OF

ELECTRICITY, MAGNETISM,

AND

ELECTRO-DYNAMICS,

EMBRACING

THE LATE DISCOVERIES AND IMPROVEMENTS,

DIGESTED INTO THE FORM OF A TREATISE;

BEING

THE SECOND PART

OF

A COURSE OF NATURAL PHILOSOPHY,

COMPILED

FOR THE USE OF THE STUDENTS OF THE UNIVERSITY

AT

CAMBRIDGE, NEW ENGLAND.

BY JOHN FARRAR, LL. D.

BOSTON:

HILLIARD, GRAY, AND COMPANY.

1839.

in the Clerk's office of the District Court for the District of Massachusetts.

CAMBRIDGE:
FOLSOM, WELLS, and THURSTON,

PRINTERS TO THE UNIVERSITY.

ADVERTISEMENT.

THE articles Electricity and Magnetism, in this volumé were selected from Biot's Précis Elémentaire de Physique, and translated with only such alterations as were deemed necessary in order to adapt the work to the English reader. There being no edition of Biot's treatise sufficiently recent to correspond to the present improved state of Electro-dynamics, the portion of the volume relating to this subject was taken from Despretz's Traité Elémentaire de Physique, fourth edition, published at Paris in 1836.

1837.

CONTENTS.

ELECTRICITY.

General Phenomena of Electrical Attraction and Repulsion ;

Conductors, and Non-Conductors; two Kinds of Elec-

tricity

Of the Laws which govern the apparent Attraction and Re-

pulsion of electrified Bodies

Of the Laws according to which Electricity is dissipated by

the Contact of the Air, and along the Supports which

retain it imperfectly

Of Electricity in a State of Equilibrium in insulated Con-

ducting Bodies

1

13

22

30

Of Combined Electricities, and their Action at a Distance 39

Theory of the Motions produced in Bodies by Electrical

Attraction and Repulsion

Of the Construction of Electrical Machines.

Of Electroscopes

Of the Condenser

Of the Electrophorus

Of the Leyden Jar

Of the Electric Battery

58

67

75

80

90

94

97

100

Of the Electric Pile and of the Phenomena presented by
Crystals capable of being electrified by Heat
Mechanical and Chemical Effects produced by the repulsive
Force of accumulated Electricity

Of Atmospherical Electricity and Lightning Rods
Of Electric Light.

Of the different Methods of developing Electricity
Of the Development of Electricity by simple Contact
Theory of the Voltaic Apparatus, on the Supposition that