The Sun.
London, England, 1857-12-26 00:00:00

THE MILITIA.

The West Norfolk Militia left Norwich on Wed-
nesday afternoon for the North of England. The
regiment, which is upwards of 600 strong, is divi-
ded into three parties, Lieutenant-Colonel Cus-
tance proceeding with three companies to Chester;
Major Bedingfeld, with three other companies, to
with two com-
pLai
nv
er
spoolto s; t
oa
enkdp Capt.or
t TNh
ea rsh
ehaadm-
uarters will be at
Chester, and the depot of the regiment will remain
at Norwich. _ .

The Dutchman and Adonis steamers, which ar-
rived at Portsmouth on Thursday morning for the
embarkation of the Ist Surrey Militia (who ar-
rived by rail from Richmond, (Surrey), will con-
vey that regiment to Waterford on Tuesday next.

ELEOTRO-MAGNETISM AS A MOTIVE

POWER.

In a recent article on the subject of Mr. Bagg's
process for applying steam to quicken the move-
ments of the electric telegraph we alluded to the
researches which weregoing forward into the value
of electro-magnetism as a motive power. We have
space now to refer to this important subject at a
length more in accordance with its merits, and to
notice the gradual steps making towards a disco-
very, the immense value and utility of which, in
spite of the progress already made by steam, will
when attained equal in importance our first know-
ledge of that great power. It is almost superfluous
to enumerate the many important advantages which
an electro-motive power has over steam. There is
perfect safety from all danger from fire or explo-
sion. There is no expenditure of materials when
the engine is not in action, and its power can be
applied at a-moment's notice.- —lt is always ready
for action without previous consumption of ma-
terials in getting up steam, and in marine en-
gines there would be no waste in freightage
as for carrying coal. These are the most important
of the advantages it offers, but many others will
occur to any who reflect for a moment on the pecu-
liar nature of the two forces employed. With such
high rewards in view plans to convert the power of
electro-magnetism into a motive force have always
been among the most cherished schemes of electri-
cians. The Russian and American Governments
have spent large sums in endeavouring to solve this
problem ; France still holds out a great reward to
those who can produce an electro-motive engi▪
ne
which shall only consume 19 ounces of zinc per
horse power per hour, and in that empire the idea
that these moderate conditions will be fully attained
is firmly believed. In this country no official en-
couragement has ever been offered to such attempts
and latterly the notion has been much frowned upon
by scientific men, who on all such questions are ge-
nerally the most conservative and impracticable
portion of the public. The grounds upon which their
opposition has lately been based are—first, the
undoubted failure of the various attempts
hitherto made ; secondly, a comparison of cost
between the working of the best kind of electro-
motive engine and a steam eneine ; and, lastly, a
hasty, but most erroneous `opinion of Liehig's,
which utterly condemned the idea of an electro-
motive
engine altogether, thoughon grounds which
men of equal eminence in science, though less in
fashion, have not hesitated to declare as " perfectly
absurd." It is needless to refer to the attempts of
the scientific men who have sought to utilise the
power obtainable from electro-magnetism. Ail the
principal electricians have dabbled in it more or
less from Oersted downward; and every fresh at-
tempthas led to fresh improvements and discoveri▪
es.
The first important invention of the kind was exhi-
bited by a Mr. Davenport, in America, in 1837, and
was followed in 1838 by another electro-m tgnetic
engine, by a Capt. Taylor. In the same year Jacobi
produced a vessel upon the Neva worked by electro-
magnets. It was 28 feet long, 7t-broad, and, with
14 persons on board, was worked against the stream
at the rate of four miles an hour. In 1842 Mr.
Davidson built an engine adapted for use on a rail-
way, and tried it on the Edinburgh and Glasgow
line. This engine with magnets and battery
weighed five tons, but in consequence of the very
faulty arrangement of the
magnets there was a
great loss of power. The utmost speed attained by
it was only four miles per hour, and the attempt
was therefore condemned as a total and irredeem-
able failure, people quite forgetting in their eager-
ness to blame that the first steam locomotive tried
in England on a level plain wade only five miles
an hour, and that ten years later Stephenson had
so little improved the machinery that with eight
carriages and 30 tons' weight he scarcely attain•
ed
four miles an hour on a dead level. This inven-
tion of Davidson's, therefore, was given up, and
attention was soon afterwards occupied by the
engine of Professor Page, in America, which was
one of the best of them all, and which was in turn
followed be the improvements of Hjorth and of the
Messrs. Harrison. The latter
gentlemen, indeed,
claim to have fulfilled all conditions, and rather
more than all which it was even hoped or expected
electricity would be able to fulfil ; but, as they
have not to our knowledge entered into details, it
is impossible to say how far their assertions can be
borne out. Nevertheless, with all these attemps,
and with others by Dal Negro, M'Gauley, and
Wheatstone, not one of the electro-magnetic engines
could be regarded as a great success in the path of
discovery towards the new power, in fact, all the
plans when tried practically were found to be at
variance either with the laws of electricity or of
mechanics, and the two main points for solution in
the employment of electricity—its application and its
economy_wereboth more or less overlooked. Nearly
itsoff m long
all these machines, then (except those of Page and
Hjorth), were made either with oscillating or rotary
direct action engines ; in the former the electric
currenftorwce had
asalwa
latter the magnets successively brought into action
aximum, before the mag-
netic
and in the
were necessarily placed at such different distances
reachedy always
cut
that it was impossible to produce an equal motion
by means of them. In the rotary engines, also,
it was of course found that in a system of mag-
nets constructed to produce a given power, when
set in revolution, an immense reduction of their
original force immediately took place, so that their
combined action in practice fell infinitely short of
their estimated force. And not only did each
magnet sustain an actual diminution of power,
amounting to at least one half, bat the power
thus lost was converted into a current of electricity,
acting in opposition to the primary current by
which the magnetism was induced. This loss of
force was great, and appeared unavoidable until
the improvements of Page and Hjorth ; but even
the machines of those gentlemen lost so much
power, and were worked at such a cost, that all

further attempts have gradually been looked upon
by scientific men almost as waste of time and
ingenuity. In a paper read before the Society of
Arts in 1850 the improbability of any result bring
()gained from electro-ma„enek iQm which could en-
able it to compete with steam as a motive paver,
was carried nem con. Very recently at a diecuss.on
at the Institution of Civil Engineers it was even more
unequivocally condemned, and declared that the
power exhibited by electro-magne' though
very great extended through so small a space as
to he practic illy useless, and that a powerful nrigeet
might be compared to a steam engine with an enor-
mous pi ;toe, hut with an excecdiegly sh r stroke
—unquestienaqy a bad arrangement. Now,
doub'loss, from the points of view at which the
inventions were . regarded, these decisions wer,
right. It is a certain fact that electro-inagne:isni
never will supersede steam, and no electrician in
his senses could really have entertained such an
idea. Much as steam has done it has never yet
been able to supersede the water-wheel, wherever
water power is obtainable. But, although steam
must and will always be employed, electricity can
find place as a motive power in many kinds of
work where steam is now out of the question. The
other objections have Leen, first, the cost of the
power, and, second, the shortness of the space'
through which the power is exerted, pr in other
words, the want of adequate stroke or motion in the
force. The power of electricity, when applied in the
.foratorelectro-magnet iswonderfully gr.( a `. from com-
paratively small means, but its dynathic power de-
creases so rapidly through intervening space, being
" inversely as some unascertained power of the dis-
tance much greater than the square," that the range
of the maximum effect, or valuable portion of the
motive force with a consequent minimum of con-
sumption extends to so small a distance as to be of
no real value in mechanics. The great problem to
stave has been to contrive such an arrangement of
parts as to convert this maximum of the motive force
through a range, although unavailable in itself, into
stroke, or to give it such an extent of motion as to
make it of practical value as a motive power. Mr.
Allan's electro-motive engine has achieved many of
these desiderata. He has utilised all his power—
has obtained length of stroke. By this invention
the maximum portion only of dynamic force is ap-
plied, and by the mechanical arrangement of parts
successively and continuously brought into action
in a direct form, in accordance with the laws of
electro-dynamics. Thus applied thole is no loss of
primary force, and any amount of power and any
length of stroke can be obtained. In fact, both
mechanical and electrical conditions are very simply
and beautifully complied with, and to this alone is
the success of the invention due. The machine may
be simply described as consisting of four galleries,
each of which contains four groups of four electro-
magnets which are alternately opposite in their
polarities, and which therefore by induction natu-
rallyreact upon and augment their collective power. '
Through these magnets pass rods connected by con-
necting rods and cranks to the shaft of the engine.
Each of these rods has a disc or keeper suspended
on shoulders above each group of magnets. The
keepers are made with a hole in the centre, so as to
slide easily upon the rod, and not impede the mo-
tion of the latter when it is receiving as impulse
from a magnet applied to any of the other keepers
or discs. The same kind of action is produced on
each rod, so that as one completes its portion of the
stroke the next one is commencing in the follow-
ing manner :—At the commencement of the mo-
tion the upper :keeper is placed so near the first
set of magnets that when a current of electricity
is applied to them they draw violently the keeper
to them, and thus move the rod longitudinally
through the space which separated them. The next
keeper is by this means brought within the same
distance from its magnet, and the current of elec-
tricity is at the same instant cut off from the for-
mer and applied to these, which thereupon draw
their keeper to them, and so drag the rod through
an additional space or distance equal to the first.
The other magnets and their keepers beneath re-
spectively act in a similar manner in regular suc-
cession, and thus complete the stroke of the rod,
when the next row takes itup,j and so on, until

the four rods have worked irithe same manner,

and given the utmost both of power and length of
stroke to the machine. Though the machines have
as yet been only fixed vertically, yet it can easily
be seen that the arrangement of the parts allow it to
be readily adapted to all ordinary purposes, whe-
ther vertical or horizontal.

Thus, as far as the first conditions of power and
length of stroke are concerned, the machine appears
to have achieved great ends. One has lately been sub-
mitted to the Emperor Napoleon and the directory
of the Conservatoire as illustrating the first prin-
ciples of the machine which, it is hoped, is to carry
off the French national prize of 2,0001. offered to
any who can solve the question of the practical
utility of electricity as a motive power. The suc-
cess of the competitor there is to be attested by the
cheapness with which he can produce his power.
According to the average price of coals in Paris one
horse steam power per hour can be obtained for 8
centimes. The average price of zinc is 80 centimes
per kilogramme, and the French conditions for
gaining the prize are that the machine shall work
one horse-power on an expenditure of not more
than half a kilogramme of zinc, or at 40 centimes
the hour. This would make the cost of the electro
motive power in Paris five times greater than that
of steam, but the many advantages which in other
respects it possesses over the latter would more than
counterbalance this disadvantage. According to
this rate Mr. Allan's machines in England, where
coal is cheaper, would work at a cost ten times
greater than the present average price of steam ;
yet many of our first machinists and manufactu-
rers say that the invention of electro-motive en-
gines at as much as 18 times the cost for steam
power will pay largely. Mr. Allan professes himself
perfectly confident that he can produce a machine
not only within the working price we have just
mentioned, but even within the French conditions.
He maintains that it is an error to consider the cost
of electro-motive power as being relatively less
" profitable" than steam, and that the error has
arisen from the misapplication of the electro-mag-
netic force, not from the necessary consumption of
the electric materials, which consumption is in-
versely as the dynamical ratios of the forgo. He
considers that the materials, on the other hand,
from their chemical admixtu,e in the battery,
although of no practical avail for the further pro-
duction of the electric fluid, become when produced
on a large scale of considerable market value,
and when sold realise a large percentage of
their original cost. But as the cost of the
power is thus taken as the standard of success, the
expenditure in fairness must be regarded from
various points of vi .w. Thus, then, we must not
forget that in Madrid and Lisbon the cost of coal
for steam power is twice as dear as at Paris ; that in
na, st parts of South America, in India, and China,
and throuehout the East generally, the cost of coal
is twice as much as that again, so that in those coun-
tries where an easily managed raoti ve power is most
wanted, elec ricity may yet compete with steam on
an equal or even advantageous footing with regard
to cost. But a great reduction in the cost of the
power may be effected by not using zinc at all,
since iron when used on a large scale as an element
in batteries may be regarded as almost equally effi-
cacious with zinc. But the cost of the power must
be at present a subordinate question—at least other
and more important questions must be decided ere
the coat can be ascertained. For instance, Mr. Allan
finds that there must be a certain relation between
the electric current and the diameter and length
of the magnet, though what these conditions are it
is difficult to say at present. With only a slight
modification of the relation of the wire to his
magnet, he suddenly found that be lost four-fifths
of his power. Now, here is a problem the solution
of which must have a vital influence on the electro-
magnetic power, and, therefore, in its cost of pro-
duction. Yet, these disturbing influences, whatever
they are, were not even known to exist until now ;
and every day the general laws which govern the
science of electro-magnetism are becoming more
and more fully developed. In a very able and a
very impartial paper which was read by Mr. Hunt
before the Institution of Civil Engineers many ob-
jec:ions, all more or less sound, were urged against
the availability of electricity as a motive force. We
are certain, however, that that gentleman was ig-
norant of the principle upon which the machine of
Mr. Allan is constructed, for a knowledge of it
must have altered the conclusion to which he was
then almost naturally led.
Many who do not take the trouble to judge for
themselves are content to base their disbelief in the
adaptability of electricity as a motive force on the
doctrine of Liebig, that zinc cannot give out more
power than the coal required to smelt it. Of course,
the reputation of Liebig is supposed to be sufficient
to secure implicit credence forphis statement—that
the scientific world, in fact, must hear and obey.
But in science nothing can be taken for granted,
and until Liebig can show that such relation exists
between electricity and heat as to make the mecba
nical power of one the measure of the mechanical
power of the other his doctrine will continue to be
regarded by those who think for themselves RS 0-