so that the gyroscope would reverse if it were possible to make F cos α > 86400 A/T2C (Föppl, Münch. Ber, 1904).
A gyroscopic pendulum is made by the addition to it of a fly-wheel, balanced and mounted, as in Gilbert’s barogyroscope, in a ring movable about an axis fixed in the pendulum, in the vertical plane of motion.
As the pendulum falls away to an angle θ with the upward vertical, and the axis of the fly-wheel makes an angle φ with the vertical plane of motion, the three components of angular momentum are
h1 = K cos φ, h2 = Aθ + K sin φ, h3 = Aφ,
(24)
where h3 is the component about the axis of the ring and K of the fly-wheel about its axis; and if L, M′, N denote the components of the couple of reaction of the ring, L may be ignored, while N is zero, with P = 0, Q = θ, R = 0, so that
M′ = h2 = Aθ + Kφ cos φ,
(25)
0 = h3 − h1θ = Aφ − Kθ cos φ.
(26)