20,647. Barclay, J. G., and Wallace, A.D. Oct. 7. Bell signals; mechanical telegraphs.-In a signalling-device for use in mines, having a pointer moved step by step to give active' signals, and a cautionary 'men' signal, both signals are released by the winding-engine or otherwise when the signal has been complied with, but when, before compliance and after a sufficient pause, it is necessary to repeat the active signal, the cautionary signal is retained in view, the previous active signal being first automatically released through mechanism controlled by a fan retarding-device by the second signalling operation. At each pull on the signal rope, a jointed' pawl 7 on the rocking axle 9 is carried over a bell-hammer trip finger 39 and over a tooth of the ratchet-wheel 6, so that on release of the rope, the wheel 6 and a pointer (not shown) on the axle 4 are moved a step forward and the bell 37 is struck. The ratchetwheel and pointer are retained against the tension of a spring 5 by a pin 10 on a lever 11. To prevent the pointer from being advanced beyond a predetermined number of strokes, the last tooth 40 of the ratchet-wheel is partly cut away, so as to be engaged by the pawl 7 but not by the detent 10. When a signal has been complied with, the detent lever 11 is withdrawn by a rod 26 operated by the engine or by band. The detent lever is retained in the release position by a lever 27 which drops and prevents its return, but at the first stroke of the next signal, a pin 30 engaging an arm 32 lifts the lever 27 and allows the detent to come into action. In order that the first stroke of any signal may restore the pointer to its zero position, if not previously restored, the axle 9 is provided with a cam 8 which rocks a lever 13. The lever 13, in passing, momentarily retracts the lever 11. A weighted pawl 14 on the lever 13 engages a ratchetwheel geared to a fan 17, whereby the return of the arm 13 is sufficiently retarded to allow subsequent signalling strokes to be made without operating the detent 11. When the cautionary 'men' signal is to be displayed, the pointer is moved through three steps, the third step causing a cam 19 to move a lever 20 into the path of the arm 13. Sufficient pause is then made to allow the arm 13 to return to the left of the detent 11. The next pull of the signal rope causes the arm 13 to operate the levers 11, 20 together. A pin 21 on the lever 20 engages a pivoted arm 22 which is moved to bring the 'men' indicator 23 opposite an opening 3 in the dial, where it is retained by a weighted hook 24 engaging a pin 25. At the same time, movement of the detent 11 allows the pointer to return to zero. When the signal rope is released, return of the axle 9 under the action of a spring 36 rings the bell and moves the pointer through the first step of the active signal as previously described. When the detent 11 is retracted by the rod 26, a tail-piece 34 on the lever 11 engages a pin 35 on the hook 24, which is thus raised to allow the 'men' signal 23 to fall back to the non-display position shown. The movement of the lever 11 by the arm 13, as in repeating a signal, is, however, insufficient .to effect this release of the member 23.