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All modern ordinances prohibit direct connection of the refrigerator with the drainage system, and reference to our sketch will show that the line is disconnected at the sink, simply carrying the drip from the refrigerators into the sink, and the sink being trapped and vented in the usual manner as shown here.

A note on Fig. 114, and also one on Fig. 113, call attention to the fact that the vent from this sink is carried into the bath room main vent line. The use of a note, as in this case, often saves the labor and space involved in showing such work as it actually exists. In Fig. 115 we give a sketch showing in detail the connection of one of the rain leaders

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ing is served by a line of waste or drip pipe. This pipe is usually of galvanized wrought iron, as stated by the note attached to Fig. 114, which shows the refrigerator work of the building under consideration. As the connection of each of the two refrigerators on the second and third floors into the main line of waste is the same as that on the first floor, we simply show the latter, with the drip sink and its connections below.

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into the drainage system. It will be noticed that the leader is not provided with a trap. As a general thing, wherever there is a main trap no separate traps

are placed on the rain leaders.

If there were no main trap on this system, however, it would be necessary to trap separately each line of rain leaders.

Fig. 116 gives a sketch in detail of the cellar drainage. It represents a well formed in the concrete cellar bottom, with the hub end of a P trap cemented into the bottom of the well, and connected with the main drain. Into this well the various lines of sub-soil drain are carried. In some cities it is required by ordinance to carry the water supply di

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The sketch shown in Fig. 117 shows the work connected with the drainage system usually found at the front cellar wall. In order to economize space, instead of carrying the fresh air inlet up to a proper height, we have carried it low, and by cutting off the cellar wall, the fact that the full height is not shown is made known. The concrete is shown with a well formed about the cleanouts on the main trap, so that easy access may be had to them. Cast iron soil pipe is shown carried two lengths or ten feet outside the cellar wall, where it is entered into the tile drain.

This provision is made in most ordinances, to provide against the leaching back into the cellar of sewage that might escape from the tile drain if for any reason broken at some future time. The fresh air inlet is represented as carried underground twenty feet out into the lawn, and brought up to the surface, ending in a ventilating cap. The carrying of the inlet twenty feet away from windows and doors is a sanitary provision required by many ordinances.

Although not so difficult to execute as much of the preceding exercise work, it will do the reader no harm to practice on the work shown in these four sketches.

As we intimated in our last article, we have come to a point now where it is necessary to use an exact scale, both in laying out drawings and in taking dimensions from drawings.

It will no doubt already be known to most of our readers what the purpose of scale drawings is.

As an example, let us suppose that the civil engineer is getting out a map of property covering several acres. It is obvious that it is utterly impossible to make such a drawing full size. The drawing must, however, show everything in

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FIG. 117-MAIN TRAP AND FRESH AIR INLET CONNECTIONS, ETC.

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haps so small that when all the dimensions are placed upon it, it will be confused, and trouble the workman to work from it.

In this case it is necessary to choose a scale which will enlarge the drawing. A scale of 2 inches equal 1 inch is possibly used, and in this case, when the drawing is complete, a measurement on it of 2 inches represents 1 inch on the piece itself.

Now, in the work which we are following, we shall have use for both the reducing and increasing scales, but more especially for the former.

In Figs. 118, 119 and 120 we show three common reducing scales, and in Fig. 121 a common increasing scale.

The double scale (Fig. 121) or 11⁄2 or triple scale, will be found of use in the practice work which we have been giving, in making an enlarged drawing from a smaller one. If there is a measurement of 11⁄2 inch on the smaller drawing, and the double scale is being used, to represent that dimension on the enlarged drawing, three inches of the double scale must be taken, that is, from 0 to 3 on Fig. 121,

The small divisions at the left of this scale represent fractions of an inch, each of the smallest divisions representing 1-16 inch, the next larger inch, the next 4 inch, and finally 1⁄2 inch.

Fig. 120 shows a scale of 1⁄2 inch equals 1 foot, and is a scale that is sometimes used, though not so often as the 14 inch and inch. The 1⁄2 inch scale will be found very handy in making a large drawing of small work, for instance, in making a good sized drawing of the plans and elevations of the plumbing for a small house. It must be understood that in Fig. 120, for instance, each figured division represents a full inch on a drawing which is drawn to a scale of inch equal 1 foot. Therefore, the full length of the scale shown would represent 14 inches, on the scale drawing, though measuring actually only half that amount.

We have chosen to consider lastly the two scales which are most important in this work, that is, the 14 and 8 inch scales shown in Figs. 118 and 119. In the next chapter these two scales will be considered fully, and examples of their application given.

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