valuable for practical use in the machine shop. It may be readily placed in confined situations where an arc light could not, and it may be used much nearer the eyes of the workman without injury.

It would therefore seem wise, in devising a system of artificial lighting, to avail ourselves of the advantages offered by both the arc and the incandescent lamps, each in the places where their special merits can be made use of. Both types of lamps may be operated by the current from one dynamo, by the use of proper transformers, but it will usually be found more practical to put in a dynamo specially designed for each system.

More recently a light has been produced by the action of an electric current upon mercury confined in a glass tube two feet or more in length. A peculiarity of this light is to render yellow tints more pronounced and giving a peculiar green tint to many objects.

Ample space has been provided in the engine room for dynamos for this purpose, as well as for furnishing the necessary current for operating the traveling crane in the machine shop and the power required in the foundry.

In the machine shop the clear space needed for the traveling crane precludes the suspending of arc lamps through this central portion, but they may be placed between and a little inside of the line of the columns. They should be about 50 feet apart, which would require 14 lamps on the main floor. In addition to these a sufficient number of incandescent lamps should be provided to accommodate the individual needs of the men operating machines, wherever such additional illumination is necessary from the location of the machines and the character of the work.

They should also be provided at the small tool-distributing room and in the foremen's offices, and a number should also be hung upon the columns, having sufficient length of conductor cord attached to them so that they may be used in erecting machines in the central space.

From the character of the machines employed and the work done in the galleries the incandescent lamp will be the most suitable. There should be at least one to each machine and in the case of long lathes one to every ten or twelve feet of bed. A lamp should also be hung at the head of each stairway.

The large open space of the foundry may well be provided with arc lamps, four of which will be sufficient, supplemented by a few incandescent lamps with long cords hung on the columns, for use in deep molds and similar places left in darkness by the arc-light shadows.

The chipping and pickling room will require one arc lamp and several incandescent lamps, all provided with wire nettings for protecting them from flying chips. The core room, wash room, foreman's office, water-closets, the space under the cupola platform, etc., will require incandescent lamps.

The forge shop will be best served by two arc lights in the main part,

and by incandescent lamps in the foreman's office, wash rooms, water-closets and perhaps in the bar stock storage space.

One arc lamp in the storehouse and one in the carpenter shop, with perhaps two or three incandescent lamps in the latter, will be sufficient.

The boiler room will require an arc lamp hung over the tram track so as to fully illuminate the boiler fronts, and two or three incandescent lamps convenient to the space in the rear of the boilers and in similar places. The same number and kind of lamps will answer for the engine room. The adjoining wash rooms and water-closets should be provided with incandescent lamps, say four in each of the former and three in each of the latter.

An arc lamp erected on a pole 20 feet high should be located in the yard between the foundry and the power house and about 35 feet from the machine shop. A similar one should be placed in the center of the space between the storage sheds, carpenter shop, power house, and the forge shop. These will greatly facilitate yard work near the close of the short winter days.

The entire front building, including the offices, tool rooms, pattern shop, pattern storage loft, drawing room, etc., should be lighted by incandescent lamps, those in each room being arranged to suit the peculiar conditions in each case, as to the kind of shades and reflectors employed.

To equip the entire plant as described above will require say 27 arc lamps and 267 incandescent lamps, the latter number being somewhat lessened or considerably increased according to the character of the machinery to be manufactured, as whatever change in this respect is made would most likely affect the incandescent lamps and possibly the arc lamps as well.

In providing for the amount of current necessary to supply this system of lighting we should make allowance for any possible increase that may be called for by unforeseeen circumstancs, or by a change in the products of the concern, and it would usually be safe to add for this purpose at least 10 per

cent.

The power necessary to run the dynamos with the added 10 per cent will be about 30 horse-power for the arc lamps and 20 horse-power for the incandescent lamps, or a total of say 50 horse-power to be provided for, in calculating the capacity of the proposed engines.

By referring to the general plan drawing given in Chapter II, the arrangement of the lamps as herein described may be readily understood.

CHAPTER XIV

POWER AND TRANSMISSION

It is ofttimes a complex subject. The different systems. Steam is at the head. Electricity. Compressed air. Transmission of power. Various systems. Belts. Ropes. Chains. All systems are merely that of transmitting power. Water and steam are our original sources of power. The systems of transmission, or distribution of power. The boiler room. Types of boilers. The best type. Mechanical stoking. Boiler settings. Longitudinal section. Cross-section. Horizontal section. Smoke connections. Steam connections. Foundations for boiler settings. Gas engines. Steam engines. Transmission by belts and shafts, or by electric motors. Compressed air for foundry and forge shop. Compressed air in the machine shop. Motors for individual machines. The system adopted. Lighting dynamos. Driving the steam hammer in the forge shop. Boiler and pipe coverings.

IN considering the question of power and its transmission to the different points in the plant where it will be required, we are confronted by a rather complex subject, and one which has been much discussed by many competent engineers in nearly all the mechanical journals during the past few years. Steam is now, and for probably an indefinite time will be, the favorite and controlling power generator, since to it we owe all other forms, not of power, but of the transmission of power. The various methods and theories have had able champions in the special line in which they have been interested, and rival claims have been ingeniously advocated to prove that they were the best methods to be adopted for nearly all conditions.

One class have proven, to their own satisfaction at least, that while electricity is still in a very imperfect state of development and generally very imperfectly understood by a large majority of mechanics, it is to be the coming power for all purposes and may be used under nearly all conditions. Many of these claims have been well substantiated and the fact is that to-day there is a far greater and more general use of electricity in transmitting power than was thought possible even ten years ago. The ultimate limit to its usefulness

no one can foresee.

Again, the advocates of compressed air have shown that this has many advantages as an easily transmitted and very useful power, and in its special sphere is doing very efficient and admirable work. New applications are

constantly being found for it, and many operations formerly performed by hand are very much quicker, cheaper, and better accomplished by its use. The sphere of its usefulness has broadened very much in the last few years and now we find it in nearly all up-to-date shops, for a large variety of purposes. In this it does not take the place of electricity, but rather is used in conjunction with it, or with steam power for the purpose of providing the compressed air, as may be most convenient.

The old-time mechanic is, however, apt to "pin his faith" to shafting and belts as the most reliable method of transmitting power, perhaps because he is better acquainted with this method; while the younger men are prone to argue the efficiency of rope transmission as the proper method. Many examples of efficient service by rope transmission might be cited, yet for the general purposes of a machine shop it is doubtful if it will ever replace leather belting altogether.

Recently the utility of transmission by chain has been revived and the interest in the subject very much increased by the improved forms adopted by later inventors. It is often exceedingly useful for the transmission of power within the limits of a single machine, formerly for operating feeds, and later for transmitting the principal power of the machine. Properly constructed, this system would seem to have a broad and practical field of usefulness in the future.

But all of these methods and systems, when reduced to the plane of practice in providing for the power plant of manufacturing concerns, are simply so many different methods of transmitting and distributing power, since it is to water or steam that we must look for our original power. We are confined, then, to these two sources of power water and steam and where the location does not provide us water power we must accept steam. Assuming the latter conditions in our manufacturing plant we must provide for steam as our source of power.

This having been settled, the best means of transmitting the power to the machines on the ground floor of the machine shop, to those on the gallery floors, to those in the tool room and pattern shop, and to the forge shop, foundry, and carpenter shop, must also be considered.

The question of boilers will naturally come first, and, in this connection, the type best adapted to the work; also the best method of setting them to produce the most efficient results. Next, the type and the dimensions of the engine, and the manner of its connections. And lastly, the method of transmitting the power to the machines to be driven.

In arranging our power plant we begin with the boiler room. We shall need a working capacity of at least 500 horse-power. This may be distributed in a battery of boilers of 100 horse-power each. One extra boiler is added so

that in case of an accident to one of them, necessitating repairs, five of them may still be in proper working condition. Four of these boilers will be needed to run the engine, which leaves a margin of 100 horse-power with which to supply the necessary steam for other purposes about the plant.

Under ordinary conditions a sixth boiler may be added, giving 200 horsepower for these purposes. By this arrangement there is the additional advantage that the boilers may be cleaned one at a time without shutting down the power.

The styles and types of boilers in the market are many and various, and most of them have good and practical claims to consideration in one way or another. But it is somewhat doubtful if any type will be devised that will become as popular for general use or in the long run any more efficient and economical for hard,. every-day service as the return tubular type.

Ofttimes the space in which the boilers must be located will determine the type, whether they shall be upright or horizontal; and the method of firing them, as well as the kind of fuel to be used, must also be taken into consideration.

Mechanical stoking is used with success in some instances, but as yet has not come into general use. Both oil and natural gas as a fuel are much

used in such localities as render them more economical than coal.

Our boilers will therefore be of the return tubular type, fired by hand, with the usual kind of soft or bituminous coal. They will be 66 inches diameter and 16 feet long, exclusive of the curtain sheet under the space occupied by the "up-take," or smoke connection.

The arrangement for setting the boilers is shown in vertical, longitudinal section in Fig. 75; in a half vertical cross-section, and half front elevation in Fig. 76, and in a horizontal section above the grate line in Fig. 77.

There are several matters in connection with the setting of boilers which should be strictly attended to. Among these are the following: Two courses of bricks should be laid above the floor line of the boiler room for the boiler fronts to rest upon; the top course at least should be headers, and carefully leveled up. They should be so located that at least two inches will project in front of the boiler fronts. The ashpits should be cemented so as to allow of the introduction of a few inches of water.

The front supporting brackets should rest fairly upon iron plates in the side walls, while the rear brackets rest on rollers, which in turn rest on the iron plates set in the walls, by which arrangement all expansion of the boiler is toward the rear. The brickwork around the brackets should be entirely clear of them so as to leave the boilers opportunity to expand and contract without injury to the walls.

The grates should incline from front to back from to inch per foot.