As the subject of lighting by electricity is occupying so much public
attention, and the merits of various inventors and inventions are so
keenly discussed, the following facts may have some historical interest
in connection with it.
In October, 1845, I was consulted by some American gentlemen concerning
the construction of a large voltaic battery for experimenting upon an
invention, afterwards described and published in the specification of
“King’s Patent Electric Light” (Letters Patent granted for Scotland,
November 26, 1845; enrolled March 25, 1846; English Patent sealed
November 4, 1845).
Mr. King was not the inventor, but he and Mr. Dorr supplied capital,
and Mr. Snyder also held a share, which was afterwards transferred to
myself. The inventor was Mr. Starr, a young man about twenty-five years
of age, and one of the ablest experimental investigators with whom I
have ever had the privilege of near acquaintance.
He had been working for some years on the subject, commencing with the
ordinary arc between charcoal points. His first efforts were directed
to maintaining constancy, and he showed me, in January of 1846, an
arrangement by which he succeeded in effecting an automatic renewal of
contact by means of an electro-magnet, the armature of which received
the electric flow, when the arc was broken, and which thus magnetized
brought the carbons together and then allowed them to be withdrawn to
their required separation, when the flow returned. This device was
almost identical with that subsequently re-invented and patented by Mr.
Staite (quite independently, I believe), and which, with modifications,
has since been rather extensively used.
Although successful so far, he was not satisfied. He reasoned out the
subject, and concluded that the electric spark between metals, the
electric arc between the carbons, and other luminous electric phenomena
are secondary effects due to the heating and illumination of electric
carriers; that the electric spark of the conductors of ordinary
electrical machines is simply a transfer of incandescent particles
of metal, which effect a kind of electric convection, known as the
disruptive discharge; and that the more brilliant arc between the
carbon points is simply due to the use of a substance which breaks up
more readily, and gives a longer, broader, and more continuous stream
of incandescent convection particles.
This is now readily accepted, but at that time was only dawning upon
the understanding of electricians. I am satisfied that Mr. Starr worked
out the principle quite originally. He therefore concluded that, the
light being due to solid particles heated by electric disturbance,
it would be more advantageous—as regards steadiness, economy, and
simplicity—to place in the current a continuous solid barrier, which
should present sufficient resistance to its passage to become bodily
incandescent without disruption.
This was the essence of the invention specified in King’s Patent as “a
communication from abroad,” which claims the use of continuous metallic
and carbon conductors, intensely heated by the passage of a current of
electricity, for the purposes of illumination.
The metal selected was platinum, which, as the specification states,
“though not so infusible as iridium, has but little affinity for
oxygen, and offers a great resistance to the passage of the current.”
The form of thin sheets known by the name of leaf-platinum is described
as preferable. These to be rolled between sheets of copper in order to
secure uniformity, and to be carefully cut in strips of equal width,
and with a clean edge, in order that one part may not be fused before
the other parts have obtained a sufficiently high temperature to
produce a brilliant light. This strip to be suspended between forceps.
I need not describe the arrangement for regulating the distance
between the forceps, for directing the current, etc., as we soon
learned that this part of the invention was of no practical value,
on account of the narrow margin between efficient incandescence and
the fusion of the platinum. The experiments with the large battery
that I made—consisting of 100 Daniell cells, with two square feet of
working surface of each element in each cell, and the copper-plates
about three-quarters of an inch distant from the zinc—satisfied all
concerned that neither platinum nor any available alloy of platinum
and iridium could be relied upon; especially when the grand idea of
subdividing the light by interposing several platinum strips in the
same circuit, and working with a proportionally high power, was carried
out.
This drove Mr. Starr to rely upon the second part of the specification,
viz., that of using a small stick of carbon made incandescent in a
Torricellian vacuum. He commenced with plumbago, and, after trying many
other forms of carbon, found that which lines gas-retorts that have
been long in use to be the best.
The carbon stick of square section, about one tenth of an inch thick
and half an inch working length, was held vertically, by metallic
forceps at each end, in a barometer tube, the upper part of which,
containing the carbon, was enlarged to a sort of oblong bulb. A thick
platinum wire from the upper forceps was sealed into the top of the
tube and projected beyond; a similar wire passed downwards from the
lower forceps, and dipped into the mercury of the tube, which was so
long that when arranged as a barometer the enlarged end containing the
carbon was vacuous.
Considerable difficulty was at first encountered in supporting this
fragile stick. Metallic supports were not available, on account of
their expansion; and, finally, little cylinders of porcelain were used,
one on each side of the carbon stick, and about three eighths of an
inch distant.
By connecting the mercury cup with one terminal of the battery, and the
upper platinum-wire with the other, a brilliant and perfectly steady
light was produced, not so intense as the ordinary disruption arc
between carbons, but equally if not more effective, on account of the
magnitude of brilliant radiating surface.
Some curious phenomena accompanied this illumination of the carbon. The
mercury column fell to about half its barometric height, and presently
the glass opposite the carbon stick became slightly dimmed by the
deposition of a thin film of sooty deposit.
At first the depression of the mercury was attributed to the formation
of mercurial vapor, and is described accordingly in the specification;
but further observation refuted this theory, for no return of the
mercury took place when the tube was cooled. The depression was
permanent. The formation of vaporous carbon was suggested by one of the
capitalists; but neither Mr. Starr nor myself was satisfied with this,
nor with any other surmise we were able to make during Mr. Starr’s
lifetime, nor up to the period of final abandonment of the enterprise.
When this occurred the remaining apparatus was assigned to me, and I
retained possession of the finally arranged tube and carbon for many
years, and have shown it in action worked by a small Grove’s battery
in the Town Hall of Birmingham, and many times to my pupils at the
Birmingham and Midland Institute.
These exhibitions suggested an explanation of the mysterious gaseous
matter, which I believe to be the correct one, and also of the carbon
deposit. It is this:—That the carbon contains occluded oxygen; that
when the carbon is heated some of this oxygen combines with the
carbon, forming carbonic oxide and carbonic acid, and a little smoke.
I proved the presence of carbonic acid by the usual tests, but did not
quantitatively determine its proportion of the total atmosphere.
If I were fitting up another tube on this principle I should wash it
with a strong solution of caustic potash before filling with mercury,
and allow some of the potash solution to float on the mercury surface,
by filling the tube while the glass remained moistened with the
solution. My object would be to get rid of the carbonic acid as soon as
formed, as the observations I have made lead me to believe that—when
the carbon stick is incandescent in an atmosphere of carbonic acid or
carbonic oxide—a certain degree of dissociation and re-combination is
continually occurring, which weakens and would ultimately break up the
carbon stick, and increases the sooty deposit.
The large battery was arranged for intensity, but even then it was
found that the quantity (I use the old-fashioned terms) of electricity
was excessive, and that it worked more advantageously when the cells
were but partially filled with acid and sulphate. A larger stick of
carbon might have been used with the whole surface in full action.
After working the battery in various ways, and duly considering the
merits of the other forms of battery then in use, Mr. Starr was driven
to the conclusion that for the purposes of practical illumination
the voltaic battery is a hopeless source of power, and that
magneto-electric machinery driven by steam-power must be used. I fully
concurred with him in this conclusion, so did Mr. King, Mr. Dorr, and
all concerned.
Mr. Starr then set to work to devise a suitable dynamo-electric
machine, and, following his usual course of starting from first
principles, concluded that all the armatures hitherto constructed
were defective in one fundamental element of their arrangement. The
thick copper wire surrounding the soft iron core necessarily follows
a spiral course, like that of a coarse screw-thread; but the electric
current or lines of force, which it is designed to pick up and carry,
circulate at right angles to the axis of the core, and extend to some
distance beyond its surface. The problem thus presented is to wind
around the soft iron a conductor that shall be broad enough to grasp
a large proportion of this outspread force, and yet shall follow its
course as nearly as possible by standing out at right angles to the
axis of the armature. This he endeavored to effect by using a core of
square section, and winding round it a broad ribbon of sheet copper,
insulated on both sides by cementing on its surfaces a layer of silk
ribbon. This armature was laid with one edge against one side of the
core, and carried on thus to the angle; then turned over so that its
opposite edge should be presented to the next side of the core; this
side to be followed in like manner, the ribbon similarly turned again
at the next corner, and so on till the core became fully enclosed or
armed with the continuous ribbon, which thus encircled the core with
its edges outwards, and nearly at right angles to the axis, in spite of
its width, which might be increased to any extent found by experiment
to be desirable.
At this stage my direct co-operation and confidential communication
with Mr. Starr ceased, as I remained in London while he went to
Birmingham in order to get his machinery constructed, and to apply it
at the works of Messrs. Elkington, who had then recently introduced the
principle of dynamo-electric motive-power for electro-plating, etc.,
and were, I believe, using Woolrich’s apparatus, the patent for which
was dated August 1, 1842, and enrolled February 1, 1843.
I am unable to state the results of his efforts in Birmingham. I
only heard the murmurs of the capitalists, who loudly complained of
expenditure without results. They had dreamed the same dream that Mr.
Edison has recently re-dreamed, and has told the world so loudly.
They supposed that the mechanically excited current might be carried
along great lengths of wire, and the carbons interposed wherever
required, and that the same electricity would flow on and do the
duty of illumination over and over again as a river may fall over a
succession of weirs and turn water-wheels at each. Mr. Starr knew
better; his scepticism was misinterpreted; he was taunted with failure
and non-fulfilment of the anticipations he had raised, and with the
fruitless expenditure of large sums of other people’s money. He was
a high-minded, honorable, and very sensitive man, suffering already
from overworked brain before he went to Birmingham. There he worked
again still harder, with further vexation and disappointment, until
one morning he was found dead in his bed. Having, during my short
acquaintance with him, enjoyed his full confidence in reference to all
his investigations, I have no hesitation in affirming that his early
death cut short the career of one who otherwise would have largely
contributed to the progress of experimental science, and have done
honor to his country.
His martyrdom, for such it was, taught me a useful lesson I then much
needed, viz., to abstain from entering upon a costly series of physical
investigations without being well assured of the means of completing
them, and, above all, of being able to afford to fail.
There are many others who sorely need to be impressed with the same
lesson, especially at this moment and in connection with this subject.
The warning is the most applicable to those who are now misled by a
plausible but false analogy. They look at the progress made in other
things, the mighty achievements of modern Science, and therefore infer
that the electric light—even though unsuccessful hitherto—may be
improved up to practical success, as other things have been. A great
fallacy is hidden here. As a matter of fact the progress made in
electric lighting since Mr. Starr’s death, in 1846, has been very small
indeed. As regards the lamp itself no progress whatever has been made.
I am satisfied that Starr’s continuous carbon stick, properly managed
in a true vacuum, or an atmosphere free from oxygen, carbonic oxide,
carbonic acid, or other oxygen compound, is the best that has yet been
placed before the public for all purposes where exceptionally intense
illumination (as in lighthouses) is not demanded.[13]
Comparing electric with gas-lighting, the hopeful believers in
progressive improvement appear to forget that gas-making and
gas-lighting are as susceptible of further improvement as electric
lighting, and that, as a matter of fact, its practical progress
during the last forty years is incomparably greater than that of
the electric light. I refer more particularly to the practical and
crucial question of economy. The bi-products, the ammoniacal salts,
the liquid hydrocarbons, and their derivatives, have been developed
into so many useful forms by the achievements of modern chemistry,
that these, with the coke, are of sufficient value to cover the whole
cost of manufacture, and leave the gas itself as a volatile residuum
that costs nothing. It would actually and practically cost nothing,
and might be profitably delivered to the burners of gas consumers (of
far better quality than now supplied in London) at one shilling per
thousand cubic feet, if gas-making were conducted on sound commercial
principles,—that is, if it were not a corporate monopoly, and were
subject to the wholesome stimulating influence of free competition and
private enterprise. As it is, our gas and the price we pay for it are
absurdities; and all calculations respecting the comparative cost of
new methods of illumination should be based not on what we _do_ pay
per candle-power of gas-light, but what we _ought_ to pay and _should_
pay if the gas companies were subjected to desirable competition, or
visited with the national confiscation I consider they deserve.
Having had considerable practical experience in the commercial
distillation of coal for the sake of its liquid and solid
hydrocarbons, I speak thus plainly and with full confidence.
There is yet another consideration, and one of vital importance, to
be taken into account, viz., that—whether we use the electric light
derived from a dynamo-electric source, or coal-gas—our primary source
of illuminating power is coal, or rather the chemical energy derivable
from the combination of its hydrogen and carbon with oxygen. Now this
chemical energy is a limited quantity, and the progress of Science can
no more increase this quantity than it can make a ton of coal weigh 21
cwts. by increasing the quantity of its gravitating energy.
The demonstrable limit of scientific possibilities is the economical
application of this limited store of energy, by converting it into the
demanded form of force without waste. The more indirect and roundabout
the method of application, the greater must be the loss of power in
the course of its transfer and conversion. In heating the boiler that
sets the dynamo-electric machine to work, about one-half the energy
of the coal is wasted, even with the best constructed furnaces. This
merely as regards the quantity of water evaporated. In converting the
heat-force into mechanical power—raising the piston, etc., of the
steam-engine—this working half is again seriously reduced. In further
converting this residuum of mechanical power into electrical energy,
another and considerable loss is suffered in originating and sustaining
the motion of the dynamo-electric machine, in the dissipation of the
electric energy that the armature cannot pick up, and in overcoming the
electrical resistances to its transfer.
I am unable to state the amount of this loss in trustworthy figures,
but should be very much surprised to learn that, with the best
arrangements now known, more than one-tenth of the original energy
of the coal is made practically available. This small illuminating
residuum may, and doubtless will, be increased by the progress of
practical improvement; but from the necessary nature of the problem,
the power available for illumination at the end of the series must
always be but a small portion of that employed at the beginning.
In burning the gas derived from coal we obtain its illuminating power
_directly_, and if we burn it properly we obtain nearly all. The coke
residuum is also directly used as a source of heat. The chief waste of
the original energy in the gas-works is represented by that portion
of the coke that is burned under the retorts, and in obtaining the
relatively small amount of steam-power demanded in the works. These are
far more than paid for by the value of the liquid hydrocarbons and the
ammonia salts, when they are properly utilized.
In concluding my narrative, I may add that after Mr. Starr’s death
the patentees offered to engage me on certain terms to carry on his
work. I declined this, simply because I had seen enough to convince
me of the impossibility of any success at all corresponding to their
anticipations. During the intervening thirty years I have abstained
from further meddling with the electric light, because all that I had
seen then, and have heard of since, has convinced me that—although as
a scientific achievement the electric light is a splendid success—its
practical application to all purposes where cost is a matter of serious
consideration is hopeless, and must of necessity continue to be so.
Whoever can afford to pay some shillings per hour for a single splendid
light of solar completeness can have it without difficulty, but not so
where the cost in pence per hour per burner has to be counted.
I should add that before the publication of King’s specification,
Mr. (now Sir William) Grove proposed the use of a helix or coil of
platinum, made incandescent by electricity, as a light to be used for
certain purposes. This was shown at the Royal Society on or about
December 1, 1845.
Since the publication of the above in 1879, I have learned, from a
paper in the “Quarterly Journal of Science,” by Professor Ayrton,
that in 1841 an English patent was granted to De Moylens for electric
lighting by incandescence.