Chapter 3

Mr. Wm. H. Preece, the chairman, in inviting discussion, said that no doubt those present would like to know something about the cost of such a boat as Mr. Reckenzaun described, and he hoped that gentleman would give them some information on that point.

Admiral Selwyn thought Mr. Reckenzaun was a little below the mark when he talked about the dream of getting 5 horse power for one pound--he would not say of coal, but of fuel. For some months he had seen ½ lb. of fuel produce 1 horse power, and he knew it could be done. That fuel was condensed concentrated fuel in the shape of oil. When this could be done, electrical energy also could be obtained much cheaper, but if it were extended to yachts, he thought that would be as far as any one now present could be expected to see it go. Still he thought there was a future for it, and that future would be best advanced by considering the question on which he had touched. First, the employment of a cheaper mode of getting the power in the steam engine; and, secondly, a cheaper and higher secondary battery. In a railway train weight was a formidable affair, but in a floating vessel it was still more important. He did not think, however, that a light secondary battery was by any means an impossibility. Mr. Loftus Perkins had actually produced by improvements in the boiler and steam engine two great things: first, one indicated horse power for a pound of fuel per hour, and next he had devised a steam engine of 100 horse power, of a weight of only 84 lb. per horse power, instead of 304 lb., which was about the average. Those were two enormous steps in advance, and under a still more improved patent law he had no doubt things would be brought forward which would show a still greater progress. Within the last fifteen days, nearly 2,000 patents had been taken out, as against 5,000 in the whole of the previous year, which showed how operative a very small and illusory inducement had been to encourage invention. He had long been known as an advocate of patent law reform, and, therefore, felt bound to lose no opportunity of calling attention to its importance. Invention was in the hands of the inventor, the creator of trade. If, without robbing anybody, one wished to produce property, it must be done by improving manufactures as a consequence of inventions. In one instance alone it bad been proved that a single invention had been the means of introducing twenty millions annually, upon which income tax was paid.

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°, 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 £800, 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.

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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.

"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."

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_.

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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.

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.