Electricity for Boys | Page 3

124 90. Electric-water purifier 127 91.
Portable electric purifier 129 92. Section of positive plate 130 93.
Section of negative plate 130 94. Positive and negative in position 130
95. Form of the insulator 130 96. Simple electric heater 137 97. Side
view of resistance device 139 98. Top view of resistance device 139 99.
Plan view of electric iron 140 100. Section of electric iron 141 101.
Thermo-electric couple 143 102. Cutting a magnetic field 146 103.
Alternations, first position 148 104. Alternations, second position 148
105. Alternations, third position 148 106. Alternations, fourth position
148 107. Increasing alternations, first view 149 108. Increasing
alternations, second view 149 109. Connection of alternating dynamo
armature 150 110. Direct current dynamo 151 111. Circuit wires in
direct current dynamo 152 112. Alternating polarity lines 154 113.
Alternating current dynamo 155 114. Choking coil 157 115. A
transformer 158 116. Parallel carbons 164 117. Arc-lighting circuit 165
118. Interrupted conductor 166 119. Incandescent circuit 167 120.
Magnetic action in dynamo, 1st 177 121. Magnetic action in dynamo,
2d 177 122. Magnetic action in dynamo, 3d 178 123. Magnetic action
in dynamo, 4th 178 124. Magnetic action in motor, 1st 179 125.
Magnetic action in motor, 2d 179 126. Magnetic action in motor, 3d
180 127. Magnetic action in motor, 4th 180

INTRODUCTORY
Electricity, like every science, presents two phases to the student, one
belonging to a theoretical knowledge, and the other which pertains to
the practical application of that knowledge. The boy is directly
interested in the practical use which he can make of this wonderful

phenomenon in nature.
It is, in reality, the most successful avenue by which he may obtain the
theory, for he learns the abstract more readily from concrete examples.
It is an art in which shop practice is a greater educator than can be
possible with books. Boys are not, generally, inclined to speculate or
theorize on phenomena apart from the work itself; but once put them
into contact with the mechanism itself, let them become a living part of
it, and they will commence to reason and think for themselves.
It would be a dry, dull and uninteresting thing to tell a boy that
electricity can be generated by riveting together two pieces of
dissimilar metals, and applying heat to the juncture. But put into his
hands the metals, and set him to perform the actual work of riveting the
metals together, then wiring up the ends of the metals, heating them,
and, with a galvanometer, watching for results, it will at once make him
see something in the experiment which never occurred when the
abstract theory was propounded.
He will inquire first what metals should be used to get the best results,
and finally, he will speculate as to the reasons for the phenomena.
When he learns that all metals are positive-negative or
negative-positive to each other, he has grasped a new idea in the realm
of knowledge, which he unconsciously traces back still further, only to
learn that he has entered a field which relates to the constitution of
matter itself. As he follows the subject through its various channels he
will learn that there is a common source of all things; a manifestation
common to all matter, and that all substances in nature are linked
together in a most wonderful way.
An impulse must be given to a boy's training. The time is past for the
rule-and-rote method. The rule can be learned better by a manual
application than by committing a sentence to memory.
In the preparation of this book, therefore, I have made practice and
work the predominating factors. It has been my aim to suggest the best
form in which to do the things in a practical way, and from that work,

as the boy carries it out, to deduce certain laws and develop the
principles which underlie them. Wherever it is deemed possible to do
so, it is planned to have the boy make these discoveries for himself, so
as to encourage him to become a thinker and a reasoner instead of a
mere machine.
A boy does not develop into a philosopher or a scientist through being
told he must learn the principles of this teaching, or the fundamentals
of that school of reasoning. He will unconsciously imbibe the spirit and
the willingness if we but place before him the tools by which he may
build even the simple machinery that displays the various electrical
manifestations.
CHAPTER I
THE STUDY OF ELECTRICITY. HISTORICAL
There is no study so profound as electricity. It is a marvel to the
scientist as well as to the novice. It is simple in its manifestations, but
most complex in its organization and in its ramifications. It has been
shown that light, heat, magnetism and