The third rail system of electric traction is now in permanent operation on an important section of a leading steam railroad. The recent opening of the line from Berlin to New Britain and from New Britain to Hartford, while it is by no means the first successful operation of third rail traction, is notable as being its first application in a permanent way to the lines of a standard steam railroad.

The first extensive test of this system took place within the grounds of the World's Fair, at Chicago, where its operation was very satisfactory. It was then adopted on the elevated roads of Chicago, where it has given reliable service. The Brooklyn Bridge trustees decided that it was adapted to the requirements of bridge traffic, and laid a third rail on the outside of the tracks. The equipment has given a good account of itself, especially in the switching operations at the terminal stations.

It is stated by Col. N. H. Heft, chief of the electrical department of the New York, New Haven & Hartford Railroad, who has afforded us every facility in the preparation of the present article, that the probability of electricity entering largely into the operation of steam railroads was suggested to the directors by Mr. Clark in his annual presidential report made in 1891. It was natural that the attention of this company should be turned to the question of electric traction, for the reason that their passenger traffic was being exposed to severe competition from the network of suburban and interurban trolley lines which have sprung up throughout the country served by the New Haven road. Fully one-half of the gross receipts of this road is realized from passenger traffic and a large proportion of this is obtained from local traffic, of a character for which suburban trolley car service has most attraction.

The first step taken by the company was to form an electrical department, and give orders for the electrical equipment of a stretch of their road which runs from Nantasket Junction to Pemberton, Mass. This equipment, which is commonly known as the Nantasket Beach line, was put in operation in 1895. Overhead conductors were used and the experiment was highly successful. The company then determined to test the third rail system of transmission, and a trial line was laid down in 1896, when an additional 3½ miles of road was placed in service. The operations at Nantasket were regarded by the company as being experimental and preparatory to a further extension of the system. The results were so promising that it was determined to apply the system on a larger and more permanent scale, embodying in the new line the results of previous experiments.

The equipment which has recently been put in operation is applied to two lines of steam railroad, one extending from New Britain to Berlin and the other from Hartford to New Britain, the total length of the line from Hartford to Berlin being 12.3 miles.

The power station has been built with a view to its enlargement as the electric equipment is extended. The building shown in the accompanying engraving is 106 feet wide by 117 feet in length, the end on which the extension will be added being temporarily walled in with wood planking. The present building contains two stories in the front devoted to the engine and generators, etc., and a boiler room in the rear extending the full height of the building. A 1,200 horse power engine is already in place and the foundations have been built for a second. There is room in the building for a third engine when the extension of the line calls for it. Further details regarding the engines and the boilers will be given in a later issue. The engine is direct connected to a General Electric Company's standard 10 pole, 850 kilowatt generator of the well known ironclad type, which furnishes current at 600 volts no load and 650 volts full load.

The third rail conductor is of a special section rolled for this purpose. It resembles somewhat a flattened A, the flanges forming a protection to the insulating blocks upon which it is laid. The rail is heavy, weighing ninety-three pounds to the yard, and it is found that wooden blocks saturated with insulating material give excellent service, and three to the rail are found to be sufficient. The flanges of the rail come within 1½ to 1-five-eighths inches of the top of the ties, the head of the rail being one inch higher than the main rails. It will be seen that this conductor is carried much lower than that on the Nantasket line, the difference being due to the height of the main rails. The ends of the rail are bonded by sheet copper plates one-eighth inch thick, 4½ inches wide and 12 inches long, which are held against the under side of the flanges at the rail ends by iron plates. The latter are bolted to each rail by sixteen bolts, eight for each plate, the copper bonds being sandwiched between the iron plates and the rail. The capacity of each bond is 900,000 circular mils, the double bond having more than the carrying capacity of the rail itself.

On the whole line there are twenty-two grade crossings, at each of which the third rail is replaced by underground cables of 850,000 circular mils. The cables are drawn into creosoted wooden conduits filled with an insulating material made of residuum and asphalt. The conduits are laid in creosoted wooden troughs filled with the same material, which are buried in the earth. Special attention has been paid to the return circuit, as it is the opinion of Col. Heft that the importance of this element is too often overlooked in the construction of electric roads. The company has put in leaf bonds of 550,000 circular mils, and these are attached to the base of the rail in preference to the web, and are secured by wedge fastenings. In order to prevent any interruption to the current when a train is passing over switches and crossings a shoe is provided on the rear car of a two-car train. This insures that connection will be made by the shoe of the motor car before the shoe of the second car has entered the gap.

The general appearance and mechanical details of the open cars are shown very clearly in our front page and other illustrations. They are 51 feet long, and are provided with sixteen seats, each of which can accommodate six passengers, the capacity of a two-car train being, therefore, 192 passengers. The current is taken from the third rail by means of a sliding contact shoe, which consists of a simple cast iron plate 5 inches wide by 12 inches long, weighing about 12 pounds. It is carried by an insulated support, to which it is fastened by jointed links, which allow it to bear upon the rail at all times with a pressure due to its own weight. Each train is made up of a motor car and a trailer. Each motor car has two 125 horse power motors, both of which are mounted upon one track, as shown in the accompanying engraving, in which the casing has been removed to show the gearing of the forward motor.

It can well be understood that in a service of this kind, where the high speeds which are customary in the steam service are to be regularly made, special attention had to be given to the question of braking. As hand-operated brakes were out of the question and steam was not available, it was determined to equip the motor cars with a separate electrically driven air brake plant. The details of this successful and highly creditable work are shown in the upper front page engraving and its position on the front platform is shown in the side view of the car.

The two cylinder, single acting compressor is driven by a direct connected 10 horse power motor. The compressor has a capacity of 52½ cubic feet of air per minute under a gage pressure of 90 pounds per square inch. The speed is 250 revolutions per minute and the consumption 16 amperes at 600 volts. The standard Westinghouse air brake equipment of the company is used on the cars, and it is controlled by the usual engineer's valve, as shown in the engraving. One of the most ingenious features is the automatic valve and switch for starting and stopping the compressor, of which a sectional view will be found on the front page. By reference to the engraving it will be seen that air is led in above a small piston, which works in a vertical cylinder and is pressed upward by a coil spring. The spring is set at the working pressure of 90 pounds to the square inch. As soon as the air pressure exceeds 90 pounds, the piston is forced down, carrying with it a small vertical valve stem and allowing the air to pass up into a small Cylinder located beneath the electrical switch which controls the motor of the air compressors. Here it pushes up a piston which throws over the electrical contacts and opens the switch. As the air pressure falls it releases the lower piston, which rises to its normal position. As it rises, a catch on the piston rod lifts the small lever shown to the left and opens a release valve below the switch cylinder above mentioned. The upper piston now falls and closes the switch, thereby starting the motor of the air compressor. The device has given complete satisfaction. It may be set to work at from 45 to 100 pounds pressure, and on a variation of from 5 to 7 pounds pressure.

The air compressor is placed, as shown, on the front platform of the car to the left of the motorman. In front of the compressor is the wheel of the hand brake, and conveniently arranged in front of the motorman are the pressure gage, the engineer's air valve and the controller. The lever for operating the air chime whistle passes through the hood just above the motorman's head. Beneath the hood on the front of the car above the door are the current breaker and the main switch. On the front rail of the platform there is also a conductor's signal whistle.

The current passes from the shoes through flexible copper cables to the circuit breakers. After passing through these it is led through a lightning arrester and a "kicking coil." It then divides, passing to the controllers on each platform. At each controller it passes through a magnetic blow-out coil, and is led by cable to the resistance situated in the center of the car. It then returns through the resistance contacts to the controller cylinder and the motors.

The danger to the public from the use of the third rail is considerably less than is popularly supposed, and in view of the precautions which have been taken to safeguard the ignorant or unwary, the chance of accident is very small. At the Berlin and Hartford stations the third rail section is fenced in on both sides. At New Britain, where the two lines converge, a switchman's tower has been built in the Y where the roads converge. Underground cables connect the rail where it enters the station with a switchboard in the tower. When a train has stopped in the station the third rail is cut out, and it is not thrown in until the train is ready to start again.

When the road which has now been electrically equipped was operated by steam, eight trains a day were run each way between Hartford and New Britain, and fourteen trains a day between New Britain and Berlin. Under the present system of two-car trains will be run every half hour between Hartford and New Britain from six in the morning till twelve at night. The run of 9.3 miles will be made in something under twenty minutes, and the fare will be ten cents each way. Sixteen trains a day will be run between New Britain and Berlin, a distance of three miles, the fare being five cents for a single trip.

We reserve further particulars and illustrations of this interesting plant for a later issue.