These locomotives are equipped with electric air compressors for the operation of the brake, signal, third rail safety cut-out switches, track sander, bell and whistle, and also with the usual steam locomotive equip

ment.

The source of power is a central steam plant generating direct current at 560 volts, from which it is transmitted through feed cables direct to the booster stations where the voltage is increased to 625, and the current then conveyed to a storage battery which is used as a reserve and for peak loads, as well as to a surface third rail system of contact line, equipped with safety cut-out device. The locomotive motors obtain about one-half the required current direct from each the storage and booster stations.

The free running speed of these locomotives is about 20 miles per hour.

On level track, with good current, rail and weather conditions, they are capable of starting and accelerating a train weighing 3,000 tons with a current consumption of 2,200 amperes, which consumption, when speed increases to and is maintained at about 10 miles per hour, reduces to about 900 amperes.

On a 1% grade these locomotives, under similar conditions, will start and accelerate a train weighing 1,400 tons with a current consumption of 2,200 amperes, which consumption, when speed increases to and is maintained at about 10 miles per hour reduces to about 1,600 amperes.

These locomotives handle eastbound through freight steam locomotives and trains at Baltimore, Md., from Camden Yard to Waverly, a distance of a little over 3.4 miles, returning light. This distance includes seven curves ranging from 5° to 11°; seven tunnels from 400 feet to 7,000 feet in length, and gradient about as follows:

The time consumed when hauling freight trains weighing 1,395 tons in cars of various capacities and lading, 105 tons in steam locomotives and 160 tons in electric locomotive, or a total moving load of 1,660 tons, averages 23 minutes actual running time, from start until electric helper locomotive cuts from head end of train to return light.

During the past one year's service the combined mileage of these two electric locomotives has been 121,015 miles, or an average of 5,042 miles per month per locomotive, computed on the basis of straight light and loaded mileage. The proportion of light and loaded mileage was half and half, about 200 miles per month per locomotive was in passenger helper service.

Considering $1.25 per net ton as a base cost for fuel delivered at the power plant, the average total operating and maintenance expenses during the year for generating the current; the labor and material for the locomotive electrical and mechanical repairs; the engineer's wages; wiping, hostlering, inspecting, oiling and dispatching; lubricating and miscellaneous supplies, was approximately $34.50 per 100 miles run per locomotive. Of this amount the average cost of labor and material applied to each locomotive for the running and shop repairs, would be $3.20 or 52% for the electrical, and $2.90 or 48% for the mechanical, making a total average cost of $6.10 per 100 miles run for both the electrical and mechanical repairs.

The above figures do not take into consideration interest, depreciation, taxes nor insurance on the investment, nor do they include the expenses incident to the maintenance of such equipment as battery, feeders, third rail, bonding wires, insulation, safety cut-out switches, extra motors, etc., which is not required for steam locomotive operation. The wages for the conductor, or second man on the locomotive, has also been omitted.

During their service considerable difficulty has been experienced with the shoes used for collecting the current from the surface third rail; the loosening and wear of pinions used to transmit the power from the motors to the gears on the driver wheel axles; breakage of gears on driver wheel axles; the lubrication, heating and wear at the armature bearings; the flange and tread wear of driver wheel tire; derailments; stalling and breaking in two of freight trains due to slipping of driver wheels more especially with wet rail or when tire of drivers connected in series are not of exact diameters, and in miscellaneous renewals and shop repairs.

The driver wheel tires which when new were 2%" thick, are now 134" thick, showing only 7,500 miles run per " metal removed at tread, and will have to be renewed within a few months.

From experience, to the present date it would appear that an electric locomotive and its source of power, to produce the proper efficiency and economy in operation for either passenger, freight or helper service should fulfill the following essential requirements:

FIRST.-A fire and collision resisting locomotive construction within the present clearance and weight limits; simple in design; reasonable in first cost; safe, reliable and economical for operation at varying speeds and power; and accessible for inspection, lubrication, cleaning, repairs and for replacement on track in event of derailment of any or all wheels, by the ordinary steam locomotive and car methods, without the necessity for the use of a power crane.

SECOND.-A locomotive that can be interchanged and operated over home and foreign tracks, which are suitable for steam locomotive or motor car equipment.

THIRD.-A locomotive composed of two or more interchangeable sections, each a duplicate of the other, and equipped so that each section may be operated from either end, and independently or jointly, with any number of coupled sections; the operation under any arrangement to be controlled from a single section by one engineer.

FOURTH.—The elimination of pilot wheels and the concentration of the entire weight on the driver wheels, with a minimum weight per wheel at the rail of 25,000 pounds; and an arrangement of driver wheels providing for a short rigid and a long flexible wheel base, without excessive end play at axle bearings.

FIFTH.—The elimination of armatures from locomotive driver wheel axles and the transmission of power to driver wheels not less than 60-inch initial diameter without the use of gearing, in a manner that will insure the economical use of current at the motors for starting and running, and eliminate the accumulation of unbalanced pressure at the wheel and rail contacts, as well as the independent revolution of one or more pairs of driver wheels when coupled in series, which occurs as the driver wheels become slightly different in diameter due to ordinary wear or material, when making transition in current at motors, or when operating on slippery track or over rails, frogs and switches of varying wear, surface, alignment and elevation.

SIXTH.-The least weight between the track and the locomotive frame carrying springs, to minimize the pressures, lateral thrusts and wear at the rail and wheel flanges.

SEVENTH.—A high centre of gravity so that the vibration of the locomotive, due to the variation in surface, alignment, elevation and curvature of track can be absorbed by the weight suspended over the driver springs.

EIGHTH.-A proper proportion between the electrical, mechanical and dead equipment weights of the locomotive.

NINTH.-Locomotive motors compact, ventilated, cooled, protected from internal damage and mechanical injury, and of ample range of adjustment and capacity to permit of continuous operation at varying or full speed or power and to stand an overload of 100% for three minutes and of 50% for one hour without excessive heating of armature, commutators or fields above the temperature of the surrounding atmosphere. A thin, tough and elastic insulation material, unaffected by humidity or a temperature of 400 degrees Fahrenheit, and having the requisite dielectric strength.

TENTH.-A development of the maximum locomotive power for rapid acceleration and regular working, requiring no transition, as from series to multiple, in the transmission of the current to the motors, and providing for a uniform increase or decrease in tractive power to prevent irregular drawbar stresses.

ELEVENTH. Suitable pumps to provide compressed air for the locomotive power brake, track sander, bell and signal operation, together with steam train heating device, and the other usual equipment.

TWELFTH.-Automatic positive devices on the locomotive to insure protection in event of accidental short circuit, or disablement of the engineer.

THIRTEENTH.-An arrangement on the locomotive which will automatically provide for electrical braking and return to the line for the use of pulling locomotives, a considerable percentage of the energy that is generated by trains descending grades, or stopping, and which energy is ordinarily wasted in destroying material and equipment by brake shoe action on wheels or rails.

FOURTEENTH.-A high potential current producing, and an aerial conveying system, reasonable in first cost and economical for maintenance; the generation of the electrical energy at a fire-proof central plant for the least cost per kilowatt hour; the transmission of the lowest current over the minnimum amount of metal contained in overhead contact lines, protected for weather, voltage and lightening conditions, and insuring continuous operation in event of line or equipment failure or accident; the conservative use of battery as storage for extra power that can be generated at small cost during light load and utilized to good advantage in the event of breakdown or during intermittent and peak loads; the least number of transformer or converter stations; the minimum feeder, conversion and resistance losses in current, and the elimination of electrolytic action.

Steam locomotive No. 2400, which is of the Mallet articulated duplex compound type, was designed jointly by the builders and the railroad, and the construction was completed in April, 1904, after which it was exhibited at the Louisiana Purchase Exposition.

After the closing of that exhibition the locomotive was brought to the Connellsville Division and put into regular service on January 6th, 1905.

For the purpose of increasing the capacity of an eastbound track, balancing of the power on the division, and to reduce the number of locomotives and crew required to handle heavy freight tonnage over a busy moun

tainous district, it was necessary to produce a locomotive with maximum adhesion for tractive and braking power, a minimum rail pressure per driver wheel, and a short rigid combined with a long flexible driver wheel base, to adapt it to a mountain line having considerable curvature and gradient. To accomplish this it became necessary to Americanize foreign railroad practice by making use of the Mallet articulated feature, which permits of the use of a maximum effective wheel base, with a materially reduced rigid wheel base, and provides for a helper locomotive that can develop an average through freight train speed without excessive wear: The sub-dividing of the power through the use of four independent cylinders, pistons, main rods, crank pins and frames, in place of two, and the better balancing of the reciprocating parts, results in less strain on all parts, and reduces the liability for breakage and failure.

While the wearing and total parts per locomotive are increased, they are greatly reduced when compared with the development of the same power by tandem locomotives, and the reduction in concentrated stresses and weight insures a more satisfactory and economical maintenance of those details most susceptible to depreciation.

To reduce the water and fuel consumption and relieve the boiler of unnecessary punishment, the duplex Mellin system of compounding was introduced, with an arrangement of independent high and low pressure cylinders, equipped with inside admission piston and double ported flat valves, respectively, providing for a uniform and maximum tractive effort, large receiver capacity and accessibility for inspection and maintenance.

The application of a motion gear to give good steam distribution; maintain permanence of adjustment; overcome the disadvantage of extreme reciprocating, revolving and suspended weight, wear and liability for failure, as in the modern development of the Stephenson eccentric driven link gear; provide opportunity for substantial bracing of the main frames, and to give accessibility to driver axle bearings, and reduction of motion gear parts and bearings with arrangement in the same vertical plane, accessible for inspection, lubrication, cleaning and maintenance, was given careful thought, with successful results, through the application of the Walschaert gear. The use of this motion also provides a location for the brake cylinders, by which means the brake shoes can be applied to the forward moving side of the driving wheels, which insures more uniform braking action and relieves the running and brake gear and frames of excessive reverse stresses and vibration during the use of the brakes.

All direct pressure steam pipes are outside and rigidly connected between the boiler and cylinders, and the flexible pipes being only made use of to convey the receiver and exhaust low pressures, has provided for a design and construction that will insure against such leakage of any of these joints as would make their use undesirable. The removal of all but the exhaust pipe from the smoke-box eliminates the objectionable steam pipe arrangement between the boiler and cylinders, which is generally followed out in American locomotive design.