The times. [volume] (Washington [D.C.]) 1897-1901, 1901-02-10

|
years of the nineteenth century. 1t made
| electrical energy available at low cost
Michael Faraday n most worthy success
| or of Davy at the Royal Institution, In
| studying the relations between electric
| currents and magnets made the exceed
| ingly important observation that wire.
| If moved in the field of n magnet would
| yield a current of electricity. Simple as
the discovery was, its effect has been stu
| pendous. Following his science for It's own
| sake. he unwittingly opened up possibili-
| ties of the greatest practical moment. The
| fundamental principle of the future dyna-
| mo electric machine was discovered by
him. This was in 1891. Faraday's invesu-
| cations were so complete and his deduc-
| tons so mastery, that little was left to be
| done by others. Electro agnetism was
supplemented by misunderstanding. Both
| the electric motor and the dynamo gen
| orator We're now potentially present with
| us. Faraday contented himself with
| pointing the way. leaving the technical
| engineer to follow In one of Faraday's
experiments a copper disk mounted on an
axis passing through It's centre was re-
volved between the poles OF large steel
y
the disk at a selected position with respect
| to the magnet and another was in connec-
ton with the axis. These wires were
| united through galvanometer or instru-
ment for detecting electric current.
current was noted present in the circuit
so long as the disk was turned. Here then
was the embryo dynamo. The century
closes with single dynamo machines of
over 5000 horsepower capacity. and with
single power stations in which the total
electric generation by such machines is
Is. 600 to 10000 horsepower. So perfect is
the modern dynamo that out of Loo horse
power expended in driving 1t, $50 or more
may be delivered to the electric line as
! electric energy. The electric motor, now
| so common, is a machine like the dynamo,
| in which the principle of action is simply
reversed; electric energy delivered from
the lines becomes again mechanical mo-
| ton or power.
Soon after Faraday's discoveries in mag
neto-electricity attempts were made to
construct generators of electricity from
| power. But the machines were small,
| crude and imperfect and the results neces-
| sarily meagre.
Pixii, in Paris, one year after Faraday's
discovery was announced, made a machine
which embodied in its construction sim
| pie commutator for giving the currents
| single direction of flow. This is the pro-
| totype of the commutators now found on
what are called continuous current dyna-
| mos After Pixii followed Saxton, Clarke,
| Wheatstone, and Cooke. Estohrer and
| others. but not until 1854 was any very
notable Improvement made or suggested.
In that year Soren Hjorth. of Copenhagen,
described in a patent specification the
principle OF causing the electric currents
generated to traverse coils of wire so dis
| posed as TO re-enforce the magnetic field
of the machine itself. A year subsequent
| iy the same idea was again more clearly
set out by Hjorth. This Is the principle
| of the modern seif-exciting dynamo, the
field magnets of which, very weak at the
start, are built up or strengthened by the
currents from the armature or revolving
part OF the machine in which power is
consumed to produce electricity.
In 1886 DR.. Werner Siemens, of Berlin.
| well known as a great pioneer in the cleo
| trio arts, brought out the Siemens arma-
| ture, an innovation more valuable than
any other made up to that time. This was
| subsequently used in the powerful ma
| chimes of Wilde and Ladd. 1t still sur
wives in magnetic can-bell apparatus for
such work as telephone signaling, in ex-
ploders for mines and blasting, and in the
| simpler types of eiectroplaing dynamos.
The decade between 1860 and 1870 opened
a new era in the construction and working
of dynamo machines and motors. 1t IL
notable for two advances of very great
value and Importance. Dr. PacciEotti, of
| Florence in 1850. described machine by
which true continuous currents resembling
| battery currents could be obtained. Up to
| that time machines gave either rapidly
alternating or liuctuating currents. not
/ steady currents in one direction The
| Paccinotu construction. in modified forms,
| is now almost universally employed in
| DYNAMO machines, and even where the
| form is now quite different the Pac-
cinotti type has been at least the fore
runner, and has undergone notifications
to suit special ends In view. Briefly, Pac-
| cinotti made his armature Of a ring of
| iron with iron projections between which
the coils o Insulated wire were wound.
| a
ring armatute and commutator were given
! out in 1864 his work attracted but little
attention until Gramme, in Paris, about
| 1870. brought out the relatively perfect
| Giramme machine. In the mean time the
| other great development of the decade
| took place.
Although Hjorth had, az stated before.
put forward tie idea that a dynamo gen.
orator might itself furnish currents for
| magnetizing its own magnets, this valua-
bic suggestion was not apparently worked
| out until 1866, when a machine was con-
| structed for Sir Charles WheatstOne.
This appears TO have been the first self
exciting machine in existence Wheat
stone read paper before the Royal So
ciety In February. 1857, ION the Augment
| tation Of the Power of a Magnet by the
Reaction thereon Of Currents induced by
| the Magnet itself" This action later be
| came known as the reaction principle in
| dynamo machines.
| As often happens. the idea occurred to
| other workers In science almost simultane
ously, and DR.. Werner Siemens also read
| a paper in Berlin about month earlier
| than that of Whea;stone, clearly describ-
| ing the reaction principle, Furthermore,
| a patent specification had been filed in the
British Patent Office by s. A. Marley. De-
cember a. 1866 clearly showing the same
| principle of action, and he was, therefore,
| the first TO put the matter on record. The
| time was ripe for the appearance of ma
chimes closely resembling the types now
| in such extended use. Gramme. in 1870.