Note 7 — Chapter XII · THE ELIMINATION OF THE QUADRANTAL ERROR
Reading edition
The directive force is proportional to the sine of the angle of deflection. The gyros K L M therefore supply at 30 deg. deflection a total directive force of D sin 30 deg. + D sin 60 deg. + D sin 0 deg., or 1.366 D. For a single-gyro compass, having a wheel of twice the inertia of K L or M separately, the directive force at 30 deg. deflection would be 2 D sin 30 deg. or D.