# Astronomical Dialogues Between a Gentleman and a Lady/Dialogue 1

Astronomical Dialogues
BETWEEN A
Gentleman and a Lady.
t is now about seven Years ago, since I presented the most Engaging Lady M. . . . . with Mr. Fontenelle's Book of the Plurality of Worlds: And I remember well what she said a few Days after.
I have look'd over your Book, Sir, said she, as my way is, first cursorily, and I intend to give it a very careful second Reading; but I perceive by it, you have cut out much more Trouble for your self, than perhaps you imagin'd: For I find there are many things previously necessary to the understanding it, which you must oblige me with explaining; but, continued she, a Conversation of that kind with me, I doubt, will be too dull and tedious, since I am not bless'd with any of those shining Qualifications, ​with which Mr. Fontenelle hath complimented M. la Marquiese; I should indeed, said she, except those two, which I suppose, in Complaisance to our Sex, he makes the Foundation of Philosophy, viz. Ignorance and Inquisitiveness for those I'm sure, I have in Perfection, as you have long experienced.
I need not mention the Return I made, nor how prettily she changed the Discourse to something more general, when she found I was going to say just things of her; those that knew her, don't want to be reminded of the many Beauties, both of Mind and Body, which render'd Lady M. . . . . one of the most agreeable Persons of her Sex; which yet were she living, tho' a just Debt to her Merit, I must not have said, for fear of offending her Modesty.
All that is necessary to introduce what follows, is, to inform you, That some Years before her Death, when I went to visit that accomplish'd Lady at her Country Seat; I was a little surprised to find her, the next Morning after my Arrival, studiously viewing a pair of large Globes, Which stood in the Drawing-Room, looking into the Garden, and which I used to make my Place of Study.
​Good Morrow, said I, Madam, what! hath Fontenelle made an Astronomer of you in good earnest? Are you really contemplating the Order and Motions of the Heavenly Bodies? Or are you rather seeking on the Earthly Globe, where to make new Conquests?
The Historians foolishly represent Alexander the Great, as Weeping, that he could carry his no further than over all the World; but I'm sure, were he present now, to see you in that Posture commanding the Globe, and giving what Turns you please to it; that Thought of your humble Servant's would appear just enough;
O! Sir, said she, your Servant, I doubt you did not rest well last Night? What did your Imagination carry you into the Poetical Regions of Fairy-Land, that you awake with Verses in your Mouth this Morning? But to speak seri​ously, I wonder you don't blush to paint so much beyond the Life, and yet suppose the Picture to be like any one; you affect to imitate our great Painters, if we sit to them, they make us all handsome; but they do it to shew themselves, not us, and they don't care so much whether it be like or no, so it be but a fine Picture; and in this our own Vanity too often indulges them.
But pray, added she, let us lay aside all these Fooleries; and be so good as to be serious with me for an Hour or two: I have a great Mind to be let a little into the Knowledge of these Instruments, the Globes; and to know something of the first Principles and Rudiments of Astronony; or else I find I shall lose half the Beauties of that very entertaining Book Mr. Fontenelle's Plurality of Worlds, which you formerly obliged me with, as well as perhaps be led into some Errors by it: And don't despise and neglect me because I am a Woman. I have heard you sometimes say, you thought that there was no difference of Sexes in Souls; nay, that our Parts and Natural Capacities were often equal, at leasi, if not superior, to those of Men. But perhaps there were some particular Reasons for your saying so then, which now altering or ​ceasing, your Judgment and Opinion may have done so too.
I was going to assure her, that I was still of the same Sentiments, when putting on a forbidding Look, with a serious Countenance the proceeded thus:
Globes.These Globes, Sir, came too late to accompany a Relation of mine to India, his Ship having sailed before they were finished, which is the Reason you see them here; and I have ordered them to be set out this Morning, and shall do so from Day to Day, tho' without obliging you to what Fontenelle had with the French Lady, an entire Week's Conference. But I have a great Mind to learn, from my Friend, something of the Nature and Use of them; for they appear to be made and finished up with that Curiosity and Care, that sure some very useful Knowledge is to be learnt from them, and is it not barbarous in you Men to confine it all to your selves?
Madam, said I, you will give me a new Rise to value any thing that I understand; if I can render it acceptable to you.
​Well then, Sir, said she, all Compliments apart, both to your self and me, pray let us go to our Business, the Tea won't be ready this Hour, and there is a little too much Dew for us to take a Walk in the Garden. Let me understand then, first the Difference between these two Globes, and why one hath the Cities, Countries, and Places of the Earth drawn on it, like a Map; and the other Circles and Stars, and these odd uncouth Figures of Beasts, Birds and Fishes: Pray why do they turn round? What doth this Brass Hoop signify in which they hang? For I perceive that it also hath Numbers engrav'd upon it: And what doth this broad wooden thing serve for, that hath the Days of the Month and other Letters, as well as Figures, pasted upon it?
I am glad, said I, Madam, by the warm Manner of your Enquiry, to find that you are in earnest; and I have often wished that the same Curiosity and Love of Knowledge would inspire more of the fair Sex, for it would mightily enlarge their Empire and Power over ours, by endowing them with more real and lasting Beauties, such as would improve with Time, and strengthen even in Age itself. ​But as to your present Questions, Madam, I will give you the most Satisfactory Returns I can.
And first, Madam, it will be necessary to acquaint you with the Meaning of the Word Globe; and what the Properties, in general, of such a Figure or Body, are.
Globe what.Your Ladyship is to understand then, that a Globe is a round Body of such a Nature, that every Part of its Surface or Out-side, is at an equal Distance from one Point within it, which is called the Center. This Body also is sometimes named a Sphere.Sphere, with regard to Astronomical Speculations; and this Science which you are now inquiring into, is hence called The Doctrine of the Sphere.
I Think I understand you; laid she, the Figure of a Globe is not flattish like that of a Cheese or a common Ninepin Bowl; but rather like a Boy's Marble, or a Bullet cast in a Mould.
Exactly right, Madam, said I, and further you are to know, that a strait Line supposed to be drawn thro' the Center of this Globe any where, from one opposite Point of the Surface to the other, is called a Diameter.Diameter
And now I know what the Plummer meant the other Day, when he talk'd of a Pipe of Lead of such a Diameter; I now know the Meaning of Diametrically opposite, &c. But, pray, Sir, go on.
You will next see easily, Madam, said I, that if a Globe were at Liberty, and any Power or Force at hand to move it, it would easily turn or roll round any one of its Diameters, as this Globe doth round this Wire; which particular Diameter, is called therefore its Axis.Axis; as being the Axle-tree on which it turns. But tho' this be true of the Nature of a Globe in general, yet the Axis, as we call it, of the Earth and Heavens, by the Will of our All-wise Creator, is one fixed and determinate Line; and about this the ​fixed Stars are usually supposed to revolve, without ever changing their Distance, or deviating from one another or from it.
I Am mightily pleased, returns she, with the Nature of these Globes, because they are unbiassed and indifferent, as to this or that particular Way of Turning; and I fancy it to be a good Emblem of the Freedom of our Minds in the State of Innocence, when they first came out of Nature's Hands; they were then perfectly at Liberty to move any way, which they lik'd best; and I dare say, that all the wrong Biasses and particular Turns that we find in any of them, are owing to the Weight or Power, as you call it, of our own corrupt Affections.
You moralize excellently well, said I, Madam, and are very just in your Notions of the Deity.
But she went on, and said; Yet I think we might be glad to receive from the first Mover and Author of all Things, such a determinate Way of moving, as you say God hath given to the Heavens and the Earth; for our own whimsical Motions, Turnings and Shiftings, seem to be as unaccountable as they are various.
Poles.
Shall I ever come to know what these Poles, and Dragons, and Bears, mean?
Pray, said she, good Sir, don't take it amiss if I interrupt you with one Question: Is this Tip of the Bears Tail, that celebrated Tip of Cardan the Conjurer; who, as Butler saith,
The very same, Madam, said I.
Go on then, said she.
This Star here by the Wire, Madam, said I, we call the Pole Star, and the Point near it, thro' which the Wire runs, the North Pole of the World. And let the Earth be where it will, in its Annual Course round the Sun, this North Point on the Earth, and here placed on the Globe, will always be either exactly or nearly under that North Pole Star or Point, in the Heavens. But of this more when I shall further explain to you the Motions of the Earth; and this Position of the Earth's Axis is so firmly fixed and determined by the Author of Nature, that from it there hath never yet been observed any considerable Variation.
Pray, Sir, said she, proceed: When I come to look over Fontenelle again, I perceive I shall understand him and you much better.
Madam, said I, the outward Figures of these two Globes you see are nearly alike; but tho' they are hung also, and ​fitted up alike, yet they are almost as different from one another in their Natures and Properties, as are the different Regions that they represent.
Terrestrial Globe.This Globe which is designed to shew the Face of the Earth; and which therefore is called the Terrestrial Globe, is truly and properly a Representation of it, round or spherical as that nearly is, and it hath the Sea and the Land, with all the Regions, Countries, Nations, Islands and Cities drawn upon it; just in that Order and Figure, that they are, in Reality, on the Face of the Earth itself; and it is, if carefully drawn, a true Map, or Description, of what is usually called The World: whereas all those flat Maps and Charts, which you see drawn upon Paper, cannot be accurately so, tho' they are exact enough for common Use.
That Word World, said she, I can't get over without reflecting, what weak, vain, and silly Mortals we are: We too often take this poor Spot of Earth to be the only World worth inquiring after; and so we can but acquire a little of its Dirt, we neglect all Care for an Eternal Mansion in the Heavens. And further, I have no Patience with Ptolomy, I think they call him, and his Astronomers, that will needs have the ​mighty Sun, and all that infinite Orb of fixed Stars, to be made only for the sake of this little dirty Planet, as I remember somebody calls it; and to have no other Use nor End, but only to dance round it, which yet, as I have heard, is a meer Point, and scarce visible to an Eye placed in some of the other Planets.
But to go on with my Lesson: Good Sir, said she, is the Figure of the Earth thus really round? and have you any good Reasons to make you think so? For I must own I had not till now a Notion of its being round like a Ball; I took it rather to be round in Compass like a Dish or Plate.
Rotundity of the Earth.Very many and substantial ones, Madam, said I, and you will be fully convinced by them, when they occur to your Reading hereafter, if you proceed on in that Way you are now going: But, however, the Sun shining so bright into this Room, will furnish me now with one Argument to make that Notion plain to you. You see, Madam, when I hold any solid Body in this Light of the Sun, its Shadow will be nearly like the Shape and Form of that of the Body; when I hold this Book in the Light, its Shadow will ​be square at the Sides, as the Book is; but when I hold this Orange in the same Light, the Shadow, you see, hath a round Edge; and therefore since in the Eclipses of the Moon, the Shadow of the Earth, which you know, Madam, occasions the Moon's being covered with Darkness, appearing always exactly round or circular, we justly conclude that the Figure of the Earth is round or spherical too, or else the Termination or Out-Line of its Shadow could never be always in a Circular Form.
I Thank you for this easy and natural Explication, said the Lady, which I think I comprehend; and I am beholding to the Sun, that great Fountain of Light, or rather to Him that made it, for being now instrumental to dispel the Darkness I had in my Mind before about this Affair; however, being no Persian, I shall not worship the Sun for it. But pray, Sir, go on with an Explication of the other Globe.
Celestial Globe.That, Madam, is called the Celestial one, said I, because 'tis designed for a Representation of the Firmament, and the Concave Arch of the Heavens; and indeed it doth well enough exhibit to us the fixed Stars, and the Tracks or Circles of ​the Sun and Planets apparent Motions, if you get a right Notion of it, as this Vid Fig. 1. Figure, which we call an Armillary Sphere, will I think help you to obtain: In order to which you must now imagine your Eye placed within at the Center of the Globe, or on the little Ball there in the Figure which represents the Earth; and that the Spherical Surface of it, on which you see the Stars there painted and gilded were transparent like Glass; so that you could actually see thro' it, not only all the Circles drawn upon it, but also all the Stars above in the Heavens, as they really appear there in a bright Night. And if you imagine further, Madam, that strait Lines were drawn from every Star in the Firmament to your Eye so placed, as before, in the Center of this Globe, those Lines would pass thro' and cut the Spherical Surface of the Globe in proper Points to paint, or to place the Pictures of the Stars upon.
You are perfectly right, Madam, said I, and Ptolomy himself, could not have expressed it better. And just in that Central Point (and just such a Point as that is it) do Astronomers of his Sect Vid. Fig. 1.suppose the Earth to be placed, as you see in the Figure, in the middle of the Sphere of the fixed Stars, which seem to revolve round about it, once in 24 Hours, because the Earth doth turn round her own Axis, tho' a contrary Way, in the same Time.
Of this, replied Clarella, I have gotten a tollerable Notion from what you said before, and from the French Author: But, pray, let us now go on with our Globes here; What is the Meaning of this broad Wooden Circle placed round each of them, and what is it called?
Madam, said I, it is called The Horizon; which is a Greek Word that signifies a Limiter or Determiner. And to conceive it right, imagine your self placed, as before, on this poor little Earth, within that immense Celestial ​Globe; which you are to suppose now to be millions of Millions of times greater than it really appears to be: Then you know, if you look round you on the Earth, its Surface will extend every way from your Eye, like a vast Plain; which will be under your Feet, and to which your Body will be perpendicular, or upright: this Plain stretching all round you every way as far as your Eyes can fee, in a flat open Country where no Hills interpose: Hemispheres.Or on the Surface of the Sea, will seem to divide or cut the Concave Orb of the Stars, or the Sky, into two Parts (which they call Hemispheres; the one seemingly above this Plain; which therefore they call the Upper, and the other apparently below it: Which therefore they call the Lower Hemisphere. Horizon.Such a Plain is this is call'd the Horizon: And if it be really that which any one's particular Eye makes upon any occasional View, 'tis call'd the Sensible Horizon: But if you imagine this Plain, as you may easily do, to pass through the very Center of the Earth on the Surface of which you then stand, 'tis called the Real or Rational Horizon; because that doth really or actually divide the Starry Regions into two equal Hemispheres; and both these Horizons are well enough represented by that wooden Cir​cle, which you now lay your fair Hand upon.
I Hope I take you right, said she; and now begin to understand better the Meaning of many Expressions which have often occurr'd to me before, but with less Light. But why do you so cautiously use the words apparently above and below?
Because, said I, Madam, there is in reality no such thing as any Difference between above and below: The Heavens are every where above or without what they contain; but we, taking our Ideas of things from ourselves, do agree to call that above or uppermost which is over our Heads, and that below, which is beneath us, or down under our Feet: And therefore as we call that Concave Half of the Region of the Fixed Stars, which we see above our Horizon, the Upper Hemisphere; so the other Half takes the Name of the Lower Hemisphere.
I am mightily pleased, said the Lady, with these Celestial Beings that are so perfectly above all the poor Trifles of Place and Station; with which we Mortals make such a bustle here below: Especially those of our Sex; as I will honestly ​own to you, now you are my Master and Teacher; for as Butler hath justly observ'd';
But let us go on. I perceive, said the Lady, that these Horizons will always vary as we shift the place of our View.
Yes, Madam, said I, and so will the Hemispheres too that they determine.
And yet, said she, we are often so vain as to take our little narrow View or Horizon for the Bounds of all that is to be seen; and judge, that what is not within our Hemisphere, to be either nothing at all, or at least not worth our knowing or enquiring after; for we are always so vain as to despise what we do not understand. But I interrupt you with my impertinent Reflections; pray, Sir, go on.
I beg you to take notice farther, said I, Madam, that when the Sun, or any Star or Planet, appears at the Eastern Edge of ​our Horizon, we say it is Rising; and when it is got quite above it, we say it is Risen, or is Up. On the contrary if it appear towards the Western Edge of it we say it is Setting; and when it is gotten below it, we say it is Set. And this Rising and Setting always respects the sensible, and not the Real Horizon.
But what is the meaning of these Circles, demands she, which I see drawn here upon the Board of the Horizon, and on both Globes alike?
The outermost of them, Madam, Sea-Compass. said I, represents the Points of the Compass, as they are called by our Seamen; who make use of an Instrument called the Compass, to steer their Ships by at Sea.
Pray let me know a little more of that matter, said she, for 'tis a Thing I have heard much talk of.
You have seen, no doubt, Madam, said I, a Loadstone; and know that it hath that wonderful Virtue, among others as strange, that if a Needle or long Iron-Wire be drawn rightly over it, that Needle will ever after that, when at liberty, point, as they call it, due North and South.
Madam, said I, you do Me and my Trifles a great deal of Honour———
Hush! said she, not a word! I won't now allow you one Syllable of Trifling; be quiet and go on with your Lecture.
Please to let me inform you then, Madam, said I, that such a Wire as this, so touch'd, as they call it, or directed by the power of the Magnet, or Loadstone, they put into a round piece of Pasteboard, on which they draw a Circle; dividing it as this on the wooden Horizon of the ​Globe is, first into four Quarters, for East, West, North and South, placing the Point of North over that End of the wire which will point that way; then they divide each Quarter into Halves, and by that means they make in the whole 32 Divisions, which they call Points; and which are there and here expressed by the Initial Letters of their Names after this manner: [See Fig. II] And therefore the Use of that Circle on the Horizon of the Globes is to shew, on what Point of the Compass the Sun, or any Star or Planet apparently Rises or Sets; as I shall shew you more fully hereafter.
Well! saith she, I fancy my self half a Sailor already; but for all that I must confess ingenuously to you, that I don't know how to find the Points of East, West, North and South in the Heavens, or on the Earth, unless I see a Church, which, they say, usually stands East and West.
Madam, said I, that is easily known, by the Noon-day or Meridian Sun; for the Sun at Twelve a Clock being always full South, when you turn your face towards it, the North will be on your Back, the East on your Left, and the West on your Right Hand.
CalendarBut pray let us go on: The next Circle I perceive is only an Almanack, with both our Own, and the Foreign or New Stile, or way of accounting Time: But pray, Sir, of what Use is this innermost Circle, and how is it divided?
Divisions of a Circle.Madam, said I, all Circles on the Globes are supposed to be divided into 360 equal Parts, which they call Degrees, and each Degree into 60 lesser Parts which they call Minutes, and so on, by a Sub-division by 60 still, as far as you please. This Circle is design'd to shew us what we call the Sun's Place for every Day in the Year; and therefore is divided actually into 12 parts, which are distinguish'd here, you see, by these Pictures of 12 Eminent Constellations, or Parcels of Stars; and which, because they do sign ​or mark out a particular Place in the Heavens, where the Sun is, or appears to be, every Month, have been called the Signs of the Zodiac.Twelve Signs of the Zodiac: And each of these Signs is divided into 30 equal Parts or Degrees, which makes up the whole 360.
Hold a little, Sir, said the Lady, for I have now so many things to ask you that I know not where not to begin ———
Madam, said I, all the Affair of the Zodiac, of the 12 Signs, and of the Sun's apparent Yearly Motion through them, I will fully explain to you hereafter: And all you need know now is, That it is the Use of this Circle to shew you in what Degree of it, or in what Place or Part of any of the 12 Signs, in which the Sun is supposed to be at Noon, answers to each particular Day of the Month: As for Instance; You see this Day, May the 20th, is placed in the Calendar, just against the first Degree of (♊) Gemini, and therefore that is the Sun's Place for this Day.
Since I must wait, said she, I will be patient, and be content to be taught in your own Way; but I will never forgive you if you don't tell me, just now, why 360 was only pitch'd upon for the Number of ​Divisions, or, as you call them, Degrees of your Circles; and why any other Number would not have done as well?
Madam, said I, any other greater Number that could have been broken into Parts without Fractions would have done better. But they had a particular Reason to pitch upon this 360, which yet I beg you will excuse me from telling you now, because it will be much more usefully explain'd hereafter, and save a great many Digressions at present.
Well! said she, I'm sure you keep me out of this only to mortify me, and to try my Patience; but that I may not tire yours, I submit.
You are so moderate and easy in your Desires, Madam, reply'd I, that I will now go out of the common Method, and explain all that Matter to you immediately.
Sun's Motion.The Ancient Astronomers observed of the Sun, that besides his apparent Motion round the Earth in 24 Hours, by which he made, as they supposed, Day and Night; the former when he was above, the latter when he was below the Horizon of any place; which Daily or Diurn​nal Motion (by the by) they supposed to be always made either in this very Equinoctial Circle, or in some other lesser ones parallel to it, or equally distant from it: These Parallel Circles also they supposed to be, in the Summer Half-year on the North side, and in the Winter, on the South side of the Equinoctial. And they took notice, Madam, that besides this Diurnal Motion (which appear'd to be circular) the Sun had also in appearance a progressive one, forward on in another circular Track in the Heavens; which, because they found that when ever the Moon came into the very same Circle, there would be an Eclipse of either Her, or the Sun, they call'd the Ecliptick. This is the Circle here on the Glove, which lies oblique to, or askew, and cuts or crosses this other, which is drawn exactly into in the middle between the Poles, and is call'd the Equinocital or Equator: This Ecliptick Circle also, because they perceived that the Sun never deviated from it in his Annual Motion towards either Pole North or South, they called the Way of the Sun: And they found that in the Time of our Common Year, he would appear to go quite round, or pass successively through all the Parts of this Circle.
Your Objection is just, said I, Madam, if you consider the thing after the Sun was actually Risen, and just before his Setting: But they took notice of those Stars which were at or near the Edge of the Horizon before his Rise, and such as were there after his Setting; and found that the Sun would not continue to rise and set always at the same distance from the same Stars; but if, for instance, on March the 10th, he would rise and set near these Stars which you see here placed on the Glove within this Constellation called Aries, about a Month after they found that he would rise and set with those in Taurus, which lie a 12th part of the whole Circle more this way, or forwards on, as the Numbers shew, to the East-ward; and after this manner the Sun proceeding still forward every Day, they found that at the end of 12 Months he would seem to have gone entirely round in this Circle, and to rise and set successively with or under all the Fixed Stars, ​which are in or near this Circular Track called the Ecliptic.
But, pray, Sir, said she, what do you mean by under the fixed Stars? Why, don't the Sun move in among them, and along with them?
No, by no means, Madam, said I, the fixed Stars are probably farther, a long way, from the Sun, than that mighty Luminary is from us; and the Meaning of the Sun's Place.Sun's Place, or his being in such a Sign, is only his being for such a Time under that Star or Constellation, or between that and our Eyes; so that if a Right Line were drawn from that Star to your Eye, it would pass thro' the Center of the Sun.
I Begin, said the Lady, I think, to comprehend this a little better than I did; but, pray, Sir, what is the meaning of the Word Zodiac.Zodiac, which you used a while ago, when you began to talk about the Sun's Motion?
The ancient Astronomers, Madam, said I, to distinguish these Constellations or Setts of Stars, under which the Sun constantly appeared to move in his An​naul Course, gave them particular Names: The first they called Aries, or the Ram; the second Taurus, or the Bull, &c. and because these Names were mostly taken from Animals, or living Creatures, they called it the Zodiack; which is a Greek Word expressing such a Collection.
Well, said she, as for your Greek, I know nothing of the matter, but now I begin to find out the Justness of those Lines, in Hudibras; wherein he describes Sydrophil's Surprise at the Discovery of his new Star, occasion'd by a Lanthorn at the Tail of a School-Boy's Kite:
And these, I suppose are the Pictures, continu'd she, of those animated Stars, or rather, as Butler hath it in the same Place, the Signs of Those:
Mighty well remember'd, said I, Madam, you see at once why the Astro​nomers call them the Twelve Signs, because, as I said before, they sign or mark out the Place of the Sun in the Heavens; and also why the Astrologers called them Houses, because they assigned them as Dwellings or Places of Abode for the Planets:
O! said she, now you talk of Astrology, I must ask you a few Questions about that either now or some other Time; for I long to know whether there be any thing in that Art or no; for I think I have heard you throw out some suspicious Words about it.
Madam, said I, if you please to go on with your Astronomy, you will soon know enough to despise that vain and foolish Cheat, as a thing perfectly beneath your Enquiry into.
Very well, said she, and so if I will be an Astronomer, it seems, I must at once bid adieu to that darling Pleasure of our Sex, Curiosity, and the Desire of knowing our Fortunes; this is very hard, and you are really, Sir, a very bad Woman's-Man; you have Philosophised me out of many a fair Pleasure already; Censure, Satyr and Gossipping are almost gone; and must dear Inquisitiveness follow them ​too? It shall never be, let it be never so silly; I remember what Butler saith:
but I ha'n't Time to quarrel with you, and to dispute it out with you now; pray, therefore, Sir, go on, about the Sun's Motion, a little farther.
You must know then, Madam, said I, that these venerable Star-Gazers, finding the Sun apparently to run thro' this Zodiac, in twelve Months, or a Year's Time, assigned one part of the Circle to a Day's Motion; and because there are but a few more than 360 Days in a Year, they supposed this Circle of the Sun's Annual Motion, to be divided into 360 equal Parts, which they called Degrees, as I told you before; and hence all Circles on the Globes came to be divided after the same manner.
I thank you, sir, said she, now this Matter begins to clear up to me; have ​you any thing more to teach me about this Circle?
Only the Explanation of a few Terms, or Words, which you will find used about it, said I, Madam: For you must know, that the Astronomers call the Distance of the Sun's Place at any time of the Year, from the Beginning of Aries here, which you see is placed at the Eastern Point, where this Circle of the Ecliptick, and that of the Equinoctial cross one another, they call that Distance, I say, his Longitude; and tho' the Sun himself apparently moves always in one Circle, exactly in the middle of the Zodiac, that is in the Ecliptic, yet the Moon, and the other Planets, do not, but sometimes are 5 or 6 Degrees to the North, and at others, as far to the South of this Circle; and this Deviation or Distance they call their Planets Latitude.Latitude; and you shall be shewn hereafter how to measure it; and the same Word is used also, with Reference to those fixed Stars which are not in the Ecliptick, but are distant from it, any Way, towards either of its Poles; for the Distance of a fixed Star from the Ecliptic, is also called its Latitude.
Yes, Madam, said I, and you will very easily comprehend it: Please to turn your Eyes to the Terrestrial Globe; this Circle which lies exactly in the middle, between the two Poles of the Earth, is here called the Equator.Equator, and by the Sailors the Line; all Places which lie under it, or which have the Equinoctial in the Heavens, passing over their Heads, are said to have no Latitude; but all other Places that lie at any Distance from it, either North or South, are accordingly said to have Latitude of Places.North or South Latitude: And its Quantity is known by turning the Globe about till the Place come to this Brazen Circle in which the Globe hangs, and there the Place will shew its own Latitude, in Degrees upon that Circle: Thus, you see, Madam, ​when I bring London to this Brass Circle, it appears to lie on the North Side of the Equator, in 511/2 Degrees distant from it.
Mighty well, Sir, said she, I now conceive what passing or crossing the Line is, which I have heard the Sailors make such a Fuss about; and I have read of strange Ceremonies and Duckings, which they make young Navigators undergo, at the first Time of their crossing the Equator: I perceive now, also, the true Meaning of several Allegorical Expressions, which, no doubt, are taken from hence, such as being a Latudinarian in Notions, &c. But pray, Sir, let us go on; now you mention that Brass Hoop, in which the Globes hang and turn round, pray let me know its Name and Use?
That Brazen Circle, Madam, said I, is called the Meridian.Meridian; and 'tis a greater Circle of the Sphere, which is supposed to pass thro' the Zenith and Nadir of any particular Place, thro' the North and South Points of its Horizon, and thro' the Poles of the World.
I See, said she, the latter part of what you say; but pray, what do you mean ​by the Terms Zenith and Nadir, the former of which Words I have often met with in Books, but never knew the Meaning of it.
'Tis an Arabick Word, said I, Madam, and signifies that Point in the Heavens that is directly over your Head, as Nadir doth the opposite one in the lower Hemisphere, at the opposite End of a Diameter of the Earth: And this Brazen Circle is called the Meridian, because, whenever the Sun comes to the Meridian of any Place on the Earth, in his daily Course, 'tis then, what the Latins called Meridies, i.e. Mid Day, or exactly Noon there.
O! Sir, said she, this Astronomy is mighty instructive; I now understand the just Meaning of such Expressions, as these,
But pray let me know the Use of this Circle here on the Globes.
I shew'd you just now, said I, Madam, That on the Terrestrial Globe it shewed the Latitude of all Places, which, by being brought successively to it, as the ​Globe turns round its Axis, do each receive it for their own Meridian, for 'tis all one as if a different Meridian had been actually drawn on the Globe thro' every Place.
No doubt on't, said she, for 'tis the same thing, as to meeting, whether the Mountain walks to Mahomet, or He stalk to the Mountain: But methinks this Earthly Meridian is either very lazy, or else takes great State upon him, that all Places must come to him, while he stands and struts here, and won't stir the least Step towards them.———Have you any thing more to tell me about this Man of Brass; Spenser did wisely to make his Man Talus out of Iron, that was to be Arthegall's Page and to bear so busy and active a Part in his Story.
Madam, said I, this Brass Meridian serves also, by its moving thus, round, North or South, Height of the Pole.in this perpendicular Situation to the Horizon, to elevate or raise the Pole of any Place as much above its Horizon in Degrees, as is the Latitude of that Place, or its Distance from the Equator, and then that particular Place will be brought to lye in the Zenith, or uppermost Point of the Globe.
I Shewed you just now, said I, that the Latitude of London is found by the Help of this Meridian to be 51° 1/2; raise therefore the North Pole so, that the Northern Edge of the Horizon cut 51° 30′ of this Brass Meridian, reckoning from the Pole, and then London will be in the Zenith Point of the Globe.
I See it is, said the Lady, and I believe I see also the Reason why it must be so; for it is just as far (viz. 90°) from the Equator to the Pole, as from the Zenith to the Horizon; so that taking away the middle Part, which is common to both, the Latitude of any Place, and the Height of the Pole above its Horizon are all one in Quantity; and so I suppose 'tis called the Height of the Pole, because the Pole Star, which is near the Polar Point (as I think you told me) will appear, in the Night, just so high above the Horizon of any Place, as is that Place's Latitude.
Excellently Explain'd, Madam, said I, and yet I fancy you want to be told further, that the Height, or Altitude of ​the Pole Star, as well as all other Altitudes of the Sun or Stars, is taken by an Instrument, which hath a Circular Edge like this Graduated Meridian, divided on Purpose into Degrees, Minutes, &c. with Sights fitted to it, to look up at the Object.
I Was just going to ask you about that, said she; for I remember to have often seen you peering up at the Stars, or catching the Sun-Beams with just such a kind of thing as you describe: But, pray, what Use is this Meridian of, on the Celestial Globe?
There, Madam, said I, it shews the Declination of the Sun or Stars, by bringing the Sun's or Stars Place in the Ecliptick on the Globe to it, as we did the Places of the Earth upon the other Globe, to find their Latitudes.
Sun's Declination.Declination! said she, there's a new Word for me to learn! which I suppose the Astronomers have coined, to avoid that of Latitude; which, when it relates to the Stars or Planets, I think you told me regards the Ecliptic only: Well! I doubt my Head will never retain the Memory of all these Cramp Terms.
I Thank you, Sir, said she, for that Information; I shall, I hope, be able to understand a little of Books of this Kind, by Degrees: But, pray, have you any thing more to shew me, relating to these Circles?
Madam, said I, 'twill be proper for you to know, that as our Astronomers make Greater and Lesser Circles of the Sphere.six greater, so they also make four lesser Circles of the Sphere; two of which they call the Tropicks, and the other two the Polar Circles. The Meaning of the Word Tropicks is, returns back again; for indeed neither the Sun seemingly, nor the Earth really, goes any further in its Annual Course, to the Northward or Southward ​of the Equinoctial than 23 Degrees and 1/2; but after it hath gone so far, returns again toward it: And because the Points in the Heavens, where these Returns are made, are under the Beginnings of the Signs ♋ Cancer and ♑ Capricorn; they suppose two Circles to be there drawn in the Heavens and on the Earth, parallel to the Equator; and the most Northern of these, and which therefore is our Summer Tropick, is called the Tropick of Cancer, and the Winter, or Southern one, that of Capricorn; because they always fall at the Beginning of those Signs.
I Like our Earth mightily, said she, for her Steadiness in her Way, and for her not going too far North or South towards the Poles: I love moderate Weather, and would have it be in neither of the Extreams of Heat nor Cold: But, Sir, this Matter now begins to clear up to me apace; when the SUn is in the Northern Tropick, I see our Days are at the longest, and all of them longer than our Nights, during the Time of his whole Stay on the North Side of the Equinoctial: Whereas the very Reverse, I see, must come to pass, while the Sun is on the Southern Side of the Line. But, pray, of what ​Use are the Polar Circles and Tropicks.Polar Circles? for I see they are drawn on both Globes, as well as the Tropicks, and just as far from the Poles as the Tropicks are from the Equinoctial.
Of no very necessary Use, Madam, said I, but only to help to distinguish the Terrestrial Globe into the five Parts, which the Ancients called Zones.Zones, and which they fancied to be like so many Girdles or Belts (as the Word Zone signifies) encompassing the Earth.
O Pray, said she, let me have some true Knowledge about these Zones, for I have heard and read a good deal of them, without being a Jot the wiser.
The great Space on the Earth, said I, Madam, which lies between the two Tropicks, having the Equator passing thro' the middle of it, the Ancients called the Torrid.Torrid, the Fiery or Roasted Zone; for they fancied the Sun, keeping always over it, had such a Power here, as to have burnt all things up; and because they had no Knowledge of it, concluded it not inhabitable; whereas 'tis now known to be very comfortably so: Tho' no doubt warm enough to those Inhabitants of it to whom ​the Sun is successively vertical, or directly over their Heads, as you easily see by the Globe he will be.
Yes, yes, said she, I understand that very well; but I can't help reflecting upon the Arrogance, as well as Ignorance, of the Ancients, in supposing their Knowledge to be the Bounds of all things; and glad I am that we know something which they did not; for I have heard them so much cried up, now and then, by Authors, that I could almost wish my self to have lived among them; but I will, at last take Comfort, and thank God that I am a Modern, and alive now.—But pray go on about your Zones.
These two Spaces of the Earth, said I, Madam, which lie between the Tropicks and the Polar Circles, each Way North and South, the old Geographers called the Temperate.Temperate Zones; and as these Oriental Sages, and the Learned Greeks and Romans, lived (as yousee here) in one of them, so they did allow the other to be habitable also.
That was pretty good-natur'd, said she, for I suppose they never saw the ​Southern Temperate Zone, any more than the Torrid one.
Not that we can find by History, said I, Madam: But to proceed; These small Spaces of the Earth, between the Polar Circles and the Poles, they called the Frigid.Frigid Zones, and did pretty justly suppose them not to be habitable, upon the Account of their Coldness; for tho' we have since discovered, that 'tis possible to subsist, and several of our Ships do yearly go within the Northern Frozen Zone, yet I can't commend it to you as a Place much worth your Enquiry after.
O! don't speak any more about them, said she, you make me shiver all over with the Thought of them, and my Blood is just going to curdle in my Veins; no Lapland or Spitsburghen; no Whale-Fishing Voyages for me!
You seem to be really a cold with the Thought of it, Madam, said I; let me warm you a little with this Description of these Zones given by Mr. Dryden,
From Virgil and Ovid.
Well, said she, these Verses have a little recovered my Spirits, as well as refreshed my Memory, and will, I find, fix in the latter, the obliging Pains you have taken to instruct me: But pardon me, Good Sir, if I stop you a Minute: Mr. Dryden here mentions the Word ClimatesClimates; Pray what are they?
Madam, said I, you will find a deal of useless Stuff in some Introductions to Geography, &c. about these Parallels.Climates; but all that is necessary to know of them, is, that the Ancients supposing two Circles to be so drawn parallel to the Equator, on the Terrestrial Globe, or at that Distance ​one from another, that to such as inhabit the lesser, the longest Day, would be a Quarter of an Hour longer, than it is to those who dwell in the larger: Then the Space on the Globe, between these two, they called a Parallel, and the Double of such a Space a Climate; you will easily see therefore, that these Climates must lessen as you go each Way from the Equator to the Poles, and must be 24 in Number.
Well! said she, I shall not trouble my Head about reckoning these Climates; but I think I understand what is meant by such a Place lying in such a Climate, as well as what the Navigators mean by sailing in such a Parallel, and that will be enough for me at present; but I will tire you no longer now, I'll get the Book you advise me to, which I believe I have above among my Brother's things; and after I have conned my Lesson well over, you must expect that I shall ask you abundance of Questions more.
Within a short Time after this, the Ingenious and Inquisitive Lady got her Globes set out again, and began with me thus:
That Greek Word, Madam, said I, signifies something to be done or practised, and I question not but you have so well considered this Affair, as to be able to work or perform any of these Problems upon the Globes your self.
I Don't know that, said she, but I'm resolv'd to try, and with a little of your Help, perhaps, I may get thro' them: Come, pray, let's begin; and, first, shew me how to Rectifying the Globe.rectify each Globe, as he calls it, and what I shall learn by that.
Rectifying the Globes, Madam, said I, is reducing them to such a Position, as that they shall truly represent the Situation of the Circles of the Sphere of the fixed Stars and Planets; and of the Position of the Earth itself at any Time assigned.
Madam, said I, for common Use, look first for the Sun's Place.Sun's Place, against the Day of the Month, in the Calendar, on the wooden Horizon (tho' if you would proceed to greater Exactness, you must find the Sun's Place in some good Tables, such as those which Dr. Harris hath given in the second Volume of his Lexicon, or such as Parker's Almanack which I have here in my Pocket, gives you every Year, or else you must determine it by Calculation, &c.) and then finding that Place, or what Degree of any Sign of the Zodiac the Sun appears to be in that Day at Noon, which you will find to be then in in the first Degree of Gemini, look it out on the Ecliptic on the Globe, and there make, either with a Pencil of with ink, a Mark to represent the Sun for that Day.
But, said she, won't that spoil the Globe?
No, Madam, said I, that being varnish'd, the Ink will easily come out again, if you rub it with your Handkerchief a ​little wetted; as soon as this is done, you may also, if you please, by the Help of Parker's or some such Ephemeris or Astronomical Diary, place all the Planets on your Globe, after the same Manner, allowing for their Latitude, either North or South, of the Ecliptic.
Thus the Moon being then in 24° 33′ of Cancer ♋, and having about 4° 41′ of South-Latitude, take, with a Pair of Compasses, those Degrees and Minutes of Latitude from the Meridian, or any great Circle, and placing one Foot in 24° 33′ of ♋, turn the other directly towards the Equinoctial, and there make this Mark ☾ to represent the Moon.
After the same Method you may place ♄ Saturn in 8° 42′ of Virgo ♍; and ♃ Jupiter in 26° 35′ of Leo ♌: Then make also this Mark ♂ for Mars in 16° 32′ of Aquarius ♒: And this Character ♀ for Venus in 28° 18′ of Gemini ♊: Lastly, placing Mercury ☿ in 11° 4′ of the same Sign, you will have adorn'd your Globe with the Characters of the Seven Planets, all appearing in their proper Place as they are in the Heavens.
This is mighty Entertaining, said she; here take this Pencil quickly, and let me ​see you just now place all your Planets upon the Glove according as they ought to be done, that i may learn how to range them another Time: For I fancy their very Characters or Figures so much, that I could almost wish our Patches were cut into such pretty Forms; but that I fear 'twill revive the foolish Notions of Astrology again, which you have taught me to despise. But, pray, continued she, how do you know the Planets from the fixed Stars when you see them in the Sky?
Pretty easily, said I, Madam, as to Saturn, Jupiter, Mars, and Venus. And Mercury is so near the Sun as to be very rarely seen at all.
That puts me in Mind, said she, of what Sir Richard Blackmore saith of him in his Poem called Creation, in these Lines.
Well remember'd, Madam, said I, But to our present Point, the Knowledge of these Planets from the fixed Stars: The former, you must know, don't twinkle as ​the fixed Stars do; besides they are always and all of them in or near this Line here called the Ecliptic: Which you may easily learn to trace out in the Heavens, by these Constellations which compose the Twelve Signs; and if you should, at last, doubt about the Planets, if you see them change as they will do, in some Time, their Distance from any fix'd Star that you know; you may easily distinguish them to be Erraticks or Planets.
I Think, said she, you reckon'd seven Planets just now; sure I have read some where, that there are more.
In that Account above, said I, Madam, I followed only the Vulgar Way of Computation, for in Reality the Sun is no Planet or Wanderer, but a fixed Number of Planets.Star placed in the Center of our System, and in all Probability like the rest of those that we see in the Heavens. And round him, as a Center, Mercury, Venus, Mars, the Earth, Jupiter and Saturn, do revolve, and are now called Primary Planets; because they revolve round the Sun, as their Center: While the others we call Secondary Ones or Satellites, i.e. Guards or Attendants, because they revolve round some one of the Primary Pla​nets, as their Center, and together with it, move also round the Sun.
Thus the Moon is a Secondary Planet, whose Center of Motion is our Earth, on which she constantly attends, and her Circle round us she performs in about a Month's Time, while at the same time, she revolves together with the Earth round the Sun in its Annual Course. Satellites.Jupiter hath four such Moons or Satellites; and Saturn five, revolving round Him: But it doth not yet appear that Venus or Mars have any Satellites at all.
As for Mars, said the Lady, I shan't trouble my Head about him; tho' one would think, the God of War, or Captain-General of Heaven, might command a few Guards or Followers: But I will never forgive the Astronomers, nor believe at all in Telescopes, if they don't find out that Venus hath some Attendants; that is such an Affront to our Sex, as we must never pass by. But to be serious, I suppose, Mercury and Venus being so near the Sun, have no occasion to be lighted in the Night by Moons, as the more remote Planets have; tho' why our Earth should have one, and yet Mars none, is not, methinks, so easily to be ac​counted for. But we have made a long Excursion from our Globes; pray let's return to them: And let me see what I shall be the better for knowing how to rectify the Globes, and to patch on the Planets, as you just now have shewed me the Way of.
Hour Circle and Index.Madam, said I, bring the Sun's Place, for May 10, to the graduated Side of the Meridian, and then turn or set the Index of the Hour-Circle (placed here as you see upon the Brass Meridian about the Pole) to Twelve at Noon; and then your Globe will be fitted to shew you the State of the Heavens. As it now stands, the Mark for the Sun represents his being on the Meridian, as he is every Day at Noon; and there it will shew the Sun's Meridian Altitude above the South Part of the Horizon to be 58 Degr. 42 Min. Then if you will bring that Mark to the Eastern Edge of the Wooden Horizon, you will see there what Point of the Compass the Sun rises upon, and your Index will shew you the Time of it; and if you bring the Sun's Place to the Western Edge, you will find how far from the true West Point the Sun sets, and what a Clock it is when he goes down, as we call it: Thus, May 10, the sun rises about 3/4 of ​an Hour before 5 a Clock; and sets 3/4 of an Hour after 7.
Well, said she, I fancy I shall be able to make an Almanack in a little Time.
That you may soon do, this Way, said I, Madam, and much better than most of those who publish them: But if you have a Mind to know the Stars and Planets, how they will appear, and are situated at any particular Time, suppose to Night at Eleven a Clock; you need only turn the Globe about till your Hour-Index points to Eleven at Night, and then putting a little Piece of Paper under the Brass Meridian, to stay the Globe in that Position, please to turn the Frame, and Globe and all, about, till the North-Pole here point up towards the Pole Star in the Heavens; and then you will have all you can wish for shewed you; for, by comparing the Pictures and Marks of the Stars and Planets with the real Ones, at that Time in the Heavens, you will find them exactly to answer to one another; and these on the Globe will make those easily and sufficiently known to you.
Sir, said she, after abundance of Thanks, I must beg you to break off ​here; we mnst defer this till Night:
And in the mean time, I'll con my Lesson in the Book, that my Ignorance may not give you too much Trouble. The Tea waits us; will you please to move, Sir?