Scientific American Supplement, No. 430, March 29, 1884

V >> Various >> Scientific American Supplement, No. 430, March 29, 1884

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Mr. Crampton said he did not think steam could ever compete with
electricity, under certain circumstances; but, at the same time, it
would be a long time before it was superseded. He should like very much
to see the compressed oil, one-sixth of a pound of which would give 1
horse power per hour.

Admiral Selwyn said he had seen a common Cornish boiler doing it years
ago.

Mr. Crampton said it had never come under his notice, and he had no
hesitation in saying that no such duty ever was performed by any oil,
because he never heard of any oil which evaporated more than eighteen to
twenty-two pounds of water per pound. However, he was delighted to hear
of such progress being made, and though he had been for so many years
connected with steam, he never expected it would last forever. He was
now making experiments for some large shipowners, for the purpose of
facilitating feeding and doing away with dust, but let him succeed to
what extent he might, steam would never compete with electricity for
such small vessels as these launches.

The Chairman asked if he rightly understood Admiral Selwyn that he had
recently seen an invention in which one-sixth of a pound of condensed
fuel would give 1 horse power per hour.

Admiral Selwyn said it was now some years ago since he saw this going
on, but the persons who did it did not know how or why it was done.
He had studied the question for the last ten years, and now knew the
_rationale_ of it, and would be prepared shortly to publish it. He knew
that 22 was the theoretical calorific value of the pound of oil, and
never supposed that oil alone would give 46 lb., which he saw it doing.
He had found out that by means of the oil forming carbon constantly in
the furnace, the hydrogen of the steam was burned, and that it was a
fallacy to suppose that an equal quantity of heat was used in raising
steam, at a pressure of, say, 120 lb. to the square inch, as the
hydrogen was capable of developing when properly burned. There were,
however, conditions under which alone that combustion could take
place--one being that the heat of the chamber must be 3,700 deg., and that
carbon must be constantly formed.

Mr. Gumpel said with regard to the general application of electricity to
the propulsion of vessels as well as to railway trains, he believed that
many of those present would live to see electricity applied to that
purpose, because there were so many minds now applied to the problem,
that before long he had no doubt we should see coal burned in batteries,
as it was now burned in steam boilers. The utmost they could do, then,
would be about 50 per cent. less than Admiral Selwyn said could be
accomplished with condensed fuel. He could not but wonder where Admiral
Selwyn obtained his information, knowing that a theoretically perfect
heat engine would only give 23 per cent. of the absolute heat used,
and that a pound of the best coal would give but 8,000 and hydrocarbon
13,000 heat units, while hydrogen would give 34,000; and calculating it
out, how was it possible to get out of one-sixth of a pound of carbon,
or any hydrocarbon, the amount of power stated? No doubt, when Admiral
Selwyn applied the knowledge which physicists would give him of the
amount of power which could be got out of a certain amount of carbon and
hydrogen, he would find that there was a mistake somewhere.

Mr. Reckenzaun, in reply, said it would be very difficult to answer
the question put by the Chairman, as to the cost of an electric
launch--quite as difficult as to say what would be the cost of a steam
launch. It depended on the fittings, the ornamental part, the power
required, and the time it was required to run. If such a launch were
to run constantly, two sets of accumulators would be required, one to
replace the other when discharged. This could be easily done, the floor
being made to take up, and the cells could be changed in a few minutes
with proper appliances. As to Admiral Selwyn's remarks about one-sixth
of a pound of fuel per horse power, he had never heard of such a thing
before, and should like to know more about it. Mr. Loftus Perkins'
new steam engine was a wonderful example of modern engineering. A
comparatively small engine, occupying no more space than that of a steam
launch of considerable dimensions, developed 800 horse power indicated.
From a mechanical point of view, this engine was extremely interesting;
it had four cylinders, but only one crank and one connecting rod; and
there were no dead centers. The mechanism was very beautiful, but would
require elaborate diagrams to explain. Mr. Perkins deserved the greatest
praise for it, for in it he had reduced both the weight of the engine
and the consumption of fuel to a minimum. He believed he used coke and
took one pound per horse power. He should not like to cross the Channel
in the electric launch, if there was a heavy sea on, for shaking
certainly did not increase the efficiency of the accumulators, but a
fair amount of motion they could stand, and they had run on the Thames,
by the side of heavy tug boats causing a considerable amount of swell,
without any mishap. Of course each box was provided with a lid, and the
plates were so closely packed that a fair amount of shaking would not
affect them; the only danger was the spilling of the acid. Mr. Crohne
had remarked that a torpedo boat of that size would have 100 indicated
horse power, but then the whole boat would be filled with machinery.
What might be done with electricity they had, as yet, no idea of. At
present, they could only get 33,000 foot pounds from 1 lb. of lead and
acid, though, theoretically, they ought to get 360,000 foot pounds. Iron
in its oxidation would manifest theoretically 1,900,000 foot pounds
per lb. of material. As yet they had not succeeded in making an iron
accumulator; if they could, they would get about six or seven times
the energy for the same weight of material, or could reduce the
weight proportionately for the same power, and in that way they might
eventually get 70 horse power in a boat of that size, because the weight
of the motor was not great. With regard to the formation of a film on
the surface, no doubt a film of sulphate of lead was formed if the
battery stood idle, but it did not considerably reduce its efficiency;
as soon as it was broke through by the energy being evolved from it, it
would give off its maximum current. They knew by experience that, with
properly constructed accumulators, 80 per cent. of the energy put into
them was returned in work. It was quite certain, as Mr. Crampton said,
that it would be a long time before steam was superseded: he did not
prophesy at all; and he entitled his paper "Electric Launches," because
it would be presumptuous to speak of anything more until larger vessels
had been made and tried. With regard to Mr. Gumpel's remark on the
friction of the propeller, he would say that it was constructed to run
900 revolutions; if it were driven by a steam engine, and the speed
reduced to 300, not only would the pitch have to be altered, but the
surface would have to be larger, which would entail more friction. Mr.
Crohne would bear him out that they lost only 5 per cent. by slip and
friction combined, on an average of a great number of trials, both with
and against the current.

The Chairman in proposing a vote of thanks to Mr. Reckenzaun, said he
rejoiced to find that that gentleman had proved, to one man at least,
that his views had been mistaken. He found in these days of the
practical applications of electricity, that the ideas of most practical
men were gradually being proved to be mistaken, and every day new facts
were being discovered, which led them to imagine that as yet they were
only on the shore of an enormous ocean of knowledge. It was quite
impossible to say what these electric launches would lead to. Certain
points of great importance had been pointed out; they gave great room
and they were always ready. For lifeboat and fire engine purposes, as
Captain Shaw pointed out at Vienna, this was of great consequence.

At first they were led to believe that there was great stability, but
that idea had been a little shaken, not as to the boat itself, but as
to the influence of the motion of the water upon the constancy of the
cells. But these boats were only intended for smooth water, and if
they could not be adapted for rough water, he feared Admiral Selwyn's
suggestion of the application of this principle to lifeboats would fall
to the ground; but if secondary batteries were not calculated as yet
to stand rough usage, it only required probably some thought on Mr.
Reckenzaun's part to make them available even in a gale. Enormous
strides were being made with regard to these batteries. No one present
had been a greater skeptic with regard to them at first than be himself;
but after constant experiments--employing them, as he had done for many
months, for telegraphic purposes--he was gradually coming to view them
with a much more favorable eye. The same steps which had rendered all
scientific notions practicable, had gradually eliminated the faults
which originally existed, and they were now becoming good, sound,
available instruments. At present, he could only regard this electric
launch as a luxury. He had hoped that Mr. Reckenzaun would have been
able to say something which would have enabled poor men to look forward
to the time when they might enjoy themselves in them on the river; but
he was told at Vienna, when he enjoyed two or three trips in this boat
on the Danube, that her cost would be about L800, which was a little too
much for most people. They wanted something more within their reach,
so that at various points on the river they might see small engines
constantly at work supplying energy to secondary batteries, and so that
they might start on a Friday evening, and go up as far as Oxford, or
higher, and come down again on Monday morning. He must congratulate Mr.
Reckenzaun on the excellent diagrams he had constructed. The trouble of
calculating figures of this sort was very great when making experiments;
and the use of diagrams and curves expedited the labor very much. At
present they were passing through a stage of electrical depression;
robbery had been committed on a large scale; the earnings of the poor
had been filched out of their pockets by sanguine company promotors; an
enormous amount of money had been lost, and the result had been that
confidence was, to a great extent, destroyed; but those who had been
wise enough to keep their money in their pockets, and to read the papers
read in that room, must have seen that there was a constant steady
advance in scientific knowledge of the laws of electricity and in their
practical applications, and as soon as some of these rotten, mushroom
companies had been wiped out of existence, they might hope that real
practical progress would be made, and that the day was not far distant
when the public would again acquire confidence in electrical enterprise.
They would then enable inventors and practical men to carry out their
experiments, and to put electrical matters on a proper footing.

* * * * *

THE FIRST EXPERIMENTS WITH THE ELECTRIC LIGHT.

Electric lighting dates back, as well known; to the celebrated
experiment of Sir Humphry Davy, which took place in 1809 or 1810, but
the date of which is often given as 1813. There exist however, some
indications that experiments on the production of the electric spark
between carbons had been performed before the above named date.

Mr. S.P. Thompson has given the following interesting details in regard
to this subject: In looking over an old volume of the _Journal de
Paris_, says he, I found under date of the 22d Ventose, year X.
(March 12, 1802), the following passage, which evidently refers to an
exhibition of the electric arc:

"Citizen Robertson, the inventor of the phantasmagoria (magic lantern),
is at present performing some interesting experiments that must
doubtless advance our knowledge concerning galvanism. He has just
mounted metallic piles to the number of 2,500 zinc plates and as many of
rosette copper. We shall forthwith speak of his results, as well as of a
new experiment that he performed yesterday with two glowing carbons.

[Illustration: SIR HUMPHRY DAVY'S ELECTRIC LIGHT EXPERIMENTS IN 1813.]

"The first having been placed at the base of a column of 120 zinc and
silver elements, and the second communicating with the apex of the pile,
they gave at the moment they were united a brilliant spark of an extreme
whiteness that was seen by the entire society. Citizen Robertson will
repeat this experiment on the 25th."

The date generally given for the invention of the electric light by Sir
Humphry Davy is 1809, but previous mentions of his experiment are
found in Cuthberson's "Electricity" (1807) and in other works. In the
_Philosophical Magazine_, vol. ix., p. 219, under date of Feb. 1, 1801,
in a memoir by Mr. H. Moyes, of Edinburgh, relative to experiments made
with the pile, we find the following passage:

"When the column in question had reached the height of its power, its
sparks were seen by daylight, even when they were made to jump with a
piece of carbon held in the hand."

[Illustration: ELECTRIC LIGHTING IN PARIS IN 1844.]

In the _Journal of the Royal Institution_, vol. i. (1802), Davy
describes (p. 106) a few experiments made with the pile, and says:

"When, instead of metals, pieces of well calcined carbon were employed,
the spark was still larger and of a clear white."

On page 214 he describes and figures an apparatus for taking the
galvano-electric spark into fluid and aeriform substances. This
apparatus consisted of a glass tube open at the top, and having at the
side a tube through which passed a wire that terminated in a carbon.
Another wire, likewise terminating in carbon, traversed the bottom and
was cemented in a vertical position.

But all these indications are posterior to a letter printed in
_Nicholson's Journal_, in October, 1800, p. 150, and entitled:
"Additional Experiments on Galvanic Electricity in a Letter to Mr.
Nicholson." The letter is dated Dowry Square, Hotwells, September 22,
1800, and is signed by Humphry Davy, who at this epoch was assistant to
Dr. Beddoes at the Philosophical Institution of Bristol. It begins thus:

"Sir: The first experimenters in animal electricity remarked the
property that well calcined carbon has of conducting ordinary galvanic
action. I have found that this substance possesses the same properties
as metallic bodies for the production of the spark, when it is used for
establishing a communication between the extremities of Signor Volta's
pile."

In none of these extracts, however, do we find anything that has
reference to the properties of the arc as a continuous, luminous spark.
It was in his subsequent researches that Davy made known its properties.
It will be seen, however, that the electric light had attracted
attention before its special property of continuity had been observed.

It results from these facts that Robertson's experiment was in no wise
anterior to that of Davy. The inventor of the phantasmagoria did not
obtain the arc, properly so called, with its characteristic continuity,
but merely produced a spark between two carbons--an experiment that had
already been made known by Davy in 1800. The latter had then at his
disposal nothing but a relatively weak pile, and it is very natural
that, under such circumstances, he produced a spark without observing
its properties as a light producer.

It was only in 1808 that he was in a position to operate upon a larger
scale. At this epoch a group of men who were interested in the progress
of science subscribed the necessary funds for the construction of a
large battery designed for the laboratory of the Royal Institution. This
pile was composed of 2,000 elements mounted in two hundred porcelain
troughs, one of which is still to be seen at the Royal Institution. The
zinc plates of these elements were each of them 32 inches square, and
formed altogether a surface of 80 square meters. It was with this
powerful battery that Davy, in 1810, performed the experiment on the
voltaic arc before the members of the Royal Institution.

The carbons employed were rods of charcoal, and were rapidly used up
in burning in the air. So in order to give longer duration to his
experiment, Davy was obliged, on repeating it, to inclose the carbons in
a glass globe like that used in the apparatus called the electric egg.
The accompanying figure represents the experiment made under this form
in the great ampitheater of the Royal Institution at London.--_La
Lumiere Electrique_.

* * * * *

ELECTRICAL GRAPNEL FOR SUBMARINE CABLES AND TORPEDO LINES.

By H. KINGSFORD.

All those who are acquainted with the cable-lifting branch of submarine
telegraphy are well aware how important a matter it is in grappling
to be certain of the instant the cable is hooked. This importance
increases, of course, with the age and consequent weakness of the
material, as the injury caused by dragging a cable along the bottom is
obviously very great.

[Illustration: ELECTRICAL GRAPNEL FOR SUBMARINE CABLES AND TORPEDO
LINES.]

It is easy also to understand the fact that in nearly all cases the most
delicate dynamometers must fail to indicate immediately the presence
of the cable on the grapnel, more especially in those cases where a
considerable amount of slack grapnel rope is paid out. In many cases,
therefore, the grapnel will travel through a cable without the
slightest indication (or at least reliable indication) occurring on the
dynamometer, and perhaps several miles beyond the line of cable will be
dragged over, either fruitlessly, or to the peril of neighboring cables;
whereas, should the engineer be advised of the cable's presence on the
grapnel, the break will probably be avoided and the cable lifted; at any
rate, the position of the cable will be an assured thing.

My own knowledge of cable grappling has convinced me of these facts; and
I am well assured that those engineers at least who have been engaged
in grappling for cables in great depths, or for weak cables in shallow
water, will heartily agree with me.

In addition to the foregoing remarks re the insufficiency of the
dynamometer as an instrument for indicating the presence of a cable on
the grapnel, I might remind engineers of the troubles and perplexities
which occur incessantly in dragging over a rocky bottom. The grapnel
hooks a rock, a large increase of strain is indicated on the
dynamometer, and it becomes doubtful whether the cable as well is hooked
or not. Again, it frequently happens in grappling over a rocky bottom
that one or more prongs are broken off, the grapnel thus becoming
useless, great waste of time being thus occasioned. Fully realizing all
the difficulties herein enumerated, it occurred to me that a grapnel
might be constructed in such a manner as to automatically signal by
electrical means the hooking of the cable, while it would ignore all
strain that external causes might bring to bear on it, and thereby
obviate the uncertainties attached to the use of the grapnels at present
in vogue. To effect this, I designed early in 1881 a grapnel fitted in
each prong with an insulated conducting surface, and a plunger and pin
so arranged that the cable, when hooked, should, by the pressure that
it would bring to bear on any of the plungers, cause the pin to come in
contact with the conducting surface, itself in electrical communication
with any suitable current detecter and battery on board the repairing
ship, and thereby complete the circuit. This grapnel was successfully
used on the Anglo-American Telegraph Company's repairing steamer Minia
in the summer of 1881.

Subsequently, in discussing the construction of the grapnel with
Captain Troot, we concluded that something was yet wanted to render
the successful working in deep water absolutely sure, and we decided,
consequently, to make certain alterations.

This improved form may be constructed, either with a contact-plate in
each prong, or with one contact-plate common to all the prongs; the
latter is somewhat simpler, and is therefore the plan that we usually
adopt. Both forms are shown in the accompanying diagrams. The form
of grapnel in Diagram No. 1 has one advantage over the other in this
respect, viz., that should a prong be ruptured so as to render it
useless, the fact would immediately be known on board. A circuit formed
in such a manner, by the breaking off of a branch lead, would have
greater resistance than that formed by the contact resulting from
pressure of cable on the plungers; this difference would be manifested
on the indicator (of low resistance) placed in circuit with the
alarm-bell, or, if any doubt remained, a Wheatstone's bridge, or simpler
still, a telephone might be made use of.

In some cases we may protect the plungers from the pressure of ooze,
etc., by guards fitted to the stem of the grapnel, but in practice we
have not found these to be necessary.

The water is allowed free access around and about each separate part, in
order that its pressure shall be equal on all sides. This arrangement
renders the grapnel as effectual in the deepest as in the shallowest
water.

By making the plungers in two pieces, with a rubber washer or its
equivalent between them, we prevent mud or ooze from getting behind and
interfering with their working. As the hole in the rubber surrounding
the contact-plate, by caused the passage of the pin through it, closes
up as soon as the pressure is removed, leaving in the rubber a fault of
exceedingly high resistance, the rubber does not require renewing.

In the rubber in which we embedded the contact-plate, we place a layer
or more of tinfoil or other easily pierced conducting surface, through
which the pin passes on its way to the contact-plate proper. This method
we have adopted in order to make the assurance of contact doubly sure.

The grapnel just described we had in use on the Minia since April last.
We have tried it severely, and have never known it to fail. No swivel
has been used with the rope, in the heart of which is the insulated
wire, as it would allow the grapnel to turn over on the bottom, and
would be apt to twist and break the wire short off. As a matter of
fact, the grapnel will turn, and does turn, with the rope; a swivel is
therefore of no value. We are perfectly awake, however, to the fact that
a grappling-rope should be made in a manner that will not allow it to
kink; and engineers should avail themselves of such rope, especially in
deep water. Patents have lately been granted to Messrs. Trott &
Hamilton for the invention of a form of rope or cable answering all the
requirements of this work.

A small type of grapnel fitted in the manner I have described may be
very advantageously used for searching purposes, to ascertain the
position either of telegraph or torpedo lines; by towing at a quick rate
much time may be saved. The position being ascertained, if it be not
desired to lift the cable, the grapnel can be released and hove on board
by a tripping line, which can always be attached when such work is
contemplated. The great importance of being able to localize an enemy's
torpedo lines without raising an alarm will be readily seen by engineers
engaged in torpedo work.

REFERENCES TO THE DIAGRAMS.

a, stem of the grapnel containing core; b, flukes; c, recess for
insulated contact-plate connected to core; d, covering plate screwed on
bottom of grapnel; e, button of plug; f, rubber washer and button; g,
metal-plate; h, stem of plug, on which in the under counter-sink, U is
a small metal disk which prevents the fittings from fallings out; i,
needle; j, spring; k, counter-sink for head of plug; l, counter-sink for
spring.

* * * * *

HUGHES' NEW MAGNETIC BALANCE.

A new magnetic balance has been described before the Royal Society
by Prof. D. E. Hughes, F.R.S., which he has devised in the course of
carrying out his researches on the differences between different kinds
of iron and steel. The instrument is thus described in the _Proceedings
of the Royal Society_:

"It consists of a delicate silk-fiber-suspended magnetic needle, 5 cm.
in length, its pointer resting near an index having a single fine black
line or mark for its zero, the movement of the needle on the other
side of zero being limited to 5 mm. by means of two ivory stops or
projections.

[Illustration]

When the north end of the needle and its index zero are north, the
needle rests at its index zero, but the slightest external influence,
such as a piece of iron 1 mm. in diameter 10 cm. distant, deflects the
needle to the right or left according to the polarity of its magnetism,
and with a force proportional to its power. If we place on the opposite
side of the needle at the same distance a wire possessing similar
polarity and force, the two are equal, and the needle returns to zero;
and if we know the magnetic value required to produce a balance, we know
the value of both. In order to balance any wire or piece of iron placed
in a position east and west, a magnetic compensator is used, consisting
of a powerful bar magnet free to revolve upon a central pivot placed
at a distance of 30 or more cm., so as to be able to obtain delicate
observations. This turns upon an index, the degrees of which are
marked for equal degrees of magnetic action upon the needle. A coil of
insulated wire, through which a feeble electric current is passing,
magnetizes the piece of iron under observation, but, as the coil itself
would act upon the needle, this is balanced by an equal and opposing
coil on the opposite side, and we are thus enabled to observe the
magnetism due to the iron alone. A reversing key, resistance coils, and
a Daniell cell are required."

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