Part 2 (1/2)

[Illustration: _Fig 13_ MAGNETIZED FIELD]

[Illustration: _Fig 14_ MAGNETIZED BAR]

In Fig 13 is shown a piece of wire (A) Let us assuh this wire in the direction of the darts

What actually takes place is that the electricity extends out beyond the surface of the wire in the fors (B) If, now, this wire (A) is wound around an iron core (C, Fig 14), you will observe that this electric field, as it is called, entirely surrounds the core, or rather, that the core is within the h the wire, and the core (C) thereby beconetized only when the current passes through the wire coil (A)

[Illustration: _Fig 15_ DIRECTION OF CURRENT]

Fro a current of electricity not only is affected within its body, but that it also has a sphere of influence exteriorly to the body of the wire, at all points; and advantage is taken of this pheno devices and almost every kind of electrical mechanism in existence

EXTERIOR MAGNETIC INFLUENCE AROUND A WIRE CARRYING A CURRENT--Bear in14) does not come into contact with the core (C) It is insulated fro substance, and a current passing from A to C under those conditions is a current of _induction_ On the other hand, the current flowing through the wire (A) from end to end is called a _conduction_ current Remember these ter which you will do well to bear in15 you will notice a core (C) and an insulated wire coil (B) wound around it The current, through the wire (B), as shown by the darts (D), moves in one direction, and the induced current in the core (C) travels in the opposite direction, as shown by the darts (D)

[Illustration: _Fig 16_ DIRECTION OF INDUCTION CURRENT]

PARALLEL WIRES--In like16) are parallel with each other, and a current of electricity passes along the wire (A) in one direction, the induced current in the wire (B) will move in the opposite direction

These fundahly understood and mastered

CHAPTER IV

FRICTIONAL, VOLTAIC OR GALVANIC, AND ELECTRO-MAGNETIC ELECTRICITY

THREE ELECTRICAL SOURCES--It has been found that there are three kinds of electricity, or, to be enerate it These will now be described

When , he produced a current by frictional means, and collected the electricity in a bottle or jar Electricity, so stored, could be drawn fro thereto suitable connection This could be effected only in one way, and that was by discharging the entire accumulation instantaneously At that time they knew of no means whereby the current could be made to flow from the jar as from a battery or cell

FRICTIONAL ELECTRICITY--With a view of explaining the principles involved, we show in Fig 17 aelectricity by friction

[Illustration: _Fig 17_ FRICTION-ELECTRICITY MACHINE]

This isthereon a flat member (B), on which is mounted a pair of parallel posts or standards (C, C), which are connected at the top by a cross piece (D) Between these two posts is a glass disc (E), h the posts, this shaft having at one end a crank (G) Two leather collecting surfaces (H, H), which are in contact with the glass disc (E), are held in position by ar supported by the cross piece (D), and the arm (J) held by the base piece (B) A rod (K), U-shaped in form, passes over the structure here thus described, its ends being secured to the base (B) The arms (I, J) are both electrically connected with this rod, or conductor (K), joined to aknob (M) On each side and close to the terminal end of each leather collector (H) is a fork-shaped collector (N) These two collectors are also connected electrically with the conductor (K) When the disc is turned electricity is generated by the leather flaps and accumulated by the collectors (N), after which it is ready to be discharged at the knob (M)

In order to collect the electricity thus generated a vessel called a Leyden jar is used

LEYDEN JAR--This is shown in Fig 18 The jar (A) is of glass coated exteriorly at its lower end with tinfoil (B), which extends up a little more than halfway from the bottom This jar has a wooden cover or top (C), provided centrally with a hole (D) The jar is designed to receive within it a tripod and standard (E) of lead Within this lead standard is fitted a h the hole (D), its upper end having thereon a ter cork (H) on the rod (F) serves as a means to close the jar when not in use When in use this cork is raised so the rod may not come into contact, electrically, with the cover (C)

The jar is half filled with sulphuric acid (I), after which, in order to charge the jar, the knob (G) is brought into contact with the knob (M) of the friction generator (Fig 17)

VOLTAIC OR GALVANIC ELECTRICITY--The secondelectricity is by chemical ents