motors under the cars by means of this trolley; the rails of the track, upon which the car runs, being used to carry the current back to the generator. Where the motor car is to be run inside of buildings, however, two trolley wires are used, one for the same purpose as before, i. e, to carry the current to the motor, while the second is used for carrying it back instead of the rails. This is done in order to have a thoroughly insulated system throughout, and to do away with any sparking which might occur between the rails of the track and the revolving car wheels. The amount of power generally used by motor cars in ordinary tramway work is either three horse-power or six horsepower; the former easily handling a load of five thousand pounds, and the latter a load of ten thousand, exclusive of the weight of the car, at a speed of four miles per hour on a level and straight track. These motors are mounted upon platform trucks of any convenient dimensions. As they are hung from the axles of the trucks, the platform itself is available for carrying the load. These cars can also be used for towing other small cars, if desired, thus increasing the carrying capacity of the system very materially. For hauling heavy loads, such as loaded freight cars, electric locomotives of thirty horse-power and over have been designed. These larger machines are also so constructed that the platform of the machine itself is available for loading, if so desired. of The small motor cars are built to operate on any gauge track from 30" to the standard 4' 8". The controlling device is extremely simple and is so placed upon the car that one man operates it with entire control of direction and of speed. Ordinary curves and grades offer no serious objection to the operation of the system, as electric cars are now doing successful work on tracks having curves of less than fifteen feet radius and grades of over twelve per cent. As before stated, the same generator used for furnishing power to stationary motors throughout the mill is equally available for supplying the necessary current for propelling the tram cars. However, should there be no other work performed about the mill electrically, a generator of sufficient size to operate the tram-road can be placed in the engine room or wheel-house, and run directly from the existing power; the engineer or wheelman being perfectly able to give it what little attention it may require, without in any way interfering with his regular duties. For transporting large and heavy loads about a mill, there are but two other systems besides the electric suitable for the work, i. e., steam and cable tramways. The former is not desirable for two reasons: First, the large annual cost for operating a locomotive, as compared with almost any other motive power. Second, a locomotive would be dangerous about a cotton or woollen mill, where there is inflammable material liable to take fire by sparks from it; particularly, as is frequently the case, where power is required for both out-door and interior use. The cable system has disadvantages also. Inasmuch as direction of motion of the cable is always the same, the cars would necessarily always move in the same direction in passing a given point, unless a second track be used having the return cable running in the opposite direction. This, in most mills, would be utterly impracticable and almost impossible. Again, the cable system is costly in power consumed, because the dead weight of the cable together with its frictional resistances has to be overcome at all times, whether cars are in actual use or not. With an electric system, however, the cost of operating is practically nothing when the car is not in use; when it is, the power consumed is directly proportional to the load carried. The cost of maintaining a cable system is much greater than that required by an electric, because of greater wear and tear. In fact, the same arguments used in favor of electric street cars over cable cars can be applied to these systems in tramway work; and the best proof of the superiority of the one over the other is shown by there being in August, 1890, two hundred and fifty-eight electric railways in the United States alone, with one thousand nine hundred and twentyseven miles of track and three thousand and twenty-four cars in daily service or under construction, while cable roads are still comparatively a novelty. The electric car also far exceeds the steam locomotive in its ability to climb grades. The latter is unable to overcome a rise of over two or three per cent. under favorable conditions, while, as has been stated, electric cars are working successfully on grades of over twelve per cent. This is an additional point greatly to the advantage of the electric system. The Thomson-Houston Motor Company, which is doing the only business in the direction of mill tramways, has in operation or under construction at this time no less than fourteen roads equipped with tram cars or locomotives of from three to sixty horse-power each and capable of hauling loads of from five thousand to one hundred and twenty thousand pounds, at a speed of from four to six miles per hour. The first mill tramway to be equipped by this company is located at the Tremont and Suffolk Mills, Lowell, Mass. The entire length of the track is about eight hundred feet, with a three per cent. grade. The car runs from one building, over a bridge, and the entire length of another building. The illustration (Fig. 2) shows the motor car in the interior of the mill. The car is used for transporting baled goods from the cloth room to the storehouse. The next tramway equipped by the motor company is located at the mills of the Salmon Falls Manufacturing Company, Salmon Falls, N. H. In this case the car runs upon a track of standard gauge (4' 8") laid with T rails. The platform of the motor car is fourteen feet long by six feet wide, and the truck is equipped with two motors of three horse-power each. This tram car is used for carrying cotton, and it is capable of handling a load of over three tons upon a five per cent. grade. The accompanying illustration (Fig. 3) shows the car standing upon a grade and being loaded with cotton. |