to enrich my Mind, and to improve it with the moft
invaluable Principles and Parts of human Knowledge.

A Defcription of the feveral Parts of the EAR.

Fig. I. A B, the external Ear. CD, the internal
Part, or Organ of the Ear, confifting of the Drum,
the Labyrinth and Cochlea. E, Euftachius's Tube.

Fig. II. Shews the Tympanum, or Drum of the Ear,
with its proper Apparatus of Bones in their natural
Situation, viz. A, the Tympanum ; B, the Malleus; C,
the Incus, or Anvil; D, the Stapes, or Stirup.

Fig. III. Shews thofe Bones feparately, viz. B, the
Malleus; C, the Incus; D, the Forepart; and E, the
hind Part of the Stapes.

Fig. IV. Is a View of the Labyrinth and Cochlea con-
nected. A, the Superior; B, the Middlemoft; and,
C, the inferior Semicircular Canals of the Labyrinth.

DE, the Veftibulum of the Labyrinth; FG, the
Cochlea with one of its Spirals opening into the Veftibulum
DE, and the other into the Drum at H.

Fig. V. Another View of the Labyrinth and Cochlea,
fhewing thofe Bones in the Tympanum which open into
them, viz. the Holes called,

1. The Feneftra Rotunda, which opens into the
Cochlea.

2. The Feneftra Ovalis, which opens into the Vef-
tibulum.

3. The Exit, or opening of another Canal.

4. The Spiral of the Cochlea, opening into the Vefti-
bulum.

5. The other Spiral opening into the Tympanum.

Fig. 6. A Section of the Cochlea, with the mem-
braneous Partition taken away, fhewing the Blood-
veffels ramified through its two spiral Cavities, A and B.

Fig. VII. Another Section of the Cochlea, fhewing
the Holes for the Paffage of the auditory Nerve to the
Cochlea.

INDEX

то THE

SECOND VOLUME.

A

MPHISCII, 91.

Analemma, or general Rectifier, its Ufe on the terrestrial
Glebe, 108.

Antaci, 93.
Antipodes, ib.

Aquarius, the Emblem of a rainy Season, 19.

Fabulous Hiftory of, ib.

Ara, a poetical Defcription of the Ufe and Occafion of this
Conftellation, 35-

Araurus, a Star of the firft Magnitude, 70.

Latitude of, from the Ecliptic, with its Declination and
right Afcenfion, ib.

Its rifing, fetting, and fouthing, 71.

Argo, fabulous Hiftory of, 36.

Aries, the firft Sign of the Zodiac, 10.

Conjectures with regard to the Name and Form of this
Conftellation, 11.

Fabulous Hiftory of, ib.

Afcii, who were called fo by the Greeks, 91.
Aftrologers, their Pretenfions often vain and impious, 4.
Auriga, fabulous History of, 27.

Azimuth of the Sun, 48.

How to find it for any Hour of any given Day of the
Year, 47.

BALENA, the Whale or Sea Monster, poetical Story of, 33.
Bays, 97.

Black, an Abfence of Colour rather than a Colour, 207.

Bootes, or Arcophylax, the Bear-keeper, fabulous History of, 27.
Break of Day and Twilight, 48, 49.

Bull, fabulous Hiftory of, 12.

VOL. II.

Ee

COELESTIAL Globe, defcribed, 1.
Wherein it differs from the Sphere, z.
What the Antients called cœleftial Houses, 3.
Camera Obscura, a new proportional one, 250.
Ufe of, principally for Drawing, ib. & feq.

The Artift cannot draw any Object in a given Proportion
by the common Camera, 252.

Cancer, the Name of this Sign not without Propriety, 14.
Fabulous Hiftory of, 15.

Canis Major and Canis Minor, the great and little Dog, 34-
Capricorn, the Origin of this Constellation, 18.

Fabulous Hiftory of, ib.

Caput Medufe, Medufa's Head, fabulous Hiftory of, 25.
Cepheus and Caffiope, fabulous Hiftory of, 22.

Charts and Maps, how properly conftructed, 128.

The Errors of thofe in common Use, 129.

Excellency of fuch as are of the globular Conftruction, ib.
Of great Ufe in reprefenting particular Places, 133-
Those representing a Spheroid most accurate, 134-
Peculiar Advantages thereof, 137.

Illuftrated by a Diagram, 139.

Circle of Illumination, 116.

Circles of the Horizon, 2.

Climates, what the Geographers mean by a Climate, 93.
A Table of thofe between the Equator and the polar
Circles, 94

Between the polar Circles and Poles, ib.

Colours, the Theory of, 198.

Sir Ifaac Newton first discovered the Caufe of, 199.
This Difcovery proved by Experiments, ib.

Seven original Colours, 200.

Why Bodies are feen variously coloured in a Prism, and
not in Glaffes of other Forms, 201.

The Colours of the Rainbow explained by an Experi-

ment, 203.

Comets, their Courfes to be traced on the cœleftial Globe,
61 & feq.

The Courfe of the Comet in 1758 particularly defcribed,
64 & feq.

Concord and Difcord in Mufic, 370. 378.

Conftellations, confift of a Number of Stars, 5.

Names of thofe in the northern Hemisphere, 5, 6.
Their Origin and Mythologic Hiftory, 32 & feq.
Of thofe in the fouthern Hemifphere, 6, 7.
Their Origin and fabulous Hiftory, 32 & feq.
The numbering and naming them of the most antient
Date, 7:

Of thofe of the Zodiac, with their fabulous History, 10&feq.

Continents, 95.

Crater, the Bowl; fabulous Hiftory thereof, 35.

Creeks, 97.

Crepufcular Circle, or Circle of Twilight, 116.

DAY; Lunar, Planetary, Sidereal, and Solar, 30g.
Delphinus, the fabulous Hiftory of, 31.
Draco, fabulous Hiftory of, 21.

EAGLE, fabulous Hiftory of this Conftellation, 28.
Ear, its various Parts defcribed, 411 & feq.

A Plate of it, with an Explanation of the Figures, 411.416.
Earth, the Axis of, has a retrograde Motion, 75.

The Effects of this Motion illuftrated on a Globe with a
particular Apparatus, 76.

The Motions of the Stars and Conftellations forward thence
accounted for, 85.

Figure of, not that of a Globe, 87.
But what is called a Spheroid, ib.
Dimenfions of, 88, 89.

Echo, the Nature of explained, 364.

Often affords an agreeable Amufement to the Curious, 365.
The Man and his Echo must be heard from two dillant
Places, 356.

Eel, the Scale of, its Appearance in the Microfcope, 186.
The Scales of this Fish differ from thofe of common Fish
in feveral Particulars, 186.

Elaftic Fluid, the Nature and Action of, 356.

Epiglottis, 407.

Equinoxes, the Proceffion of, illuftrated by a Globe of a par
ticular Conftruction, 76, 77.

See Plate XXXVI. 81.

The equinoctial Points being moved, the Phænomena of
any Age may be reprefented on a cœleftial Globe, 84.
Eridanus, a Conftellation fo called, fabulous Hiftory of, 37.
Evening, ftarry, a poetical Description of, 10, 11.
Explanation of a Plate reprefenting the Machinery in a new
Apparatus to the terreftrial Globe, 112. 126.

Of a Plate representing the different Parts of the Ear,
411. 416.

Experiments.

To prove the Sun's Rays when refracted to be the natural
Caufe of Colours, 199.

To explain the Nature of the Rainbow, 203.

To iuftrate the magnifying Power of a Telescope, ib.
To fhew the Caufe of the Defect of Sight in the Myops
and Prefbyta, 15.*

Ee a

Experiments.

To fhew the prodigious Degree of Vibration Glafs is capable of, 379.

To fhew in what a furprizing Manner mufical Strings are
affected by each others Vibrations, 389.

To prove that a String may be put into Motion by two
Parts, and yet at rest between them, 390.

Eye, the Form and Structure of, 333.

What the Anatomifts call the Optic Nerve, 334.

The Retina the immediate Inftrument of Vifion, ib.
Form of the Eye fuch as the Laws of Optics require, 337-
The Cornea, why transparent and convex, ib.

The Ufe of the Uvea with the Pupil, 339.

The chryftalline and vitreous Humours, 340 & feq.

A Defect of the Eye in old People, to what owing, 344.
In young Perfons, from what proceeding, ib.

Structure of an artificial Eye, 348.

Of the three Glaffes which are screwed on in the artificial
Eye, 349.

The well formed and defective Eyes illuftrated by an Expe-
riment, 350.

GAMUT, in Music, what, 376.

Gemini, Reafons for the Denomination of this Sign, 14.
Fabulous Hiftory of, ib.

Glafes, convex, necellary to help the decayed Sight of elderly
People, 346.

Muft be fo placed, that the Axis of each may coincide with the Eye, 348.

Concave, proper for fhort-fighted People, 346.

Mufic of, 387.

Globe, cœleftial; a Defcription of, 1 & feq.

Ufe of, in folving folar Problems, 42 & feq.

In folving lunar Problems, 52 & feq.

An Appendage to, for fhewing the various Motions of
the Moon, 51.

Ufe of, in Problems relating to Planets and Comets, 60&feq.
In fuch as relate to the Stars, 68 & feq.

An antique cœleftial Globe, found in the Ruins of antient
Rome, 80.

Conjectures concerning the Age thereof, 81.

This Globe a Demonftration of the retrograde Motions of the equinoctial Points, Sz.

Terrestrial, a Defcription of, 87.

Its Ufe in the Solution of many curious and useful
Problems, 98 & feq.

Defcription of a new Apparatus thereto, 110 & feq.

3