A treatise on land-surveying; comprising the theory developed from five elementary principles; and the practice with the chain alone, the compass, the transit, the theodolite, the plane table, &cIllustrated by four hundred engravings, and a magnetic chart . arallels, is by means of a Tsquare, an instrument very valuable for many other purposes. Itis nothing but a ruler let into a thicker piece of wood, very trulyat right angles to it. For this use of it, one side of the cross-piecemust be even, or flush, with the ruler. To use it, lay it on thepaper so that one edge of the Fig. 14. ruler coinc
A treatise on land-surveying; comprising the theory developed from five elementary principles; and the practice with the chain alone, the compass, the transit, the theodolite, the plane table, &cIllustrated by four hundred engravings, and a magnetic chart . arallels, is by means of a Tsquare, an instrument very valuable for many other purposes. Itis nothing but a ruler let into a thicker piece of wood, very trulyat right angles to it. For this use of it, one side of the cross-piecemust be even, or flush, with the ruler. To use it, lay it on thepaper so that one edge of the Fig. 14. ruler coincides with the given lineAB. Place another ruler againstthe cross-piece, hold it firm, andslide the T square along, till itsedge passes through the ^venpoint C, as shown by the lowerpart of the figure. Then drawby this edge the desired line paral-lel to the given hne. (40) Perpendiculars, These may be drawn by the variouaproblems given in Geometry, but more readily by a triangle whichhas one i-ight angle. Place the longestside of the triangle on the given line,and place a ruler against a second sideof the ti-iangle. Hold the ruler fast,and turn the triangle so as to bring itstlurd side against the ruler. Then willthe long side be perpendicular to the.
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License: Licensed
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectsurveying, bookyear18
