GEOMETRICAL AND GRAPHICAL

ESSAYS:

CONTAINING,

1. A felect Set of Geometrical Problems; amongst these are some very curious ones for dividing Lines and Circles with Accuracy.

II. A Description of thofe Mathematical Inftruments which are usually put into a Cafe of Drawing Inftruments, and many other new ones for Geometrical Purposes.

III. A Description of the Inftruments used in Surveying and Levelling of Land.

IV. A Description of those Instruments that have been contrived to affift the Artift in delineating with Accuracy, and in true Perfpective, the Outline of a Landscape, Building, or any other Object,

Alfo Preparing for the Prefs,

AN ESSAY ON VISIO N, So far as relates to the Ufe of Spectacles; pointing out the Criteria, by which every Perfon may judge when the Ufe of them will be beneficial, and how to chufe them without injuring the Sight.

(xi)

TABLE

O F

CONTENTS.

F the Solar Syftem, as seen from the Sun

Of the Celestial Signs and Conftellations

Of the Planets, as feen from the Sun

Of the Paths of the Planets

Of the Motion of the Planets round their Axis

PAGE

Of the Phænomena of the Heavens, as feen from the

Of the Apparent Motion of the Sun

Of the Apparent Phænomena of the Moon

Of the Apparent Motion of the Stars

The Appearance of the Planets

Of the Copernican System

ibid.

30

3

33

41

Of the Annual Motion of the Earth

Of the Phænomena occafioned by the Annual and

Diurnal Motions of the Earth

97

104

PROB. I. To find the Longitude of any Place

275

11. To find the Difference of Longitude

between any two Places

277

111. To find all those Places where it is Noon

at any given Hour of the Day, in ano-

ther Place

279

IV. When it is Noon at any Place, to find

what Hour it is at any other Place

v. At any given Hour where you are, to find

the Hour at a Place propofed

282

283

VI. To find the Latitude of any Place

287

VII. To find all thofe Places which have the

x. To find the Distance of one Place from:

XIV. To exemplify the Sun's Altitude

xv. Of the Sun's Meridian Altitude

316

318

XVI. To

XXIII. To find the two Days on which the Sun

is in the Zenith of any given Place, &c. 334

XXIV. To find where the Sun is vertical on a
given Day and Hour

xxv. At a given Time of the Day in one Place,

to find at the fame Inftant thofe Places

ibid.

where the Sun is rifing, fetting, &c. * 335

XXVI. To find all thofe Places within the Polar

Circles, on which the Sun begins to

fhine, &c.

· 337

XXVII. To make Ufe of the Globe as a Tellurian 339

XXVIII. To rectify the Globe to the Latitude and

Horizon of any Place.

XXIX. To rectify the Sun's Place

xxx. To rectify for the Zenith of any Place

XXXI. To fhew at one View, for any given

Place, the Sun's Meridian Altitude,

Amplitude, &c.

343

ibid.

344

· 345

XXXII. To fhew at one View the Length of the

Days and Nights at any particular

Place, &c.

346

XXXIII. To