History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c17.s2.t3.9

v1.c17.s2.t3.9

A very interesting instrument made of shell is a hollow cylindrical object with symmetrical loop-like curves, produced at regular intervals by partially sawing across the opposite margins. Four grooves on the upper margins of the cylinder and four on the lower when joined, give intersecting lines producing exactly 45 degrees. The instrument must have served the same purpose as a modern compass and helped in marine and land survey, alignment of road etc. Another leaf-shaped object with a semi- circular end might have been used as a plectrum for playing on a stringed instrument.