111,640. Atherton, J. June 25, 1917. Mine and colliery signals.-A mine signalling system is provided with an electro-magnetic stepby-step indicator having two movable arms, one of which indicates signals or " men," while the second indicates signals when the first indicates men. The magnets are controlled by a mechanical bell or rapper. Each arm is provided with an actuating and a retaining pawl and ratchet mechanism so arranged that when a second signal follows a signal which has not been cancelled by the operation of a depth indicator the arm is returned to position " 1 " on the receipt of the first impulse of the second signal. The release magnets are provided with two windings, one of which is controlled by a depth indicator to return the arms to zero and to energize a lamp ; while the second is energized in parallel with the operating winding when the first signal impulse is received, but not when the subsequent impulses of signal are received. The indicator arm C', Fig. 1, is mounted on a shaft d' provided with an actuating pawl and ratchet h<1>, f<1> and with a retaining pawl and ratchet e<1>, g<1>, and the arm c<2> is mounted on a sleeve d<2> provided with an actuating pawl and ratchet h<2>, f<2>, Figs. 1, 2, and with a retaining pawl and ratchet e<2>, g<2>. The actuating pawls L<1>, L<2> are spring controlled and are mounted on arms m', m<2> connected by rods l<1>, l<2> to the moving parts of magnets j<1>, j<2>, Figs. 1, 2, 5. The rods l<1>, l<2> are provided with pins L<1>, L<2> adapted to engage pins M<1>, M<2> secured to piston rods N<1>, N<2> which carry contacts P<1>, P<2>, Figs. 2, 5. The rods N', N<2> are adapted to rise quickly and to fall slowly by means of dash-pots O<1>, O<2>. The pawls e<1>, h<1>, c<2>, h<2> are provided with pins r<1>, s<1>, r<2>, s<2> respectively adapted to be engaged by spring-controlled levers q<1>, q<2> when the magnets n<1>, n<2> are energized to release the pawls from their ratchets. The working ratchet wheel f<2> is provided with an elongated tooth y<2> and the ratchet wheel f<1> with a similar tooth; while the retaining ratchet wheel e<1>, Figs. 1, 4, is provided with an elongated tooth and a pin z adapted in the normal position of the wheel to close contacts X<1>, X<2> in the circuit of a lamp, to indicate that both indicators are in their normal positions, a pair of contacts t<2>, t<3>, Figs. 1, 4, 5, in the third position of wheel to energize a magnet t, Figs. 2, 5, and a pair of contacts T<2>, T<3>, Fig. 1, to illuminate a sign " men." The plunger t<5> of the magnet t carries a contact t<6>, and is adapted to rise slowly by means of a dash-pot t<4>. The contact t<6> is adapted to engage two fixed contacts t<7>, t<8>. If both arms C<1>, C<2> are in their normal positions and a signal of one, two, or more than three impulses is received the magnet j' is energized one, two, or more than three times to step around the arm C', and the circuit of the winding 0' of the release magnet n<1> is broken at the contacts P<1>, Q<1> by the first operation of the operating magnet, so that the retaining pawl e' is operative. If, however, three impulses are received, the arm C<1> is moved to indicate " men," and the pin z on the wheel e<1> operates to close the contacts t<2>, t<3> in the circuit of the magnet t and to close the contacts T<2>, T<3> in the circuit of a lamp illuminating a sign " men." The operation of the magnet t opens the circuit of the operating magnet j<1> and closes the circuit of the second operating magnet j<2> which operates on the receipt of other signal impulses to move the second arm C<2>. The arms C<1>, C<2> are returned to their normal positions by the closure of a circuit 1, 2, Fig. 5, containing windings p', p<2> on the release magnets n<1>, n<2> and a battery u, by a depth indicator. If, however, a second signal is sent before the previous signal has been cancelled, the winding O<1> or O<2> in parallel with the winding j<1> or j<2> is energized by the first signal impulse, and the indicator arm is brought back to position " 1 " since the operating pawl h<1> or h<2> is raised by the energization of its magnet and arrests the operating wheel f or f<2> in its first position by engagement with the elongated tooth in the operating wheel.