tion of electrolyte. But in the laboratory there must be regularity and this regularity shortens the life of one cell, while it lengthens the life of another. Furthermore, it signifies nothing that one battery can stand what is called a breakdown test better than another. They are not like steam boilers. To discharge two batteries a hundred times or more at ten times their respective normal rates, provides no data upon which to calculate or compare their durabilities in commercial service.

In making a durability test I charge at the normal rate to 2.3 volts and discharge to 1.9 at the same rate, beginning the charge and discharge each day at the same respective hours. When the capacity of the cell has fallen to 70 per cent. of the maximum, the positive and negative elements are separated and reassembled each with a new element, and the test continued with whichever one has a capacity over 70 per cent. of the original maximum. In this way the length of life between maximum capacity and 70 per cent. of it, in terms of discharges, is determined for both positives and negatives, and a man who had previously combined some commercial with his laboratory experience, might be able from such data to make an approximate estimate of the cost of maintenance.

Such a test should be conducted with at least two cells simultaneously; but under no circumstances should they be charged or discharged in series. I need hardly say that great care should be exercised in getting accurate measurements. Separate sets of instruments should be used for each cell. Lord Kelvin's quadrant electrometers will be found preferable for measuring the potentials. The measurements for internal resistance require such delicacy as to demand special treatment; but I may say that little dependence can be placed upon the figures usually given for this quantity.

In regard to the limits of working potential here suggested, I should add that it is customary to charge up to 2.4 and discharge to 1.85. The circulars and printed instructions of the principal manufacturers give these figures, but the tendency of the best modern practise is toward narrower limits. (See Journal of London Institution of Electrical Engineers Vol. XIX., page 561.) It must not be supposed that the above described durability test is particularly light service for any battery. Some batteries can withstand very rough and irregular commercial use better than they can a great number of successive charges and discharges of similar quantity and character. It is possible to make a fine cell for this work that would not possess the greatest merit as a commercial investment, and it would be equally possible to construct one that would make a good record in commercial work, and yet would be a poor competitor for honors in the above test.

THE BRUGER SOLENOID MEASURING INSTRU

MENT.

The inaccuracy in the readings of electrical measuring instruments due to the inconstancy of the magnets employed has been an annoying source of trouble in many forms of apparatus. To avoid this difficulty Mr. Theodor Bruger, of Bockenheim, Germany has recently produced a device the construction of which is based on the mutual action of two co-axial solenoids, one of which is stationary and the other movable relatively to the stationary one, in such a manner that a considerable sensitiveness and an accurate scale are obtained.

In Fig. 1 of the accompanying illustrations a represents a stationary polarized solenoid which acts simultaneously on two co-axial short solenoids I and II, rigidly connected with each other but having a common movement and joined in series or parallel in such a manner that the succession of their poles is positive-negative and negativepositive.

If one of these movable solenoids be moved slightly

toward the stationary solenoid in the direction of the arrow, the strength of the current being constant, the motive power which is exerted on the solenoid I, decreases rapidly during the movement from the positive end N of the solenoid a to its centre. If therefore, the solenoid I is under the influence of a variable current and the opposite solenoid II under the influence of a spring or of gravity, a scale is obtained with sub-divisions which decrease in size. If on the contrary the solenoid II alone is moved on the solenoid a from the centre of the latter toward the negative end s and is subjected to the same influences as the solenoid I, a scale is obtained the divisions of which are very small at the beginning of the movement and increase rapidly when the solenoid II approaches the negative pole

s. Hence it follows, that by the simultaneous use of the two solenoids I and II an equalized movement is obtained which produces a nearly uniform scale.

In alternating currents also the mutual induction which would occur between a fixed coil and a movable solenoid is avoided in consequence of the opposed polarity of the two movable solenoids.

Fig. 2 shows the arrangement and connections. The stationary straight solenoid a of Fig. 1 is here replaced by a circular solenoid, and the two movable solenoids I and II are mounted on an axle. The current is admitted through narrow silver bands b, while the torsion spring e acts against the turning action of the current.

This instrument can, according to its winding, be used for various purposes. If designed for watt-meters the stationary solenoid is provided with a thick wire for the main current and the movable coils are placed in shunt, while the stationary solenoid is tapered toward the ends so as to obtain a uniform scale. If the instrument is to be constructed as an electro dynamometer, the movable solenoids are connected with the stationary solenoid either in parallel or in series, as the case demands.

THE CONNECTICUT STREET RAILWAY ASSOCIATION.

Representatives of the various street railway companies of Connecticut, have formed the Connecticut Street Railway Association. Roads are represented in Derby, New Haven, Waterbury, Stamford, Hartford, Fair Haven, Westville and Norwalk. The fol lowing officers have been elected: President, H. Holton Wood, Derby; vice-president, Henry S. Parmelee, New Haven; treasurer, E. L. Goodrich, Hartford; secretary, R. A. Fosdick, Stamford; executive committee, A. M. Young, Waterbury; G. A. W. Dodge, New Haven; Israel Kelsey, New Haven. Monthly meetings will be held, with the annual meeting the third Wednesday of November.

Sir-I have lately succeeded in producing motion in a little machine by a power, which, I believe, has never before been ap. applied in mechanics-by magnetic attraction and repulsion. It is well known that an attractive or repulsive force is exerted between two magnets, according as poles of different names, or poles of the same name, are presented to each other. In order to understand how this principle can be applied to produce a recipro cating motion, let us suppose a bar magnet to be supported horizontally on an axis passing through the centre of gravity, in precisely the same manner as a dipping needle is poised; and suppose two other magnets to be placed perpendicularly, one under each pole of the horizontal magnet, and a little below it with their north poles uppermost; then it is evident that, the south pole of the horizontal magnet will be attracted by the north pole of one of the perpendicular magnets, and its north pole repelled by the north pole of the other; in this state it will remain at rest, but if, by any means, we reverse the polarity of the horizontal magnet, its position will be changed and the extremity which was before attracted will now be repelled; if the polarity be again reversed, the position will again be changed, and so on indefinitely. To produce therefore, a continued vibration, it is only necessary to introduce into this arrangement some means by which the polarity of the horizontal magnet can be instantaneously changed, and that too by a cause which shall be put in operation by the motion of the magnet itself. How this can be effected will not be difficult to conceive when I mention that instead of a permanent steel magnet in the movable part of the apparatus a soft iron galvanic magnet is used.

The change of polarity is produced simply by soldering to the extremities of the wires which surround the galvanic magnet two small galvanic batteries in such a manner that the vibrations of the magnet itself may immerse them alternately into vessels of diluted acid; care being taken that the batteries are so attached that the current of galvanism from each shall pass around the magnet in an opposite direction.

Instead of soldering the batteries to the ends of the wires, and thus causing them at each vibration to be lifted from the acid by the power of the machine, they may be permanently fixed in the vessels, and the galvanic communication formed by the almalgamated ends of the wires dipping into cups of mercury."

If the tumblers be filled with strong diluted acid, the motion is at first very rapid and powerful, but it soon almost entirely ceases. By partially filling the tumblers with weak acid, and occasionally adding a small quantity of fresh acid, a uniform motion, at the rate of seventy-five vibrations in a minute, has been kept up for more than an hour; with a large battery and very weak acid, the motion might be continued for an indefinite length of time.

The motion here described is entirely distinct from that produced by the electro-magnetic combination of wires and magnets; it results directly from the mechanical action of ordinary magnet. ism: galvanism being only introduced for the purpose of changing the poles."

It is easy to see how motion could be given by this arrangement to a wheel or other mechanical apparatus. "This simple but original device comprised the first automatic pole-changer or commutator ever applied to the galvanic battery-an essential element not merely in every variety of the electro-magnetic machine, but in every

1. The picture given is from a photograph.

2. Silliman's American Journal of Science, Vol. XX, pp. 342 and 343.

variety of magneto-electric apparatus and in every variety of the highly useful induction apparatus."3

If Henry could have looked up with pardonable pride to the wires of his telegraph stretched around that upper room in the Academy at Albany, surely he might have regarded with some elation the see-saw motion he had been able to produce and have allowed his imagination to dwell upon the future represented by his machine. The introduction of steam as a motor was an era in the world's history; this use of electricity as a motor was another era; but not for a moment in the enthusiasm of his success was Henry led to believe that the one would supersede the other. He recognized from the first the place of the electro-motor. He considered the source of the power of the machine, namely, the oxidation or burning up of the zinc in the battery; and immediately concluded that the coal required for the preparation of zinc would, if directly applied, give a much greater amount of power at much less expense; but he predicted for his engine a useful and important future in applications where economy is not the consideration. He sums up the question later in these words: "All attempts to substitute electricity or magnetism for coal power must be unsuccessful since these powers tend to an equilibrium, from which they can only be disturbed by the application of another power, which is the equivalent of that which they can subsequently exhibit. They are however, with chemical attractions, etc., of great importance as intermediate agents in the application of the power of heat as derived from combustion. Science does not indicate in the slightest degree the possibility of the discovery of a new primary power comparable with that of combustion as exhibited in the burning of coal. We therefore do not hesitate to say that all declarations of

the discovery of a new power which is to supersede the use of coal as a motive power, have their origin in ignorance or deception and frequently in both." Mr. Taylor says, "In Henry's deliberate contemplation of his own achievement his remarkable sagacity and propriety of judgment were conspicuously displayed."

Henry sent his little machine, as he had his magnets, out into the world, through Silliman's Journal. It received, as the magnets had before, an enthusiastic welcome from Sturgeon, who immediately constructed a rotary engine, exhibited in 1833 in London to a large audience. We have here a glimpse of a noble soul: for, when hailed on account of this machine as pioneer in the field, and by an American, Sturgeon took pains to contradict the statement and to give to Henry the priority; worthy of praise, he could not take praise which was not his due. This is especially gratifying since Henry's discoveries were as a general thing taken up and used, as a matter of course, without any reference to himself. In 1834, Davenport of Vermont, an ingenious blacksmith, made a rotary machine; but I may not follow closely the history of the electro-motor; I refer my readers to Mr. F. L. Pope's well known and interesting article upon this subject. The problem of the appli

8. Edward N. Dickerson: "Joseph Henry and the Magnetic Telegraph." 4. THE ELECTRICAL ENGINEER, Jan. 7, 14, 21, 28 and Feb. 4, 1891.

cation of electricity as a universal motive power was taken up with great zeal both in Europe and this country; and contrary to Henry's fundamental and, as time has shown, prophetic conception of the field of the electro-motor, it was everywhere confidently supposed that in time it would supersede steam. In this expectation the misunderstood electro-motor disappointed the hopes reposed in it and for a time it was in disgrace; but, not a success certainly as a prime mover, it has found its place and it is exactly the place to which it was assigned by Henry; it is the assistant of steam, not its rival. Its value lies in its capacity to receive power from a distant source and to transfer it without waste immediately to where it is needed. Mr. Pope says: "Henry accurately foretold the true place, in the domain of industry, of the electric motor. Much confusion of thought exists in the popular mind of the present time in reference to this very point. * * * * Electricity, in its important application to machinery, is never in itself a source of power. It is merely a convenient and easily managed form of energy, by which mechanical power is transferable from an ordinary prime motor, as a steam engine or a water wheel, to a secondary motor which is employed to do the work. It performs an office precisely analogous to that of a belt or line of shafting, which, however useful in conveying power from one point to another, can, under no conceivable circumstances, be capable of originating it." 5

In comparison with other modes of transmitting power the electro-motor is well nigh indifferent to the extent of the distance from the source of its power. Who made the instrument thus indifferent to distance? Let us go back to it as it was in its infancy in 1831, in Henry's cabinet. Henry knew that his magnet, in the telegraph in the upper room, could respond as easily to its battery if that one mile of wire stretched around those walls were extended to hundreds; and he knew as well that his little machine could be made to work if its batteries were equally far away. The means of producing electro-mechanical effects at a distance, this was what Henry had discovered, and in this machine he showed how the power might be used in other ways than in the telegraph.

"In 1834 Dr. Edmonston of Baltimore published a description of the rotary motor, a modification of Henry's arrangement, and these two forms are the prototypes of all the electro-motors, which have been constructed from that day to this."-(Frank. L. Pope.)

Henry's friends urged him, not only to take out patents for his magnets and his telegraph, but also for this machine. Hundreds of patents have been granted in this country for modifications of the electro-magnetic-telegraph, and as many for varieties of the electro-magnetic machine; all of which would have been tributary to Henry as the original patentee. His constant answer to all such solicitations was, "My desire is to add to the sum of human knowledge; what I give, I wish to give freely."

PUBLIC SPIRITED JOURNALISM.

IT will be remembered that some time ago the London Electrical Review assumed the uphill task of endeavoring to expose the tricks and wiles of "electric belt" quackery, and as a result became involved in lawsuits for libel, which it had the deserved good fortune to win, although as might have been expected, the quacks are still rampant, for the general public rarely reads technical literature and the daily papers persist in printing the quacks' advertisements.

The Electrical Review obtained damages, with Science Siftings, its colleague in the fight, and Mr. J. Swinburne now has returned to the subscribers to its Defence Fund the entire amount of their subscriptions less a small percentage to cover expenses of printing, stationery, postage, etc. The Review is entitled to the congratulations of the electrical profession on its success in this fight, and to admiration for its honorable and public spirited action throughout.

5. Electricity in Daily Life, Chas. Scribner's Sons, New York, 1891, page 41. (Reprinted from Scribner's Magazine.)

LITERATURE.

Elektrotechniker's Literarisches Auskunftsbüchlein. By F. Schmidt-Hennigker. 2d Edition. Leipzig, 1894. Oskar Leiner. 48 pages. 51⁄2 x 8 inches. Price, 40 cents.

THIS is an index of the works published in the German language between 1884 and 1893 on the subjects of electrotechnics, electricity, electro-chemistry, magnetism, telegraphy, telephony and lightning protection. The works are indexed alphabetically, by authors and by subjects. Each reference is accompanied by the number of pages, size and place of publication.

Electricity Up to Date. By John B. Verity, London and New York. F. Warne & Co. Paper, 226 pp. illus. Price, 75 cents. (Fourth Edition).

Mr. Verity's useful and handy little book reaches us again, and we can only repeat of this what has been said of previous editions, namely, that it is one of the best of the popular books. There is nothing pedantic about it, yet nothing foolish or inaccurate. It tells the story clearly and plainly, and every page is interesting. Such a book ought to reach its fortieth edition, with constant and careful revision.

Premiers Principes d'Electricité Industrielle. By Paul Janet, Paris, Gauthier-Villars et Fils. 1893. 275 pages, 5%1⁄2 x 8%. Price $2.

This is a reproduction of a course of lectures delivered by the author at the Faculté Des Sciences of Grenoble, and is intended therefore. more particularly for students. It carries the reader through the study of batteries, including primary, secondary and thermo cells, dynamos and transformers. The book is devoted more to inculcating the principles of these various types of apparatus, giving only such details of construction as to enable the student to form a fair idea of the actual apparatus, all the standard types of which are illustrated. The book is well up to date and the explanations are quite lucid.

Reference Book of Tables and Formulas for Electric Street_Railway Engineers. By E. A. Merrill, Author of "Electric Lighting Specifications." New York. The W. J. Johnston Company, Ltd., Flexible Morocco, Pocket Size. Price, $1. The appearance of this little reference book is very timely as it puts in the hands of the electric railway constructor and superintendent a considerable amount of valuable information. The author has followed the plan of beginning with the steam plant and passing successively through the subject of cars and their equipment, overhead work, track work and miscellaneous tables and formulas. While the works of the best authorities have been consulted, a number of tables and formulas are original, and many others have been modified and extended to adapt them to the conditions imposed in electric street railway work.

This very handy little work has recently received a thorough revision at the hands of Mr. W. D. Weaver, and among the new things embodied in it is the calculation of alternating current wiring. These include tables of alternate current wiring coefficients, those on alternating currents for exterior wiring and on the candle power of arc lamps, and tables enabling those for the three standard lamp voltages to be used for any voltage or drop; as well as several others, including a complete set of wiring tables calculated on a uniform basis of 55 watt lamps. In addition we find a good deal of valuable miscellaneous information in the book.

Dynamo and Motor Building for Amateurs, with Working Drawings. By Lieut. C. D. Parkhurst, U. S. A. New York. The W. J. Johnston Company, Ltd., 1893. 163 pages. 5x7 inches. Price, $1.

Although the continued manufacture of electric motors of small sizes has brought their price down much below what it was some years ago, there are still not a few who prefer to gain the practice which only actual work propriis manibus can afford. The amateur will find here little or no theory to embarrass him, but straightforward descriptions with diagrams and working drawings, which will enable him to construct three or four kinds of machines, ranging from a small electric motor, driven by battery current, to a 50-light incandescent dynamo. The book has

special value as it represents the author's own experience in this class of work, which he has succeeded in laying before the reader in very clear language.

Twenty-Fifth Annual Report of the Board of [Massachusetts] Railroad Commissioners. (Pub. Doc. No. 14.) January, 1894. Wright & Potter Printing Co., Boston. 8°, pp. xix + 311; Мар.

EACH succeeding annual report of the Massachusetts Railroad Commissioners devotes an increased amount of space to a discussion of the problems which continually present themselves in connection with the rapid extension of the electric railway service within that commonwealth. While the actual number of street railway companies shows but little increase-in fact, owing to consolidations and other causes, the number reporting is one less than in the preceding year-the aggregate mileage in operation shows, as might be expected, a notable increase. The returns are made up, as usual, to September 30, 1893, at which date, the total length of street railway including double tracks, but not sidings, was 874.14 miles; an increase over the preceding year of 119.29 miles. There has been during the year an increase of mileage operated by electric power of 214.78 miles, and a decrease of mileage operated by horse-power of 95.49 miles. The first successful commercial use of electricity as a motive power in the state is said to have been on the Lynn & Boston line in July, 1888.

The gross assets of all the street railway companies are given as $50,130,273.20, and the gross liabilities as $49,589.687.91. The percentage of surplus to capital stock, which in 1887 was 13.89 fell the following year to 6.82, and has since decreased progressively year by year, until it was in 1893 only 2.09 per cent. A comparison of the traffic returns for the past decade, shows between 1883 and 1893, an increase of 142 per cent. in the passengers carried; of 125 per cent. in number of miles run, and of 96 per cent. in the number of round trips, annually. During the past five years, the average net earnings have increased from $2,420 to $3,810, per mile of railway owned, from 5.56 to 9.65 cents per carmile run, from 40 to 74 cents per round trip run, and from 0.96 to 1.56 cents per passenger carried.

The average cost of the street-railways of Massachusetts per track-mile, as per books of the companies on September 30, 1893, was for construction, $26,792; for equipment, $15,455.06; and for land, buildings, etc., $11,738.63, making a total average cost per mile of $53,985.69. Of course these figures furnish no basis for estimating, even approximately, the cost of any particular railway. The cost of different lines varies, as returned by the companies, from a minimum of $13,745 to a maximum of $98,907 per mile of track.

These results, for convenience of comparison, have been thrown into a table as follows:

Discussing these results, the Commissioners say :

The gains which the above table shows in the average net earnings per passenger carried, per mile run and per round trip, ranging from 62 to 85 per cent. in favor of the year 1893, are certainly at first view very striking; and, if these were the only elements in the case, the financial success of the electric system might be pronounced at once to be not only assured, but marvelous. There are, however, other important and decisive factors which must not be overlooked.

In the first place, any increase in the net earnings must obviously be compared with the increase in the cost and capitalization of the electric over the horse system. The manufacturer whose new factory brings him in twice the net income of the old one, has gained nothing in the way of return on his investment, if the new plant has cost him twice as much as the old. So here, the most direct and conclusive test of the net earning capacity of the two systems, is a comparison of the increase in the net earnings per mile of railway with the increase in the cost of the railway per mile. Applying this test, it will be seen that, while the net earnings per mile are 57 per cent. greater, the cost and capitalization per mile are respectively 60 and 65 per cent. greater in 1893 than in 1888,-the odds being clearly in favor of the horse system.

In the second place, it must be taken into account that the electric railways, with their power-stations and electrical equipment, are all of new or recent construction. For this reason, the cost of the maintenance of the new system, which is chargeable to operating expense, has thus far been abnormally small, and the consequent showing of net earnings from operation has been abnormally large. The generation and distribution of electric motive power involve extensive plants, costly machinery and intricate apparatus and appliances, all of which must be kept in perfect working order. The wear and tear of roadbed and track are increased by the heavier rolling stock of the new system. As time goes on, the cost of renewals and repairs cannot but increase or be otherwise than large; and this cost must go into operating expense. The net earning capacity of the electric system will not, therefore, have been fully tested, until time and experience have demonstrated the normal and full average cost of its maintenance; and the net results, as they now appear, must be qualified accordingly.

We must conclude, therefore, taking everything into the account, that there has been thus far no demonstration of the superior net earning capacity of the

electric as compared with the horse system, but rather the reverse. It is not, however, intended to raise the inference that, the electric system is, or is likely to prove, under conservative and proper management, a serious financial failure. The conditions attending its further and fuller development will probably be found to differ in no essential respect from those attaching to the old horse railway system, or to the steam railroad system. It can and should be said however, without hesitation or qualification, that the electric system has not shown or indicated any such margin of profit as to justify the expectation of more than moderate and ordinary returns on money legitimately invested in it. The idea, which seems to have obtained some currency, that the electric railway system is a bonanza of rare and inexhaustible wealth is clearly a delusion, and has doubtless proved to some a snare. The absolute cost and expensiveness of the system, under the most conservative, able and honest management, are sufficient to task its earning capacity to the full limit. There is no margin for fictitious or inflated capitalization. It presents no safe or inviting field for speculative enterprise and manipulation, unless it be to the unscrupulous operators of an inside ring who are willing to practice on the credulity of a misinformed public.

The statistics of accidents show that during the year covered by the report, the total number of persons killed and injured by electric cars was 271, being in the ratio of 1 to each 52,475

miles run.

The Commissioners call attention, in very forcible language, to the rapidly increasing number of grade-crossings of electric and steam railroads, the returns for the year showing the appalling increase in these death-traps of from 26 to 100. They say:

It is not to be believed that the [original] allowance of 100 such crossings outside the public highways would for a moment be thought of. The remarkable condition of things now existing has crept in unawares, as it were, under a code of laws intended only for horse-railway travel, enacted before the operation of street-railways by mechanical power had come to be regarded as more than a remote possibility. Of all the perils which attend travel on railroads and railways in this Commonwealth, there is no one which, in the apprehension of the Board, is so serious, both in its character and extent, as that here pointed out; and the Board would be derelict in duty to itself and the public, if attention were not again called to it, without waiting for some serious casualty-of the imminence of which, hardly a week passes without giving fresh warning-to emphasize the recommendation.

The Board again call attention to the desirability of legislation limiting the amount of bonds which may be issued by streetrailway companies, a recommendation, not acted upon by the last Legislature, but which is obviously quite as much in the interest of all solvent corporations as in that of the investing public, inasmuch as no well-informed person would be likely to invest knowingly in the bonds of any company, with which the market might at any time be flooded to an unlimited extent.

The deductions and observations of so careful and conservative a body of experts as the Massachusetts Commissioners in reference to the questionable profitableness of electric railways as a permanent investment, have not unnaturally given rise to no small amount of comment and criticism. While there is no doubt abundant room for caution in the direction pointed out, and while it must be admitted that there is much reason to fear that as soon as the present financial stringency has in some measure passed away, the extension of electric railways into unprofitable fields may be prosecuted to an extent which cannot but ultimately result in a disastrous collapse, the figures given in the report do not appear to necessarily warrant all the deductions which have been drawn from them. This will appear, for example, from an examination of the comparative results during the same period [188893] of a local street railway, with whose affairs the writer happens to be somewhat acquainted, and which has always been justly regarded as an exceptionally well and liberally-managed system. It serves a manufacturing population something in excess of 60,000. In 1888 this system was operated by horse-power and did not extend much beyond the thickly settled parts of the city. Between that date and 1893, the trackage was increased, in round numbers, from 14 to 33 miles; the system was converted into an electric one: the capitalization per mile was increased from $22,000 to $30,000; the construction account from $11,000 to $18,000, and the equipment account from $5,000 to $10,000. A comparison of net receipts for the same period shows an increase per mile operated of $2,260 to $3,000; per round trip of 39 to 53 cents; per mile run a decrease from 8.1 to 6.9 cents, and per passenger carried a decrease from 1.4 cents to 1.3 cents. Nevertheless, the company has never once failed, during that time, to pay its regular dividend of 8 per cent., and it has actually a larger surplus to-day than it had in 1888, notwithstanding there has been a trifling increase (from 74 to 75 per cent.) in the ratio of gross expenses to gross income. The falling off in net income, per mile run and per passenger carried, has been caused by the extension of the company's tracks into thinly settled suburban districts, but it is evident that within the next ten years, the increase of population along these suburban routes, will materially augment the gross receipts, without adding in anything like the same proportion to the necessary expenses. It will be contrary to all previous experience, also, if the actual cost, per car mile, of operating an electric railway should not be largely reduced by the progress of science and invention during the same period. This example however, only serves to enforce the moral drawn by the Commissioners, that an electric railway, no less than any other, must be judiciously located and carefully managed, if it is expected to be profitable.

F. L. P.

THE LYNCHBURG ELECTRIC COMPANY'S first mortgage 6 per cent. 25-year gold bonds are offered at par and accrued interest.

LETTERS TO THE EDITOR.

INTRODUCING THE QUADRUPLEX INTO ENGLAND.

MR. W. H. PREECE, C.B., F.R.S., in a paper entitled, "Notes of a Trip to the United States and Chicago, 1893," published in the Journal of the Institution of Electrical Engineers, Volume XXIII., No. 109, March, 1894, as the result of an official visit and inspection of the telegraphic system of the United States in 1877, speaks among other things of the practical introduction of the quadruplex system on the Government postal lines. The subscriber hereto is thus reminded of his most delightful visit abroad, the cordial welcome and generous hospitality extended to Mr. George A. Hamilton and himself during their two months sojourn in London and Liverpool having on hand the pleasant and easy task of establishing quadruplex working between the points named.

In view of the openly expressed doubts as to the success of the system abroad, the trial was looked upon as purely in the line of experiment; and predictions were freely made that stormy weather, with the usual accompaniment of a London fog, would prove an effectual barrier to its successful working. It was therefore with considerable pride that from time to time during the first week or two, information was communicated to Mr. Preece of the satisfactory working during weather that proved almost too much for the duplex circuits between London and Liverpool; but these occasions served to indicate what might be expected when the now anxiously looked for London fog should arrive.

The patience of my faithful co-operator at the Liverpool end was soon rewarded by the arrival of a storm from across the Atlantic bringing with it conditions for the development of a veritable London fog which reached a maximum density about 11 a. m. when even the street traffic was rendered somewhat perilous. The service with Liverpool opened rather tardily upon all the regular circuits, the quadruplex being the exception. It was at once supplied with business for all sides owing to the partial suspension of other circuits. At about ten o'clock a. m. the various duplex circuits between the London and Liverpool exchanges and main offices began to fail, and at eleven o'clock the condition of circuits had arrived in which it was deemed useless to attempt further working, and with the various Liverpool files well filled with business awaiting transmission the following memorandum was dropped to Mr. Preece: "11 a. m., Liverpool duplexes all suspended work. Quadruplex working finely four sides."

In less than five minutes Mr. Preece came to the operating room accompanied by Mr. Patey and a sufficient number of the officials from the various departments interested to form a complete circle around the quadruplex table, at which four operators were easily working, two sending and two receiving. Among the group also was Sir William Thomson, whose interest in the exhibition was clearly shown by earnest inquiries respecting details of the service, condition of the line, etc.

46

The experimental stage having been so successfully passed, the incident above narrated is put on record as part of the heretofore unpublished history of the introduction of multiplex telegraphy abroad; I will simply add thereto the following clipping from the Telegraphic Journal of December 1st, 1877, as follows:The quadruplex instruments continue to work excellently well between London and Liverpool. There can be no doubt that the system is a perfect success. Messrs. Gerritt Smith and Hamilton who have so ably superintended the setting up and working of the apparatus have returned to America." GERRITT SMITH. NEW YORK CITY, April 14, 1894.

DESIGN OF CONSTANT TORQUE VARIABLE SPEED MOTORS.

As a subscriber to the ENGINEER I wish to ask a few questions in regard to a motor intended for variable speeds and such work as requires nearly the full torque or pull at almost any speed. The speed desired is to be widely variable, and yet it is desirable to operate with as little current as possible and as near full voltage at the motor terminals as possible.

How would a series motor with some form of commutated field controller answer the purpose? What would be the average electrical efficiency of such an equipment? Is there a better way than the "commutated field" method of doing this, when one wants in use but one motor?

motor may be run at constant speed although the work may be done under variable speed and torque, such as the various epicyclical gears, invented by Henry, Main, Beaumont, and others.

For using only one motor, and where mechanical complication is inadmissible, the only resource is the commutated field series motor. It is impossible to give directions for the winding, without predetermining the characteristic of the machine, by Hopkinson's method or some modification thereof. For this one would need all the data, sizes, proportions, in fact, working drawings, and also the necessary data as to what the motor is intended for, the circumstances and conditions of its use, whether its service is continuous or intermittent, etc. It all depends on how skillfully the magnetic circuit is designed. In a word, the design and proportions involve careful planning and calculation which should be done by a skilled, experienced, and generally competent person. Even then, it is not unlikely that there will be some modifications required in the first machine made, before it is exactly satisfactory. Some information on this subject will be found in papers read before the American Institute of Electrical Engineers, by H. F. Parshall, "Methods of Electrically Controlling Street Cars, April, 1892, and by Geo. D. Shepardson and E. P. Burch, "Electric Railway Motor Tests," June, 1892.

As for the efficiency it will depend largely on the conditions of operation, the relative steadiness and constancy of load, etc. Probably the only conclusive way to determine it is by actual test. EDS. E. E.]

PATENTS AS ASSETS.

I have read your editorial and those of other journals on the General Electric Co.'s report and note more particularly the reflections on those "ghostly" assets, viz., patents, franchises, etc. I am sure it is not your intention to reflect in any way on the labors of the inventors and electrical engineers, but it seems to me you are doing so in a very pronounced way.

You are aware that the General Electric Co. have acquired property rights in the inventions of Brush, Edison, Thomson and a thousand other inventors of less note who have been mainly instrumental in developing (at an enormous cost) the principal electric arts, which in this country alone are saving the time and adding to the convenience of at least a million inhabitants daily.

Is the laborer worthy of his hire? Do you know of any of them who has been overpaid? Do you think from the knowledge you have of the cost of these developments (which are supposed to be protected by patents) that they and their legal protection have actually cost much less than the amount credited to this asset?

Your idea appears to be that the value placed on those patents is mainly a fictitious one, that they are not worth what they have cost. Mine is, that it is greatly underestimated. Neither of our opinions will amount to anything until the courts of last resort have done their guessing.

One of the journals advises the Company to wipe out the patent asset, stop all litigation, and confine themselves strictly to a manufacturing business. My idea of the theory of anarchism is conveyed in the advice: Don't protect patents but open the gates and let everybody profit at the inventor's expense and labor.

Where would the electrical industries be which we are now enjoying had such policies prevailed during the past twenty years? When you bear on the value of electrical patents you tender discouragement to the electrical engineer.

I hope you will pardon my criticism. I was afraid you had not given the inventor's side due consideration and I hoped to get you thinking in the interest of the inventor. JNO. C. HENRY. WESTFIELD, N. J.

[An examination of its files will acquit THE ELECTRICAL ENGINEER of any intention, from first to last, to reflect at all on the labors of inventors and electrical engineers. Of course the laborer is worthy of his hire and we should be glad if he were always sure to get it.

How much of the $8,159,000, standing for the value of patents and franchises in the General Electric report, does Mr. Henry think ever reached the pocket of the inventors? EDS. E. E.]

THE STORAGE BATTERY CHALlenge.

In reply to the challenge of the Chloride Accumulator Co. we wish to say that there are several reasons why we do not wish to take up that challenge. A fear that our battery, working under the conditions for which it was especially designed, will suffer by comparison with the Chloride accumulator is not one of these reasons. We are ready to supply Mr. Gibbs with all the DonaldsonMacrae batteries he may order at our list price with best trade discount, and would be pleased to have them tested not only by Messrs. Houston and Kennelly, but by everyone in the United States who is interested in storage batteries.

BALTIMORE, MD., April 6, 1894.

WM. W. DONALDSON, Pres.