The design of an oscillation magnetometer is shown in figure (36.30). It consists of a rectangular wooden box having glass walls at the sides and at the top. Three of the walls are fixed and the fourth be slid in and out. This is used to close or open the box. A plane mirror is fixed on the inner surface of the bottom of the box. A line parallel to the length of the box is drawn on the mirror in the middle. This is known as the reference line. There are levelling screws at the bottom on which the box rests. A vertical cylindrical glass tube T, having a torsion head H at its top, is fitted to the top plate of the box. A hanger A is suspended in the box through an unspun silk thread. The upper end of the thread is attached to the torsion head.
