Lessons on the globes

V. T. The month, day, and hour at any place being

given, to find that particular place on the earth where

the sun is vertical, and all others that have noon;

those places also that have morning twilight, and

those to which the sun is rising; those places where

the sun is setting; those which have evening twilight;

and those places at which it is midnight

VI. T.-The day of the year being given, to note all places

to which the sun on that day does not set, and those

places where the sun does not rise; and to record his

elevations at noon and midnight in the longitudes of

the former places, and his depressions below the

horizon at noon and midnight in the longitudes of

the latter

VIII.

VII. T. Given the longitude and the sun's meridian altitude

on a certain day, to find the place where the observa-

tion was made

C.-Having a given day, to find at what time a certain

star comes to the meridian

IX. C.-The day, hour, and the latitude of the place being

given, to find what stars are rising, culminating, and

setting; and so to arrange the axis of the globe, as

that the stars depicted on its surface may, each of

them, be exactly opposite their corresponding stars

in the heavens

X. C.-Having a latitude within the north frigid zone, to

find the length of the period of the continual presence

or absence of the sun; and to note some of the pha-

nomena of the heavens during those periods

XI. T.-A number of days being given during which the

sun is above the horizon or below it in the frigid

zones, to find the latitude and the places

XII. T.-To find what places are situated in a given climate.

Conversely, To find the climate in which a given place

is situated

XIII. C.-To find that portion of the equation of time which

results from the obliquity of the ecliptic

XIV. C.-The latitude, day, and hour being given, to find the

azimuth or bearing of the sun or of a star, and its

altitude. Conversely, To find the hour of a certain

day, and the altitude of the sun, or of a star, the

azimuth and latitude being given

XV. T.—(Marked erroneously, XVI.) Having the latitude,

to find the two days of the year which are of a given

length, and in what time that length of day is altered

by a certain quantity.

119

123

125

126

128

143

146

PROB.

XVI. T.-To find the situations of the perioci, antœci, and

antipodes of the inhabitants of any place; and to

explain some of the various phænomena in those

situations

XVII. C.-To find the latitude and longitude of a star or

planet. Conversely, The latitude and longitude of a

star, &c., being given, to find that star, &c.

XVIII. C.-Having the longitudes and latitudes of the planets,

to find their times of rising and setting; their ampli-

tudes, azimuths, &c., at any given place

*XIX. T.-Having the instant of the immersion or emersion

of a satellite of Jupiter, to determine those situations

from which it may be viewed

PAGE

CEL. GL. Exercises, chiefly recapitulatory, on the

Right, Oblique, and Parallel Positions of the

Sphere

160-164

PROBLEMS. SECT. III.

RELATING TO THE TRADE WINDS, THE MOON'S NODES, ECLIPSES,

THE TIDES, THE PRECESSION OF THE EQUINOXES, ETC.

PROB.

PAGE

A. TER. GL.-To find the result of the transfer of a portion

of the atmosphere into a higher or lower latitude

(Trade Winds of the Pacific and Atlantic)

291

B. T. To find the result of the transfer of a portion of the

atmosphere into a higher or lower latitude (Monsoons) 297

C. C.-To find, nearly, the stars over which the moon will

pass during several lunations; and to exhibit the effect

of various positions of her node upon her altitude

D. C.-To find the time of the moon's "transit 99

or coming

310

312

to the meridian, her longitude at noon being given

E. T. From the time of the moon's southing on a certain

day, and her declination for our noon of that day, to

find where she will be vertical at that noon, nearly 314

F. C.-Given, the moon full on the 23d of September, to

find the times of her rising for several preceding and

following evenings

319

G. T.-Given, the moon in the zenith of a certain place at

the instant of her occultation of a star, &c., to find her

appearance with regard to that star from certain other

places

321

* In the Rule to this Problem (page 158, line 15), for "sun's place" read

H. C.-Having the time of new or full moon, to find whether

an eclipse be possible

330

K. T.—A time being given at which the sun is eclipsed where

it is passing the zenith, to find where, also, at that time,

the eclipse may be visible

332

T.-The time of a lunar eclipse being given, to find to

what places it may be visible

334

M. C.-To find the time of high water at the London Docks,

or certain other places, on a given day

N. C.-Given the latitude, to find the time of year at which

a certain star now rises or sets cosmically, acronychally,

or heliacally

350

359

361-364

CEL. GL.—Ēxercises concerning the effect of Precession

on the places of the Stars in relation to the Equinoctial

and its Poles, the Equinoxes, Solstices, &c.

P. C.-To find the time elapsed since the recorded heliacal,

acronychal, or cosmical rising or setting of certain stars 366

Q. C.-To examine, by the globe, quotations, &c., respect-
ing the ancient risings, &c., of certain stars

R. T.-For sunshine.

S. T.-To find the hour-arcs, or angular distances of the

hour-lines, for a horizontal dial, the latitude being

given

T. T. To find the hour-arcs of a vertical dial facing the

south in north latitude, or facing the north in south

latitude, the latitude being given

Z. C.-To map down a group of constellations, having a

certain star given as central

370

. 376

382

. 386

388

LESSONS ON THE GLOBES.

DEFINITIONS, ILLUSTRATIONS, ETC.

CLASS I.

B A Point is that which has position, but not magnitude. c A Straight Line is that which lies evenly between the two points at its extremities.

DA Plane is a surface, real or imaginary, such, that any two points in it being taken and joined by a straight line, the straight line will lie altogether in that surface or plane.

FA Circle is a plane figure, contained by one line which is called the circumference; and is such, that all straight lines drawn from a certain point within the figure to the circumference, are equal to one another.

That point within the circle which is thus equally distant from the circumference, is called the Centre.

HA Circle may be described from any centre, at any distance from that centre.

Illustration. The sensible horizon, or circular boundary, which every individual, standing in a clear space, beholds around him, where the sky appears to touch the earth, has the station of that observer for its centre; and this horizon will vary its position with every step he takes.

The magnitude likewise, of this circular boundary, varies as his eye is elevated or depressed; for instance, if the individual ascend a ship's mast, or look out of its cabin window, or swim with his head just above the surface of the water.

The distance of the centre from every part of the circumference is called the Radius.

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