Knight's American mechanical dictionary : a description of tools, instruments, machines, processes and engineering, history of inventions, general technological vocabulary ; and digest of mechanical appliances in science and the arts . was identical with Alhazen,the Iberian (See pages 141, 212, 1154.) Another Roman level was the chorobaks, which was a light wooilen fiame about 20 feet in length,and mounted on a leg at each of its longitudinal piece and the end pieces werebraced hy diagonals marked with vertical lines. Aplumb-line suspended at each extrendty swung over
Knight's American mechanical dictionary : a description of tools, instruments, machines, processes and engineering, history of inventions, general technological vocabulary ; and digest of mechanical appliances in science and the arts . was identical with Alhazen,the Iberian (See pages 141, 212, 1154.) Another Roman level was the chorobaks, which was a light wooilen fiame about 20 feet in length,and mounted on a leg at each of its longitudinal piece and the end pieces werebraced hy diagonals marked with vertical lines. Aplumb-line suspended at each extrendty swung overa diagonal, and indicated, by reference to the line,the horizontality of the instrument. It was muchlike the modern level. When the wind disturbed the quietude of theplumb-line, a chan-nel in the upper Fig. of the horizon-tal bar was filledwith water. Whenthe water equallytouched each end ofthe channel, the in-strument was con-sidered level. JIariottes levelhas a long surface ofwater made so as toreflect to the eye aninverted image ofthe object, the pointwhere the two ob-jects appear to meetbeing on a level witlithe place where thesurface of the wateris found. Cassinis level hasa steel mirror placeda little before the.
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