History of the Atlantic Cable & Undersea Communications
|Experimental Observations on Submarine Electric Cables
Introduction: Edward O.W. Whitehouse, “Wildman Whitehouse” as he generally styled himself, was a surgeon by profession and an electrical experimenter by avocation. In 1856 he was appointed Electrician to the Atlantic Telegraph Company and was responsible for the testing of the 1857/58 cables, and for the design and operation of the equipment which would transmit the telegraph signals between Ireland and Newfoundland.
Whitehouse was an early experimenter on long telegraph lines, and in 1855 he presented a paper on his findings to the annual meeting of the British Association for the Advancement of Science at Glasgow. The following month he had the paper privately printed, and the text of this version appears below.
Footnotes have been incorporated into the text at the point they were referenced in the original.
OF A SERIES OF
ON TWO LENGTHS OF
SUBMARINE ELECTRIC CABLE,
CONTAINING, IN THE AGGREGATE, 1,125 MILES OF WIRE.
Being the substance of a Paper read before the British Association for
Submarine Electric Cables.
THE study of the varied phenomena of Electricity is no longer the exclusive privilege of the philosopher. The term “Electrical currents,” and the great results associated with them, are now so familiar that it may, perhaps, be permitted, even to those unknown in the world of science, to record their experiments and observations on a subject of such general interest.
The adoption of some system of Electro-telegraphic communication has become, for every civilized nation, a matter of absolute necessity; whether we regard it in a political, social, or domestic aspect. The same facility of inter-communication which has been found necessary between the various members of civilized states as individuals, is now no less urgently called for between nation and nation, as members of a world-wide family.
The spirit of commercial enterprise in our own country, nobly led by one whose name will be handed down to posterity as the practical originator of Submarine Telegraphy [John W. Brett, Esq.]—has pushed our lines of electrical intercourse first across the narrow straits which separate us from our gallant and noble allies; next to Holland, to Belgium, and to Ireland; then, with a longer reach, stretching from the shores of the Mediterranean to the islands of Corsica and Sardinia; and yet still farther even to the battle-field and unfriendly shores of the Crimea. Following up his earliest achievements, Mr. Brett is now co-operating in the establishment of an electric link between the island of Newfoundland and the continent of America; and he is also personally superintending the submersion of the final instalment of the cable which is to unite the opposite shores of the Mediterranean—placing Paris in direct communication with her colony of Algiers.
These facts prove, conclusively, that any nautical and engineering difficulties, which at first existed, have been overcome; and that the experience gained in submerging the shorter lengths of cable has enabled the projectors to provide for all contingencies affecting the greater. With this view, a glance at our insular position on the map of the world, at the distance which separates us from our colonies and dependencies, as well as from the vast continents of India and Australia, awakens at once the inquiry,—“Are these remote families of the earth (or rather parts of our own family) accessible by Telegraph? Or, are they to be for ever denied the advantages which we already enjoy?” The world is prepared, and society is eager, for its unlimited extension. Public interest is awakened; nations are stirring; and in America as in England, capitalists are not wanting who are ready to aid in the stupendous work of an Indian or a Transatlantic line. They wait only for an answer to the question—Can it be proved to be practicable—that is, commercially practicable—and capable of working at such a speed as will admit of messages being sent at a low tariff?
The subject of submarine telegraphic communication appeared to me of such magnitude and of such importance that I may, perhaps, be pardoned, if I have investigated the phenomena exhibited by electrical currents in subterranean and submarine wires, as a speciality, and with a direct leaning towards their practical application, rather than in their more general and more extended theoretical aspects.
Many of the phenomena to be observed are so unlike what we see in other wires, that we are compelled to examine them closely, patiently, and experimentally, before we can arrive at a just appreciation of their practical effects. Thus theory must guide our steps, or we shall inevitably fall into empirical routine.
Faraday, the Electrician of the day, opened the subject on a late occasion, with his usual felicity of experiment and explanation. His lecture, delivered at the Royal Institution, was, I believe, the first thing that awakened public attention. The interest excited by that lecture has not subsided, nor have the suggestions, as to the difficulties to be encountered, been yet forgotten.
For several weeks during the months of March, June, and July, in the present year, I enjoyed the unusual advantage to be derived from unlimited access to lengths of cable wire, amounting, in the aggregate to no less than 1,125 miles; every part of which was wholly under the control of the operator.
The cables in question were those for Newfoundland and the Mediterranean, to which I have already alluded; the one 75 miles in length, and containing three wires; the other 150 miles in length, and containing six wires. Both of these were completed and closely covered with iron wire spun round them [Specimens were exhibited.], and laid in three large continuous coils, in contact with the earth, on the premises of the manufacturers [Messrs. Kuper and Glass, Morden Wharf, East Greenwich.], to whose courtesy I am indebted for the facilities which they afforded me.
It seemed to me wrong to let such an opportunity pass, without making a series of experiments and observations, which should, on the one hand, enable us to demonstrate conclusively, as far as the means at our disposal would admit, the practicability of working through unlimited lengths of submarine wires; or, on the other hand, make us better acquainted with the electrical difficulties to be encountered, and so place us in a position to meet the enemy with the true indomitable English spirit,—determined to conquer.
The results have been gratifying beyond expectation. New, instructive, and most encouraging phenomena have been elicited; and the entire success of a transatlantic line is no longer, in my own mind, doubtful.
The details of these experiments it will be now my endeavour to explain to you; in a short, practical, and suggestive manner, rather than in the form of an elaborate paper. I do this, hoping that others may be induced to verify the results. I would here express my intention to repeat them, in various forms, through any longer lengths of subterranean or submarine wire which may be placed at my disposal.
One word as to the precautions observed:—In an ordinary wire circuit with perfect insulation, it matters little, if at all, in what part of the circuit the test-instrument be placed; the results being uniform throughout the wire. In experiments on submarine wires, the position which the test-instrument occupies in the circuit may make the difference between its receiving the whole available influence of the current, or receiving practically none. In all my experiments, therefore, the receiving test-instrument, in the long circuit, was placed in such a position, to be as far as possible from the source of the current; thus approximating to the actual condition of a distant station.
Another precaution adopted throughout the experiments was the interchange, at regular intervals, of the recording styles, used for the long and short circuits respectively; so that any error accidentally arising from the position of the styles, might thus be compensated in the subsequent observations.
After testing for continuity and insulation, I had to habituate myself to some of the more obvious phenomena, in order that I might know how to work fairly and correctly through the wire,—to learn its language, as it were, before I ventured to interrogate.
I need hardly do more than allude to Faraday's beautiful description of the “rush of electricity” observed on the galvanometer at the instant of making contact with the battery, even though the circuit be open at the distant end; the “charging of the wire” which takes place; the “retention” of this charge for several minutes after contact has been broken; and the “discharge” again observable either on the galvanometer, or by shock or spark, to the earth-wire or spectator; the direction of the current, during this discharge, being reversed at the home end of the wire. All these phenomena, with which you must be well acquainted, were tested and repeatedly verified until the mind became familiar with them.
My first experiment was so to arrange a seconds’ pendulum, as to give contact at each beat; recording through the long circuit (1,125 miles) upon a slip of electro - chemical paper, drawn at an uniform speed under a steel style.
When placed in circuit with the cable it gave a continuous line; variable somewhat in breadth and intensity of colour, but, in reality, continuous. It was evident that the wire did not discharge itself entirely between beat and beat. The amount of “charge” given at each beat was more than could discharge itself in the interval.
Instead of passing through the wire, as would have been the case in ordinary wires the moment the contact was made, the current passed into the wire, as it were, at the instant of contact, and discharged itself slowly; dribbling itself out continuously.
All other conditions of the apparatus remaining the same, the seconds’ pendulum, when arranged to work through a short home circuit, recorded alternately the stroke and blank perfectly.
My next attempt was to use two currents, or rather two equal parts of the same (let us call it a split current), one of which should travel a few feet only, and the other the long circuit; both being made to mark by adjacent styles upon the same slip of paper. The pendulum was retained, and so arranged as to divide the paper by the use of a separate style and short circuit into seconds’ lengths. In order to make a current divide itself into equal parts, the two circuits which are used must offer equal resistance. It was necessary, therefore, to provide resistance equivalent to about 1,125 miles. A column of distilled water, 3/8ths of an inch in diameter, and 30 inches in length, was, as regards resistance, found to be an adequate representative of the mileage worked through.
The split current was laid on, running continuously through both circuits and recording. If the length of the column of water were now reduced by a single inch, the mark from the resistance style became obviously the more intense of the two, and vice versa.
The slip here presented is the result of this experiment; which was varied and repeated until satisfactorily verified by numerous observations. Thirty inches of a column of distilled water, 3/8ths of an inch in diameter may, therefore, be taken as equivalent in resistance, to 1,125 miles of gutta percha covered copper wire of No. 16 gauge.
Connexion was made with this “resistance tube,” or “Intensimeter,” as it may be called, by means of a small piece of stout platinum wire, about half an inch of which was immersed in the water at each end.
The apparatus was now applied to the special purpose for which it was constructed, viz., to split the current into two parts, equal in intensity and quantity, which should record themselves by similar and adjacent styles upon the slip of electro-chemical paper; one part of the current having travelled only a few feet, the other part through the entire cable of 1,125 miles of wire, and having been subjected to the effects of induction.
The slips which were the result of this experiment are numbered 1, 2, and 3, and the diagrams show fac-similes, on an enlarged scale of 10 inches to 1. The arrows denote the direction in which the paper moved.
In these experiments we get what may be termed the handwriting, the autograph, of the current itself;—we see its features and learn something of its habits, under the widely differing conditions to which the two equal parts of the same current are subjected. The mark made by the short circuit current is abrupt in its commencement, of equal breadth and depth in its whole extent, and ends as it began—abruptly. The other mark is an appreciable interval later in point of time, it is exquisitely fine in its marking at the commencement—increases gradually to its maximum, when its depth and intensity quite equals the other, and then tapers off to a point usually more delicate than at its commencement—so fine indeed that it is sometimes difficult to fix its precise limit.
In speaking of the velocity of the current, is it fair to take the first visible trace of the long circuit current as its arrival? Or should we count only from that part of the mark at which it has attained an equal depth of colour with the other? In all our estimates of velocity this point must be taken into consideration, whether we use the current direct upon the paper, or cause it to actuate an instrument of any sort. May not this help to explain some of the discrepancies noticed in the recorded results of different observers? We are not aware that they adopted similar modes of observation. One might have taken the commencement of the current, another have counted only from its maximum.
Hitherto I had operated with the ordinary voltaic current. My next endeavour was to get an automatic record,—an “Autograph” of the magneto-electric current, and to observe its habits and behaviour in the cable wire. For this purpose I availed myself of a series of magneto-electric induction coils, capable of being excited by a Grove’s, Maynooth, or Smee’s battery of tolerable power—all being included in the same quantity-circuit of the battery.
The secondary wire of one of these coils was made to record itself through a short circuit (of 18 or 20 feet) direct upon the paper. The secondary wires of the remaining coils were arranged in series, and connected with the long circuit, of 1,125 miles; the receiving or test apparatus with the paper, being placed in the middle of this length. or, in other words, at as great a potential distance as possible from the source of the current. (See fig. 11.)
These two currents, (call them twin currents) recorded by their respective styles (needles), side by side upon the same slip of paper, became, therefore, fair subjects of comparison. (See fig. 4.) Disregarding for a moment the consideration of velocity, what a remarkable autograph is that! A current of the most sudden and momentary description, as a magneto-electric current must necessarily be, is brought under constraint by the conditions to which it is subjected in these wires; so that it occupies more than a second and a half from the commencement to the completion of its discharge.
Compare the two currents, marking well the space that intervenes between the commencement of the short circuit mark and that of the long circuit mark; and then again look at the length of time, indicated by the space upon the paper over which the discharge of this latter current is diffused.
If we were to stop here, there would be little probability of ever working across the Atlantic rapidly, or indeed of working at all at a commercially profitable speed; when the most sudden and abrupt current with which we are acquainted requires such a length of time for its discharge. But the laws of nature, though in this instance apparently against us, may be engaged on our side; and though we cannot coerce them, by proper management they may be made to co-operate with us.
At this point of the experiments it became obvious that it was possible, as I had suspected, to discharge the wire more rapidly—I had almost said forcibly and suddenly, and the words are not altogether inappropriate—by giving it an adequate charge of the opposite electricity. This is not only theoretically possible, but practically easy and certain. We shall see, hereafter, wherein, under certain circumstances, this fact may embarrass us; and, on the other hand, wherein, properly used, it may become invaluable.
An experiment was made with the object of determining this, and was conducted as follows:—
A positive magneto-electric current was sent, and allowed to record itself spontaneously upon the electro- chemical paper, which was kept moving at an uniform speed. It occupied, as you will see, a certain space upon the paper, and was repeated several times to verify it. Other positives were then sent, succeeded at varying intervals, by negative currents of equal strength. The effect of this procedure is most obvious in the various lengths of the positive marks recorded upon the slip, and of which No. 5 is a fac-simile. I need hardly remind you that in this electro-chemical arrangement, the negative current leaves no trace upon the paper; its presence, therefore, is indicated only by the absence of a mark, or by its effect in cutting short the marks made by the immediately preceding positive currents.
Let me for a few moments, call your attention, to another slip, on which, paradoxical as it may appear, though working through the same length of wire, and with the same magneto-electric current which, as before described [See Fig. 4], required a second and a half to discharge itself; by availing myself of the principle just mentioned, I have been able to make as many as seven and even eight currents record themselves within a single second of time. The secret of this consists in the rapid and perfect discharge of the remains of the current which may be in the wire, by a current of the opposite quality; positive following negative, and negative positive with perfect regularity, and thus maintaining or rather restoring, at intervals, so far as is desirable, the electric equilibrium of the wire.
Hence, it is obvious, that any telegraphic instrument, whose efficiency depends upon the rapid repetition, in succession, of similar currents, must fail if used under the conditions which these wires present; whilst those instruments only can succeed which are specially constructed for using the alternating currents.
To return to our experiments. I ask your attention to a very remarkable phenomenon, hinted at and anticipated by Faraday, and the truth of which I have satisfactorily proved. We have seen that the negative current neutralizes the remains of the positive which had preceded it. Will it surprise you to find, that if sent too closely and rapidly upon the heels of the preceding current it will neutralize or destroy it entirely?
The test-instruments, included in the circuit at the home end of the wire, may show positive and negative currents entering the wire in their proper order, and of the accustomed energy; and yet at the middle junction, if working beyond a certain speed, not a vestige of a current shall be found; not anything that shall move the most delicate instrument; leave a trace upon the most sensitive paper; or even communicate the slightest perceptible sensation to the tongue.
This negative evidence is rather difficult to produce. We are asking for testimony where there is no witness. A reference to the slip before you will assist us; for up to this point, the long circuit current had been recording as usual, but when the speed (as seen by this rapid repetition of the short circuit marks) exceeded a certain limit, then the long circuit marks ceased entirely. If, however, from the nature of the apparatus used, there be a preponderance of either positive or negative, then a proportionately (more or less) feeble evidence of a current is obtained.
Another remarkable and very interesting phenomenon has imprinted itself upon the paper in the course of these experiments.
Faraday had proved the possibility of several successive waves of force being present in the wire at the same time, and following each other in due order. I now present you a slip, No. 9, which bears evidence of the co-existence of no less than three waves of force in a length of 900 miles—that is to say, by sending alternately positive and negative at the maximum rate of about eight in the second, two will arrive after you have ceased to transmit.
The beats of the pendulum are recorded by No. 1 and No. 4 styles alternately, without subdivision into fractional parts; whilst the effects of the “twin currents” upon the relays in the long and short circuits respectively, are recorded by No. 2 and No. 3 styles, by the use of a local decomposition or printing battery.
The earlier part of this slip shows the style marking the arrival of a long circuit positive current, simultaneously with a short circuit negative, as seen by the blank, and vice versa. The latter part of the slip, where the working speed is greater, shows the coincidence in the time of arrival of a positive in each circuit; but they are not the two which started at the same time—the “twins” as I have ventured to call them; for the short circuit positive current has arrived simultaneously with the preceding positive in the longer circuit.
The run of currents, during a second of time, may be thus expressed in letters:—
The slip to which I refer, and its fac-simile, is very clear upon this point; but it was however, even more striking, to observe the phenomenon upon a dial representing the distant station, placed side by side with a similar one in the home circuit. The distant one could always, by rapid and dexterous manipulation, be left two steps behind in the race, though without the slightest derangement of their ultimate and perfect correspondence. Perhaps an examination of diagram No. 10 will give a clearer view of these phenomena than words alone can convey. It is intended to represent the relative conditions of the long and short circuit wires, at a given instant, during the transmission of the rapidly alternating currents, shown in slip No. 9. At the instant that any given positive current is generated in the induction coils, and is passing through the short circuit wire, its twin current enters the long wire, and finds there two currents in advance of it, and still undischarged. We may suppose that midway between the parts of the long wire oppositely charged, and indicated by the respective signs of + and — there must exist a point of equilibrium or constrained neutrality, depending upon the juxta-position of opposite currents; and it is readily conceivable that on multiplying these neutral points by a more rapid reversal, we may, while increasing the number, reduce the energy of these waves of force to a minimum, and at last produce an absolutely neutral state of the wire at the distant junction.
I am not aware that Faraday contemplated the possibility of opposite currents existing simultaneously in the same wire, and arriving at their destination in due order. From the tenour of his remarks, as recorded, I rather think that he referred simply to successive waves of the same current; and that he judged such instruments as required the use of reversed currents would probably be incapable of working through long submarine wires.
We come now to a consideration of the experiments on the “velocity of the current.” And here I must again call attention to the difficulty about the part of the current from which to begin to count; whether the earliest and most feeble trace shall be called, by courtesy, the current, or whether you are content with nothing less than its full energy.
It appeared to me an unexceptionable mode of comparison, that two currents passing through the long and short circuits respectively should be received upon similar and equally sensitive instruments, and tested by the effects which they produced.
Let us consider the slips numbered 6, 7, and 8, and ranging from 300 to 900 miles. The mode in which these experiments were conducted is as follows:—A slip of moistened electro-chemical paper was kept moving by a train of wheels, at a moderate speed, over a metallic drum. Pressing upon the upper surface of this paper on the drum, and parallel to each other, were four steel springs or styles, insulated from each other as well as from the drum, and in connexion each with its proper wire. Two of these styles, the first and the fourth in order, recorded the beats of a seconds’ pendulum, upon each side of the slip of paper alternately; the seconds having, in this instance, been subdivided into fractional parts (twelfths) by a very simple revolving arrangement. This mode of operating admits of great delicacy in the determination of the results, as the seconds can afterwards be divided into hundreds by the use of a “vernier,” and read off with the same facility as barometrical observations.
Two separate magneto-electric currents,—“twin currents,” as we have called them,—synchronous in their origin, but differing in their destinations, and wholly distinct in their metallic circuits, are sent by one and the same movement of a handle. One, travelling about 20 feet, is received upon a “relay,” or instrument, which instantly gives contact for a local printing battery, and is thus recorded by No. 2 style. This serves to note the instant when the current going the long circuit, began its journey. The other current, and, of course, a much stronger one, is sent through 900 miles of wire, and is received upon a similar “relay,” placed in the middle junction of these wires, and, therefore, at the greatest practicable distance from the generator of the current. This, actuating the “relay,” when it arrives, gives contact for the printing battery in the same way as the other, and is similarly recorded by No. 3 style; but after an appreciable interval of time. Thus, the commencement of the mark is simultaneous with the arrival of the positive current, whilst the termination of the mark, owing to the peculiar construction of the relay which I need not now more particularly explain, denotes not necessarily the cessation of the positive, but the arrival of the next negative.
The result of a great number of observations (more than 5000), collected in this way, and carefully measured, shows from one-twelfth to one-sixteenth of a second as the time occupied in the 300 miles’ circuit; one-sixth to one-ninth of a second for 600 miles; and one-fourth to one-fifth for 900 miles; giving a velocity varying from 3,600 to 4,500 miles in the second. When we compare these results with those previously obtained by autograph of the voltaic current, we are startled at the discrepancy; from a minimum of 1,000 or 1,100 miles in the second, to a mean average of not less than 4,000 miles, and yet both are equally truthful and were obtained with equal care.
I find, therefore, contrary to what I had previously accepted on authority as an undoubted fact, that the velocity in these wires, at least, is greatly dependent upon the amount of energy in the current employed.
Let me now refer to the difference of the velocity of the current as marked on the slips No. 1 and 2, and which I have purposely placed side by side; both, be it observed, being autographs, and the results of experiments on the same length of wire, on two consecutive days. The former was produced by an exhausted battery, of a very moderate number of cells; the latter was among the early proofs of a battery of three times the numerical amount, recently excited, and therefore of undiminished energy.
Even if it be not deemed fair to draw a comparison between the voltaic and the magneto-electric currents, the influence which the energy of the current exerts has proved itself spontaneously, on more than one occasion, by the steady and gradual diminution of velocity from 5,400 to 3,600 miles in a second, observed even in the progress of one continuous experiment, by the simple exhaustion of a small Grove's battery, employed for exciting the induction coils —all other conditions remaining the same.
Velocity observations, recorded by the direct action of the current upon the paper,—time calculated from the commencement of the earliest visible mark.
Velocity observations, recorded by means of “twin currents” received upon “relays,” with local decomposition battery for printing.
One other point connected with the measurement of velocity, I have not had the opportunity of practically testing, and yet it is of high interest. It is this:---Would the addition of an equal amount of earth circuit, by doubling the actual mileage, produce double the retardation observed in the use of the metallic circuit alone, or would it leave it unaltered? May not the determination of this question throw some light upon the function of the earth when used to complete an electrical circuit? If we regard the earth as a “reservoir of electricity,” it would seem unreasonable to expect a considerable, if any, increase in the time occupied in travelling. Experiment and observation will alone decide.
The facilities afforded for arranging and grouping these wires at pleasure, enabled me to investigate, satisfactorily, another point of great practical importance—I mean the question whether, in a submarine wire of given length, any additional advantages would be obtained in working, or any of the impediments arising from. the effects of resistance or induction be removed, by adopting wire of a larger gauge. Working through a 300-miles circuit, I had it in my power to double and to treble the mass of conducting wire, by the use of collateral wires added to the existing circuit, and carrying equal portions of the current. The result of nearly two thousand recorded observations, most carefully noted for this object, proves, so far as time has allowed me to measure and compute them, that no adequate advantage would be gained by any considerable increase in the size of the wire; nor is the effect of induction materially lessened, nor the velocity or the working speed, materially increased thereby.
Let me recapitulate, briefly, the facts to which I specially invite attention. These are:—
In conclusion, I will lay before the Association a few thoughts which have suggested themselves. It appears from these experiments, as well as from other trials which I have made, with an instrument of the simplest form, actuated by magneto-electric currents, that the working speed attainable in a submarine wire of 1,125 miles, is ample for commercial success; and we may hence fairly conclude, that India, Australia, and America are readily accessible by telegraph, without the use of wires larger than those now commonly employed in submarine cables.
The result of the velocity experiments leads me to the conviction that it is not “distance” alone, but rather the combined influence of “induction” and “resistance” that retards the passage of the current.
It seems probable that we may be able to imitate, by some simple arrangement, this effect of the wires, and, if so, may learn further to control and modify it.
Throughout these experiments I have felt the great want of an instrument analogous to the Galvanometer, say a Magneto-electrometer, adapted to measuring the force of magneto-electric currents, and affording us an accurate standard of comparison.
This want I have since endeavoured to supply; and propose the form of instrument as shown in the drawing before you, as a simple and unpretending arrangement fitted for the purpose. (No. 12.)
It is, in fact, a “Steelyard,” capable of weighing from one grain to ten thousand, adapted for testing mechanically the amount of magnetic energy developed during the passage of a current.
The movements of this instrument are adjusted by the use of two insulated banking-screws. Between these the long end of the lever has a play of about one-hundredth part of an inch, sufficient to indicate, by connecting a voltaic battery and galvanometer therewith, the response which the instrument makes to the magneto-electric current to be tested.
Finally, I have to thank the Members of the Association for the courtesy which they have extended to me, and to beg their forbearance, not only as to the manner in which this paper has been put together, but also as to any points which may have escaped my attention, in the very limited time which I have been able to devote to the preparation of it:—time snatched, at intervals, amidst the imperative duties and requirements of an arduous profession.
POSTSCRIPT.—Since the foregoing has been in type, the engineer of the English and Irish Magnetic Telegraph Company, Charles Bright, Esq., has, with the sanction of the Directors, in the most liberal manner, offered me the privilege of free access to their system of subterranean and submarine wires. These wires extend from London via Dumfries to Dublin, and are 660 miles in length; whilst in the aggregate the number and length of wires laid down, in connection with the main trunk, gives the opportunity, which no other company possesses, of working through a circuit wholly subterranean and submarine, amounting to not less than 5,000 miles. In prosecuting a series of experiments, with the assistance and co-operation of the Engineer, precautions will be taken, by the introduction of test-instruments at every available junction, to provide against the possibility of error.
ARTHUR WALLIS, PRINTER AND LITHOGRAPHER, BRIGHTON.
Note: Prior to his presentation of the paper to the Brtitish Association and the subsequent publication of the pamphlet above, Whitehouse had given permission to the Illustrated London News to report on his results. The story was printed in the issue of 6 October 1855, and was accompanied by an illustration of the apparatus used to make the measurements. For convenience of reference, this is reproduced below.
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Last revised: 22 January, 2010