hundred volts, as this would insure the greatest economy in copper wire, without danger to persons handling the apparatus.

These machines, set upon substantial brick or stone foundations and fed with the best dynamo oil, should need practically no attention except at starting and stopping, as the modern generator is so wound that the voltage or electrical pressure is kept constant under any variation of load.

It is always better, where there are two or more machines in a generating station, to drive each of them from the existing water or steam powers through the medium of a friction clutch; by this means any one of them can be stopped, if necessary, without any other part of the machinery being shut down.

Let us now take up the different heads before enumerated, always bearing in mind the fact that the same generators can be used for all classes of machinery mentioned hereafter.

Electricity as applied to isolated motors, located in different parts of a mill, and used to drive lines of shafting, separate machines, etc.

The amount of power which would be saved by doing away with cumbersome jack shafts, heavy pulleys and dangerous belting has never been considered by many. As a rough approximation, one hundred feet of shafting, three inches in diameter, and making one hundred and twenty revolutions per minute, requires one horse-power to overcome its friction, under conditions of fairly good alignment and good care. Should this shafting become out of alignment, as is frequently the case, its frictional resistance would be proportionally increased.

It has been estimated that from thirty to fifty per cent. of the power generated in mills and factories is unremunerative, because of the wasteful method of driving in vogue at the present time. Should a judicious arrangement of electrical transmission be employed, on the contrary, fully eighty-five per cent. of the power developed by the wheels would be expended in useful work.

That the transmission and distribution of power by electricity is a profitable investment is proven by the large number of electric stations scattered throughout the country, and furnishing power to a large number of consumers, in small and large units. Not only can power be saved by electrical transmission, but also a large amount of space is made available for other purposes. An electric motor is of such dimensions that it can be suspended entirely out of reach, if necessary, on shelves or by other means, and driven in this position.

The following table shows the weight, floor space and outside dimensions of the standard motors manufactured by the Thomson-Houston Electric Company, of seventy-five horse-power and under:

NOTE.

The motors of the higher classes, from twenty horse-power, inclusive, are furnished with cast-iron sliding bases.

Another point which should be considered by mill men, and which would seem to be a very essential one, is this:

* Approximate.

By a subdivision of shafting into small units, a much more complete control is had over it in case of accident or of any breakdown which is liable to occur, and which means, as mills are driven to-day, the shutting down of an entire room and sometimes of an entire factory, at an immense loss, while repairs are being made.

On the contrary, should motors in small units be used, simply that portion of the room in which the breakdown occurred would be stopped, the rest of the mill running as before.

It is unnecessary to go to the motor in order to stop it, it being a very simple matter to arrange a supplementary electrical system of running throughout the factory which will enable any employee, who should see the necessity of so doing, stopping the machine from different parts of the

room.

As an electric motor has but one running part, the armature, there is very little about the machine to get out of order; but should an accident happen to any part of it, this can, under ordinary circumstances, be quickly repaired. If, however, the injury be of such a nature as to render it necessary to send to the manufacturer, a duplicate part could be returned in a comparatively short time.

The question of the spreading of fire in mills is one of great interest to mill owners, and anything that could be devised to aid in preventing this should be carefully considered. One method which naturally suggests itself is to isolate each room in a factory, as far as practicable, by closing all belt holes in floors and walls, thereby getting rid of that very dangerous element, the risk of carrying fire from floor to floor and room to room. No better method can be secured to accomplish this than the use of electricity for transmission. In cases where belt towers are used the arrangement is generally a very costly one.

The danger of fire occurring from the use of electricity has been reduced to a minimum by the many safeguards and protectors which are to be found in all well-installed plants.

The New England Insurance Exchange state, over their signature: "Permission to use electric motors has been fully granted in all risks controlled by this Exchange when properly installed. Under those conditions they add nothing to the danger from fire, and in our opinion are greatly to be preferred to steam-engines with their attendant danger. From an insurance stand-point, we heartily welcome the electric motor."

A notable instance of the use of electric power in the factory was in 1885, when the driving of all the shafting and machinery in factory "A" of the Thomson-Houston Electric Company was accomplished by using a motor of sixty horse-power capacity. The power required was from fifty to fifty-five horse-power. The company now employs in its factory over twenty stationary motors in the various departments, for the distribution of power.

By a properly proportioned winding of the armature and fields, automatic regulation of speed of less then two per cent. variation is obtained on all of the Thomson-Houston motors, no matter what the variations of load may be. This feature is of special value, as it permits the simplest possible construction of the motor and at the same time secures an automatic regulation of speed well within the range of that which is guaranteed for the best regulated high-speed steam-engines.

The next head to be considered is the application of electricity for driving tram cars.

The electric mill tramway, in its sphere, has operated fully as successfully as the electric street railway, although its adoption has not been so general. As yet many of the mills are not entirely willing to give up their old methods of transporting goods in and about their mill yards by means of hand or horse power, and to install an electric tram-road, the first cost of which will amount to considerable, but, after once put in, meaning a saving in operating expenses.

A mi tramway is practically a modified electric street railroad, the principle of propulsion being the same. Usually a single overhead trolley system is used, as in street railway work, the electricity being carried from the dynamo to the