employment and more remunerative occupation for boatmen. Other advantages readily suggest themselves. It should be clearly understood, moreover, that the adoption of electricity as a motive power does not mean the abandonment of horse, mule, or steam power if boat-owners prefer to have their boats propelled by these powers. The idea is that whether the state furnishes the electric power from its own plant, or whether individuals or corporations furnish it under contract, there will be no compulsion to use it, but the endeavor will be to supply it at such a low cost to boatmen that they will find it advantageous to apply it to their boats in the interest of economy.

"This plan need not interfere, either, with any proper enlargement or deepening of the canal. Instead, if the plan is found to operate satisfactorily, the next logical and necessary step would probably be to so improve the canal as to enable the use of larger boats. But for the present I am quite convinced that the proper course is to give electric propulsion a fair trial, and if it accomplishes what is claimed for it, a new era of activity and prosperity should begin for our canals. Grain has been carried during the last season from Chicago to Buffalo for as low as one cent a bushel; boatmen can carry it profitably at two cents a bushel. If by cheaper and quicker propulsion the cost from Buffalo to New York by way of the Erie Canal can be reduced to three cents a bushel, as is reasonable to suppose, there is no other carrying route that can successfully compete with it, and a continuance of New York's supremacy is assured. Moreover, the harnessing of the tremendous water torrent of Niagara to the wheels of industry will furnish the cities of Buffalo and Rochester and all western New York with the cheapest power for manufacturing in the United States. We may look forward to the time when the great flour mills of the world will be located there, for the cheapness of power would more than compensate for the cost of transportation of grain from the fields of the Northwest. So with other manufactories. Then, more than ever, will be needed cheap transportation through the State. To day the Erie Canal does not carry one-half its capacity. Reduce the cost of transportation and increase the speed and the tonnage will increase, and when the tonnage increases then will be the proper time to seriously con. sider expensive schemes of enlargement.

"The essential point in arranging for the application of electric propulsion on the canals is that the power should be furnished at the lowest possible cost, and any construction of state works for this purpose or any contract with individuals or corporations for supplying power to the boatmen should be hedged about with abundant safeguards for the protection of the public interests."

and by means of a trolley wire communicate it to motors in canal boats acting to turn a screw wheel. The other is the generating of electricity in large quantities by means of water power at some point or points where nature has provided the means, and then transmitting the current over long distances by wire.

From the figures furnished by the Albany Electric Railway, I conclude that if, as was shown me, we succeeded in developing in an engine cylinder one horse power per hour with two pounds of coal, we would have a consumption of coal to obtain one horse power per hour applied at a distance of eight miles from power house of from four and a half to four and three-quarters pounds. This is in excess of the amount of the coal consumed by canal steamers, to say nothing of difference in first cost of plant required.

The method of generating electricity in large quantities at points where large water powers exist and thence transmitting it by wire over long distances is the one which, to my mind, contains the greatest promise of success. In order, however, to economically transmit the large quantities required, the current in the feed wire must pass at very high voltage, and in order to secure safety that in the trolley wire must pass at a low voltage. While it is perfectly feasible to transform an alternating current from a high to a low and from a low to a high voltage, unfortunately no means have yet been found for thus dealing with a continuous current, and it is the continuous current alone that has as yet been successfully applied to the operation of motors.

Upon the solution of one or the other of these difficulties, and upon the devising of means to more economically and perfectly insulate the feed wires, depends, in my opinion, the success or failure of the efforts now being made in this direction.

I am advised that there has been developed by a corporation operating at Niagara Falls a water power yielding on the American side 200,000 horse power per hour (sic), and on the Canadian side 120,000 horse power per hour, which, they state, could be disposed of at a profit to the corporation at the price of $4 horse power per annum, measured on wires at Niagara Falls, if sold in its entirety. In considering this question it must be remembered that the steamboat has and must continue to hold an advantage over a trolleypropelled electrical boat in that she is independent of outside aid in navigating the Hudson River.

I commend this subject to your careful consideration and hope that you will adopt the necessary legislation to secure the continuance of the investigations and experiments necessary to reach a conclusion.

THE NEW YORK STATE ENGINEER ON CANAL TROLLEYS.

STATE ENGINEER SCHENCK, in his annual report to the New York State Legislature has a very interesting discussion of the application of electricity to the canals of the State. It is as follows:

Of the several schemes of improvement advocated by the friends of the Erie Canal, one of the most feasible, when its comparatively small cost is taken into consideration, is that known as the Seymour plan, by which it is proposed to deepen the canal to a depth of nine feet of water, by raising the banks one foot and by excavating the bottom one foot, except through locks and over aqueducts and culverts, and lengthening the locks so as to permit the passage of double headers.

I have plans for an enlarged canal, 100 feet in width and 12 feet deep, capable of bearing barges 250 feet in length and 25 feet broad on beam, with 10 feet draught of water, and of the lowest possible height above water, so that the greater part of the bridges crossing it could be fixed structures, instead of movable ones. The cost should not exceed $25,000,000.

I recommend that a commission be appointed, whose duty it shall be to examine into this matter and to report its conclusions to the Legislature at the earliest time practicable.

While there are some minor difficulties to be overcome in the application of the trolley system to canal navigation, such as the holding of the boat while not in motion or moving at a low rate of speed and exposed to the action of high winds, in proper posi tion to secure easy contact of the trolley with the wire carrying the current, the devising of means by which boats traveling in the same direction at different rates can pass each other, or by which boats can be brought up to or taken away from a dock, etc., I think none of these difficulties are so serious but that they will be surmounted by the inventive genius of our people. The main question is a purely economic one, and the success or failure of investigations now in progress will be decided by the answer to the question, Can the electric power be furnished to each propeller at less cost than that of steam?

Two trolley methods have been suggested by which to reach the desired end-one by establishing power houses along the line of the canal at such distances apart as may be found economical or desirable, and in these power houses, by the use of fuel to to generate steam, transform this steam power into electric power, transmit this electric power by wire between these power houses,

FROM NEW YORK TO PHILADELPHIA BY ELECTRIC RAILWAY.

WHAT will be, when completed, the longest electric railway in existence is about to be built between New York and Philadelphia by way of Newark, Paterson and Trenton. The originator of the enterprise is Mr. Joseph H. Reall, of Bloomfield, N. J.,_ who is well known as a railway builder, and the New Jersey Railway Company has been formed to carry out his plan.

There is already an electric railway projected along the banks of the Delaware from Philadelphia to Trenton. Beginning where this ceases, Mr. Reall's system leaves the latter town and passes through Lawrenceville, Princeton, Kingston, Rocky Hill and East Millstone to Bound Brook, whence branches lead to Somerville and Raritan on the west and New Brunswick on the east. Passing north from Bound Brook the line runs northeast to Westfield, passing through Dunellen, Plainfield and Fanwood. From Westfield a branch will run to Rahway, Elizabeth, Woodbridge, Boynton Beach and Perth Amboy, forming a short line from North Jersey and Eastern Pennsylvania to the seashore.

The line continues northeast from Westfield passing through Springfield, Millburn, Wyoming, South Orange, Orange, West Orange, East Orange, Bloomfield, Montclair, and thence to Paterson, with a branch from Millburn to Irvington and Newark on the east and to Morristown on the west. Another branch extends from Montclair to Caldwell. Altogether, the system comprises more than one hundred miles of track. From Newark to Jersey City there is now a well equipped electric road in actual operation.

The entire line has been surveyed, the right of way has been secured and the necessary franchises are assured. The people from one end of the line to the other are highly in favor of its construction, and the leading and most influential men in the different towns and the intermediate country through which the road passes are actively interested in and warm supporters of the enterprise. The road will be laid with seventy and ninety pound steel rails and equipped with thirty four foot, double motor cars of thirty horse power each. The speed will be eight to ten miles per hour in cities and towns, and twenty-five to thirty miles in the country. The cars will be run on from fifteen minutes to one hour headway, according to the amount of traffic, and where the trade demands it, five minutes head way. Five power plants of 1,000 horse power each, located at Trenton, Rocky Hill, Bound Brook, Westfield and Orange will supply the power.

The road will connect with the principal steam roads of the State. It will intersect both the Pennsylvania and Reading at Trenton, the Pennsylvania at New Brunswick, the Lehigh Valley,

Reading and New Jersey Central at Bound Brook, the New Jersey Central at Plainfied and Westfield, the Morris & Essex at Millburn, South Orange, Orange and Montclair, the Delaware, Lackawanna & Western at Paterson, the New York & Greenwood Lake at Orange and Montclair, the Erie and the Susquehanna & Western at Paterson.

The New Jersey Improvement Company has been incorporated to build and equip the north end of the road ready for operation and work will be commenced early in the spring. Its officers are: J. L. Stadelman, president; E. W. Hine, vice-president; Charles E. W. Smith, treasurer; John U. Bethell, secretary. Another construction company will probably be organized by Mr. Reall to build the southern end and the branch lines.

STORAGE BATTERY TRACTION AT BEREA, OHIO.

THE beautiful little town of Berea is located west of Cleveland, O., with which it is connected, bes des the railroads. by the Cleveland and Berea Street Railway. This road is ten miles long, and runs through a fertile farming country its entire length, for it connects at the Cleveland end with the terminus of the Woodland Avenue and West Side Street Railway. Starting from the Cleveland end the car has to mount one 4 per cent. grade 600 feet long; then after half a mile stretch of nearly level road comes a grade a little over 5 per cent. about 800 feet long. These two grades are the only large ones on the line but the road is made up of smaller ones as it is in no place level. The track is laid on one side of the country road and follows the ups and downs of the land, as very little grading has been done. The road crosses the L. S. & M. S. R. R. twice and runs under the C. C. C. & St. L. R. R. by a tunnel, The road is operated by the storage battery system of the Ford-Washburn Storelectro Co., of Cleveland, Ohio. At present there is but one car on the road and this is equipped with only one set of storage batteries; yet this car has been making three round trips, or sixty miles, every day since October 2, and in the first 31 days carried 4,753 passengers and covered about 2,000 miles. Part of the time an open trail car has been attached to the battery car and on Sunday, October 22 the two cars carried 460 passengers on the three round trips; 142 passengers at one time, one way, on the two cars.

On November 19, the motor car without the trailer brought 78 passengers from Berea to Cleveland. In drawing the trailer and carrying 142 passengers up the 5 per cent. grade the ampere meter registered 130 amperes. A large permanent power house will be erected at the Berea end, which will be equipped with modern machinery for handling and charging the cars and batteries. At present there is a temporary power house, with a 10 h. p. threshing engine and boiler, belted direct to a 16 ampere 500 volt Ford

a wheel base of 7 feet with 33-inch wheels. The car is propelled by one 35 h. p, series wound Ford-Washburn street car motor weighing 2,000 lbs.

The car is 28 feet long over all and 21 feet inside measure, and was built by the J. G. Brill Co., of Philadelphia, especially for this road. It is painted white with gold trimmings, has plate glass windows, fancy hard wood interior finish and is handsomely upholstered. The batteries are placed under the seats, in three rows of 28 cells each, on either side, making 168 cells in all. The car body is mounted on a Tripp truck with extension springs having

The Ford-Washburn Storelectro Co. have two means of varying the speed of their cars, the first dependent on the manner of coupling the batteries by which three speeds are obtained, i. e., with four sets of 42 cells each in multiple, giving 84 volts, with two sets of 84 cells in multiple giving 168 volts, or with the entire 168 cells in series giving 336 volts; the second consists in com

GENERAL DESCRIPTION OF A 5,000 H. P. ALTERNATOR. On the bed-plate a vertical cylinder is bolted, with projections to support the fixed armature and the bearings of the revolving part. The armature coils are wound independently and can be removed and changed. They are fixed in slots in the fixed armature. They are encased in an oil-tight casing through which oil can be circulated. The field magnet is external to the armature, and has the poles pointing radially inwards. It consists preferably of forged steel supported by a spider with eight arms, which may be of steel with a covering of thin sheet metal, on which cups are provided for forcing air into the interior of the machine. The pole-pieces are bolted on to the steel rim. The field coils are of copper strip, two coils being wound upon each pole, with a space between them for air circulation. The exciting current is applied by rings of tempered copper on the spider, having fixed brushes rubbing on them. The hub of the spider is firmly fixed to the upper end of the shaft. The spider supports the heavy rim by 16 studs and nuts. The shaft is supported by two bearings, each of which has four radial arms, which are bolted to four corresponding projections on the castiron cylinder. This cast-iron cylinder is bolted to the bed-plate, and adjusted thereon by wedges. Besides having on it the projections for carrying the bearings on its inner side, it has on its outer periphery a series of vertical ribs against which the stampings, or sheets of iron forming the armature, rest. It also supports the lower end plate on which the armature is built up, and the armature is keyed to it, by a single key. The armature is wound drum fashion-that is, all on the outside. This enables the coils to be wound independently and laid in their place, and also to be easily replaced in case of accident. In order to do this satisfactorily, the slots for each coil in the iron are cut, not radially, but parallel to each other. Each coil is encased in insulating material, which forms a tube through which oil may flow as in a transformer, but may be forced, in which case its circulation is maintained by a pump. Round the base of the machine there are two oil pipes, one being the inlet the other the outlet. The inlet pipe is connected with a reservoir of oil in the powerhouse. The outlet pipe leads by another pipe to cooling arrangements in running water, from which the oil is pumped to the reservoir. From the inlet pipe 16 brass tubes are led to the junction boxes at the bottom of the 16 coils; the 16 other brass tubes

are led from the junction boxes at the top of the coils through the interior of the fixed armature and bent over the foundation plate. and so connected to the outlet pipe which surrounds the bed-plate. The bed-plate is a single iron casting, and in order to enable it to be transported over the railways it was necessary to limit its diameter, as shown in a supplementary drawing, which shows the improved oiling arrangements, which were worked out by my chief draughtsman at Niagara Falls, Mr. Baumann. The armature is built up of thin sheet iron, with ventilating spaces as shown on the drawing. The bolts which hold the armature together are eight in number, to be made of nickel-s eel, a metal which has the great advantage of being non magnetic, and of very high electrical resistance and great mechanical strength. The amount of nickel is 25 per cent.

There are 16 armature coils, eight being of one kind, called "short" coils, and eight of another kind, called "long" coils, the length of wire on each coil being the same. The short coils are bent over at the end plate, and the long coils are wound in one plane, and enclose the short coils. I find that if we are to have a very stiff field, with first class quality of iron in the fields, each coil would consist of 72 turns of pure copper wire, No. 0 of the Brown & Sharpe gauge, which gives a very low density of current, and reduces the heating. In fact, it has been my view that in designing the machines for so great and permanent a work every effort should be made to reduce the rise in temperature, even to far below what has ever been done in the past. The unequal expansions and contractions of materials in a machine of this kind are very injurious to its permanence, and affect the insulating material seriously. The layers of wire in the coils are separated by mica. Each coil when wound has strips of insulating material laid spirally round it, so that oil may circulate freely in the intervals, and the whole is enclosed in a casing of strong insulating material.. The material which I prefer for this purpose is certainly woodite, an eighth of an inch of which will not break down with 30,000 volts, and which is not acted upon by oil even at high temperatures. I have a record of tests with oil which are conclusive on this point. It is quite the best material I have seen for the purpose, though costly, and, being a secret process, it may be difficult to ensure uniformity.

The frames of the bearings are of cast iron, with four radial arms, which rest upon four projections cast on the vertical cylinder, and are bolted to them. By this means, when the field magnets with the shaft have been lifted out of place, the bearings can be twisted through an angle of 45 degrees in a horizontal plane and then raised out of place, leaving a space of five feet in diameter through which portions of the turbine shaft can be raised for repair. The bearings are oiled at the centre by oil forced under pressure through a pipe. The oil is then distributed over the bearings by spiral grooves. A spiral groove is also cut in the hub of the frame, with a pipe at each end to admit of water circulation to cool the bushing. At two opposite sides of each bearing the bushing is made thin, and a rod of bismuth is soldered thereto; so that if the bushing is heated, a thermo-electric current shall be created which, by means of a relay, can ring a bell in the powerhouse. When this occurs, water can be immediately admitted to cool the bearings, and the attention of the workmen drawn to the necessity of an examination.

One of the parts which required most consideration was the material of which the spider supporting the field magnets should be constructed. The best plan is to make it of steel, for the sake of lightness, and to cover it with a copper covering, which might, I think be spun; or, perhaps better, electro-deposited nickel might be used.

Between the pole-pieces the space is filled up with a screen or plate of metal so as to direct the air ventilation only upon the parts which most require cooling.

It will be obvious from this design, considering that the speed of revolution is 250 per minute, that great care has to be devoted to the balancing of the revolving parts; everything has to be calculated not only for a speed of 250 revolutions, but for double that amount, which is the maximum speed at which the turbines could possibly run-at which speed they might run through a break down of the governor, although this is an accident almost impossible to occur. Each of the revolving parts will of course be balanced individually, and I have suggested a plan for the final balancing which seems likely to be effective. A temporary bushing would be put in the bearings, of india-rubber lined by a thin metal tube. The dynamo would then be rotated slowly and the balance adjusted in the usual way. The speed of revolution would be gradually increased-a new adjustment being made at each speed-until a speed of 500 revolutions a minute is attained, and when an adjustment has been made at this speed it is pretty sure that the balance at 250 revolutions per minute will be very perfect, and the mechanical friction reduced to a minimum.

As stated before, the oiling arrangements have been intro. duced not only to ensure higher insulation and to preserve the insulating material, but also to lower the temperature as much as possible, because every step we take in the reduction of temperature is an advance. These oiling arrangements may perhaps be adopted in the future, but at present we are not making use of them in the machines which are in process of construction.

When we have had experience with these we may in future adopt the oiling arrangements; and as there is likely to be a great development in the direction of electric transmission of power in connection with the utilization of water power in many parts of the world, it has seemed well to me to put before you these details, so that they may be considered in other cases that may arise.

At a meeting of the Board of Directors in New York lately it was resolved, on the recommendation of the consulting engineers of the Company, that the contract for two or three alternators, each of 5,000 h. p., should be assigned to the Westinghouse Electric and Manufacturing Company of Pittsburgh. I would wish to state how much we owe to Mr. Westinghouse, and to his chief engineer, Mr. Schmid, for the zeal with which they have taken this matter up and their desire to meet our views and to secure for us machines of which they felt they could guarantee the satisfactory performance.

Before leaving the subject of the dynamo, I would wish to point out that it has been designed for special circumstances in connection with the Cataract Construction Company's work. If a dynamo of the same type were being constructed for another place, it is certain that modifications would have to be introduced. I particularly draw attention to the fact that some trouble in getting out a good mechanical design arose from the necessity which existed of being able to provide a clear space of about 5 ft. diameter in the middle of the machine without taking the whole machine to pieces, the object of this being to enable us to lift up portions of the turbine shaft which it might be required to put into repair. In any case, where the long shaft existing in our case is not required, the design of the dynamo is much simplified and would more nearly approximate to the first design but arranged for 33 periods a second.

If the present paper were intended to relate solely to the subject of the utilization of power at Niagara Falls I would be content with describing what has actually been done; but I foresee that there is going to be a great development in utilization of water power and its electrical transmission. I am, therefore, inclined to say a few words on some other details which we have been carefully considering, but about which no definite decision has been arrived at.

Before doing this I would direct your attention to the drawing1 representing a plan of our power house, in which you will perceive the inlet passages A, from the great canal, B, which draws its supply of water from the upper river. From these inlet passages the iron pipes or flumes, C, pass vertically downwards to the bottom of the great wheel-pit, which is a slot cut in the ground to a depth of nearly 200 ft., at present large enough to contain four turbines in line, but which can be extended to a much greater length, the whole capacity of our tunnel being 100,000 h. p. The drawing shows circles, D, in the plan, which indicate the position of the turbine and dynamo above it, and the position of a hatchway F, by which material can be raised or lowered. It will be noticed that between the inlet channels and the wheel-pit the flumes are bent downwards, and thus leave a V-shaped space G, which I have appropriated to make a subway, running along the whole length of the power-house, to carry the high-pressure conductors. It will, of course, be understood that the slot forming the wheel pit is arched over at the top to form the floor of the powerhouse, upon which the dynamos rest. It will be noticed that at the north end of the power house there is a large square chamber, H, in which I propose that all the measuring instruments and other apparatus under the control of the chief electrician shall be assembled. Underneath this chamber there is a cellar in direct communication, first, with the subway which I have described as existing in the power-house; and, second, with the subway which leads outwards from the power-house at present as far as the Pittsburgh Reduction Company's works, and may possibly eventually lead to Buffalo. In this cellar all the high-pressure wires, the transformers, the artificial load, and other high pressure machinery will be placed. It will be noticed that other spaces are left in the floor forming trenches along which the conductors can be carried With these arrangements there can be no possibility of danger to any person in the power-house; and if any wires are to be found laid along the walls of the power-house or elsewhere, I wish it to be a maxim that we shall be able to place upon these wires a card marked "No Danger," so that there will be no possibility of danger from any person touching anything in the power-house.

With regard to the exciting current, the best plan available at this moment is to use one of the machines which are generally known as the Schuckert machines, for converting the alternating into a continuous current, transformers being inserted in order to lower the pressure. In order that the exciting current may increase with the load, it would be well to make these transformers of special construction, each having two primaries and one secondary. One of the primary coils would be in series with the main circuit, and the other in shunt. I would furthermore make these transformers sufficiently large to deal with all the dynamos which are in the central station, and I would subdivide the secondary

1. The drawings accompanying Prof. Forbes' paper are not yet available for publication.-EDS. E. E.

coil into sections, to enable us to cut out a section of the transformer when we cut out one of the dynamos. When we wish to cut out a dynamo, a switch would be worked which would at the same time short-circuit the field coils of that dynamo and also cut one section of the secondary of the transformer which is supplying exciting current to all the dynamos. This plan allows the fields of all the alternators to be put in series-a desirable arrangement for parallel working. A resistance may, of course, be put in circuit with the fields of the alternators for regulation.

I presume it will be taken for granted that in any large work of this sort the primary circuit should never be broken when in action. For my part, I hold that this should be the case even in smaller stations.

An important feature for putting the dynamos in parallel, and for removing a dynamo, is an artifical load. It is desirable that this artificial load should consist partly of a resistance and partly of self-induction. It is only by this means that the dynamo which is going to be put in circuit can be brought to exactly the same condition as those which are working, both as regards volts and amperes. It may be well to describe the operation which take place when a dynamo is switched in parallel with the others. First, connection is made between the armature and the artificial load; then the exciting switch is turned so that an extra section of the transformer is put into play, and the short-circuit on the field coils of the dynamo is broken. The dynamo being excited, the turbine is then started, or this may be done at first. The artificial load is then adjusted until the dynamo is giving the same volts and amperes as the others. A synchronizer is then placed between the artificial load and the external circuit, and so soon as the synchronism is attained a switch is closed which connects the artificial load with the external circuit. Resistance is then put into the artificial load until there is very little current going through it, when it is switched out, and the dynamos are all working in parallel. To cut out a dynamo from the circuit the operations are performed in the opposite order. The artificial load with high resistance is put in connection with the external circuit; the resistance is gradually diminished until it indicates the amount of work that is being performed by one dynamo; the connection between the artificial load and the main circuit is then broken, leaving the dynamo (which is being switched out) feeding the artificial load. The resistance of the latter may then be increased, and the exciting switch actuated so as to short-circuit the fields of the dynamo, and to remove one section from the secondary of the exciting transformer. The supply of water to the turbine may then be shut off.

If machinery is worked, even at 20,000 volts, in the manner I have described, there is no possibility of injury from any great rise of electrical pressure, unless the external circuit be by any means accidentally broken. To provide against this sort of trouble I would have wires coming from the external circuit where it enters the power-house, connected through a large resistance, or through the primary of a transformer, the secondary of which contains a resistance. In circuit with it I would have a break consisting of two carbon points at a distance of about half an inch apart if we were dealing with 20,000 volts, so that an arc could not be formed unless the pressure rose above the normal value. Under these circumstances, so soon as any resonant effect due to the breaking of the circuit or due to any other cause raises the electric pressure above the normal, an arc is established across the carbon points, and so a load is put on which removes the cause of the extra high pressure. This is the only automatic means which I have been hitherto able to think of which is sufficiently rapid in its action to overcome any possibility of injury to the dynamo or transformers.

I have attempted in the course of this Paper to give you some idea of the work which has been actually done or decided upon at Niagara Falls, and also to show you the views to which I have been led by any special experiences which I may have had as to the general ideas which ought to guide us in the construction of plant in the future for transmitting power to a distance electrically.

In describing the different plans which are available I have avoided mentioning the names of those numerous electrical engineers and manufacturers who, by their inventions, researches, or applications have advanced the art; or discussing their claims to priority; but I cannot conclude this Paper without mentioning the names of some of those who, in one way or another, have made great steps in the applications of alternating currents to power purposes. I would particularly mention the names of Messrs. Ganz and Co., Mr. Schuckert, the Allgemeine Electricitäts Gesellschaft (of Berlin), the Oerlikon Fabrik, and Messrs. Brown, Boveri & Co.; also Mr. Eickemeyer, Mr. Ferranti, Prof. Ferraris, Prof. Fleming, Dr. J. Hopkinson, Messrs. Hutin and Leblanc, Mr. Rankin Kennedy, Prof. Mengarini, Mr. Mordey, Mr. Tesla, Prof. Elihu Thomson, and Mr. Henry Wilde. I feel that all of us owe a great deal to their work.

In conclusion, I wish to draw attention to the figures which show the relative merits of high and low frequency with polyphase motors.

Everything is identical in the two figures, except that, the frequency of one (a) being double of the other (b), a has 16 poles,

b has 8. The armature is identical in both, and revolves at the same speed and does the same work; and the field revolves at the same rate in both, and the induction and current-density are the same. The differences are that a has more copper and less iron than b. The comparison of efficiency depends on the depth of both. As an example, assume that a has 50 per cent. more copper in the fields than b, the ampere-turns per pole being necessarily the same in both, and that b has 50 per cent. more iron than a, and that the hysteresis loss in b (= H) is equal to the resistance loss in its copper coils (= C). The values for a are

How to Wire Buildings. By Augustus Noll, E. E. New York, 1893. C. C. Shelley. 162 pages, 5%1⁄2 x 8 inches. Price $1.50. In this utilitarian age when practice keep so closely at the heels of theory the successful workman in any branch must fortify himself in every way if he is not to be outdistanced by his more studious fellows. This demand for more knowledge has given rise to a host of so-called "practical" books intended to convey to the artisan the results of actual experience, as distinguished from the theory or laws on which the subject treated of is based. But there are two kinds of "practical" works. One of these is the result of a gathering together of materials and knowledge acquired by hearsay, as it were, and frequently the outcome of much painstaking labor on the part of the authors. Such works have a certain value, but they almost invariably fall short of their intended purpose by lacking those small but all-important details which serve as the links that join the whole together and the knowledge of which makes the successful workman.

The other type of the "practical" book is that which is written by one who has actually done the things which he describes, who knows in just what manner they are carried out most conveniently and expeditiously and who is thus in a position to note the little, all important details above alluded to. It is of this second type that Mr. Noll's book is an excellent example. Himself a successful workman (in the true sense), of long and varied experience, he is eminently qualified to describe to others what he has himself found to give the best results in practice.

In these days of Boards of Fire Underwriters and numberless wiring rules and constant threats of increased insurance rates on buildings lighted by electricity it is specially desirable to put into the hands of every one connected with the installation of a lighting plant, from the architect down to the wireman, a source of correct information, and the work before us is the first of its kind which can be said to meet broadly the requirements.

The author in carrying out his design first gives us a series of considerations governing wiring work in general, and introduces here the duties and qualifications of a wiring foreman. That allimportant question of the location of the conductors serves to bring out forcibly the value in a work of this kind of that personal experience about alluded to. Throughout all this section of the book we read between the lines the instances of the "troubles" encountered in the past, the removal of which has often been accomplished at the cost of much time and money. The way "how not to do" work of this kind is here forcibly brought home to the reader. The location of the conductors, with reference to the other numerous adjuncts to modern buildings, having been discussed, the author takes up the question of the division of circuits and distribution of current, and the laying out of wiring plans, and here again Mr. Noll's ripe experience is manifested. He describes clearly, and by the aid of diagrams, the "panel" or "grouping" system, and various other systems, and the means to be adopted for obtaining equal pressure throughout the system, and pointing out the situations in which one or the other will be found to be most advantageous. The wiring from converters is also fully explained and shown by diagrams.

That later outgrowth of necessity, conduit wiring, has afforded the author opportunity of showing the beauty and value of this system to its fullest extent, and the methods of carrying out such work are treated with corresponding fullness in a well-illustrated chapter.

Not the least important part of work of this nature is the location of the lamp outlets in order to obtain the best illumination. On this subject, that is, the distribution of light, we find much of value, especially to the architect, on whom the duty of selecting