History of the Atlantic Cable & Undersea Communications
|Papers Presented at the British Association
Annual Meeting, August 1856, Cheltenham
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.
At the August 1856 meeting of the British Association in Cheltenham, Whitehouse presented two papers.
The titles are:
Report of the Twenty-Sixth Meeting
Notices and Abstracts
In the prosecution of some electrical studies, requiring an estimateof the values of different magneto-electric currents, Mr. Whitehouse found that the ordinary galvanometer was totally inadequate to indicate the required results.
However suitable that instrument might be for a continuous or voltaic current, and within a very limited range, yet the problem before him involved the numerical estimate of currents of the widest range and of the shortest duration.
It therefore occurred to Mr. Whitehouse that the amount of magnetic force developed by the current in its passage through fine wire surrounding an electro-magnet, seemed to offer the most ready, and at the same time the most practical mode of attaining the object;—an idea which received confirmation from the fact, that whenever such currents were used in telegraphy, they were always received upon and made to actuate electro-magnets.
He therefore wound an electro-magnet with fine wire, placing its poles very near to a keeper of soft iron, poised in the manner of a lever steelyard and loaded to any given weight; the current either lifted or did not lift the given weight, and this was the test of what Mr. W. proposed to call its “value” in telegraphy.
So delicate was this test that he had been able to determine accurately the “value,” as it may be termed, of a current too feeble in its energy, and too brief in its duration, to give the slightest indication of its presence on one of the most sensitive “detectors” usually employed in critical telegraphic operations.
Hehad actually weighed with accuracy a current whose force was represented by 7/10ths of a grain; and on the other hand currents with a wide range of quantity and intensity, and of varying amounts of force up to no less than 600,000 grains.
Mr. Whitehouse then described in detail the principle and construction of the instrument. The reels of fine wire were so arranged as to be easily removeable, in order to substitute others carrying wire of different gauges, or even without this change any two reels might be either joined up in series for intensity or in parallel currents, which thereby halved the length while it doubled the area of conducting wire.
Mr. Whitehouse then illustrated its uses and practical capabilities.
1st. It had contributed valuable aid in the analysis of several forms of induction coils, varying in size and construction; it not only estimated in grains the value of each secondary current thus produced, but approximatively determined their relative amounts of quantity and intensity, by noting the arrangement of wire which gave the best result.
2ndly. It speedily indicated the advantage of using induction coils in pairs rather than singly, under which head some surprising results were given, the near presence of an unexcited iron bar augmenting the value of the current in the coil under observation.
3rdly. It would evidently afford the means of practically determining a point of considerable interest in the comparison of voltaic and magneto-electric currents, to the solution of which Mr. Whitehouse had pledged himself: this was to ascertain the economico-practical limits of battery aeries; because the penetrating power or intensity and value of currents so produced might hereby be accurately compared with the force of coil currents educed from batteries of much simpler and less wasteful construction, consisting only of one or two elements, instead of hundreds.
4thly. It had, conjointly with the use of a pendulum and automatic recording arrangements, led to the production of a series of curve diagrams, representing a minute analysis of any given current, denoting its force, however variable, in the several fractions of a second of time.
5thly. It had enabled Mr. Whitehouse, with the assistance and cooperation of Mr. Bright of the Magnetic Company, after weighing the value, upon short circuit, of the currents from many of their magneto-instruments, so as to determine their average value, to weigh the same currents after working through various distances, from 40 to 320 miles of subterranean and submarine wires; thus showing with certainty and minute accuracy the loss due to the combined influence of resistance, induction and defective insulation.
Lastly. It had done good service in working out the laws relating to induction in submarine circuits; and some striking illustrations were given in conclusion.
Working upon a 498 mile length of very perfectly insulated cable-wire, the phenomena of induction and retardation, of charge and discharge, as originally described by Faraday, were exhibited in a remarkable manner.
A current, lifting 18,000 grains on short circuit, was sent into the long wire, the further end of which was insulated; but on cutting off the battery, and instantly discharging the wire to earth through the same instrument, it gave a lifting power of 60,000 grains; so strikingly cumulative was the tendency of this gigantic Leyden jar. While, if both ends of the wire were discharged to earth simultaneously, a lift of 96,000 grains was obtained, thus realizing as a return, more than five times the amount which the battery gave on short circuit. Again: A feeble magneto-current of only 4 grains was adequate to work a telegraphic receiving instrument, a sensitive galvanometer being placed in the same circuit; but this latter gave most uncertain indications of value; its unsteady movements ranged wider with slow and feeble currents; and indicated a lesser value for stronger currents, which followed more rapidly in succession, all which however were accurately pourtrayed by the new instrument. Again: A pair of induction coils, excited by six small Smee cells, gave 27,000 grains; the mere addition of a soft iron armature at one end augmented this to 43,000, while a similar one at the other end increased the current's value up to 47,500.
Mr. Whitehouse called it a “Magneto-electrometer” from its special adaptation to the measurement of magneto-electric currents, while the terms galvanometer, voltameter, and electrometer sufficiently indicated for these instruments their connexion with other forms of electricity.
The desirability of a definite and common standard of comparison was insisted on, and Mr. Whitehouse promised to set aside for this special use the most accurately finished and perfect instrument he could obtain, for the free use of any fellow- labourers in the same field.
Referring to the proceedings of this Section last year at Glasgow, the author quoted Prof. W. Thomson's paper on this subject, where he stated “that a part of the theory communicated by himself to the Royal Society last May, and published in the ‘Proceedings’ shows that a wire of six times the length of the Varna and Balaklava wire, if of the same lateral dimensions, would give thirty-six times the retardation, and thirty-six times the slowness of action. If the distinctness of utterance and rapidity of action practicable with the Varna and Balaklava wire are only such as not to be inconvenient, it would be necessary to have a wire of six times the diameter; or better, thirty-six wires of the same dimensions; or a larger number of small wires twisted together, under a gutta-percha covering, to give tolerably convenient action by a submarine cable of six times the length.” The author then stated, that circumstances had enabled him to make very recently a long series of experiments upon this point, the results of which he proposed to lay before the Section; adding, that an opportunity still existed for repeating these experiments upon a portion of cable to which he could obtain access, and that he was ready to show them before a committee of this Section in London, if the important nature of the subject should seem to render such a course desirable. Although the subject of submarine telegraphy had many points of the highest importance requiring investigation, and to the consideration of which he had been devoting himself recently, Mr. Whitehouse proposed to confine his remarks on this occasion to the one point indicated in the title, inasmuch as the decision of that one, either favourably or otherwise, would have, on the one hand, the effect of putting a very narrow limit to our progress in telegraphy, or, on the other, of leaving it the most ample scope. He drew a distinction between the mere transmission of a current across the Atlantic (the possibility of which he supposed everybody must admit) and the effectual working of a telegraph at a speed sufficient for “commercial success;” and we gathered from his remarks that there were those ready to embark in the undertaking as soon as the possibility of “commercial success” was demonstrated.
The author then gave a description of the apparatus employed in his researches, of the manner in which the experiments were conducted, and, lastly, of the results obtained. The wires upon which the experiments were made were copper, of No. 16 gauge, very perfectly insulated with gutta percha—spun into two cables, containing three wires of equal length (83 miles), covered with iron wires and coiled in a large tank in full contact with moist earth, but not submerged. The two cables were subsequently joined together, making a length of 166 miles of cable, containing three wires. In addition to this, in some of the latest experiments he had also the advantage of another length of cable, giving with the above, an aggregate of 1020 miles. The instruments, one of which was exhibited, seemed to be of great delicacy, capable of the utmost nicety of adjustment and particularly free from sources of error. The records were all made automatically, by electro-chemical decomposition, on chemically prepared paper. The observations of different distances recorded themselves upon the same slip of paper; thus, 0, 83, and 249 miles were imprinted upon one paper, 0,83, 498 miles upon another slip, 0, 249, 498 upon another, and 0, 535, 1020 upon another. Thus by the juxtaposition of the several simultaneous records on each slip, as well as by the comparison of one slip with another, the author has been enabled to show most convincingly that the law of the squares is not the law which governs the transmission of signals in submarine circuits. Mr. Whitehouse showed next, by reference to published experiments of Faraday's and Wheatstone's (Philosophical Magazine, July, 1855), that the effect of the iron covering with which the cable was surrounded was, electrically speaking, identical with that which would have resulted from submerging the wire, and that the results of the experiments could not on that point be deemed otherwise than reliable. The author next addressed himself to the objections raised against conclusions drawn from experiments in “Multiple” cables. Faraday had experimented, he said, upon wires laid in close juxtaposition, and with reliable results; but an appeal was made to direct experiment, and the amount of induction from wire to wire was weighed, and proved to be as one to ten thousand, and it was found impossible to vary the amount of retardation by any variation in the arrangement of the wires. Testimony also on this point was not wanting. The Director of the Black Sea Telegraph, Lieut.-Col. Biddulph, was in England, and present at many of the experiments. He confirmed our author's view, adding, “that there was quite as much induction and embarrassment of instruments in this cable as he had met with in the Black Sea line.” The author considers it therefore proved, “that experiments upon such a cable, fairly and cautiously conducted, may be regarded as real practical tests, and the results obtained as a fair sample of what will ultimately be found to hold good practically in lines laid out in extenso. At the head of each column in the annexed Table is stated the number of observations upon which the result given was computed,—every observation being rejected on which there could fall a suspicion of carelessness, inaccuracy, or uncertainty as to the precise conditions; and, on the other hand, every one which was retained being carefully measured to the hundredth part of a second. This Table is subject to correction, for variation in the state of the battery employed, just as the barometrical observations are subject to correction for temperature. Of this variation as a source of error I am quite aware, but I am not yet in possession of facts enough to supply me with the exact amount of correction required. I prefer, therefore, to let the results stand without correction.
“Now it needs no long examination of this Table to find that we have the retardation following an increasing ratio, that increase being very little beyond the simple arithmetical ratio. I am quite prepared to admit the possibility of an amount of error having crept into these figures, in spite of my precautions; indeed, I have on that account been anxious to multiply observations in order to obtain most trustworthy results. But I cannot admit the possibility of error having accumulated to such an extent as to entirely overlay and conceal the operation of the law of the squares, if in reality that law had any bearing on the results. Taking 83 miles as our unit of distance, we have a series of 1, 2, 3, 6, and 12. Taking 166 miles as our unit, we have then a series of 1, 3, and 6. Taking 249 miles, we have still a series of 1, 2, and 4, in very long distances. Yet even under these circumstances, and with these facilities, I cannot find a trace of the operation of that law.” The author then examined the evidence of the law of the squares, as shown by the value of a current taken in submarine or subterranean wires at different distances from the generator thereof, which he showed were strongly corroborative of the previous results. He next examined the question of the size of the conducting wire; and he had the opportunity of testing the application of the law, as enunciated by Prof. Thomson last year. The results, far from confirming the law, are strikingly opposed to it. The fact of trebling the size of the conductor augmented the amount of retardation to nearly double that observed in the single wire. The author, however, looked for the experimentum crucis in the limit to the rapidity and distinctness of utterance attainable in the relative distances of 500 and 1020 miles. 360 and 270 were the actual number of distinct signals recorded in equal times through these two lengths respectively. These figures have no relation to the squares of the distance.
“Now, if the law of the squares be held to be good in its application to submarine circuits, and if the deductions as to the necessary size of the wire, based upon that law, can be proved to be valid also, we are driven to the inevitable conclusion that submarine cables of certain length to be successful must be constructed in accordance with these principles. And what does this involve? In the case of the Transatlantic line, whose estimated length will be no less than 2500 miles, it would necessitate the use, for a single conductor only, of a cable so large and ponderous, as that probably no ship except Mr. Scott Russell's leviathian could carry it,—so unwieldy in the manufacture, that its perfect insulation would be a matter almost of practical impossibility,—and so expensive, from the amount of materials employed, and the very laborious and critical nature of the processes required in making and laying it out, that the thing would be abandoned as being practically and commercially impossible. If, on the other hand, the law of the squares be proved to be inapplicable to the transmission pf signals by submarine wires, whether with reference to the amount of retardation observable in them, the rapidity of utterance to be obtained, or the size of conductor required for the purpose, then we may shortly expect to see a cable not much exceeding one ton per mile, containing three, four or five conductors, stretched from shore to shore, and uniting us to our Transatlantic brethren, at an expense of less than one-fourth that pf the large one above mentioned, able to carry four or five times the number of messages, and therefore yielding about twenty times as much return in proportion to the outlay. And what, I may be asked, is the general conclusion to be drawn as the result of this investigation of the law of the squares applied to submarine circuits? In all honesty, I am bound toanswer, that I believe nature knows no such application of that law; and I can only regard it as a fiction of the schools, a forced and violent adaptation of a principle in Physics, good and true under other Circumstances, but misapplied here."
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Last revised: 11 September, 2014