Reflecting Circle
an instru- 1744, and afterward improved by Borda and Troughton. In principle and construction it is similar to the sextant, the graduations, however, being continued completely round the limb of the circle. Also called a repeating circle.
GALVANOMETER, REFLECTING Sir William Thomson's instrument, consisting of a very small magnet, made of a piece of watch spring, suspended between two flat bobbins of fine insulated copper wire. The magnet carries a very small concave mirror, which is adjusted by means of a directing magnet to throw the rays of light, issuing from a lamp and concave mirror, which is adjusted by a horizontal graduated scale when no current is passing, rays of light, issuing from a lamp and reflected from the mirror, on the zero of other. In any other case the vibrations of the magnet cause the image to be current is passing, or when two equal and opposite currents neutralize each an amount proportional to the force and ssing, or when two equal duration of the current.