A regular service was established, according to a fixed time-table, to which each motor was required to conform. Each journey was reckoned as starting from the end near the exhibition, proceeding to the beginning of the triangle, and returning to the starting point. An hour was allowed between the commencement of each journey, fourteen minutes were allowed for a stoppage at the end near the exhibition, and eighteen minutes at the other end—thus allowing twenty-eight minutes for traveling 2 miles 1,500 yards, or a traveling speed of about 6 miles an hour. The motors were required to work four days out of six, and on one of the four days to draw a supplementary carriage.
An official, assisted by a storekeeper, was appointed to keep a detailed record—
1. Of the work done by each of the motors.
2. Of any delays occurring on the journey, and of the
causes of delay.
3. Of the consumption of fuel, both for lighting the
fires and for working.
4. Of the consumption of grease.
5. Of the consumption of water.
6. Of all repairs of whatever nature.
7. Of the frequency of cleaning and other necessary
operations required for the efficient service of the
motor.
The experiments lasted about four months. Five competitors offered themselves, which may be classed as follows: Three were propelled by the direct action of steam, and two were propelled by stored-up force supplied from fixed engines.
Propelled by the direct action of the steam. 1. The Krauss locomotive engine, separate from the carriage.
2. The Wilkinson locomotive engine (i.e., Black and
Hawthorn), also separate from the carriage.
3. The Rowan engine and carriage combined.
Propelled by stored-up force. 4. The Beaumont compressed-air engine.
5. The electric carriage.
It is somewhat to be regretted in the public interest that other forms of mechanical motors, such as the Mekarski compressed-air engine, or the engine worked with superheated water, or cable tramways, or electrical tramways, were not also presented for competition.
1. The Krauss locomotive is of the general type of a tramway locomotive, but with certain specialties of construction. It has coupled wheels. The weight is suspended on three points. The water-tanks form part of the framing on each side; a covering conceals all except the dome of the boiler. Above the roof is a surface condenser, consisting of 108 copper tubes placed transversely, each of which has an external diameter of 1.45 inches. The boiler is similar to that of an ordinary locomotive; its axis is 3 feet 10½ inches above the road. The body of the engine is 9 feet 11 inches long, and 7 feet 2½ inches wide. The axles are 4 feet 11 inches from center to center. The platform extends along each side of the boiler; the door of the fire-box is in the axis of the road. The engine driver stands on the right-hand side, in the middle of the motor, where he has command of all the appliances for regulating the movements of the engine as well as of the brake.
The Wilkinson (Black and Hawthorn) engine had a vertical boiler and machinery. The cylinders were on the opposite side of the boiler from the door of the fire box, and mounted independently; the motion of the piston was communicated by means of a crank shaft and toothed wheels to the driving axle. The wheels were coupled. A regulator, injector, and a hand-brake were placed at each end, so that the engine driver could always stand in the front, whichever was the direction in which the engine moved; and there was a platform of communication between the two ends, carried along one side of the boiler.
The boiler was constructed with "Field" tubes, the horizontal tube plate having a flue in the middle which carried the heated gases into the chimney.
The visible escape of the steam is prevented by superheating. To effect this, the steam, as it leaves the cylinder, passes into a cast iron chamber adjacent to the boiler, which is intended to retain the water carried off with the steam. From thence the steam passes into a second chamber, suspended at a small height above the grate in the axis of the boiler and of the flue which conveys the heated gases into the chimney, and thence into a sort of pocket inclosed in the last-mentioned chamber, which is open at the bottom, and the upper part of which terminates in a tube passing into the open air. This method of dissipating the steam avoids the necessity of a condenser; but if it be admitted that the steam in escaping has a minimum temperature of 572° Fahr., it will carry away 12 per cent. more caloric than would have been required to raise it to a pressure of 150 lb. per square inch.