Trade Notes
Notes and Novelties

AND MECHANICAL DEPARTMENT.

LUNDELL DIRECT-CURRENT DYNAMOS AND
MOTORS.

THE Lundell type of direct-current dynamos and motors is so simple that an elaborate description of the different parts seems to be unnecessary. The chief characteristics are embodied in the novel construction of the field magnet, whereby a single energizing coil magnetizes all the pole-pieces and a strong protecting shell for the windings of both field and armature forms the magnetic circuit.

and the resistance of the magnetic circuit reduced to a minimum, whereby a considerable economy in the ampere turns of the energizing coil is effected.

The armature adopted for these machines is of a modern Pacinotti form. This type of armature has in the past been subject to unfavorable criticism on account of the resultant heating of the pole-pieces, but it is now recognized that this heating was not due to the Pacinotti ring itself, but to the lack of knowledge with regard to its proper design. A little reasoning will show that when the ratio of the distance between the teeth and the magnetic gap is too small, a concentration of the lines of force will take place, so that the pole-pieces will be swept over alternately by sections of the highly concentrated lines of force, and by practically inert material. The result is that Foucault currents must inevitably be set up in the pole-pieces and cause the heating, which has been noted in the past. By so proportioning the teeth,

The arrangement of the field-magnet and its energizing coil is clearly illustrated in the accompanying engravings.

It will be noted that the two field-magnet halves when bolted together form a shell which completely protects the armature, the whole of the shell being utilized in the magnetic circuit. These field-magnet halves are so designed that they are readily withdrawn from the mould in casting. The cross-section of the shell equals the cross-section of the base of the pole-pieces, so that no choking of the lines of force can occur at any point. Cast steel is employed for all these dynamos and motors. The single energizing coil not only reduces the construction of the machine to the simplest point, but by having only two terminals it is especially adapted to be placed in the hands of inexperienced users, as it avoids any possible mistake in connecting up or any delay or trouble in examination when such becomes necessary. Another feature of the design is that the pole pieces are magnetized directly,

however, that the lines of force emanating from the pole-pieces are more evenly distributed over their entire surface surrounding the armature, this abrupt demarcation is avoided, with the result that Foucault currents are also avoided in the pole-pieces.

The result of actual practice with the Lundell machine has shown the soundness of this theory, which is carried into practice by the employment of deep and narrow slots.

Notwithstanding the iron clad nature of the machine, the concentric position of the field-coil allows the armature to be withdrawn without disturbing either the field-coil or the pole-pieces.

The openings around the armature at the ends of the fieldmagnets are, in the larger machines, covered with metal screens to protect the working parts, and to secure at the same time perfect ventilation. The commutator portion of the armature alone projects outside the screen, and is well protected by a strong bracket which carries the out-board bearing. The brushes are

end of a brush-holder; while its forward end in the shape of a T presses against the carbon which slides in the ways in the brushholder. To remove the carbon, it is merely necessary to press the spring upwards out of the slot, which releases it so that the T can be withdrawn, and the carbon slides out.

The bearings are constructed with mechanical accuracy, are self-oiling and are provided with a vision gauge. The bushings are made of the best material and are so arranged as to be readily removed and renewed when worn out.

The oiling is accomplished by means of a number of rings which encircle the shaft and dip into the reservoir, thus continually feeding fresh oil to the bearing. In order that the attendant may know the exact condition of the oil, a simple device has been added, consisting of an elbow with an oil-chamber, rising slightly above the normal level of the oil. The vertical arm of this elbow is so arranged that when the visual gauge is half filled the bearing is properly oiled. The glass tube is made so short that by no possible inadvertency can the attendant pour in oil sufficient to flood the bearing and cause the oil to run out at the inner surface of the shaft and so go into the armature.

power plant, it is highly necessary to run a dynamo very close to schedule speed, which can only be determined by an instrument such as the above.

JOHN SCOTT MEDAL AWARDED FOR THE EDSON GAUGE.

THE John Scott legacy medal and premium, held in trust by the city of Philadelphia under the legacy of John Scott of Edinburgh, to be used for the encouragement of "ingenious men and women who make useful inventions," provides for the distribution of a medal incribed, "To the most deserving," and money premium in the sum of $20, has just been awarded to Jarvis B. Edson of New York, for his pressure-recording gauge, by the Franklin Institute.

The general adoption of these valuable instruments proves their indispensable nature, for in no other way can a proprietor place himself in a position to know how the steam pressure is carried during night and day, or how much inattention accompanies the firing. As it is a well established fact that carelessness and indifference at the furnace door wastes coal in an amount often

The Interior Conduit & Insulation Co., manufacturers of the Lundell dynamos and motors, claim that their efficiency is as high as can be obtained by any first-class machine.

THE SOUTHERN PACIFIC RAILROAD COMPANY will build a new cotton shed at New Orleans, 120 feet wide and 350 feet long. They bave placed the contract with the Berlin Iron Bridge Company, of East Berlin, Conn. The building will be entirely of iron, the sides being made with the Wilson patent rolling shutters.

sufficient to pay an extra dividend, to say nothing of loss in the cylinder from lack of initial pressure and proper economy from expansion of the steam, for the firemen little understand the necessity for maintaining high initial pressure. "Following" too far or "cut-off" too short, are both wasteful of steam and can only be controlled by the fireman carrying uniformly such a pressure on the boilers as the engine requires for the work it has to perform.

It is equally evident that such records, similarly produced, are as valuable where compressed air, water or other fluids are desired to be maintained under prescribed degrees of pressure.

The accompanying illustration shows the type of their machines ranging from four to eight kilowatts. They have large commutators and very strong fields, and are claimed to be entirely free from sparking. The bearings of the smaller sizes are of phosphor bronze and, in the larger, of compressed Babbitt metal in cast iron shells. These machines do not in any way greatly depart from ordinary accepted engineering practice, but they are claimed to embody all the favorable points possible which modern practice has found reliable. It is unnecessary to recite the points which are necessary to make a good machine as they are well known to all our readers. The company have now, in spite of the business depression, orders ahead for two months.

POWER HOUSE OF NEW ORLEANS AND CARROLLTON ROAD,

THE new electric plant of the New Orleans & Carrollton Railway Co., at New Orleans, La., consists of a car-shed and powerhouse, both designed and built by The Berlin Iron Bridge Company, of East Berlin, Conn.

The former is 128 feet in width and 300 feet in length. Light for the interior is secured through the side windows in the monitor, ventilation being provided for by means of louvers, the louvers and the windows alternating from panel to panel. The sides of the building for a distance of about 10 feet from the ground are left entirely open so as to admit of free access to the interior of the building. The ends of the car-house are also left open below the tie beams so that cars can be moved in and out without

this part of the plant is the portable crane shown in the foreground. This is so arranged that it can be easily moved to any part of the building, and is of sufficient capacity to raise and lower the machinery in and out of place. In the case of this power-house a traveling crane of the full width of the building would be an expensive matter. Owing to the general arrangement of the steam pipes and belts, this construction would be inexpedient and unadvisable. To meet this necessity the crane shown in the illustration was designed and built by The Berlin Company, and has proved a great success. The construction of both buildings is creditable both to the builders and the New Orleans Railroad Co.

is readily apparent not only in the added neatness of the switch but in its simplicity of action.

The interior construction of the switch is shown in the cut. The action, which is readily apparent, is very positive and at the same time the switch can be manipulated with great ease. The break is quick and is made in such a manner that the switch cannot be left half off or on and a short circuit cannot occur.

The 66

"Standard" single push switch is intended to take the place of any 5 or 10 ampere snap or flush switch, and is made in the regular 10 ampere single pole, and 10 ampere three way styles. A third style is now under way and will shortly be ready for the market, to be known as the "Standard" commutation switch. In general appearance it is the same as the regular switch shown here but the contacts are so arranged that a light or group of lights by the use of the commutation switch can be controlled from any number of points without extra wiring; that is, a light or group of lights can be turned on or off from any three or more points independently.

All of the "Standard" switches are very compact and neatly made, no money being spared to make them first-class in every respect. The price at which the Electric Appliance Company are placing them on the market is also very low. Large numbers have already been sold and the demand is rapidly increasing.

POWER HOUSE OF NEW ORLEANS AND CARROLLTON ROAD.

trouble. A building can be constructed in this way at New Orleans on account of the warm climate-it being unnecessary even in the coldest days to protect the interior or to provide for heat. The power-house shown in the illustration has a construction similar to the car-shed, except that the side walls are of brick, the roof only being of iron. The particular feature, however, of

THE WESTERN TELEPHONE CONSTRUCTION CO.

THE WESTERN TELEPHONE CONSTRUCTION Co., of 440 Monadnock Building, Chicago, who have been for the past year making preparations to enter the telephone field on a large scale as soon as the telephone patents had expired sufficiently to warrant them in so doing, will begin extensive operations on or about the first of next month.

This company, by purchase and otherwise have obtained control of some of the most valuable devices in telephonic apparatus, including everything necessary for the complete installation of first-class modern telephone exchanges, as well as complete outfits for cities, towns and villages, private lines or factory plants. They control nearly 100 patents, and contemplate dealing exclusively in telephonic apparatus.

Contracts will be made for the sale outright of the entire equipments or any portion of the apparatus necessary for a telephone plant and the company's factory facilities and financial recources make it possible for them to operate on an extensive scale. A number of large contracts have already been obtained.

ELECTRIC LIGHTING COMBINATION FOR THE SOUTHERN HOTEL, ST. LOUIS.

THE state of perfection at which the latest types of steam engines have arrived is shown in nothing so clearly as in the increased demand for automatic types of engines to be directly connected to dynamos. The fluctuations in load, especially in street car service, are so great and so numerous-fluctuations of 25 to 100 per cent. of the entire load, occurring almost instantaneously, that it has taxed the inventive genius of our engine builders to the utmost to produce engines that will stand the strain. In the case of belt-driven dynamos, a severe short circuit will usually cause the belt to fly off and thus relieve the engine, but a direct connected engine must not only be able to maintain a uniform speed under these sudden changes of load, but it must not fly to pieces if a short circuit brings the engine to a sudden stand-still,

That the day of slow-speed engines with bursting fly wheels is past for electrical work is freely claimed. Where space is not very valuable, dynamos belted to high speed engines will continue to be used, but where space becomes a matter for grave consider

armatures are therefore entirely free from any danger that could result from a splash of oil. That these engines are peculiarly adapted to work in places where space is valuable, will be apparent from those dimensions:

The 14 x 14 engines, with armatures attached complete as shown in the illustration, can be placed in a box 68 inches high, 81 inches wide, 10 feet and three inches long, and their rated horse power is 125. The 18x12 engine-100 h. p.-can be placed in a box 68x74 x 9 feet and 11 inches.

THE "WHITE PLUME" OF KERITE.

MR. W. R. BRIXEY is "nothing if not original," and he has just given another proof of his fertility of resource in presenting to the friends of "Kerite" a beautiful aluminum pen as a New Year memento. It is stamped out in the shape of an old-fashioned quill, and has the word "Kerite" in large letters on the plumage, together with the injunction to specify that insulation whenever any wire orders are to be given out. The pen is curiously bright, light and pretty, and will be warmly welcomed by

ation, the future demand must be for direct connected engines as soon as engine builders can supply a suitable engine.

To meet this demand, the engine shown in the accompanying cut has been built by A. L. Ide & Son, of Springfield, Ill. The illustration is taken from one of three ideal engines recently shipped by this firm for use in lighting the new Southern Hotel in St. Louis, Mo. Two of these engines had 14x14 cylinders, the third had a 13x12 cylinder. All were regulated to run at 275 revolutions. Each of these engines had a General Electric Co. armature keyed on the crank shaft in place of the plain pulley. The construction of the armature and engine are such that no outboard bearing is required. The two 14x14 engines are to drive dynamos belted from the governor pulleys in addition to the direct connected armatures.

The points of superiority claimed by the builders of these engines for this form are as follows: They claim that they will not vary over 1 per cent. in speed for a sudden change of 100 per cent. in load. They are perfectly self-contained and balanced. Every engine was adjusted before leaving the works to run at its specified speed under full load, and so balanced as to run without shaking with all anchor bolts removed. Excellence in workmanship and material-steel and bronze entering into its construction to an unusual extent. The engines are provided with the wellknown Ideal system of self-oiling, which supplies all the working parts with a constant stream of oil that is used over and over again. There is positively no oil scattered in any direction. The

every lucky recipient. We have no doubt that requests for an exemplar, sent to Mr. Ham, at the headquarters of Kerite, 203 Broadway, will be courteously complied with.

CHRISTMAS CALENDARS.

THE DIRECT U. S. CABLE Co. has issued a neat pad calendar from its headquarters at 40 Broadway. It is mounted on a handsome lithographed card, which shows Puck putting his girdle around the earth.

THE COMMERCIAL CABLE Co.'s staff has issued seasonable greetings in the shape of a fine picture of the "Vigilant" surrounded by a horseshoe. It is printed on heavy board, and is a work of art.

MR. S. A. DOUGLAS has resigned his connection with the Brush Electric Company whose Western manager he has been for some time past and has become general sales agent of the General Incandescent Arc Light Co., of 572 to 578 First Ave., New York.

Departmental items of Electric Light, Electric Railways, Electric Power, Telegraph, Telephone, New Hotels, New Buildings, Apparatus Wanted, Financial, Miscellaneous, etc., will be found in the advertising pages.

Vol. XVII.

THE TESLA ELECTRICAL OSCILLATOR. N the lecture delivered before the Chicago Electrical Congress, Mr. Nikola Tesla first drew attention to the method and means which he had devised for the continuous production of alternating currents of constant period in which all rotating parts are avoided by the employment of his oscillating engine directly to the movement of the generating coil in the magnetic field.

The main reason why no engine heretofore has been capable of producing results of this nature is that it has been customary to connect with the reciprocating parts a heavy fly-wheel or some equivalent rotary system of relatively very great inertia, or in other cases where no rotary system was employed, as in certain reciprocating engines or tools, no regard has been paid to the obtainment of the conditions essential to the end which Mr. Tesla had in view.

In applying the Tesla oscillator for the generation of currents of constant period certain conditions are encountered which must be taken into consideration in order to satisfactorily secure the desired result. When a conductor is moved in a magnetic field and a current caused to circulate therein, the electromagnetic reaction between it and the field might disturb the mechanical oscillation to such an extent as to throw it out of isochronism. This, for instance, might occur when the electromagnetic reaction is very great in comparison with the power of the engine, and there is a retardation of the current so that the electromagnetic reaction might have an effect similar to that which would result from a variation of the tension of the spring; but if the circuit of the generator be adjusted so that the phases of the electromotive force and current coincide in time, that is to say, when the current is not retarded, then the generator driven by the engine acts merely as a frictional resistance and will not, as a rule, alter the period of the mechanical vibration, although it may alter its amplitude. This condition may be readily secured by properly proportioning the self induction and capacity of the circuit including the generator.

Mr. Tesla has, however, observed the further fact in connection with the use of such engines as a means for running a generator, that it is advantageous that the period of the engine and the natural period of electrical vibration of the generator should be the same, as in such case the best conditions for electrical resonance are established and the possibility of disturbing the period of mechanical vibrations is reduced to a minimum. Mr. Tesla has found that even if the theoretical conditions necessary for maintaining a constant period in the engine itself are not exactly maintained, still the engine and generator combined will vibrate at a constant period. For example, if instead of using in the engine an independent cylinder and plunger, as an air spring of practically constant rigidity, the piston may impinge upon air cushions at the ends of its own cylinder. Although the rigidity of such cushions or springs might be considerably affected and varied by the variations of pressure within the cylinder, still by combining with such an engine a generator which has a period of its own, approximately that of the engine, constant vibration may be maintained even through a considerable

1. See THE ELECTRICAL ENGINEER, August 30, 1893.

No. 297.

range of varying pressure, owing to the controlling action of the electromagnetic system.

Indeed Mr. Tesla has even found that under certain conditions the influence of the electromagnetic system may be made so great as to entirely control the period of the mechanical vibration within wide limits of varying pressure. This is likely to occur in those instances where the power of the engine, while fully capable of maintaining a vibration once started, is not sufficient to change its rate. In our issue of November 8, 1893, we gave the details of construction of the Tesla oscillator and a patent just issued