TO MY LEARNED FRIEND MR. JOHN EAMES,

DEAR SIR,

Fellow of the Royal Society.

IT would be mere trifling to say any thing to you of the excellency and great advantage of those sciences, whose first rudiments I have here drawn up. Your large acquaintance with these matters hath given you a just relish of the pleasure of them, and well informed you of their solid use. But, perhaps, it is necessary to excuse myself to the world, if I publish some of the fruits of my former studies on such subjects as these. I would therefore willingly have the unlearned part of mankind apprized of the necessity and general use of this sort of learning; and that not only to civil, but to sacred purposes.

1

If you, Sir, would please to take upon you this service, you would make it appear with rich advantage how far the knowledge of things human and divine are influenced and improved by these studies.

You can tell the world, that it is the knowledge of this globe of earth on which we tread, and of those heavenly bodies which seem to roll around us, that hath been wrought up into those two kindred sciences, Geography and Astronomy. And there is not a son or daughter of Adam but has some concern in both of them, though they may not know it in a learned way.

This earth is given us for a habitation: It is the place of present residence for all our fellow-mortals: Nor is it possible that there should be any commerce maintained with those who dwell at a distance, without some acquaintance with the different tracts of land, and the rivers or seas that divide the regions of the earth.

The heavenly bodies, which are high over our heads, measure out our days and years, our life and time, by their various revolutions. Now life and time are some of the dearest things we have, and it is of important concern to distinguish the hours as they pass away, that proper seasons may be chosen and adapted for every business.

You know, Sir, that those necessary and useful instruments, clocks, watches, and dials, owe their origin to the observations of the heavens: The computation of months and years had been for ever impracticable without some careful notice of the various situations and appearances of those shining worlds above us.

I shall be told, perhaps, that these are not my special province. I is the knowledge of God, the advancement of religion, and converse with the scriptures, are the peculiar studies which Providence has assigned me. I know it, and I adore the divine favour. But I am free and zealons to declare, that without commencing some acquaintanee with these mathematical sciences, 1 could never arrive at so clear a conception of many things delivered in the scriptures; nor could I raise my ideas of God the Creator to so bigh a pitch : And I am well assured that many of the sacred function will join with me and support this assertion from their own experience.

If we look down to the earth, it is the theatre on which all the grand affairs recorded in the bible have been transacted. How is it possible that we should trace the wanderings of Abraham that great patriarch, and the various toils and travels of Jacob, and the seed of Israel in successive ages, without some geographical knowledge of those countries? How can our meditations follow the blessed Apostles in their laborious journies through Europe and Asia, their voyages, their perils, their shipwrecks, and the fatigues they endured for the sake of the gospel; unless we are instructed by maps and tables,

wherein those regions are copied out in a narrow compass, and exhibited in one view to the eye?

If we look upwards with David to the worlds above us, we consider the heavens as the work of the finger of God, and the moon and the stars which he hath ordained. What amazing glories discover themselves to our sight? What wonders of wisdom are seen in the exact regularity of their revolutions? Nor was there ever any thing that has contributed to enlarge my apprehensions of the immense power of God, the magnificence of his creation, and his own transcendent grandeur, so much as that little portion of Astronomy which I have been able to attain. And I would not only recommend it to young students for the same purposes, but I would persuade all mankind (if it were possible) to gain some degrees of acquaintance with the vastness, the distances, and the motions of the planetary worlds on the same account. It gives an unknown enlargement to the understanding, and affords a divine entertainment to the soul and its better powers. With what pleasure and rich profit would men survey those astonishing spaces in which the planets revolve, the hugeness of their bulk, and the almost incredible swiftness of their motions? And yet all these governed and adjusted by such unerring rules, that they never mistake their way, nor lose a minute of their time, nor change their appointed circuits in several thousands of years! When we muse on these things we may lose ourselves in holy wonder, and cry out with the Psalmist, Lord what is man that thou art mindful of him, and the son of man that thou shouldest visit him?

It was chiefly in the younger part of my life indeed that these studies were my entertainment; and being desired both at that time, as well as since, upon some occasions, to lead some young friends into the knowledge of the first principles of Geography and Astronomy, I found no treatise on those subjects written in so very plain and comprehensive a manner as to answer my wishes: Upon this account I drew up the following papers, and set every thing in that light in which it appeared most obvious and easy to me.

I have joined the general part of these two sciences together: What belongs particularly to each of them is cast into distinct sections. And I wish, Sir, you would present the world with the special part of astronomy drawn up for the use of learners in the most plain and easy method, to render this work more complete.

Most of the authors, which I perused in those days when I wrote many parts of this book, were of older date: And therefore the calculations and numbers which I borrowed from their astronomical tables, cannot be so exact as those with which some later writers have furnished us : For this reason

the account of the sun's place in the ecliptic, the declination and right ascension of the sun and the stars in some parts of the book, especially in the solution of some of the problems in the 20th section, may perhaps need a little correction; though I hope the theorems will appear true in the speculation, and the problems so regular and successful in the practice as is sufficient for a learner. However, to apply some remedy to this inconvenience, there are added at the end of the book some later tables, which are formed according to the celebrated Mr. Flamstead's observations.

I have exhibited near forty problems to be practised on the globe, and thirty-five more of various kinds, to be performed by manual operation with the aid of some geometrical practices. These were very sensible allurements to my younger enquiries into these subjects, and I hope they may attain the same effect upon some of my readers.

It was my opinion that it would be a very delightful way of learning the doctrine and uses of the sphere, to have them explained by a variety of figures or diagrams; this is certainly much wanting in most authors that I have perused. I bave therefore drawn thirty figures with my own band, in order to render the description of every thing more intelligible.

I have endeavoured to entertain younger minds, and entice them to these studies, by all those easy and agreeable operations relating both to the earth and the heavens, which probably may tempt them on to the higher speculations of the great Sir Isaac Newton and his followers on this subject.

Yet there should be a due limit set to these enquiries too, according to the different employments of life to which we are called: For it is possible a genius of active curiosity may waste too many hours in the more abstruse parts of their subjects which God and his country demand to be applied to the studies of the law, physic, or divinity; to merchandize or mechanical operations.

If I had followed the conduct of mere inclination, perhaps I should have laid out more of my serene hours in speculations which are so illuring: And then indeed I might have performed what I have here attempted in a manner more answerable to my design, and left less for the critics to censure, and my friends to forgive. But such as it is, I put it entirely, Sir, into your hands to review and alter whatsoever you please, and make it answerable to that idea which I have formed of your skill. Then if you shall think fit to present it to the world, I persuade myself I shall not be utterly disappointed in the views I had in putting these papers together, many of which have lain by me in silence above twenty years.

Farewel, dear Sir, and forgive the trouble that you have partly devolved on yourself by the too favourable opinion you have conceived both of these sheets and of the writer of them, who takes a pleasure to tell the world that he is with great sincerity,

Sir, Your most obedient Servant,

heobalds in Hertfordshire,

June 11, 1725.

1. WATTS.

TO THE READER.

I THINK myself obliged, in justice to the ingenious author as well as the public, to assure them that the alterations I have ventured to make in the revisal of this work, are but few and small. The same perspicuity of thought and ease of expression which distinguish his other works running through the whole of this, I don't question but the world will meet with equal pleasure and satisfaction in the perusal.

August 20, 1725.

JOHN EAMES.

THE FIRST PRINCIPLES

OF

GEOGRAPHY AND ASTRONOMY.

SECTION I,

Of the Spheres or Globes of the Heaven and Earth.

THERE is nothing gives us a more easy or speedy ac quaintance with the earth and the visible heavens than the representation of them on a globe or sphere; because hereby we have the most natural image of them set before our eyes.

The terrestial globe represents the earth with its several lands, seas, rivers, islands, &c. The celestial sphere or globe represents the heavens and stars.

Several points and circles are either marked or described on those spheres or globes, or are represented by the brass and wooden work about them, to exhibit the places and the motions of the sun, moon, or stars, the situation of the several parts of the earth, together with the relation that all these bear to each other.

The earthly globe, with the lines and signs and points that are usually marked upon it, is sufficient to inform the reader of almost every thing that I shall mention here, even with regard to the heavens, the sun and the planets; unless he has a mind to be particularly acquainted with the fixed stars, and the several uses of them; then indeed a celestial globe is most convenient to be added to it.

Note 1st, Half the globe is called a hemisphere; and thus the whole globe or sphere of the heavens, or of the earth, may be represented on a flat or plane in two hemispheres, as in the common maps of the earth, or in draughts or descriptions of the heavens and stars.

Because globes are not always at hand, the several points and circles, together with their properties, shall be so described in this discourse as to lead the reader into some general and imperfect knowledge of these things (as far as it may be done by a map of the world, which is nothing else but a representation of the globe of earth and waters on two flat or plane surfaces ;) or at least I shall so express these matters, that a map will assist him to keep them in remembrance, if he has been first a little acquainted with the globe itself.