The floors of the wash rooms in the power house are of 1 x 6 inch matched planks, planed on both sides, and laid on 2 x 12 inch joists placed 16 inches from center to center. Iron or steel floors may be here used to advantage on account of the disagreeable odors produced by saturated wood floors.

Floors in the office building, including the drawing room and pattern. shop, are laid with a lining of ordinary pine 3-inch thick, and covered by 1-inch hard pine, planed and matched, and not over 3 inches wide, with the grain of the wood as shown in Fig. 47.

The floors are laid on 3 x 12 inch joists placed 16 inches from center to center and supported by 10 x 12 inch beams set 12 feet from center to center.

For the second floor these beams are supported on iron columns in the office and on 8 x 8 inch posts in the tool room, set 16 feet apart, making four posts or columns in the building 50 feet square, outside measurement.

The timbers of the ground floor are supported on brick piers rising from the ground, which is excavated to a depth of at least three feet below the floor. One of these piers is under each post or column.

In place of wooden beams and joists, iron or steel girders or I-beams may be introduced, making a construction more nearly fire-proof, particularly for the second floor, but adding materially to the expense.

The floor of the pattern storage loft is of 1-inch matched planks laid on 3 x 12 inch joists placed 16 inches from center to center and supported by I-beams inches deep, one end resting in the front wall and the other on an 18-inch box girder carrying the rear wall and resting on iron columns, as shown in the plan.

15

As to the kind of lumber used in the floors of manufacturing buildings, spruce is by far the most common, and if properly selected is best for all ordinary purposes. Hard pine makes an excellent floor and is preferable where extra expense is not an obstacle.

Occasionally, when cost is a secondary consideration, and a perfectly smooth surface is necessary, floors of hard maple are laid and carefully surfaced off by hand-planing. This makes probably the most durable of any of the wood floors.

The author saw a floor about 125 x 250 feet, prepared with a concrete bed and then laid on the wet flowing coat with hard maple blocks 2 x 4 x 12 inches, laid on edge, and in the "herring-bone pattern" shown for bricks in Fig. 43. After the concrete had thoroughly set the surface was hand-planed and oiled.

Of whatever kind of wood floors are made the material should be well seasoned, and if shrinkage cracks are to be avoided, the narrower the planks are the better, although 3 inches may be the minimum width.

If they are 3 inches thick or more, then 6 inches should be the minimum width.

CHAPTER XII

THE SYSTEM OF HEATING AND VENTILATION

Various heating systems. Leaking steam pipes. The condensation nuisance. Hot water heating. Hot air furnace. Of heating and ventilation. General requirements of a heating system. Form, size, and location of pipes. Construction of elbows, tees, Ys, and branches. The heating apparatus for the machine shop. Plan and cross-section. Heating surface required. General plan of the system. Location of the heating apparatus. Power for driving fans. Steam for heating. Heating apparatus for the foundry. Plans and cross-sections. Heating the office building. Plans and longitudinal sections. The proper temperatures for the different buildings.

THE Construction of our several buildings being now completed and all arranged with proper consideration of the existing conditions and the expected circumstances by which we shall be governed, it is necessary that we should arrange for their proper and efficient heating and lighting. In this article the first of these questions, that of heating, will be considered.

There are many systems of heating buildings, among which are: By means of exhaust steam or of live steam, in lines of pipe arranged overhead or along the walls; by coils or radiators; by hot water utilized in a similar way; by air heated by furnace arrangements or by contact with pipes through which steam flows. All these systems have their good and bad features, both as to their warming qualities and their cost, as well as the expense of operating them. The hundreds of feet of steam pipes, with their numerous fittings, furnish at each joint opportunities for leaks, and special arrangements must be made to keep them clear of water. The distance from the boiler to the further end of long systems frequently requires much time to force enough steam to these points to warm the rooms so that they will be endurable to workmen.

The hot-water system works slowly and the temperature of the surrounding air rises gradually, so that the hour for beginning work in the morning must. be anticipated by such a length of time as to be a serious drawback to complete success. The hot-air furnace gives air from which much of the moisture is evaporated and which is therefore unwholesome, aside from the fine dust so often brought along with it. In all these systems heating is the only end gained, ventilation being left largely to chance.

The ideal system of warming and ventilation would seem to be that in which fresh air, warmed by steam heat, is distributed by a suitable mechanical process, as evenly as possible to every part of the building, and one in which this can be done in the shortest time (as in most shops the heat is not maintained during the night except at sufficient temperature to prevent freezing of water pipes, etc.), and in which cold air may be readily introduced whenever needed.

This seems to be best accomplished by drawing fresh air from without the building, passing it through a heating apparatus consisting of an iron case containing a large number of steam pipes, and, by means of a fan and suitable pipes, distributing this warmed air to every part of the building by numerous outlets. The whole should be controlled by proper dampers, by which a due proportion of warm and cold air may be furnished as needed, so that proper ventilation as well as warming may always be maintained.

In the warming of such large buildings as those under consideration it is not necessary to draw cold air from the outside atmosphere to any great extent. The number of cubic feet of air contained in the building is largely in excess of that required for each person; and, moreover, cold air comes in through frequently opening large doors, while the swinging windows at the roof may be opened when necessary to permit the vitiated air to pass out, thus providing ample ventilation.

Many pages might be written on this subject, but space permits only a few general requirements which are practically indispensable, and may be summed up as follows:

The heating apparatus should be located near the center of the building so as to distribute the warm air to all points with the least amount of piping. Openings should be so arranged as to be not over 30 feet apart, and to open toward the outer walls of the building. They should not be less than 8 feet above the floor, nor less than 5 inches diameter, and usually incline downward at an angle of about 10 degrees. The aggregate area of openings should exceed the area of the main pipe at the fan by about 25 per cent.

About 6 square inches area of openings should be allowed to every thousand cubic feet of space contained in the building or room, where the building is so divided. The velocity of air should not be less than 1,500 feet per minute, and a sufficient quantity should be supplied to change the air every 15 to 20 minutes.

The pipes are preferably circular, as less material is required to make them of this form; furthermore, the circular pipes are stronger, and there is less friction of air in passing through them. For instance, a circular pipe 5.65 inches in diameter will have an area of 25 square inches and its circumference will be 17.88 inches. A square pipe 5 inches each way will also have

an area of 25 square inches, but the sum of its four sides will be 20 inches. A rectangular pipe 2 x 12.5 inches will be of equal area, but the sum of its sides will be 29 inches, or about 1.6 times greater than the circular pipe.

Nevertheless it often happens that square or rectangular pipes are necessary, on account of lack of space. When such is the case this area of cross-section must be increased accordingly, so as to avoid undue friction. Galvanized iron is the most desirable material for these pipes and is almost universally used where pipes separate from the building construction are employed. In factory buildings having several floors, proper flues and air ducts are arranged in the walls, and in the basement, where the heating apparatus is usually located.

In constructing pipes several important rules must be observed. In making a change of direction of 90 degrees the elbows should be made of not less than 5 pieces, and the radius of the inside of the bend should not be less than the diameter of the pipe, as shown in Fig. 55.

Where a main pipe is divided, the construction should be as shown in Fig. 56, the pieces A A being the frustum of a cone whose diameter at the base and whose height are equal to the diameter of the main pipe, and whose smaller end is equal to the diameter of the branch pipe, as shown in Fig. 57. This pipe is then cut to the proper form to fit its counterpart, as shown in Fig. 56.

Where branches are taken off from a main or leading pipe they should be so arranged as to leave the larger pipe at an angle of not over 45 degrees, and the inside radius should be not less than their diameter, as shown in Fig. 58. The contraction of the leading pipe, due to the taking off of this branch, should be made by the next sheet, the sheets being usually 30 inches wide.

This reduction of area should not be quite as much as the area of the branch pipe.

The further the air travels from the fan, the less force it has, and this should be compensated for, as far as may be, by slight allowances in area as the various branches are taken off, bearing in mind that this allowance should finally lead up to 25 per cent excess of outlet areas over the area of the main pipe at the fan.

In offices and comparatively small rooms the outlets are usually in the form of rectangular registers

placed in the side walls near the ceiling. The area of these should be from two to three times the area of the pipe leading to them.

Fig. 59 shows the plan of the arrangement of the heating system of the machine shop and Fig. 60 a cross-section of

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FIG. 58. Branch leading from
Main Heating Pipe.

the same, giving the diameters of the pipes at various distances from the heaters; and the number, direction, diameter, and location of the openings, not only for the machine shop proper but for the carpenter shop, wash rooms, etc.

The heating apparatus consists of a rectangular iron case containing a large number of steam pipes of practically U-shaped form, inverted and connected to a cast iron base in such a manner that one leg of the pipe connects with the space through which the steam is admitted and the other leg connects with the space from which the drip is taken. These pipes should be located as close to each other as practicable, the rows of pipes being set "staggering" so as to break up the currents of air. The casing which surrounds. them and connects with the inlet of the fan should also be formed as closely to the pipes as may be, in order that all air which is drawn through may come into close contact with the heating surfaces of the pipes.

It is customary to allow one foot of 1-inch pipe, or its equivalent, to each 100 to 150 cubic feet of contents of the building to be heated, when all the air is taken from out-of-doors. In the case under consideration, with one half or more of the air from within the building the higher figure would probably be ample. At the end opposite the fan are located dampers for regulating the amount of air supply. One of these may be connected with a cold-air duct from out-of-doors, where necessary.

Referring to Figs. 59 and 60 the location of the apparatus is seen to be in the gallery floor, near the center of the building. The fan has two discharge