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Fig. 4.

The two sides of the square, shown at Fig. 3, represent the carpenters’ popular square, No. 100. This square has been a special favorite with workmen for nearly thirty years, and is still looked upon by many as being the ne plus ultra of steel squares. I show both sides of the square in order to enable the workman to see, before he buys, the kind of tool he will get. Like the Nicholls square, this may be obtained in polished steel, nickel plated, or oxidized copper as the purchaser may desire.

Fig. 5.

I show the complete square, reduced to page size. Sometimes this square is catalogued by dealers as No. 1000, practically, however, it is the same square as the No. 100. If we examine this square we will find on the tongue near its junction with the blade a series of lines and cross lines (see Fig. 4), making a figure known as the “diagonal scale.” This scale is drawn to a larger size at Fig. 5 and is shown alone and is used for taking off the hundredths of an inch. The line ab is here an inch long, and is divided into ten equal parts; the line cd being also divided into ten equal parts, and diagonal lines are then drawn connecting the points as shown in the diagram. Suppose we wish to take off 76-100 of an inch, we proceed as follows: Count off seven spaces from c, e, g, which equals 70-100 of an inch; then count up the diagonal line until the sixth horizontal line, e, is reached, when e f will equal the required distance of 76-100 of an inch, which is a trifle over ¾ of an inch.

Fig. 6.

Quoting from the table of directions given in Sargent’s circular describing this square, we have, for rafter cuts, the following explanation: “This run of a rafter set up in place is the horizontal measure from the extreme end of the foot to a plumb-line from the ridge end—from A to B, Fig. 6.

Fig. 7.

“The rise is the distance from the top of the ridge end of the rafter to the level of the foot. From C to D, Fig. 7.

“The pitch is the proportion that the rise bears to the whole width of the building. The illustration, Fig. 8, shows one-third pitch; the rise of 8 foot being one-third of the width of the building.

Fig. 8.

“The cuts or angles of a rafter are obtained by applying the square so that the 12-inch mark on the body and the mark on the tongue that represent the rise shall both be at the edge of the rafter. The illustration, Fig. 9, shows 8 foot rise, the line A the cut for the ridge end of the rafter and B the cut for foot end.”

Fig. 9.

The portion of square shown at Fig. 10 exhibits the tool having on its face a table of the run, rise and pitch of rafters, being specially figured for this purpose, and shows the measure of the rafter for any one of seven pitches of roof based upon the length of the horizontal measurement of the building from the center to the outside.

The following table, which was prepared especially for this square, shows the manner of working the square:

Fig. 10.

RAFTER TABLE DIRECTIONS.

The rafter table and the outside edge of the back of the square, both on body and tongue, are in twelfths. The inch marks may represent inches or feet, and the twelfth marks may represent twelfths of an inch or twelfths of a foot (that is, inches) as a scale. The rafter table is used in connection with the marks and figures on the outside edge of the square.

At the left end of the table are figures representing the run, the rise and the pitch.

In the first column the figures are all 12, which may be used as 12 inches or 12 feet, and they represent a run of 12.

The second column of figures is to represent various rises.

The third column of figures in fractions represents the various pitches.

These three columns of figures show that a rafter

with a run of 12 and a rise of 4 has 1-6 pitch,

with a run of 12 and a rise of 6 has 1-4 pitch,

with a run of 12 and a rise of 8 has 1-3 pitch,

and so on to the bottom of the figures.

To Find the Length of a Rafter.—For a roof with 1-6 pitch (or the rise 1-6 the width of the building) and having a run of 12 feet, follow in the rafter table the upper 1-6 pitch ruling, find under the graduation figure 12 the rafter length required, which is 12 7 10, or 12 feet and 7 10-12 inches.

For ½ pitch (or the rise ½ the width of the building) and run 12 feet, the rafter length is 16 11 8, or 16 feet 11 8-12 inches.

If the run is 25 feet, add the rafter length for run of 23 feet to the rafter length for run of 2 feet.

When the run is in inches, then in the rafter table read inches and twelfths instead of feet and inches. For instance:

If with ½ pitch the run is 12 feet 4 inches, add the rafter length of 12 feet to that of 4 inches, as follows:

The brace measure