FOR USE WITH A 20-METRE CHAIN. Engineers accustomed to thinking their degree of curvature with reference to the 100-ft. chain may find it convenient to remember that the degree of curvature, if a 20-metre chain be used, is approximately two-thirds of the foregoing. Thus a 3° metric curve would be about equivalent to a 4 curve laid out with the 100-ft. chain. A 20-metre chain = 65.618 feet; a 100-ft. chain = 1.524 chains of 20 metres each, one foot being equal to 0.3048 of a metre, and a metre equal to 3.2809 feet. If a metric curve is to be retraced with a 100-ft. chain, the exact degree of curvature should be ascertained with reference to the radius in feet, as set forth in Art. XVIII. It is convenient to mark stakes with the even numbers, 2, 4, 6, etc, when using the 20-metre chain, distance being thus recorded in tens of metres. |