitude of 35 Degrees . CHAP. XVII . Of the Phenomena of the third Position . 1. ALL the Stars , which are comprehended within the North Polar , remain always above the Horizon , neither do they ever set , unless it be , by a general setting Heliace : and contrariwise , all the Stars , which are comprehended within the South Polar , have a perpetual Night ▪ therefore the Polars , according to the Antients , are now equal to our Polars . 2. The longest Artificial Day is , when the Sun passeth over our Zenith ; the shortest , when the Sun is farthest in the Meridian removed from it . 3. Once a Year only is the Sun Vertical , to wit , when he is in the beginning of Cancer . 4. The Sun in the Meridian , never descendeth from the Zenith towards the North , but returning from the Tropick of Cancer , he is alway in the South . 5. There are here , but two Solstices , one high , another low . The highest , when the Sun is in the Tropick of Cancer ; the lowest when the Sun is in the Tropick of Capricorn . 6. The Day is longest , when the Sun is in the Tropick of Cancer , it is shortest when the Sun is in the Tropick of Capricorn . 7. There is one Summer , when the Sun is in the Zenith , and one Winter , when he is in the Winter Solstice . 8. They have four different Shadows , one Perpendicular , one Oriental , one Occidental , and one Meridional . Here begin the Heteroscii , for the Meridional Shadows begin there to decay , that is , the Shadows projected towards the South . 9. The extremity or end of their Gnomon , upon their Dials , describe also the Figure called Hyperbole , the sides opposite being unequal . CHAP. XVIII . Of the Phenomena of the fourth Position . AS the Artick and Antartick of the Antients , are greater than our Polars , so there are more Stars in this Position of the Sphere , seen perpetually , and more perpetually lurking under the Horizon , than in the last Position . 2. The unequality of Days and Nights , are also augmented . The Artificial Day is at the longest , when the Sun comes nearest to our Zenith , and at the shortest , when he is furthest removed from it : and as the shortest Artificial Day cannot be less , than 13 Hours and a half , so the longest Day cannot be 24 Hours . This least Artificial Day , is truly the longest Day , our Vertical Point coming nearest to the Tropick . It is called the least Artificial Day , because it is the shortest of all the longest Days , which can arise from the variation of the Vertical Point , between the Tropick and the Polar : and therefore , itis not called Minima the least , in respect of the rest of the days of the same Elevation of the Pole , but in respect of the rest of the longest Days , which may be found between the Tropick and Polar . The longest Day in this fourth Position of the Sphere , the Zenith coming nearest to our Tropick , cannot be less , than 13 Hours and a half , as the longest Day cannot contain 24 Hours . For this comes to pass , when the Zenith is in the Polar : therefore we must read , as the shortest Artificial longest Day , cannot be less , than 13 Hours and a half , &c. 3. The Sun can never come to their Zenith , neither can he ever touch lightly ( stringere ) their Horizon , when he is in the Meridian . 4. There are two Solstices , one when the Sun is in Cancer , and highest , another lowest , when he is in the Tropick of Capricorn . 5. There is one Summer , and one Winter . 6. There are only three different Shadows , one Oriental , the second Occidental , and the third Northern . 7. The extremity or end of their Gnomons , fixed upon the Ground perpendicularly , describe as yet Hyperboles . CHAP. XIX . Of the Phenomena of the fifth Position . ALL the Stars , whose distance from the Equinoctial , is greater than the Obliquity of the Ecliptick , either do not set under the Horizon , if they be Northern Stars , and do not rise above the Horizon , if they be Southern Stars : Therefore the Artick , and Antartick of the Antients are equal to the Tropicks . 2. The longest Day contains 24 Hours , and then there is no Night : and contrariwise , the longest Night consists of twenty and four Hours , and the Artificial shortest Day is nothing . 3. The Sun every year toucheth lightly the border of the Horizon twice , without rising and setting , namely when he is in the Tropicks . 4. The Sun at twelve a Clock in the Day , is alway South , nevertheless , when he is in the Tropick of Cancer , the half of his Body may be seen in the North , at 12 a Clock at Night . 5. There are here two Solstices , one high in Cancer , the other low in Capricorn . But according to the similitude of Solstices , which are in other Zones , we may say there are three Solstices there , one high in Cancer , when the Sun is high in the Meridian , to wit , 47 Degrees above the Horizon , which is the distance of the Tropicks ; there are two lower , of which one is in the same Tropick of Cancer towards the North , when he toucheth lightly the border of the Horizon , the other in the Tropick of Capricorn , where he also lightly toucheth the border of the Horizon . 6. There is one Summer , and one Winter . 7. There are four different Shadows ; one Eastern , one Western , one Northern , and one Southern ; tho this happens but once a Year , the Sun shineing with the half only of his Rays , which makes the light more obscure and dark , than when he shines with his full Rays . Here begin the Heteroscii . 8. The extremity or ends of the Gnomons , describe the Figure called Parabola , upon the Horizontal Dials , but an Hyperbole , so soon , as the Sun is gone from the Equinoctial , whereas on all other Plains , he describes always straight and right Lines . CHAP. XX. Of the Phenomena of the sixth Position . THere are very few Stars , which can rise or set , to wit , those only , whose Declination is less than the distance of the Tropicks ; because the Artick , and Antartick Circles , comprehending within them , the Stars which do set , and do not set , are greater than the Tropicks . 2. They have an Equinoctial , as other parts of the Earth . But when the Sun is in that Parallel whose Declination from the Equinoctial , is equal to the distance of the Poles of the World from the Zenith , the Day is twenty and four Hours , and the Artificial Day excresceth , and shoots out , into many Natural Days . 3. The Sun being in the same Parallel , he lightly toucheth , the border of the Horizon , and coming to it , she shines only with an half Orb. 4. They have but only one Solstice , in the Tropick of Cancer ; for the other in the Tropick of Capricorn cannot be seen . But Analogically , and ●…n similitude there are six Solstices . Two high , when the Sun is in the Tropick of Cancer : for there , as well to the ●…outh , as to the North , the hight of ●…he Sun in the Meridian is highest , al●…eit the Northern be greater than the ●…outhern : and four lowest , when the ●…he Sun toucheth lightly the Horizon . ●… . They have one Summer , and one ●…inter , but their Summer may be so ●…alled only Analogically : for these ●…laces of the Earth , are perpetually stiff ●…ith Snow and Yce . 6. They have four different Shadows , one from the East , one from the West , one from the South , and one from the North. Here are the Periscii . 7. The Gnomons , and stiles of their Dials , describes with their Points , Elliptical Figures . CHAP. XXI . Of the Phenomena of the seventh and last Position . 1. THere are here no Stars , which either rise or set , but all of them are whirled about , equally distant from the Horizon . The Artick and Antartick Circles , are one and the same with the Horizon , and Equinoctial , which are now united . Understand this of the fixed Stars only ; for the Planets absolving their course , rise and set , in their appointed times . 2. The Artificial Day is extended to half a Year ; so is the Artificial Night , and therefore the quantity of the Natural Day , and the whole Year is one and the same . 3. When the Sun is in the Equinoctial , he shines only with half his Orb , and toucheth lightly the Horizon , and there he riseth and setteth only at those times . 4. No point of the Heavens , can be called , either West , East , South or North , seing the Pole of the World doth not incline to any part of the Horizon , by which Inclination the four Points of the Universe , have their distinction . 5. They have only one Solstice , to wit , in Cancer , but Analogically two other may be added , to wit , when the Sun is in the beginning of Aries , and Libra . 6. There is one Summer and one Winter : but their Summer is rather to be called a slender slaking of the Cold. They have one Winter , because the Sun is under their Horizon a whole half Year together . 7. The Gnomons of their Dials , describe with the extremity of the Shadow , upon an Horizontal Plain , perfect Circles . FINIS . Proteus Bound with Chains : OR , A Discovery of the Secrets of Nature , which are found in the Mercurial-Weather-Glass , unfolding the Reasons , and Causes , why before Fair Weather the Quicksilver Ascends , and before Foul Weather , it falls down , and Descends . A Subject not hitherto Treated of . TOGETHER With some brief Observes upon the Parisian Weather-Glass , and an Explanation of the Sealed Weather-Glass , and common Weather-Glass . To all which is Added The Theory of the Weather , according to the Perpendicular Weather-Glass . By GEORGE SINCLAR , sometime Professor of Philosophy in the Colledge of GLASGOW . Felix qui potuit rerum cognoscere causas . Edinburgh , Printed by the Heir of Andrew Anderson , Printer to His most Sacred Majesty , Anno Dom. 1688. Proteus bound with Chains : OR , A Discovery of the Secrets of Nature , which are found in the Mercurial Weather-Glass , &c. THere are many excellent Questions to be Refolved , and Causes of the various Phenomena of Nature to be rendred , before a man can have knowledge to mount the Mercurial-Weather-Glass . Yet there are many , who rashly adventure , and bring upon that unerring and infallible Master-piece of Nature , the scandalous and odious Character of Falibility , either by raising the Mercury too high , or fixing it too low in the Cylindrical-Glass , both which Extreams must be cautiously shunned . For if it be not ordered according to the Authentick Observations of the Weather for many Years past , it cannot but err . And herein its infallibility and perfection consists , to give the Theory of the Weather a just and determinate hight , according to long Observation , and by consequence the top of the Cylinder the same hight , none of which no ignorant person can do . The Questions to be resolved , are such as follow , 1. What sustains the Mercury in the Glass-Tube , whilst the Orifice is always downward , and open ? 2. Why the Glass must exceed in length , one and thirty Inch ? 3. Why the Mercury falls not down , if it be shorter than twenty and eight ? 4. Why the Mercury is carried up with violence to the top of the Glass-Tube , whilst the Orifice is raised above the surface of the stagnant Mercury ? 5. Why as much Mercury in hight , is sustained in the wide Glass , as in the narrow ? 6. Why , tho the Glass were in hight many Foot , yet the whole Mercury falls down to twenty and nine , or thirty Inch above the Cistern ? 7. What fills up the space left empty behind ? 8. Why the Mercury subsides by degrees , as the Weather-Glass is carried up some high Mountain , and why it rises again , as it is carried down ? 9. Why a Glass of thirty six Foot high is required to make a Weather Glass with Water in it ? 10. What 's the reason , I do not find the weight of the Mercury within the Glass , whilst I poise it between my Fingers , and yet I find another weight exactly the weight of it ? 11. What that other weight is ? All these and many more are fully and clearly resolved in my Philosophical Experiments twenty years ago . But there is a late Question , which troubleth all the Learned to resolve , which now I intend shortly to explain , viz. What 's the reason , why the Quicksilver in the Weather-Glass creeps up before Fair Weather , and falls down before Foul Weather ? For an answer to this considerable Question , it is to be observed , that in the foulest Weather , I have found the Quicksilver fall down to twenty and eight , and in the dryest , and fairest Weather , I have found it up at thirty and one Inch. From this excellent Phenomenon only , it is called the Weather-Glass , Kat'exohen , by way of excellency : because before this alteration was found in it , it was called by the most part of Philosophers , the Torricellian Experiment . For clearing the Question in hand , I suppose that in the Beginning , there went up a Damp from the Earth to water the whole face of the Ground . Moses ( Gen. 2. ) relates now the ordinary means appointed by God in Nature , for bringing forth of Herbs , Bushes , and Trees out of the Ground , viz. the Damp , which causeth the Rain , and moistneth the Earth , which Damp being by the heat of the Sun rarified , ascendeth to the middle Region of the Air , where by means of the coldness thereof , these Vapors are condensat , and thickned , and tur●…d into a Cloud , and afterward are turned into Rain , and so fall down . That there are such Damps and Vapors , which ascend from the Earth , and Waters , cannot rationally be denyed ; nay many Thousands and Millions of them ascend , which we do not see nor observe . I have seen in Frosty Mornings the mouths of Coal-sinks , and empty passages from waste Ground , where Coals have been digged out , Fumes and Vapors coming out so plentifully , as Fumes from a Salt-pan . Some do fitly compare this Earth to a Bag-pudding , taken out of a Boiling-pot , which sends forth Vapors in abundance . Likewise from the surfaces of standing and running Water , what numbers may be seen in a warm Summers Evening . Nay from the Bodies of Men and Beasts , there is a perpetual Perspiration . But the finest and purest of all , are those which are exhaled from the Earth , and Waters . We see , that when the Sun is hot in Summer , the whole face of the Ground after Rain , covered over with Unduls , or little curled Waves , a small Gale of Wind being stirring , like unto the curled Waves of the Sea , Analogically . And so slender and pure are they , that whilst a man is among them , he cannot see them , but at a distance he may , looking alongs the face of the Ground . Likewise what multitudes of them may be seen alongs the surface of the Sea , a man standing at a considerable distance from the Coast. And so thick are they , that they have wonderfully lifted up , and magnified , much of the Land , and have made it appear , far otherwise than it was ; nay , eclipsed whole Villages and Towns , and metamorphosed them into various shapes and forms , all which have come to pass , by reason of their multiplicity and thickness . Now these Vapors , flowing from the Earth and Waters , are carried up to the middle Region of the Air , where by process of time , they are condensat , and thickned , by the coldness thereof , and fall down in Rain . But here it may be inquired , By what cause , ●…r power , are these Vapors carried up , seing they are Material things , and endued with weight ? For answer , I must premit some few things , which do not ordinarly occur . First , That in all heavy Bodies , there is a twofold weight , one Specifical , the other Individual . The Specifical weight is found in Bodies , which differ by Nature , as Wood , and Stone , ballanced one with another , equal quantity with equal quantity . ●… Individual weight , is likewise found in the same Bodies , but after a different way and manner . For example , Stone is naturally , or specifically heavier than Wood , putting equal quantity against equal quantity ; for a Cubical-foot of Stone , is heavier , than a Cubical-foot of Water . Bodies of the same Individual weight , or such as are weighed in a pair of Scales , as a Pound of Lead , and a Pound of Wool , are individually of the same weight , but of different weight Specifically . Secondly , There are two sorts of Ballances , the one Natural , the other Artificial . The Natural Ballance , is the Mercurial Weather-Glass , wherein the Mercury counterpoiseth the Air , and the Air the Mercury , both of them observing an equal Altitude , according to their natural weights : for since the Mercury is reckoned 14000 times heavier than the Air , the pillar of the one must be 14000 times lower than the other ; and so both are of the same hight , according to their Specifical weights . The Artificial Ballance , is that Mechanical Power , called the Libra . Thirdly , That one Body naturally lighter than another , may become of equal weight , or heavier , than that other . For example , the Vapors , which ascend are far lighter specifically , than the Air , yet they become heavier specifically , when contracted , and reduced by a Cold , to a thicker habit , or consistency , and most of all when they are converted to Rain . But how shall it be known , that the Vapors are naturally lighter , than the Air ? I answer , If it were possible to take an equal quantity of Vapors , with an equal quantity of Air , and weigh them in a Ballance , the Air would be heavier . We know that Oil is lighter than Water , for being put under Water , it riseth to the Surface : so the Vapors go up thorow the Air , as Oil goeth up thorow the Water . Now I come to the Question in hand , and I affirm , that the Vapors are carried upward , not by the heat of the Sun , which is an vulgar error , but they being specifically , and naturally lighter , than the Air , are prest up by it , as Smoak , till they come so far up , as the pressure of the Air , is able to carry them . I shall make this evident , by the following Experiment . Let a Diver go down to the bottom of the Sea , with a Bottle of Oil in his Hand , and pour it out there , he shall find , that such is the pressure of the Water , it shall drive it all up to the Surface above . For as the Oil is naturally lighter than the Water , so these Vapors are naturally lighter than the Air. Now these Vapors , which are infinite in number , ascending from all the parts of the Earth , to the Atmosphere many Miles above the Clouds , causeth the Air here below press with greater weight , upon the stagnant Mercury , and so raiseth the Quicksilver in the Weather Glass , one Inch or two , and sometimes three : for it is not possible , that the Air above , can be prest down , and burdened , with that new weight , and addition of Vapors ascending , but the stagnant Mercury below must find the said pressure . But how are these Vapors condensat and thickned together , and fall down in Rain ▪ I shall do this , by a most evident , and clear example . We cannot more fitly compare these Vapors , ascending and descending again in Rain , than to an Alembick , or Distillater . For these Fumes being carried upward within the Pot , and meeting with a cold Receptacle ( for the Pipe descending goeth ordinarly thorow a Vessel full of cold Water ) they are presently reduced , to their first condition , and fall down in Liquor . So are the Vapors , which ascend from the Stomach to the cold Brain received and distilled . But why should the falling down of the Rain cause the Quicksilver fall down , and why should the rising of the Vapors , cause the Quicksilver to rise ? For clearing of this , it is to be adverted , that whilst the Mercury is up at one and thirty Inch , there is an equal ballance or weight between the weight of the Atmosphere and the weight of the Quicksilver , so that there cannot be the least weight subtracted from the pressure of the Atmosphere , but as much must be subtracted , from the hight of the Quicksilver : as by taking away one Ounce from this Scale of a Ballance , the other presently goeth down , or by adding one Ounce to this Scale of a Ballance , the other Scale presently goeth up . Hence is it , that the pressure of the Atmosphere becomes less , by the falling down of the Vapors , and consequently the hight of the Quicksilver , must decresce also . And contrariwise ( which clears the second part of the Question ) whilst the Vapors are ascending , and going up , the Atmosphere is more burdened , and by consequence the Quicksilver riseth , sometimes less , and sometimes more , sometimes one Inch , sometimes two or three . But how comes it to pass , that the whole Air , or that great and vast bulk of it , can be in equal weight , with so small a portion of Quicksilver , granting the Air to be so heavy , as is commonly reported ? I answer , It is not the Air according to its thickness , or bulk , which makes any counterballance with the Quicksilver , but it is the Air reckoned according to hight , because Fluid Bodies do not counterpoise one another , according to all their dimensions , but only according to Altitude ; this is only proper to Solid Bodies . For let never so much weight be added to the Air in thickness , itshall never make the least alteration in the Mercury . But if there be but the least addition made in hight , the Quicksilver presently knows it , by rising and falling accordingly . For by how many thousand times the Air is specifically lighter than Quicksilver , by so many thousand times is the pillar of Air , higher than the pillar of Quicksilver . And contrariwise , by how many thousand times the Quicksilver is naturally heavier than the Air , by so many thousand times must the Cylinder of Quicksilver , be shorter than the Cylinder of Air , which sustains it . The proportion is ordinarly reckoned as 1 to 14000. That is to say , one Cubick-Inch of Quicksilver counterpoiseth 14000 Cubick-Inches of Air , both being put into a Ballance . It is evident from this , and many other things , that there is a proportion observed in all the Works of Nature , as here between the hight of the Atmospere , and the hight of the Quicksilver : for all the Lords Works , are made in Weight , Measure , and Number . This truth is so evident in the Mathematical part of Learning , that there is no need of proof . And if this proportion be not observed in things Artificial , viz. by Architects and Builders of Houses , the whole Fabrick looks pitifully , and wants that face , and delicate aspect , it ought to have . And as the most wise Artist of the World , hath created all things in proportion one to another , so all the parts of his Holy Word , are in such a proportion one to another . For this we have Scripture , and Divine Authority : for it is said , Whether we prophesie , let us prophesie according to the proportion of Faith. The Original word is , Analogia Pisteos , well rendered in our Vulgar Language , the proportion of Faith , or Analogy of Faith , not as some , the Measure of Faith. GOD is not tied to Numbers , yet nevertheless , he doth and disposeth his Works , by Number , Weight , and Measure . It is observed , that after the going up out of Egypt , GOD caused to be numbred all the Israelites , from the Age of twenty years and upward , ( Exod. 38. 26. ) and there were found six hundred three thousand five hundred and fifty men . The year following , GOD commanded to make a second Review of the People , ( Numb . 1. 46. ) but without comprising the Levites , which had been numbred the first time with the other Tribes . Notwithstanding this Subtraction , and the Casualities , which might have changed the number of the People , since the year foregoing , it is found that their number was yet justly and precisely six hundred three thousand five hundred and fifty men . In which is seen a proportion which GOD held in the multiplication of that People . There is also observed a Mystery in the exact number of the two and twenty thousand Levites , which were then reckoned ( Numb . 3. 39. ) For the rest , I contend not against the common opinion , touching the hundred fourty and four thousand of the seventh of the Revelation , that they ought to be taken for an indefinite number , as well as the seven thousand which had not bowed the Knee to Baal . But it ought to be considered , why the Holy Ghost , who speaketh nothing superfluous , is not contented to have named the total sum of them , that were sealed in Israel , but also divideth it , in twelve times twelve thousand , distributed by equal portions among the twelve Tribes , every one of which is mentioned , the one after the other , with the expression of its particular number : for this sheweth , that the number of the Elect , and the multitude of Believers , are measured by certain proportions , which are known to him , who is the Author . Certainly , the resemblance of the seventy Disciples of Christ , to the seventy Judges , which were substituted to Moses , and to the seventy Children , which Iacob had when he went down into Egypt , is a line of this admirable Symmetry , with the which God hath limited , and proportioned the Body of the Church . Now this fortifieth that Maxime , that the number of the Elect cannot suffer addition , nor diminution : and that Election proceedeth not , from the Will of the Elect , but that of God , which prevented them . For it cannot be said , that all the Elect , from the beginning of the World to the end , have agreed together to make a Company composed precisely of a number certain and regular . But I return . It may be here inquired , Whether those Vapors , and Exhalations go perpetually up from the Earth , or not ? 'T is probable , that they are alway ascending , tho insensibly to us , and as many of them in the Night , as in the Day-time . Nay , more ( it seems ) in extream Frost and Cold Weather , than at any other time ; as we see in Greenland , where the greatest extremity of Cold is , there are infinite Treasures of Snow , which Snow could not fall down so plentifully , if there were not Vapors perpetually ascending . Next , after Rain , and the falling down of the Mercury to 28 , or 29 Inch , I have found the ascent of it , in that same Night eight or ten Degrees , which could not happen , unless there had been an addition of new weight to the Atmosphere . And this is observed , to be rather in the Winter , than in the Summer Season , especially in calm Nights . I have observed , that the next Morning after Frost all the Night , the standing Waters in Furrows , which have remained many Days entire , dry up , and nothing remaining , but emptiness below a surface of thin white Y●…e . This Water could not sink into the Ground , more that Night , than many others before ; but the Frost coming on , and the Air becoming dry have turned all the Waters into Vapors , and so have been exhaled . I would have it made more evident , how the greater pressure of the Atmospere by the weight of these Vapors make the Quicksilver rise in the Weather-Glass ? I answer , Take the Weather-Glass , and place it within a dry Harbour , before the Water begin to flow . Then suppose the hight of the Mercury to be eight and twenty Inch. I say , when once the Water hath flowed , but three Foot and a half in hight , above the stagnant Mercury in the Cistern you will find the Mercury in the Weather-Glass three Inch higher . For as the growing of the Tide above the stagnant Mercury raiseth it higher , and higher in the Glass , so the ascending of the Vapors loadneth the Atmosphere , more and more , and consequently it presseth with more weight upon the Mercury in the Cistern . And as the Vapors are turned into Rain , and the Mercury falls down ; so by the ebbing of the Water , the three Inch of Mercury , falls down within the Weather-Glass . It may be inquired , How far do these Vapors ascend ? I answer , That Philosphers distinguish the Air into three Regions , the first , second , and third . But both Philosphers and Astronomers do vary exceedingly in determining the hight of any of them . I shall not curiously inquire , but shall speak a little to what concerns the present purpose . 'T is probable , that these thin and light Vapors , which flow out of the Earth and Waters , go many Miles above the Clouds , where there is neither Wind nor Rain : for the pressure of the Air being powerful many Miles up , must carry the Vapors , so far up . But to determine particularly , it is not possible , only in general they ascend very far . Now it is evident , that the Atmosphere , is composed , and consists of such Vapors being called Sphaera halituum , which no doubt , is of a considerable thickness , and hight . These Vapors , when they are once past the inferior Region of the Air , which will not exceed an English Mile , and a half , go up quickly , and are received by the Atmosphere , where they accresce to a considerable hight , perhaps 40 or 50 Mile above the Clouds , where by some extrinsick cause , as extremity of Cold , they fall down from the Atmosphere , first as Mist or Dew , till they come to the lowest Region , where in a very short time , they cover the whole Heavens , tho never so clear before . How many times before Rain , will this be seen . Besides , there is above the Atmosphere , that which Astronomers call the Diluculum and the Crepusculum , that is , both the Dawning of the Day , and the Twilight in the Evening , the one beginning about two Hours before the Sun rise , and the other ending about two Hours after the Sun is gone down . For if that Crepusculum were not there , we should have no Light , until the Body of the Sun were above the Horizon , and should have no Light after the Body of the Sun is set . This Sphere is unalterable , and without accresce or decrease , but the Atmosphere is not so , by reason of the Vapors coming to it , and decreasing again . Next , the Refraction , which makes the Sun or Star to appear above the Horizon higher , than really it is , is caused by the Atmosphere . 'T is observed by Shepherds , that if the Sun appear sooner above the Horizon , than ordinary , the Day following shall be Rainy . They see indeed the Image of the Sun , a little before he rise , which is caused by the Refraction , or thick Medium of the Vapors , which ly about the Horizon . For example , Let a man so fix his Eye , upon a wide Vessel , with an open mouth , with a piece of Money in the bottom , he shall not see it , till the Vessel be fill'd with Water . For Water being a thick Medium raiseth the Image of the Money , and brings it to the Eye by a broken and crooked Line , which is Radium refrangere , or rather refringere . It may be further inquired , Why the Clouds are sustained , or what keeps them up from falling down ? This is a considerable Question , and well worthy of a Divine Answer . The Lord says to Iob , Dost thou know the ballancing of the Clouds , the wondrous works of him who is perfect in Knowledge ? The Clouds then are suspended , not miraculously , yet wonderfully by Natural Causes ; for as a Ship is sustained from sinking by an even Ballance with the Water , so are the Clouds keeped up , by an even and equal Ballance with the pressure of the Air , which really sustains them . If they be light and thin , they go further up , but if they be heavy and black , they come nearer to the Earth , but are still in an equal Ballance , with the pressure of the Air. And as the Loadned Ship goeth further down in the Water , than the Ship , that 's not burdened ; so do the black and heavy Clouds swim lower , than the light and white Clouds . But when there is a great convocation of Clouds together in one place , each one presseth upon another , and so like Honey-Combs they distil their Drops upon the Earth . Note , That the greatest Ship in Europe , with all her Furniture for War , is but the just and exact weight of the Water , thrust out of its place by the Ships Water-draught . It may be yet inquired , How far are these Clouds from the Earth , which send down the Rain ? I answer , The surest way to know , is by the Thunder . Observe then , how many Seconds of Time , do pass , between the first seeing of the Glance , and the hearing of the Crack . If the Noise be straight up , five or six will pass , which make an English Mile . In Mountainous Ground , which lyeth higher , three at the most will interveen , about five hundred pass . To know exactly a Second of Time , whereof 3600 make an Hour , follow this method . Take a small Chord of thirty and seven Inch and a half exactly . To which append a Lead-bullet of seven or eight Ounce . Hang it so , that it may swing to and fro of its own accord . Each one of these Swings are a Second of Time. But may it not be affirmed , that the greater pressure of the Air , which raiseth the Quicksilver , is caused by the weight of the Clouds , which swim above us : and that the falling down of the Quicksilver is caused by the dissolution of these Clouds into Rain ? I answer , This cannot be : for when the Heavens are most serene and clear , the Mercury is furthest up ; and when the Heavens , are nubilous , and covered with Clouds , the Mercury many a time is furthest down . It may be inquired , Whether the cracking of Thunder , maketh any alteration upon the Weather-Glass ? I answer , There are three things to be considered in Thunder , First , The Lightning . Secondly , The Crack . Thirdly , The Thunder-bolt : which three are lively represented to us by the shooting of a Cannon ; for the Fire coming out of the Muzzle , represents the Lightning ; the Report , represents the Crack ; and the Bullet , the Thunder-bolt . But there is a more lively representation of Thunder , in Aurum fulminans , which like the Thunder-bolt carrieth its stroak downward , three Grains of which , tho never so little made hot , takes Fire , and gives a greater Report , than two Ounces of Gun-powder , so stupendious is it . But there is nothing here , which can make any alteration upon the Weather ▪ Glass . It may be inquired , If the Winds make any alteration upon it ? I answer , Winds are nothing but Air agitated ; nor Tempests , but Air-floods , or violent Agitations of the Air. These do really influence the Weather-Glass , not only in causing the Quicksilver subside , and fall down , but in causing the top of the Mercury tremble , and make some visible reciprocations up and down , especially , when the Wind blows very high . Next , Winds which come from the South and South-west , by reason of much moistness , which they bring alongs with them , influenceth the Quicksilver much indeed . But Northerly Winds , which are more drying , have less influence . Nay Easterly and North ▪ east Winds even with Rain , keep up the Mercury , and suffers it not to fall down so far , as other Winds . Because such Winds come from the Great Continent , bringing with them many Earthly Particles , and Atoms , which being dry , have not that influence upon it , as moist Winds from the South and West . It may be inquired , If the Weather-Glass doth foretell Winds , as it doth Rain ? I answer , It doth not so much foretell Winds , as it is actually influenced by them . Yet , if a man were a diligent Observer of the Winds , before they blow , and took narrow inspection of the Weather-Glass , he would surely foresee them approaching , by some alteration or other in it . It may be inquired , Whether Mist or Fog , doth affect the Weather-Glass ? I Answer , Yes , for I have observed , when the Mercury has been up at Fair , the falling down of a Fog , hath brought it down three or four Degrees . It may be inquired , When the Mercury i●… at the highest Station , in the fairest Weather , as above Long Fair , how many Days doth it prognostick Rain , before it come ▪ I Answer , When it first begins to alter , it must fall down to Long Fair , half an Inch ; next to Fair , another half Inch. Thirdly , To Changeable , as much : And lastly , To Rain . This Motion is slow , and therefore it foretells , sometimes three Days , sometimes four , sometimes less ▪ But this is sure , it cannot fall down in one Day so much bounds , nor in two , neither in three . I have seen it fall down from Long Fair to Fair , and then halt , by reason of some stirring Winds , or by reason , of some small change of Weather , in some County near hand . When it 's far up , as at Long Fair , or above it , it is next to impossible , that either Wind or Rain can be . Some , who are not acquaint with the Weather-Glass judge it erring , when they see the Mercury at Rain , and yet no Rain . I confess it may be so , if it be not rightly adjusted , at the first setting up ; but if it be set , according to Art , the Mercury cannot be at Rain , but there must be Rain , either here , or some place near hand . It may be inquired , If Snow and Hail have the same effects upon the Weather-Glass , which Rain have ? I answer , Yes ; for they are both from the same cause , namely moist Vapors . I have 〈◊〉 s the next adjacent Hills covered with Snow , when there was neither Rain nor Snow in the Valley Countrey , and the Mercury down at Rain , tho it had been always up before the Snow fell . And many times it is found , that Rain falling in the next Shires , or Counties , tho none here , have made the Quicksilver fall down to Rain . The last year 1687 , in November , I have seen the Quicksilver , below Much Rain , and yet the Days going before , or following , have been pretty fair . But the Weather , was under a strong disposition , and inclination to be Tempestuous and Stormy , which soon followed . 'T is observable , that the Quicksilver , is never so high in the Weather-Glass , as about the hinder end of the Month of October , or rather in the Winter Season . In Rainy Years , I have not seen the Mercury further up than Fair , and that seldom . Might the Weather-Glass be useful in Ships ? I answer , Yes ; but the commotion of the Ship , ( you say ) renders it useless . I answer , it might be so suspended , that it might hang always perpendicular . And tho this were not , yet the Nature of it is such , that it can recline without hurt , as much as the Ship can●…ly , either to Starboord , or Larboord , and fall right again , when the Helm is righted . In a word , whatever advantage a man might have by it , in his Chamber , he may have as much , by having it in his Cabin . There is a person of Honour , and great Learning , who hath written lately in Natural Philosophy , and among other things , hath not omitted to shew the reason of this marvellous Phenomenon , whereof I have been Treating . He toucheth it briefly in 9 or 10 Lines , and says , Id autem mirum satis videtur , &c. 'T is a strange thing ( says he ) that in Rainy and Windy Weather , when the Air seems to be heaviest , yet the Mercury is furthest down . The reason ( says he ) is taken from the temperament of the Air , where the Clouds are ; for when the Clouds are grosser , tho much elevated , they intercept the Rays of the Sun , and are thereby melted , and turned into Rain . And the Air being eased of the burden of these Clouds , and being rarified above , by the Sun-beams , is becomes lighter , and so bears less down the surface of the stagnant Mercury in the Cistern . But when the Air is nubilous and Cloudy , the weight of the Air , is augmented , by the weight of the Clouds , which make it press with greater weight upon the stagnant Mercury in the Cistern . I dare not oppose any thing to the Opinion , of such an eminent man , tho I might , he being a hundred Stages beyond many . Yet there are not some wanting , who male-apartly set at nought his Philosophical System , as insufficient both for Matter , and Form ; whereas among all the Learned Abroad , his Writings are held in great Estimation . There is one of the Professors of Philosophy at Aberdeen , whose publick Theses the last Year , came to my view : yet I shall adventure to say something anent them . The Author , ( whom I have not the favour to know ) seems to be well acquaint with the new Philosophy , and a good Schollar . He confutes rationally Malebranch , and Spinosa , two wild Philosophers . He seems to be a Cartesian in his Philosophy , yet affirms that the Demonstration ( as he calls it ) of God's Existence , by the Idaea , being abstract and Metaphysical , goeth far beyond the capacity of the Vulgar , and therefore being compell'd by Reason , he averreth , that the Apostle Paul reasons far better in the first to the Romans . He speaks honourably of the late Lord President in confuting some of his Doctrine , for which he deserveth more thanks for his good Estimation of him , than for the strength of his Reasonings against him . He hopes the Lord Stair , will hold him excused , if he do not acquiesce to his Decisions . This seems to be jeastingly spoken . Casting my Eye further thorow , I found somewhat anent the Causes of Winds , Tempests , and Rain , and the reason why the Atmosphere , is sometimes lighter , and sometimes heavier . But he hath not touched the Nail upon the Head. Some Notes upon the Parisian Weather-Glass . THere is a New Invention of a Weather-Glass , which cometh from Paris ( facile est inventis addere , ) set in a curious gilded Frame , more specious to behold , than profitable and useful . It is lyable to several Abatements . The first makes it a dumb Weather-Glass , wanting the whole Theory of the Weather , so that when a man looks to it , he knows not whether it shall be Fair or Foul. A man seeth indeed the sides of the Frame , divided by French Measure into Inches and half Inches ; but these Measures have no signification of the Weather . When a man looks upon it in the Morning , he sees the Tinctured Liquor at such a hight ; and in the Afternoon , he observes again , and finds it higher or lower . This is all it signifieth . And if perhaps he be informed that in Fair Weather , the Liquor descends , and in Foul Weather it ascends , then he may conclude , observing it further down than it was , that it is probable to be Fair. The second Abatement is , that there are two Oval-Glasses , which rather ought to be Cylindrical . Now unless there be a just and exact measure in hight , between the top of the one Oval-Glass , and the bottom of the other , it cannot be un-erring , or between the middle of the one , and the middle of the other . Because the Mercury cannot raise the Liquor in the right side , by equal portions , since the rising of it depends essentially upon the falling down of the Mercury from the left Oval-Glass . For the Glass being in form of a Pullets Egg , more Mercury falls down , whilst it is terminate about the middle , being there wider , than whilst the Mercury , is near either of the extreams , which are narrower . And I believe the Contriver hath foreseen this . The third Abatement is , that the Tinctured Liquor is subject to Corruption , the Orifice of the Glass being open , suffering Evaporation , by which means , the whole Contrivance is rendred useless . The fourth Abatement is , that the Orifice of the Glass , upon the left Hand , must be Hermetically Sealed , which few or none can do . The fifth Abatement is , if it be once Mounted , and set a going , it cannot be well Dismounted , for the end which is Hermetically Sealed , must be opened , and cannot be well Sealed again . Lastly , The Glass is brought Home from Abroad , not without hazard of breaking , the Glasses being very small and slender . But there are none of these Difficulties found in the Perpendicular Glass . For it may be set up , and dismounted , as oft as you please , and transported from one place to another . And the excellency of it is , that it sets it self ; for whatever weight of Mercury it once takes , the same will suffice it for ever . And which is marvellous , the Mercury falls down alway according to the Nature of the Weather , and there halts , whether it be Fair , or Foul. There is a second sort of Weather-Glass much in use , called the Sealed Weather-Glass , whose use is only to shew the Heat and Coldness of the Air. It hath a round Glass below , about two Inch in Diameter , and a Stem going up from it , about a Foot and a half in length , but slender and narrow within . This Glass is filled with the finest Spirit of Wine , three or four times distilled , so in effect , being full of fiery Spirits , the least Heat or Warmness in the Air , rarifieth it , and the least Coldness contracteth it . When the Ball is once full , and the Stem too , the open Orifice above is Hermetically Sealed , and coming to the cold Air , from the warm place it was in , the Liquor creeps down towards the Ball , and by this means , it demonstrats by its creeping up , the warmness of the Air , and by creeping down it shews the Degrees of Cold. It is Hermetically Sealed , that the outward ▪ Air , may have no influence upon it . It is set in a curious gilded Frame , with the several Degrees of Heat and Cold affixed to it . They come from Paris , and London , not without hazard of breaking by the way . There is a third sort , specially different from the rest , called the Water Weather-Glass . It hath a round Head above , with a long Stem going down from it , and the Mouth below remaining open , is drown'd among Tinctured Water . To set it a going , they use to warm the Head , and Body of it , at the Fire , and then to thrust the open end among the Liquor in the Cistern . When the heat begins to abate in the top , the Air within , begins to contra●… it self , and so the Water follows up , and hangs about the middle of the Stem . This in cold Weather creeps up , and in warm Weather creeps down . It creeps up for fear of Vacuity , as was maintained long since , before the pressure of the Air was known by the Torricellian Experiment . This Weather-Glass was esteemed infallible ; but now it is known to be most fallacious , and uncertain . The reason is , because it is acted and moved , not only with Heat and Cold , but with the greater and lesser pressure of the Air. If it be demanded , how shall I know , whether it be the coldness of the Air , or the greater pressure of the Air , which causeth the Water to ascend : and whether it be , the warmness of the Air , or the Iesser pressure of the Air which causeth the Water to descend ? I answer , It is difficult to know ; for both do sometime concur , that is , the weight and greater pressure of the Air , and the coldness too . And sometime the lesser pressure of the Air with warmness , make the Water fall down . And sometime the greater pressure of the Air raiseth the Water , without any addition of Cold : And sometimes the addition of Cold , without any alteration in the Air , as to more weight , will raise it . And tho by this means it be fallacious , yet many notable Phenomena do appear from it . By the help of this , and the Mercurial-Weather-Glass , and the Sealed one , and by the help of the Hygroscope , which marvellously shews the least alteration in the Air , as to Moisture and Dryness , and by contemplating the Heavens , the Sky and the Clouds , and considering the Winds , how they blow , and the various Aspects of the Planets one to another , ( as Star-gazers do affirm ) men might come to foretell the Weather particularly . The Theory of the Weather , according to the Mercurial-Weather-Glass . THE Theory of the Weather , is either Ingraven upon Brass-Plates tichtly polished , or upon a piece of Lombard-paper , wrought in the Taliduse-press . The Brass , or the Paper , is divided into Six half Inches ; and every half Inch into Five Degrees ; or every whole Inch into Ten equal parts . I call the upmost Station , Long Fair ; the second half an Inch under it , Fair : the third , Changeable : the fourth , Rain : the fifth , Much Rain : the sixth , Storm●… ; and if you please to add the seventh , call it Tempests . These six or seven , contain the whole Alterations , which use to be in the Weather . When the top of the Quicksilver is at Long Fair , it toucheth exactly the Line under it . If it fall down , it is said to be one Degree under Long Fair , or two or three , accordingly as it falls down , till the top be at the Line under Fair , and then it is Fair Weather , and so of the rest of the Stations . It may be asked , At what hight , must Long Fair be affixed ? I answer , The Situation of the place must be considered , and the Climat under which we live : for a Glass appropriated to this Parallel , will not serve in the Braes of Athol , or Annandale . And if there be not a just , and exact hight , to a Hairs breadth , of all the Stations from below , it cannot be un-erring . The several Stations are found out , not by Algebra , or any Mathematical Demonstration , but by many years Observations . Whosoever taketh upon him to mount a Weather-Glass , without the knowledge of these Praecognita , he plays but the Fool. There are many other things necessary to be known , which every Fallow , which hath no more in his Scull , but a Bag-pudding in stead of Brains , is not capable to understand . I shall briefly run thorow the several Stations , with some Observes upon each one of them . In the first and upmost , is Long Fair , or most pleasant Weather . I have seen the Quicksilver sometimes above it , yet seldom doth this fall out , but in extraordinary Seasons . The Mercury being at this hight , it is next to impossible , either to be Wind or Rain . Nothing for several Days , but settled calm Weather . Sometime the Heavens are covered with dry and gray Clouds , but not the least appearance of Rain . The second ●…tation , half an Inch lower , is Fair. The Mercury being here , I have observed a small Showre of Rain to fall , from the lowest Region of the Air , as a th●…ck Dew or Mist , but immediatly after , the Day became Clear and Fair. The whole year 1686 almost , it was a rare thing to see the Mercury up at Fair , but frequently below Rain , and Changeable , because of the frequent Rains , which fell out that year . And which is observable , all that Summer , the Hygroscope went not once about , whereas in dry Summers , it goeth twice about , sometimes more and sometimes less . The third Station half an Inch lower , is Changeable . That is , sometimes Fair , sometimes Foul , sometimes Frost , sometimes Thaw , sometimes Sleet , and sometimes Snow , sometimes Wind , and sometimes Calm . The fourth Station is Rain , not actually Rain , but a stormy inclination in the Air to be Rain , and sometimes Rain . Nay , sometimes the whole Day will be Fair. But still the Rain is approaching , or hath been Rain , either here , or some place about . The fifth Station is Much Rain , the worst of Weather almost , as in the Summer , or Winter Season , when Rain is accompanied with stormy South-west Winds , or westerly Winds . This last October , or November , I have seen the Mercury below this Station , and yet no Rain in the mean time , nor all the Day , but the Sky black , and tempestuous , thick Clouds lying about the Horizon . Above Fife , great Heaps of them : some like Castles and Towers , others like ragged Rocks , hanging over each one another . All of them fore-runners of Rain . The sixth Station , Stormy , extraordinary Foul Weather . In the last place , I have subjoyned Tempests , or Hirricano's , which do not fall out in this Countrey . If it be asked , Why doth not the Mercury fall down to Tempests ? And why doth it not go half an Inch above Long Fair ? I answer , There are here two Tropicks , namely Storms , the nethermost , and Long Fair the upmost . Above this , the Air is not able to press , except some few Degrees . And at Storms the pressure is least . The length of the Tropicks then , are about three Inch. General Rules . The further the Mercury goeth up , the Weather inclines to be the Fairer , and the further it falls down , it inclines to be the Fouler . Secondly , When the Mercury is highest , Fair Weather seems to be universal ; when it is lowest , Foul Weather seems to be universal . Thirdly , It is not so much Foul Weather actually , which influenceth the Mercury , as it is the Disposition and Inclination of the Weather to be Foul : so that the Mercury will be many times at Rain , when it is not actually Raining , which is wanting when the Quicksilver , is at Fair , or Long Fair. Fourthly , Not only Foul Weather in this County or Shire , maketh the Mercury fall down , but Foul Weather , in the next adjacent County , tho there be none here : as the Weather-Glass at Edinburgh , will be altered , with Rain in Tweeddale , or in Lammer-moor . And as it shews the Nature of the Weather , so it predicts and foretells , sometimes a Day , sometimes two or three , if so be the Mercury hath been far up . But if it hath been only at Changeable , or below Fair , it predicts some few Hours , before it be Rain , by falling down a Degree , two or three , or four . When it is a falling down , the top of the Mercury is flat and level , but when it is a rising , it is somewhat round . 'T is said , that the Ladies , and Gentlewomen at London do Apparel themselves in the Morning by the Weather-Glass . Whatever be in this , 't is certain , that when a man riseth in the Morning , he may know infallibly , what sort of Weather will fall out ere Night . It is most useful for the Husband-man , both in Seed-time , and Harvest , and for winning of Hay . It is useful for taking a Journey , for when I see the Mercury up at Fair , or Long Fair , I may be confident , there shall be no Rain for eight or ten Days , chiefly when it 's up at Long Fair. There are many other uses , for which it is profitable , which are needless here to repeat . It is always infallible , because guided by God in Nature , tho to our apprehension it seems to err . There are so many Changes , and Alterations in the Air , that a particular Rule cannot be assigned for each one of them . But the general Observations which are affixed , are sure . If any man would find out all these Intricacies , he must diligently observe , the Changes , and Quarters of the Moon , and the several Aspects of the Planets , and the Winds how they blow , comparing them with the Changes and Alterations of the Weather-Glass . Neither can it be subject to Corruption , tho it stand an hundred year . The Glass cannot fail , neither the Quicksilver , which are incorruptible by Nature . Neither can the Frame decay , for many years , being made of Oak . FINIS . Postscript . To Buoy up a Ship , of any Burden , from the Ground of the Sea. THE Art of Diving hath not been much known , but of late ; for it depends essentially upon the knowledge of the pressure of Fluid Bodies , which knowledge hath not been further known to the generality of Learned Men , than by name : tho some ignorantly have averred , that the Hydrostaticks , is a Science long ago perfected . Among the first , who have essayed in this Nation , was the late Marquess of Argile , who having obtained a Patent from the King , of one of the Spanish Armado , which was sunk in the Isle of Mull , anno 1588 , employed Iames Colquhoun of Glasgow , a man of singular knowledge , and skill , in all Mechanical Arts and Sciences . This man , not knowing the Diving Bell , went down several times , the Air from above , being communicated to his Lungs , by a long Pipe of Leather . He only viewed , and surveyed the Ship , but I suppose buoy'd nothing up . About the year 1664 , when this Art became more perfected , and was advanced , by the Practice , and Invention , of Learned Men. The late Lord Argile did employ a most ingenious Gentleman , the Laird of Melgim , who went down with a Diving Bell , and made a further inquiry . After some pains , and labour , he buoy'd up three Guns , one of Iron , judging it to be of some other Mettal , one of Copper , and one of Brass , about eight Foot long apeice , and eight Inches of Diameter . The third Essay was made by the late Earl of Argile himself , several years after , who did more . There was one Captain Smith , who undertook after that , yet more , who thought himself so sure of the Spanish Gold , that he would not suffer a Carpenter with himself : but this Interprize turned to nought . To effectuate the Proposal , I shall offer these six Propositions , which with small pains may be made evident , from Hydrostatical Principles ; and next infer some Conclusions , needful for the design in hand . First , The whole Ship , with all its Loadning , is the just and precise weight , of as much Water , as the lower part of the Hull expells , or is expelled by the Ships Water-draught . Secondly , When the Ship becomes heavier than the said quantity of Water , it sinks . Thirdly , Water doth not weigh in Water . This is evident , for when a man pulls a Bucket full of Water from the bottom of a Well , he finds no weight thereof , till it come to the Surface . Fourthly , Nothing lighter in specie than Water , or of the same weight with Water , can sink . Hence , neither Timber , Wine , Bear , nor Oil , can tarry at the Sea Ground , but must be buoyed up of necessity . Fifthly , By how much , the whole Timber of the Ship , is lighter in specie , than as much Water equal to it in bulk , by so much is it the more able to buoy up . Imagine , the whole Timber of the Ship , reduced to a Cube of so many Foot , and a Cube of Water given of the same quantity . Now I say , as many Pounds , as this Cube of Water , is heavier , than that of Timber , so many Pounds of Iron , Lead or Stone , will the Ship buoy up , or support , even tho full of Water . Sixthly , A heavy Body , as Iron , Lead or Stone , weighs as much less in Water , than in Air , as the quantity of Water it expells . A Square Foot of Lead , which I suppose weighs in the Air 728 Pound , weighs but 672 Pound in the Water , less by 56 , the weight of a Square Foot of Water . From these Propositions , I infer , that when a Ship is to be buoy'd up from the Ground of the Sea , nothing of her weighs , save her Ballast . By Ballast , I understand , taking the word largely , every thing in the Ship , heavier in specie , than Water , as Guns , Ankers , Bullets of Iron , and Lead , Iron-bolts , Nails , and all manner of Iron-work . Next , That the whole weight of the Ballast , doth not preponderate or weigh down . Lastly , That the Timber of the Ship , and all things in it , lighter in specie , than Water , concur for buoying up the Ballast . The best expedient for raising of Ships entirely , are Arks of Wood , applyed either to the sides of the Ship without , or just above the Orlop . These Arks must be so close , on all sides , that neither Air , nor Water , can pass . The Ark , to describe it more particularly , must have four Sides , and a Cover above , but open compleatly below . At every Corner , next to the Mouth , must be fixed , a strong Iron-Ring . Four likewise above , that is , one in each Corner , answering to the four below , which are for fixing a second Ark above the first , if need be . If the Ship , which is to be raised , be twenty Foot over , make your Ark twenty Foot wide , and as much in hight . Bring it just over the place , where the Ship lyeth , and filling it with Water , that it may sink without difficulty , thrust it down , till it come just above the Orlop , and fasten it within five or six Foot of the same , with Ropes passing thorow the four Rings , and the Beams or Balks of the Ship. The Arks being thus fastned to the Ship , by a Diver , the next work is to beget a power , or force within it , which shall be able to buoy up the Ship from the Ground of the Sea. This may be done , either by sending down Buckets full of Air , with their Mouth foremost , one after another , from the Surface of the Water , and then cause a Diver receive them , and thrusting them somewhat within the Mouth of the Ark , turn up the Orifice , by which means , the whole Air in it , shall ascend up thorow the Water of the Ark , and rest above , next to the top . This Device being often repeated , will at last expell , the whole VVater of the Ark , and fill it compleatly with Air. This is so sure an Experiment , that none needs to call it in question . Or by communicating Air to the Ark from above , by the help of a pair of large Bellows , and long Pipes of Leather , going down within the Mouth of the Ark. Or thirdly , By the multiplication of Bladders full of VVind , filling the Ark within , which may be done more easily . The Ark being oncefull of Air , will have a considerable pull with it , which is more , and less , according to the dimensions thereof . For knowing this , you must consider , that whatever t●…e dimensions of the Ark are , it will buoy up , as much weight as the VVater weighs , which fills it . I●… then , the Ark be twenty Foot wide , and as much in hight , it must contain eight thousand Square Foot of Water ; and since every Square Foot of Water thereof weighs fifty six pound Trois , the whole must be 448000. An Ark then of twenty Foot Square , will buoy up , four hundred and fourty eight thousand pound weight , the weight of 58 Cannons Royal , each one whereof , I suppose weighs 8000 pound . Or the weight of 74 Demi-cannons , or the weight of 97 Culverings : or of 149 Demi-culverings : or of 298 Sakers , each one of this sort weighing 1500 pound . Or lastly , the weight of 250 Tun of Wine , reckoning four Hogsheads to a Tun , and each one of these weighing 448 pound . If you fasten a second Ark above the first , by the help of the Rings upon the top , which I mentioned , both will buoy up together 896000 pound , the weight of 112 Cannons Royal. But if your Ark be 30 Foot in all its dimensions , it must contain twenty and seven thousand Square Foot of Water , which will weigh , one million , five hundred and twelve thousand pound weight of the weight of 189 Cannons Royal , or the burden of 252 Demi-cannons , which is the weight of 844 Tun of Wine . But supposing the Ark to be more in quantity , the one way than the other , that is 40 Footlong , it shall be able to buoy up , two million and sixteen thousand pound , the weight of 252 Cannons Royal , or the weight of 1125 Tun of Wine , or Water . If the Arks be applyed to the sides of the Ship , you must fix , as many upon the one side , as upon the other , which need not be so large , as those which are fastned upon the Orlop . I shall suppose , that upon each side , there are four Arks , each one 10 Foot Square . If this be , every single Ark , must contain 1000 Square Foot of Water , which will weigh fifty six thousand pound . All of them together , therefore must buoy up 448000 pound weight , the burden of 56 Cannons Royal. To know , how to proportion the quantity of your Ark , to the burden of the Ship , which is the great secret , follow this Method . Consider first , that neither the Timber of the Ship , nor the Water which is in her , nor any other thing , which is lighter in specie than Water , ( that is , any thing which floats upon the Surface ) or of the same weight , with it , preponderats , or weighs down , but only what is heavier in specie , than Water , as Guns , Ankers , Iron-bolts , Iron-nails , and such like , the just quantity , or very near , may be found . Calculate then , as near as you can , and supposing the weight of all this Ballast , to be about 448000 pound ; you must next consider , what the dimensions of the Ark , must be , which is able to buoy up so much weight , which may be found out thus . Divide the just account of your Ballast by 56 , and the Cubique Root of the Product , gives you the just dimensions of the Ark. For example , Divide 448000 by 56 , and you will find 8000 , the Cubique Root whereof is 20 , the quantity of your Ark within . If you judge ▪ it more convenient to apply lesser Arks , namely to the sides of the Ship , ye may have eight , by dividing this into so many parts , four for each side , and every single Ark 10 Foot Square , which are equivalent . Remember , that tho the whole Ballast , weigh 448000 pound , yet this whole weight is not to be buoy'd up by the Ark , seing heavy Bodies weigh less in Water , than in Air , according to the sixth Proposition . As for fastening the Arks , either to the sides of the Ship , or just above the Orlop , several ways may be thought upon , which I leave to the Invention of others , who are skilful in building of Ships . Let it suffice , that I have made it probable , if not evident with Reason , that the greatest Ship may be buoy'd entirely up from the ground of the Sea , which was the thing to be demonstrated . If it be Objected , That the strong pressure of the Water , will put the Ark in hazard of bursting , when its full of Air. I answer , There is here not so much hazard , as every one may believe . The Reason is , because the pressure within the Ark , is very near equal , to the pressure from without . This I add , because the top of the Ark within , is more prest up by the Air within , than it is prest down with the Water without . The pressure upon the sides , is more uniform , and so there is the less hazard there . In a word , if the Ark be able to support , as much VVater , as fills it , without bursting , it shall go down thorow the deepest VVater imaginable without trouble . That is , hang it by Ropes in the Air , full of VVater . If the bottom be able to support this weight , there shall be no hazard of bursting , when it 's full of Air within the deepest VVater . From this unequal pressure , which the top of the Ark suffers , it follows of necessity , that if there be any Rift , or Leck in it , the whole Air will go out by degrees , and so render the Ark useless . I answer , this endeavour , which the Air within , hath to be out , is just the same , with that , which the VVater within , hath to be out , when the Ark is full , and hung in the Air with Ropes . If Art can cure the one , it may find a remedy for the other also . But I leave this to such as are skilful in Calking of Ships . Tho I seem to insinuate , that the Arks must be Cubical or Foursquare in their form , yet there is no necessity for that ; for they may be made under what fashion or form you please , provided they contain , as much Air as will be sufficient to raise the Vessel . And though I mention Arks of 20 or 30 Foot Square , which will go near to buoy up the greatest Ships , as Men of VVar ; yet for ordinary Vessels , Arks of far less size will suffice . Some may imagine , that a Ship sunk ( for example ) with Coal , is as difficult to buoy up , as to raise her out of a dry Harbor . But this cannot be , since a pound of Coal , will not weigh three or four Ounce in the VVater . A Ship loadned with VVine or Oyl , weighs nothing at all in the VVater , but may be very easily buoy'd up , if the Ballast be considered , as I said . Many Ships have been buoy'd up entirely , by thrusting down empty Hogsheads , and putting them below the Deck . But here occurs a difficulty , if the Water exceed eight or nine Fathom , the strong pressure of it crusheth the sides of the Hogshead together . But here is a soveraign cure against that trouble . Bore a small Hole in any part of the Vessel , where you please : for the Water entering , brings the Air within , to press equally with the Water without . Tho this Invention , may seem difficult to some , to be made practicable , yet to such who are intelligent , and know well the Principles of the Hydrostaticks , it appears plain and easie . But the very Speculation of it wants not its own pleasure , being founded upon infallible and sure Conclusions , drawn from the surest grounds in Nature . Labor improbus omnia vincit .