. Appleton's dictionary of machines, mechanics, engine-work, and engineering. constituting what is called the grade line. All those parts of the section above the line abed will re-quire to be cut down, and are called cuttings ; and those portions below this line will require to be filledup, and are designated as embankment, or fillings. Where a trifling variation in the general inclination of the line or of the grades is not of great im-portance, it is very advisable that the line should be so laid out that the quantity of earth, or materialrequired for making the embankments, should not be g
. Appleton's dictionary of machines, mechanics, engine-work, and engineering. constituting what is called the grade line. All those parts of the section above the line abed will re-quire to be cut down, and are called cuttings ; and those portions below this line will require to be filledup, and are designated as embankment, or fillings. Where a trifling variation in the general inclination of the line or of the grades is not of great im-portance, it is very advisable that the line should be so laid out that the quantity of earth, or materialrequired for making the embankments, should not be greater than what is to be obtained from the ex-cavations. There is, however, an exception to this in cuttings or embankments of great lengths. Casesmay occur where the distance between the cutting and embankment is such, that the expense of con-. veying the earth from one part of the line to another is greater than the increased expense of borrowingmaterial alongside the line of railway, or near the embankment, for the purpose of forming the embank-ment ; and of depositing the earth from the cut, which ought to have formed the embankment, uponwaste ground alongside such cut, in spoil bank. These are, however, cases to be judged of by the en-gineer of the work, and are entirely questions of comparative expense between the one mode and theother. RAILKOADS. 557 Width of the railway.—Fig. 3180 is a cross section of an excavation or cutting, and Fig. 3181 a crosssection of an embankment; ab being the original surface of the ground, and g h the bottom level or extreme depth of the excavation. The first question to determine is the width at the bottom level, as bythis the whole of the operations are guided; and this depends upon two considerations: first, the widthbetween the rails; and next, the width between the two lines, if the
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