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ELECTRICAL REVIEW.

53.18 watts when the secondary circuit was open. We will imagine that the transformer is loaded for six hours out of the twenty-four, the secondary circuit being open for the remaining 18. This puts 53.18 × 18 957.24 watt-hours on the debit side of the account. If the load is maintained at the maximum for two hours, at two-thirds for two hours, and at onethird for two hours, the efficiencies are 96, 94, and 85 per cent. respectively. We take this as a fair estimation of the loading, and we get the following: Expended during two hours at full load, 3,125 watt-hours; during two hours at two-thirds load, 2,126 watt-hours; during two hours at one-third load, 1,176 watt-hours, which, with the 957 watt-hours for the 18 hours, make a total of 7,384. This is in round figures, and giving the account the benefit of the fractions. Now, for the receipts we have at full load 3,000 watt-hours; at twothirds, 2,000 watt-hours; and at one-third, 1,000 watthours; total, 6,000 watt-hours; Efficiency, 81 per cent. These figures may be objected to on the grounds that we have assumed full load for too great a proportion of the total time of lighting, and that there may be a period during which the load falls considerably below onethird of the maximum. The criticism is probably a just one, but in giving these figures we wish to place the transformer at the greatest advantage. In practice we do not get the time divided into two-hour periods as here assumed, and for the actual variation under different loads a calculation to suit the actual conditions must be made..

Our object in bringing these figures to the notice of our readers, has been to show that the usual way of estimating the efficiency of a transformer is wrong, that the ratio of the work being received to the work being expended at any instant is not the commercial efficiency, and that the correct method of obtaining this is by taking the ratio of the work received from and given to the transformer throughout the whole period of its connection to the primary circuit. As an example, we have taken a period of 24 hours, for six of which the transformer is loaded, but it will be obvious that for the summer time this number of lighting hours is too great. It might fairly represent the amount of light required in the winter, but in the summer the hours would be less, and the efficiency therefore lower. It is evident, then, that the cfficiency should be estimated on the basis of 12 months continuous working. Taken on this basis, and allowing for the fact that large transformers are more efficient than small ones, we imagine that an estimate of from 70 to 75 per cent. efficiency will be found very near the truth.

So much for the transformer losses, but the waste in other parts of the system must be found before we ascertain the efficiency of the whole. From the most reliable tests made it seems that there can be obtained on the crank shaft of a first-class compound engine from 90 per cent. of the indicated horse-power at full load to about 80 per cent. at half load. The percentage necessarily alters with every varying condition of working, but roughly 85 per cent. may be assumed as the average return. The dynamos we may take as having Commercial efficiency of 90 per cent., and this makes

[SEPTEMBER 27, 1889.

the electrical output at their terminals average 76-5 per cent. of the I.H.P., assuming that the engines are directly coupled, or allowing for the loss in belting direct we may put it down at 72 per cent. For the ratio of the E.H.P. to I.H.P. a value very close to this has been determined by several experimenters, so there is little doubt about its approximate accuracy. The loss in the mains may be merely fractional, so we will not now take it into account. Taking the average efficiency of the transformers at 75 per cent. then, we get 54 per cent. as the efficiency of the whole system; that is to say, the watt-hours received in the secondaries of the transformers are rather over half the number of watt-hours expended in the engine cylinders.

As we said at the beginning, we have before us no records of actual working, and the figures given are more or less hypothetical. But estimates must be based on some figures before the central station is an accomplished fact, and it seems to us that engineers in computing the useful return should not reckon on a higher efficiency under actual working than 50 per cent. We doubt whether even this is attained as a general rule. The 18-6 lbs. of coal used at Brighton per electrical horse-power hour seem a very bad case, and we trust though these are figures from actual work that they are figures capable of vast improvement. With more care taken to design transformers in accordance with the hours of lighting farther improvement may be effected, but for obvious reasons progress in this direction is limited. We require the light for much longer periods in winter than in summer, and it is our misfortune that we cannot have a summer and winter set of transformers, the latter of which might be thrown out during the spring cleaning and reinstalled in the autumn. We must be content with transformers which for the whole twelve months give a fair average efficiency.

In conclusion, let us hope that those of our friends having actual figures in their possession will not hesi tate to bring them forward. Need we say that it will give us the greatest pleasure to see discussed in these columns a subject of such growing importance?

WITH reference to the efficiency of distribution systems, we have before us a pamphlet issued by the Electrical Power Storage Company describing very fully their system of distributing electricity by the aid of storage batteries. The unfortunate Brighton figures are, of course, referred to, the company observing that the consumption of coal on their system will, under no circumstances, exceed 11:19 lbs. per E.H.P. hour supplied to the consumer. The plan of distribution consists in employing at the central station separately excited dynamos of about 500 volts placed in series, according to the requirements of the district, until the limiting difference of potentials for the charging circuit is reached. Storage or sub-stations are placed at convenient points in the district, these being all connected to the distributing mains in parallel or on the threewire system. The cells in each station are divided into sets of 54, suitable for feeding lamps of 100 volts, and half the number of sets is charged in series, while the other half is connected in parallel to supply the lamps.

SEPTEMBER 27, 1889.]

ELECTRICAL REVIEW.

only half the battery being therefore in the charging circuit at a time. When the charging of half the battery is complete the current is switched automatically on to the other half, while the sets of the charged half are placed on to the lamp circuit. In each sub-station there is placed a continuous current transformer to augment the capacity, the charging current from the dynamos feeding these during the maximum hours of lighting. The system seems to have been well thought out, and there are given comprehensive estimates of both first cost and working expenses, which we may notice on another occasion.

Modern Light and Heat, of Boston, predicts "that ere long, in view of the steady increase in the use of the electric motor, we shall see central stations equal to those at present used for lighting devoted entirely to the generation of the electric current for power purposes." Without hinting that our contemporary is over sanguine, we only wish that we could predict with truth such a state of things for this effete monarchy of

ours.

IT is a pity that the three societies named below should have held their meetings so close together, as this tends to diminish somewhat the interest in such assemblies. Those persons connected with one society are generally directly or indirectly associated with the others-consequently, without a suitable interrval between the meetings, the interest of those concerned decreases, and we have as a result papers brought forward which are not up to the anticipated standard. This has been demonstrated at the Paris Electrical Congress, the British Association, and again this week at the Paris meeting of the Iron and Steel Institute, which opened on Tuesday last. The only electrical paper read before the latter was On the Thomson Process of Electric Welding," and the members were shown the process in operation in the main aisle of the Machinery Hall at the Exhibition.

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As will be seen from an article in another part of the present issue, the Bradford Corporation have officially inaugurated the central electric light station in that town. This is the first practical step taken in this country by a Town Council and it is very probable that others will follow the example set them by Bradford. Already the municipalities of Leeds, Barnsley, Manchester, Salford, Dublin and others are considering the subject, and the work done in Bradford will doubtless have its effect.

"C'est une ouvrage de longue haleine," said one competitor to another, referring to the motor competition instituted by Industries. "Yes! it is a long job," replied the electrician addressed, "but the prize will be awarded shortly. I was round at the other

evening when Edison's phonograph was exhibited in operation, and the instrument actually rolled out the words: Well, it is agreed, then, that although the designs are not up to the standard required by our conditions, that by is the best, and must have the prize; but we must in future have no more competitions of a similar nature. The award will therefore shortly I could hear no more, as the sounds were indistinct." Our office boy, who brought us this astounding information, says that he thinks somebody

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will get the prize before the end of the year. Those of our readers who are interested in the matter would do well to bear this in mind.

MR. PREECE, it appears, in his recent remarks before the British Association, did not intend to convey the notion that death could not be produced with certainty by the electric current, though there can be no question that a statement was made to this effect, and, moreover, the statement that the American law with reference to execution by electricity would have to be rescinded, seems to bear out what he was understood to say. However, we hear that what Mr. Preece meant was-that the current strength required to produce death with certainty, and without torture, was not yet determined. Possibly this may be the case, but we ourselves have no doubt that ample evidence exists to show how instantaneous death can be produced by the current.

IN the discussions which have from time to time taken place, and notably at the late meeting of the British Association, on the dangers of electric lighting, special stress has been laid upon the high voltage causing the shock, as if this were the one element of danger, though, on the other hand, it has been brought forward as an argument against the danger theory that shocks from an enormously high voltage have been taken with impunity. It seems to be forgotten that high voltage is but the element tending to cause a strong current to be set up through a high resistance, and that what causes danger is the continuance of a current of a certain strength for a certain time, through the human body. A low potential cannot set up a strong current because the resistance it has to encounter in the human body is great, but a high potential can set up and maintain a strong current, but only provided this high potential lasts for a certain period. High potential alone cannot maintain a strong current, thus a Leyden jar of an exceedingly small size can be charged to an enormously high potential, a 100,000 volts, or more, but the duration of the current which it will cause to flow when the jar is discharged is an infinitesimally small period, a time much too short to enable any very marked pysiological effect to be produced. The same is the case with the shock received from a Rhumkorff coil; the latter gives a spark, say, half an inch long, the potential which causes this spark must be many thousand volts, but the shock which the coil will give, even when continually applied, would not (except in special cases) cause death, simply because the high potential only sets up a current for an extremely short period. The case, however, is totally different with a high potential dynamo; here the high potential which sets up the current can, and does, maintain the latter for a considerable period, and this passing through the human body will, in most cases, produce a fatal result.

THE more one reads of the proceedings of the Paris Congress with reference to electrical standards, the more one wonders how that absurdity, the "Legal Ohm," ever came to be authorised. To substitute one incorrect value for another certainly does not improve matters, for it is known that the legal ohm is not the true ohm. As a matter of fact, the legal ohm has never, and never will, come into use, and will only continue to exist as a name.

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ELECTRICAL REVIEW.

THE ZIPERNOWSKY ELECTROSTATIC

ELECTRO-MOTOR.

[BY A CORRESPONDENT.]

THE well-known phenomenon that bodies charged with identical electricity repel each other, was first used in 1780 by Franklin for the production of continuous motion. He employed a horizontal wheel constructed of horizontal strips of glass fitted at each end with copper balls. The wheel was placed upon a point between the balls of two Leyden jars with opposite charges, so that two diametrical balls of the wheel became charged similarly with those of the jars and were consequently repelled by the latter. After a revolution of 180°, each ball discharged itself on the ball of the opposite Leyden jar, receiving at the same time a part of

[SEPTEMBER 27, 1889.

Fig. 1 gives a perspective view of this small motor, and fig. 2 a diagrammatic representation, with the arrangement of connections shown in both the

cases.

The movable part of the apparatus consists of two pairs of aluminium sectors, insulated from each other, which, for the sake of perspicuity, are represented in fig. 2 as the quadrants, A A', B B'. The fixed part consists of four double (hollow) sectors of brass, which enclose the movable sectors, and which are also shown in the diagram as the quadrants, C C', D D'. The movable part is further fitted with a commutator in four parts, by means of which the two pairs of sectors, A A' and B B', are charged identically with the opposite fixed pairs of sectors by means of the points, s s'. If the clamps, K K', are connected with the terminals, SS', of the transformer, T, which converts the low tension of the

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the electricity there accumulated, and was repelled. Franklin named this apparatus an electrical kitchen jack.

Poggendorff subsequently showed that a movable disc of glass or ebonite begins to rotate if opposite electricities are conveyed to it by means of two diametrically opposite combs, and if at the same time it receives an initial impulse in any direction.

Poggendorff also set a Holtz influence machine in rotation by charging the combs of this machine by another influence machine.

In order to study the so-called static effects of high tension alternating currents, Herr Zipernowsky, amongst others, has constructed a small rotatory apparatus which he derived from Thomson's quadrant electrometer in. the idiostatic form indicated by Joubert. Zipernowsky has been able to set this apparatus in rapid motion both with a high tension alternating current and with * high tension continuous current. In the former Can he introduced the apparatus between the secondary terminals of a transformer whose primary was connected to an alternating current machine of low tenmon. With 1,000 volts the rotation was so rapid that it could not be followed with the eye.

In the second case he took the electricity from a dri band which connects the shafting in the 200m of the electrotechnical department of 'establishment with the motor, a high engine. In this case the number of ronuch greater than with a 2,000 volt alter

FIG. 1.

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SEPTEMBER 27, 1889.]

ELECTRICAL REVIEW.

with the receiving device, V, and the other is connected with the earth. It must be remarked that in this second arrangement a momentary charge of the movable sectors would suffice, as the fixed segments do not alter the sign of their charge. In the former arrangement the charge must be continued, so that the electricities in the fixed and the movable parts may change their signs simultaneously.

It is possible that this apparatus, in some form or other, will be suitable for practical purposes, e.g., as a volt-counter for arc lamps in series, as a registering apparatus for the resistance of earth connections, or for changes in the primary tension in alternating current circuits, and perhaps in the case of very high tensions as a motor.

REVIEW OF THEORIES OF ELECTRICAL ACTION.*

By Prof. H. S. CARHART.

THE physics section of this association congratulates itself because it deals with topics of the most lively and general interest, not only from a practical point of view, but still more from a theoretical one. Even popular interest in electricity is now well nigh universal. Its applications increase with such prodigious rapidity, that only experts can keep pace with them. At the same time, the developments in pure electrical theory are such as to astound the intelligent layman, and to inflame the imagination of the most profound philosopher.

Of the practical applications of electricity it is not necessary to speak. They bear witness of themselves. A million electric lamps nightly make more splendid the lustrous name of Faraday; a million messages daily over land and under sea serve to emphasise the value of Joseph Henry's contribution to modern civilisation. Blot out these two names alone from the galaxy of stars that shine in the physical firmament, take from the world the benefits of their investigations, and the civilisation of the present would become impossible. The value of the purely scientific work of such men is attested by the resulting well-being, comfort, and happiness of mankind.

But the mind can never rest satisfied with the facts and applications of a science, however interesting and useful they may be. It feels an inward impulse to link the facts into a related whole, to enquire into their causes, to frame a satisfactory theory of their correlation, and so to build on them a true science. It is, indeed, interesting to study the history of any scientific doctrine, and to trace its development from the crude notions of its earliest stages to the more refined conceptions of later periods, comporting indefinitely better with the marvellous processes of nature. Such a history we have in the views which have been held regarding the nature and action of electricity. The transition from the glutinous effluvium of the sagacious Robert Boyle to the magnetic and electric waves of the present, traversing the omnipresent ether with the velocity of light, is not an easy one to make, even in a period of 200 years. For more than 20 centuries natural philosophers had nothing better than the emission theory to account for the attraction exhibited by rubbed amber and other similar substances. Their notion was that the rubbing of the amber caused it to emit an effluvium which returned again to its source, and carried light bodies back with it.

In one respect this fanciful attempt to explain electrical attraction deserves commendation, for it evinces a mental inaptitude to account for physical actions "at a distance," or without some intermediate agency. Later philosophers, satisfied perhaps too easily with mathematical explanations founded on the observed.

Address by Prof. Carhart, Vice-President Sec. B, American Association for the Advancement of Science, delivered at the annual meeting, Toronto, August 28th, 1889.

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laws of attraction and repulsion, and not demanding a medium, did not feel the same intellectual necessity of filling the space between bodies acting on one another, either with emanations from those bodies or with an invisible, imponderable medium, suspected by no sense of man, but required only to meet a demand of his highest intelligence. For when the Newtonian philosophy had made some progress, the doctrine of unctuous effluvia was given up, and physicists acquiesced in the unexplained principle of attraction and repulsion as properties of certain bodies communicated to them by the Divine Being, the mechanism of which they scarcely attempted to explain. "Many superficial philosophers thought they had given a very good account of electricity, cohesion and magnetism, by calling them particular species of attraction peculiar to certain bodies."* The discovery by Stephen Grey that "the electric virtue could be conveyed along a wire for several hundred feet without sensible diminution, and the invention of the Leyden jar by Kleist, or Cuneus, had the effect of annihilating many mushroom_theories constructed on the slimmest basis of facts. The latter discovery disclosed a power in electricity not previously suspected, and excited the greatest interest in both Europe and America. At this period Franklin turned his attention to the subject, and "spent more time in diversifying facts and less in refining upon theory" than some of his European contemporaries. In fact, he tells us that he was never before engaged in any study that so totally engrossed his attention and his time. His discovery that the two electricities are always excited in equal quantities, that the charge resides on the glass and not on the coatings of the Leyden jar, and his experimental identification of lightning with frictional electricity excited the liveliest interest abroad, and secured for him the Copley medal of the Royal Society; while his theory of positive and negative electricity made a permanent addition to the nomenclature of the science. His conceit that a turkey, killed with the discharge of a battery of jars, was uncommonly tender eating-a discovery gravely communicated to the Royal Society by William Watson-is not so well known, and does not appear up to the present to have been verified.

We cannot agree with him, I am sure, when he says: "Nor is it of much importance for us to know the manner in which Nature executes her laws; it is enough if we know the laws themselves." For the pursuit of the manner in which Nature executes her laws is the distinguishing characteristic of the science of the present day. It has led to most brilliant discoveries, and bids fair to do more than all other agencies combined to show the intimate and necessary relations existing between the different branches of physics. We need to be reminded often that accumulated facts do not constitute a science; and that utility is not the highest reward of scientific pursuits. A bit of polished marble plucked from the ruins of the Roman Palatine Hill is an interesting relic; but how much more interesting to reconstruct the palace of Nero and to see this fluted marble in its proper and designed relation to the whole, of which it was once a necessary part! Science is constructive. Laws are derived from an attentive consideration of facts; generalisations group laws under broader relationships; and great principles unite all together into one related, impressive whole.

From the time when the famous Boyle caught sight of a faint glimmer of electric light to the present physicists have been in pursuit of the connection between light and electricity. As early as Newton's time the ether was conceived by some to be a subtle medium confined to very small distances from the surfaces of bodies, and to be the chief agent in all electrical phenomena. "But," says Priestley,† "the far greater number of philosophers suppose, and with th greatest probability, that there is a fluid, sui generis principally concerned in the business of electricity. They seem, however, though perhaps without reason,

*Priestley's Hist. of Elec., Vol. II., p. 18. + Hist. of Elec., Vol. II., p. 22.

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ELECTRICAL REVIEW.

entirely to overlook Sir Isaac Newton's ether; or, if they do not suppose it to be wholly unconcerned, they allow it only a secondary and subordinate part to act in this drama.' Among the branches of knowledge that this writer recommends as likely to be of especial service in the study of electricity is the doctrine of light and colours. The invention of the voltaic battery and Sir Humphrey Davy's celebrated experiment in producing the electric arc stimulated enquiry in this same direction. Mrs. Somerville, Morrichini, and others sought to produce magnetism by means of sunlight, but ultimately, as is now known, without success. Notwithstanding these negative results, Faraday had such a "strong persuasion derived from philosophical considerations" of a direct relation between light and electricity that he resumed the inquiry in a most searching manner, with the happy result of discovering the rotation of the plane of polarisation of light by means of magnetism. "Thus is established," he says, "a true, direct relation and dependence between light and the magnetic and electric forces; and thus a great addition [is] made to the facts and considerations which tend to prove that all natural forces are tied together, and have one common origin."

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It was thus reserved for Faraday to make those discoveries and to obtain that insight into electric and magnetic action which were needed by his great disciple and interpreter, Maxwell, to construct a most marvellous theory of the connection between these two departments of physical science.

Respecting the failures to obtain magnetism from the direct action of sunlight, to which allusion has been made, Maxwell says that we should not expect a different result because the distinction between magnetic north and south is one of direction merely; that there is nothing in magnetism indicating such opposition of properties as is seen at the positive and negative poles of a battery in electrolysis; that even right and lefthanded circularly polarised light cannot be considered the analogue of the two poles of a magnet, for the two polarised rays when combined do not neutralise each other, but produce plane polarised light.

It may be said, however, that if a right-handed circularly polarised ray produces magnetism in one direction, and a left-handed ray in the opposite, then the combination of the two rays may neutralise their magnetic effect inasmuch as plane polarised light may have no magnetic influence. Prof. J. J. Thomson has lately shown mathematically that a circularly polarised ray does have a magnetic effect, but that it is so small, even with strong sunlight, as to be much beyond the limits of experiment; and Mr. Shelford Bidwell has produced a bar of iron in such an exquisitely sensitive magnetic state that magnetic changes are certainly produced in it by the direct action of light. This he has secured by rendering the bar more susceptible to magnetic influences in one direction than the other. We may not, I venture to affirm, be without hope that magnetism and electric currents may yet be evoked by the direct agency of sunlight.

Faraday was deeply convinced that space had magnetic properties, and that the space or medium around a magnet is as essential as the magnet itself, being a part of the complete magnetic system. To him all magnetic and electric action took place by contiguous particles along lines of force. "What that magnetic medium, deprived of all material substance, may be, I cannot tell," he says, "perhaps the ether." No doubt existed in Faraday's mind that these lines represent a state of tension; but whether that tension is a static state in the ether, or whether it is dynamic, resembling the lines of flow of a current between the poles of a battery immersed in a conducting fluid, was uncertain. He inclined, however, to the latter view. He was thus ed to advocate, though not without hesitation. the phytical nature of lines of force.

Faraday's discoveries and his method of regarding all magnetic and electric actions as propagated through

*Exp. Researches, 2,221.

+ Exp. Researches, 3,277.

[SEPTEMBER 27, 1889.

a medium by means of contiguous parts have been of the utmost productiveness. They have revolutionised the science of electricity, and have been the most potent factors in the genesis of a theory, including all radiant energy, which has recently received such remarkable and conclusive confirmation. His name has become almost a household word. His earnest, unselfish life has added unnumbered millions to the world's wealth. His ideas and words, which have been instruments in the hands of philosophers, have become the current coin of the commercial tyro, who talks as glibly about lines of force and the magnetic circuit as if he really knew something about them.

Fruitful as Faraday's ideas were they yet awaited a mathematical interpreter for their highest development. A good Providence sent James Clerk Maxwell, whose brilliant mathematical ability was equalled by his philosophic insight, his poetic feeling and imagination, his profound sincerity and his great sympathy with Nature. Hear him sing at Aberdeen :—

Alone on a hillside of heather,

I lay with dark thoughts in my mind,
In the midst of the beautiful weather,
I was deaf, I was dumb, I was blind,

I knew not the glories around me,

I counted the world as it seems,
Till a spirit of melody found me,
And taught me in visions and dreams.
For the souud of a chorus of voices

Came gathering up from below,
And I heard how all Nature rejoices,
And moves with a musical flow,

O strange! we are lost in delusion,
Our ways and our doings are wrong,
We are drowning in wilful confusion,
The notes of that wonderful song.

To appreciate Maxwell's relation to theories of electrical action, it is desirable to take a retrospect of the views that have been held regarding its nature. Three periods in the history of these views may readily be distinguished. The first was introduced by Dr. Gilbert in 1600, and it lasted for about 225 years. The little that was known previous to Gilbert constitutes only the preface or introduction to the history proper. Nearly three-fourths of this period was utterly barren and unfruitful. It knew nothing better than unctuous effluvia and electric atmospheres. In the latter half of the period the Newtonian philosophy had become the orthodox doctrine. The great success attending the mathematical investigations, founded upon the law of inverse squares, naturally carried with it the acceptance of the underlying hypothesis of "action at a distance." There were not lacking, indeed, men of deeper philosophic insight who denied this doctrine, which they looked upon as entirely unphilosophical and which must utterly bar the way to any inquiry into the process by which the law is executed. Action at a distance by attraction or repulsion, varying inversely as the square of that distance, means an ultimate fact not admitting of further analysis.

The second period was one of contention. It began not with the important discovery of current electricity. nor of the electro-magnet, but with the philosophical methods and concepts of Faraday. The physical postulates of the mathematical school were entirely alien to the views which he adopted. "Faraday, in his mind's eye, saw lines of force traversing all space where the mathematicians saw centres of force attracting at a distance; Faraday saw a medium where they saw nothing but distance; Faraday sought the seat of the phenomena in real actions going on in the medium, they were satisfied that they had found it in a power of action at a distance impressed on the electric fluids."" Prior to Faraday the supporters of a medium to explain electric and magnetic action were always thrown out of court for lack of evidence; Faraday gave them a legal standing by furnishing the facts and evidence on which they could well afford to base their

case.

* Maxwell's Elec. and Mag., p. 10.

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