Washington standard. [volume] (Olympia, Wash. Territory) 1860-1921, 1891-05-01
WHAT A DYNAMO Is
A Very Simple Explanation OF the Ac-
ton ALTERNATING Currents IN Elec-
tric Lighting.

Enuart..
The first dNuamu-cl"otfic machine
yer constructed Wi- that made 10y
faadiy THIS great phy-lcirt, IL"
nrlnc. II cNp,rimcutcr-. ~ he has been
allied. discovered that when dix or
Hat plate Of copper was made to rotate
between the poles ut powerful mag
net. currents were pro.ucod IN the
plate from the center outward. By
making a wire touch the revolving
plate with one 81 IT, ,ul- and bringing
the other one ~ contact with the rim
lac found that = current 81 electricity
passed along the wire and could h"
made tu indicate it, existence 10y tie
iIccting the needle oi n galyanomctcr.
dccumposlng u chemical solution, or 10y /
any II the we'll known effects produced |
hy electricity in motion.
Faraday saw the Importance ot tins
discovery and the great uses IN the way |
oi practical Application to which II
qnight be- put, but he did not himself
-liy to develop II lac left that 10 oth"rs.
aud with IL the wealth which might
thu. hc acquired. and himself went on
o. investigate other obscure and little
known phenomena connected with
physics and clcctrlCitv, regarding TINS
~ his proper work. AMI exhibiting IN
hs conduct the true scientific spirit.
when. many years aitcrwar'l, he went
e. see the first Application OF this dis
co,cry of hi4 tu the production al the
illumination 81 the North forcland
lighthouse. hc -aid, after luuking ut the
large magnetic electric machines there,
q" gave II To- you an infant, y"u have
, made Il n giant
pynam" aud magnetic electric ma
chimes consist essentially 81 n coil of
wirc-"thc nrmaturr, ~ II Is called
rotating between the poles OF a large
magnet, the poles being bent round So
~ 20 approach each other aud have the
armnture between them. This magnet
may hc either n permanent magnet al
hard steel ar an electro magnet con
-i.tlng Of wire cuilcd round n soft iron
core. "a current of electricity being
made To- circle round the wire coil. and
thus magnctifing the iron core while II
lasts II il the latter arrangement
which Is almost universally used now.
though magnetic machines with per
mancnt magnets were the earliest form.
\ magnet produces an influence in
the ncighhofhood around II. aud this
surrounding ncighhorhopd i known ~
the field oi force" oi the magnet /. g,
the sphere In which It's influence can
hc felt A magnetic needle or bit 81
iron filing placed in this field sets itself
Ia point along the " lines Of force OF
the field that j.. the lines along which
the magnetic force acts, and which
forms curves round the magnet, run
ming out. n II were. from pole To pole,
aud cursing round 90 the other. Any
one may see the form II these lines Of
force for himself by placing bar mag
net underneath a sheet Of paper, and
then sprinkling ironiilings ON the
paper.
On tapping this the filings will set
Themselves along the lines of force in
beautiful regular curves. Here the
small fragments 81 iron are themselves
made magnets while under the in
iiucnce 81 the powerful magnet IN
whose field" they are. and therefore
place themselves lcngthways along the
lines Of force that Is. along the line of
action Of the resultant magnetic fore
al the place where each one IL.
When a coil Of wife, or armaturc, il
made Ia rrvolve rapidly in the strong
field of force which occupies the space
between the poles oi powerful electro
magnet currents are produced in the
coil. These currents alter their dircc-
ton through the coil every time the
latter changes its position with refer
cnce Ia thc poles 81 the magnet The
side Of the coil which was opposite the
north pole il after hall q revolution OPP
} posite the south pole. and the influence
81 the south pole tends TO produce an
opposite current to that Of the north
pole. Here We have an alternate eur.
rent" dynamo machine.
As the coil. or armaturc, rotates with
great speed-some hundreds Of revolu
tions per minuie-thesc currents, IN
! alternating directions, succeed each
other very rapidly. and II an electri,
arc lamp IL placed ON the Circuit, il
= will he liz up. In this case IL Is moi
= necessary that the current be sem
u round the circuit In one direction only
= but although the terminals cf the LAM
. are constantly changing their polarit,
: that IL. the north pole where the cur
i rent enters fhe next instant becomei
the south pole where the current
J. icaycs--yet. ~ this occurs man,
u times In one second, the effect pro
= duced IL the same ms II the curren
was In one uniform direction.
= The lamp has no time TO get cool
!, IL does not 40 out before oppositcl,
y directed current passes through IL ant
produces the same effect ~ the prev
- ipus one. No Pickering Is observable
. The impression produced by the glow
, ing carbon on the human eye IL re-
tanned by the retina for a far longe
. period than the duration Of one surg
!, of electricity through the lamp, and j
~ not gone before the effect produced b.
the succeeding opposite wave makes IL
impression on our nerves. Tn
> Jablochkoff lamps used lately on tn
. Thomas embarkmcnt are meant 70
!. this system Of electric lighting will
!, alternating currents.
!, Ina "continuous-current' dynamo
n which Is necessary for some purpose,
n such as elcciro-plating. where the 81
a feet desired could not he produced
"a the direction of the current was con
a tinually altering, the electric curren
q IL made 10 pa-s always one way roun'
a the external circuit. This result
i got by using the ingenious device Of
4. commutator. which automatically do
a. fleets the current so as always TO sen,
IL in an unvarying direction through
!. the plating hath or the electric lamI
q n the case may be.
I. The commutator consists simply O
,. q split tube. which IL attached 10 tn
/. revolving arnaturc. and may bc sect
4 IN any dynamo working on the contin
n nous system. This tube revolvcs will
the revolving armatnre, and IL il iii
;. vided by an insulating substance int,
e two parts each part IL alternately oi
:. the left and right of the space bctwcc,
n the poles 81 the magnet and IN,
q brushes" which collect the current
,. from the armature--i. q. the bundle
!. 81 copper wire spread out like brilsl
4 which form each end II the QUITE
:. circuit--arc fixed in position. and III,
revolving commutator attached 10 IN,