rooms, because they thus heat the rooms in the most direct manner. With the indirect method, however, the heat is conveyed from the radiator to the room by means of a current of air. Indirect radiators are usually hung from the cellar-ceiling, and are enclosed in a sheet-metal casing (usually No. 20 galvanized sheet iron), or a tin-lined wooden casing, which is provided with a chamber above and one below the radiator, as shown in the figure. Cold air from the outer atmosphere enters the lower chamber through a No. 20 galvanized sheet-iron pipe a, called the cold-air duct. It then passes up between the sections of the radiator b and is heated before it enters the upper

custom:

FIG. 1.

Sheathe the roof diagonally with roofingboards well nailed at each bearing. Cover the entire roof with two-ply felt or roofing-paper, as in Fig. 1. Securely nail the tilting-fillets to the roof-boards, as at f, Figs. 2, 3, and 5. (b) The gutter at the cornice should have a galvanized-iron frame, or cradle, or, if of cast iron, the frames should be cast the shape of the gutter and set at not more than 30-inch centers and tied with a band, o rod, on the outside. The end of the frames

chamber c. Another galvanized-iron or bright tin pipe, called the hot-air pipe, or duct, joins this chamber to a register in the floor or side wall of the room to be heated, and thus permits the warm air to rise and flow into the room, as shown by the arrows. If you decide to show the location of the indirect radiators on your plans, you can easily do so by simply drawing their outlines on the cellar plan. You should also locate the boiler and chimney on the same plan. This will enable the steam-fitter to give you an accurate bid on the work.

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(44) I consider the Answers to Inquiries in your magazine most interesting. (a) Kindly inform me how Spanish tiles are fastened on a roof. (b) How are gutters constructed? (c) How are valleys constructed? (d) How are hips constructed? (e) How are connections made with gable walls? (f) Will snow blow through a properly constructed tile roof? (g) How does terra-cotta of special design compare with stone in cost and durability for outside facings? (h) How is the stone hectograph made?

J. W. R., Hammond, Ind.

ANS. (a) Spanish roofing-tiles are made in two styles. One is the plain shape with one roll concave and one convex, and having nail-holes punched about 1 inch from the top. The other has the same shape, and is known as interlocking, which term is applied because about 3 inches below the top of the tile and below the nail-holes is a neck, or fillet,

HOME STUDY

FIG. 2.

should extend into the wall and form an anchor. The cradle should then be filled in with cement or concrete, and covered with roofing-felt. The crown molding of 18-ounce copper should next be put in place, and the gutter proper, of the same weight metal, in lengths of 6 or 8 feet and joined by -inch lock-seams, thoroughly soldered and sweated together, should be placed in the cradle. The inner

tilting-fillet with copper nails, turned down over the fillet and connected with the inner side of the gutter by a double-locked seam. (See Fig. 2.) These outer and inner seams of the gutter should not be soldered, as the expansion and contraction must be provided for. It would be well, also, if the gutter is a very long one, to pitch it both ways and use a 2-inch or 24-inch roll lock-seam at the center, unsoldered, as an expansion-joint. (c) The valleys should be constructed of from 16 to 18 oz. copper in not more than 6-foot lengths, laid with a lock-seam and secured to the roof-boards by cleats of copper, soldered or sweated on the back of each length, and fastened to the roof with copper nails or with copper screws. The sides of the valley should be turned up 1 inch against the tilting-fillet, bent over its top, and nailed securely along its length. The general appearance under this treatment will be as in Fig. 3. (d) The hips do not require any flashings. Nail a 2" x 5" strip on the angle of the roof, the 5-inch side standing up, bring the tile against it, and cover with a hip-roll, as in Fig. 4. (e) The connection with the gable-walls should be made by first nailing the copper to the tilting-fillet and turning it down over the same to the

FIG. 4.

HOME STUDY

structed tile roof for the following reasons: The roof being boarded and covered with roofing-felt, effectually stops the passage of air, and the open space under the tiles forms an air cushion, or pocket, which prevents any drift. On laths this would not be the case, as there would be no backing. A boarded and felted roof, if exposed to the air on the under side, will last as long as a lath roof if the boards are not too closely laid and if the tiles are uncemented. The tiles on the eaves, gutters, valleys, hips, and ridges should be laid in elastic cement composed of linseedoil, whiting and resin and applied while hot. (g) Terracotta of special designs in small quantities is always more expensive than stone. If, however, the whole front is to be of terra-cotta, it will be 18 or 20 per cent. cheaper than limestone, and about 30 per cent. cheaper than brownstone or bluestone, in a building of ordinary width and 5 or 6 stories high. Terra-cotta is just as durable as stone, and possesses the advantage of being absolutely fireproof. (h) A hectograph consists of a gelatin pad to which impressions of

roof and then up against the wall at least 7 inches. From the under side of the coping turn down a 6pound lead apron-flashing, overlapping the copper 3 inches. The vertical part of the roof-flashing should be secured to the wall by cleats not more than 18 or 20 inches apart. The lead apron will be held in place by lead plugs 1"x" at 12-inch centers. (f) Snow will not blow through a properly con

(45) Will you kindly inform me how a narrow church-spire can be prevented from swaying in the wind? The rafters of the spire seem to be as well braced as possible, but, nevertheless, the spire bends like a mast in a gale of wind.

BUILDER, Washington, D. C. ANS.-The swaying of a spire or steeple may be prevented by suspending a heavy beam or weight from the apex of the spire. The lower the weight below the spire the greater will be the stability of the structure. The Japanese resort to this mode of treating the roofs of their towers as a precaution against earthquakes, allowing the beam to swing free so as to act as a pendulum, bringing the structure back to its perpendicular position after deflection by wind or earthquake tremor. Whether a weight so swinging actually tends to draw a deflected spire back to its perpendicularity or not is doubtful; but by attaching a weight to the apex of a spire and suspending it some distance below the spire-roof, the center of gravity will be lowered in proportion to the distance the weight may hang below the natural center of gravity of the spire.

(46) I am thinking of using a rope for transmitting power. The driver-pulley is 28" in diameter, the driven 36". The shafts are 10 feet center to center, and I intend to use a tightener on the slack side of the rope. Those claiming to have had experience say that this arrangement will not work, but that the pulleys should be at least 100 feet apart. Is this so? J. R., Kanopolis, Kansas.

ANS.-You can, of course, use a rope drive in the way you propose; but, leaving out of consideration all question of space, it is much preferable to have the pulleys farther apart, say 30 feet at least. The general practice is to place them much farther apart than this, sometimes twice as far, depending on circumstances. This is done with a view to the increased weight of rope producing the necessary adhesion on the pulley, the sag of the rope at the same time increasing the arc of contact. (The top side, of course, is made the driving side.) The ropes should not rest on the bottom but on the sides of the grooves, the wedging action thus set up supplying the resistance to slipping that is secured in flat-belt drivers by means of great initial tension. The sides of the groove may include an angle of 45°, this being found to give good results. In a long drive, the weight of rope secures the necessary adhesion without any great initial tightening of the rope. This gives a greater life to the rope than would happen in your case. The tension pulley or tightener you propose to use has an injurious effect on the ropes, inducing a reverse bending, although this will perhaps not be so marked as in a longer drive, with, consequently, a greater sag.

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(47) (a) Please tell me how to level across a stream 1,500 feet wide, if the water-level is not to be depended upon. (b) Where should I establish a bench-mark in a city? (c) Where in the country? (d) How should I establish it in a swamp? (e) In framing posts how do I find the distance A B in the accompanying diagram? (f) How do I find where to cut mortise at 4 to carry roof-thighs CA and A E? (g) How do I find length of CA and A E?

NEW YORK READER.

ANS.-(a) Level across with an engineer's level having a high-power telescope, preferably with a precise level, such as is used in the United States Coast Survey. In order that the result may be accurate, several observations should be taken. If all observations are taken from the same side of the river, a correction for curvature and refraction should be made. For a distance of 1,500 feet, the correction for the earth's curvature and refraction under ordinary atmospheric conditions will be .046 of a foot. This correction is to be deducted from the reading of the leveling-rod. If observations are taken from both sides of the river, however, the error due to curvature and refraction may be eliminated by taking a mean of the results obtained by the observations from opposite directions. (b) and (c) On any permanent and well-defined object, such as the water-table of a public building, or upon a stone monument planted in the ground. The water-table of a stone or brick dwelling-house will do, but the more permanent and sharply defined the object is, the better. (d) Cut into the root of a large tree in such a manner as to make a projection shaped somewhat like an inverted letter V, the top coming to a well-defined point, and drive a tack in the top on which to hold the rod. Blaze the top of the tree so it can be found easily, and, in order to easily distinguish it from other blazed trees, mark the letters B. M. on the blaze with red chalk. If the bench-mark is to be used frequently, it is a good plan to also mark its elevation on the blaze. Keep an accurate record of the position and elevation of each bench-mark, with a

(48) Referring to the answer to question 241 which appeared in the July number of HOME STUDY MAGAZINE, how was the constant angle. 74° 46′ 15′′ obtained?

J. L. McL., San Marcos, Texas. ANS.-Let y be the circular measure of the angle A; then, bp == arc acb (circumference - arc axb) bp 2ob(π-y) 2 o b(y). 2(y). This equation tan y 2(y) determines the angle y, or A; this equation can only be solved by trial. As the angle y increases from o to, tan y

And tan y = ob

=

b

HOME STUO

ob

increases from o to infinity; and 2(y) decreases from 2 to π, or from 6.28318 to 3.14159. Hence, tan y must lie between 6.28318 and 3.14159. From a table of natural tangents, tan 74° 46′ 3.67217; from a table of circular measures of angles, circular measure of 2(180° 74° 46′) circular measure of 2(105° 14′) 3.67334. Since tan 74° 46′ is less than the circular measure of 2(180° 74° 46′), this angle is too small. A second trial gives tan 74° 46′ 15′′ = 3.67322, and circular measure of 2(180° 74° 46′ 15′′) = 3.67320. Therefore, A = 74° 46′ 15′′.

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