(9) At the point where a line of force intersects the perpendicular **bisector** of the axis r=r'=r o, say, and cos 0 - cos 0 obviously =l/r o, l being FIG.

If the centre of S'N' is on the perpendicular **bisector** of SN, 0 = Zir, and the couple will be MM 'cos cp/r 3, (20) tending to increase 4); this is the " broadside on " position.

**Bisector**, from bi-, two, secare, to cut), in geometry, the same as **bisector**, i.e.

A point which divides a line, or a line which divides an angle, into two equal parts; in crystallography it denotes the **bisector** of the angle between the optic axes.

If now a line be drawn from A to the **bisector** H of the side BC, it will meet the vertical through G in I and IJ =c(cos a+a sin a)/ur.

5) is the direction of a ray, either from a heavenly body or from a terrestrial point, impinging at 0 upon the surface of quicksilver, and reflected in the direction OR, the vertical line is the **bisector** OZ, of the angle POR.