1. In a device of the class described, the combination of a source of electrical energy having positive and negative terminals, a pair of resistors, a first condenser having one plate connected to said positive terminal and the other plate conNected in series with one of said resistors to said negative terminal, a second condenser having one plate connected to said positive terminal and the other plate connected in series with the other of said resistors to said negative terminal, a potentiometer connected between said other plates of said condensers, a center tap on said potentiometer, electroresponsive means connected between said center tap and the negative terminal of said source of energy, and means for selectively discharging said condensers.

2. In a device of the class described, the combination of a source of electrical energy having positive and negative terminals, a pair of resistors, a first condenser having one plate connected to said positive terminal and the other plate connected in series with one of said resistors to said negative terminal, a second condenser having one plate connected to said positive terminal and the other plate connected in series with the other of said resistors to said negative terminal, a potentiometer connected between said other plates of said condensers, a center tap on said potentiometer, electroresponsive means connected between said center tap and the negative terminal of said source of energy, a pair of electronic tubes each having a plate circuit and a grid, means for connecting the plate circuits of said tubes across said condensers respectively, and means for selectively energizing each of said grids.

3. In a device of the class described, the combination of a source of electrical energy having positive and negative terminals, a pair of resistors, a first condenser having one plate connected to said positive terminal and the other plate connected in series with one of said resistors to said negative terminal, a second condenser having one plate connected to said positive terminal and the other plate connected in series with the other of said resistors to said negative terminal, a potentiometer connected between said other plates of said condensers, a center tap on said potentiometer, a pair of electronic tubes each having a plate circuit and a grid, means for connecting the plate circuits of said tubes across said condensers respectively, means for selectively energizing each of said grids whereby the electronic tubes will discharge the respective condensers, an electronic device having an input circuit and an output circuit, an electroresponsive device connected to said output circuit and controlled thereby, and means connecting said input circuit to said center tap and to the negative terminal of said source for firing said electronic device when both of said condensers are discharged within a predetermined period of time.

4. In a device of the class described, the combination of means for producing signals of opposite polarities, a pair of energy storage devices, means for gradually storing energy therein, means controlled by said signals for selectively discharging energy from said energy storage devices in accordance with the polarities of said signals, a circuit, means for closing said circuit responsive to discharge by said discharging means of energy from one of said devices when less than a predetermined amount of energy has been stored in the other of said devices by said storing means, and electroresponsive means in said circuit operated upon closure thereof.

5. In a device of the class described, in combination: a source of electrical energy having positive and negative terminals, a pair of resistors, a first condenser having one plate connected to said positive terminal and the other plate connected in series with one of said resistors to said negative terminal, a second condenser having one plate connected to said positive terminal and the other plate connected in series with the other of said resistors to said negative terminal, a potentiometer connected between said other plates of said condensers, a center tap on said potentiometer, a pair of electronic tubes each having a plate circuit and a grid, means for connecting the plate circuits of saId tubes across said condensers respectively, means for selectively energizing each of said grids whereby the electronic tubes will discharge the respective condensers, an electronic device having an input circuit and an output circuit, an electroresponsive device connected to said output circuit and controlled thereby, means connecting said input circuit to said center tap and to the negative terminal of said source for firing said electronic device when both of said condensers are discharged within a predetermined period of time, a third condenser connected across said output circuit, and means to charge said third condenser within a predetermined interval.

6. In a device of the character disclosed, the combination of a mine comprising means responsive to the magnetic field adjacent a moving paramagnetic object for producing signals of opposite polarities in accordance with changes in said magnetic field, a pair of energy storage devices, means for gradually storing energy therein, means controlled by said signals for selectively discharging the energy stored in said energy storage devices in accordance with the polarities of said signals, a circuit, means responsive to the amount of energy stored in said devices for controlling said circuit, and means in said circuit for firing the mine when the amount of energy stored in each of said devices is less than a predetermined maximum.

7. In a submarine mine for damaging a vessel, the combination of a mine comprising means responsive to the magnetic field adjacent said vessel for producing signals of opposite polarities in accordance with changes in the magnetic field, a pair of condensers, means for gradually charging said condensers, means controlled by said signals for selectively discharging said condensers in accordance with the polarities of said signals, a circuit, means responsive to the charges on said condensers for controlling said circuits, and means in said circuit for firing the mine when the charge on each of said condensers is reduced to less than a predetermined value.

8. In a submarine mine for damaging a vessel, the combination of a mine comprising means responsive to the magnetic field adjacent said vessel for producing signals of opposite polarities in accordance with changes in the magnetic field, a pair of condensers, means for gradually charging said condensers, a pair of electronic tubes, means controlled by said signals and including said tubes for selectively discharging said condensers in accordance with the polarities of said signals, a circuit, means responsive to the charges on said condensers for controlling said circuit, and means in said circuit for firing the mine when the charge on each of said condensers is reduced to less than a predetermined value.

9. In a submarine mine for damaging the vessel, the combination of a mine comprising means responsive to the magnetic field adjacent said vessel for producing signals of opposite polarities in accordance with changes in the magnetic field, a pair of condensers, means for slowly charging said condensers, a pair of electronic tubes, means controlled by said signals and including said tubes for selectively discharging said condensers in accordance with the polarities of said signals, a circuit, means responsive to the charges on said condensers for controlling said circuit, and means in said circuit for firing the mine when both of said condensers are discharged within a predetermined period of time.

10. In a submarine mine for damaging a vessel, the combination of a mine comprising means responsive to the magnetic field adjacent said vessel as the vessel moves through the water for producing signals of opposite polarities in accordance with changes in the magnetic field, a source of electrical energy having positive and negative terminals, a pair of resistors, a pair of condensers each having one plate connected to said positive terminals and the other plate connected in series with one of said resistors to said negative terminal, a potentIometer connected between said other plates of the condensers, a center tap on the potentiometer, a pair of electronic tubes each having a plate circuit and a grid, means for connecting the plate circuits of said tubes across said condensers respectively, means controlled by said signals for selectively energizing said grids in accordance with the polarities of said signals thereby to discharge the respective condensers, an electronic device having an input circuit and an output circuit, mine firing means connected to said output circuit and controlled thereby, and means connecting said input circuit to said center tap and to the negative terminal of said source for firing the electronic device when said condensers are both discharged within a predetermined period of time.

11. In a submarine mine for damaging a vessel, the combination of a mine comprising means responsive to the magnetic field adjacent said vessel for producing signals of opposite polarities in accordance with changes in the magnetic field, a source of electrical energy having positive and negative terminals, a pair of resistors, a first condenser having one plate connected to said positive terminal and the other plate connected in series with one of said resistors to said negative terminal, a second condenser having one plate connected to said positive terminal and the other plate connected in series with the other of said resistors to said negative terminal, a potentiometer connected between said other plates of said condensers, a center tap on said potentiometer, means controlled by said signals for selectively discharging said condensers in accordance with the polarities of said signals, an electronic device having an input circuit and an output circuit, a mine firing device connected to said output circuit and controlled thereby, means connecting said input circuit to said center tap and to the negative terminal of said source for firing said electronic device when both of said condensers are discharged within a predetermined period of time, a third condenser connected to energize said output circuit, and means for charging said third condenser within a predetermined interval.

12. In a system of the class described, the combination of means for producing signals of opposite polarities, means including a relaxation oscillator cooperating with said signal producing means to produce voltages varying in phase in accordance with the polarities of said signals, an electroresponsive device, means responsive to the production of voltages of opposite phase within a predetermined period of time for energizing said electroresponsive device, and means responsive to shocks applied to the system for rendering said relaxation oscillator inoperative for a predetermined interval.

13. In a system of the class described, the combination of means for producing signals of opposite polarities, means including a relaxation oscillator cooperating with said signal producing means to produce voltages varying in phase in accordance with the polarities of said signals, means responsive to production of a voltage of one phase for rendering said relaxation oscillator inoperative for a predetermined interval, an electroresponsive device, and means cooperating with said last named means and responsive to the production of a voltage of opposite phase within a predetermined period of time after said predetermined interval has elapsed for energizing said electroresponsive device.

14. In a system of the class described, the combination of means for producing signals of opposite polarities, means including a relaxation oscillator cooperating with said signal producing means to produce voltages varying in phase in accordance with the polarities of said signals, means responsive to production of a voltage of one phase for rendering said relaxation oscillator inoperative for a predetermined interval, an electroresponsive device, means cooperating with said last named means and responsive to the production of a voltage of opposite Phase within a predetermined period of time after said predetermined interval has elapsed for energizing said electroresponsive device, and means responsive to shocks applied to the system for operating said means for rendering said relaxation oscillator inoperative for a predetermined interval.

15. In a submarine mine for damaging a vessel, the combination of a mine comprising means responsive to the magnetic field adjacent said vessel as the vessel moves through the water for producing signals of opposite polarities in accordance with changes in the magnetic field, a relaxation oscillator for generating intermittent pulses of current, a magnetic amplifier network energized by said relaxation oscillator and responsive to said signal producing means to produce voltages varying in phase in accordance with the polarities of said signals, means responsive to production of a voltage of one phase for rendering said relaxation oscillator inoperative for a predetermined interval, and means cooperating with said last named means and responsive to production of a voltage of opposite phase within a predetermined period of time after said predetermined interval has elapsed for firing the mine.

16. In a submarine mine for damaging a vessel, the combination of a mine comprising means responsive to the magnetic field adjacent said vessel as the vessel moves through the water for producing signals of opposite polarities in accordance with changes in the magnetic field, a relaxation oscillator for generating intermittent pulses of current, a magnetic amplifier network energized by said relaxation oscillator and responsive to said signal producing means to produce voltages varying in phase in accordance with the polarities of said signals, means responsive to production of a voltage of one phase for rendering said relaxation oscillator inoperative for a predetermined interval, means cooperating with said last named means and responsive to production of a voltage of opposite phase within a predetermined period of time after said predetermined interval has elasped for firing the mine, and means responsive to countermine shocks for operating said means for rendering said relaxation oscillator inoperative for a predetermined interval.

17. In a submarine mine for damaging a vessel, the combination of a mine comprising means responsive to the magnetic field adjacent said vessel as the vessel moves through the water for producing signals of opposite polarities in accordance with changes in the magnetic field, a relaxation oscillator for generating intermittent pulses of current, a magnetic amplifier network energized by said relaxation oscillator and responsive to said signal producing means to produce voltages varying in phase in accordance with the polarities of said signals, a source of electrical energy having positive and negative terminals, a pair of resistors, a pair of condensers each having one plate connected to said positive terminal and the other plate connected in series with one of said resistors to said negative terminal, a potentiometer connected between said other plates of the condensers, a center tap on the potentiometer, means controlled by said voltages for selectively discharging said condensers in accordance with the phases of said voltages, means connected between said center tap and the negative terminal of said source for firing the mine when both of said condensers are discharged within a predetermined period of time, and means operatively connected to said potentiometer for rendering said relaxation oscillator inoperative for a predetermined interval whenever one of said condensers is discharged.

18. In a submarine mine for damaging a vessel, the combination of a mine comprising means responsive to the magnetic field adjacent said vessel as the vessel moves through the water for producing signals of opposite polarities in accordance with changes in the magnetic field, a relaxation oscillator for generating intermittent pulses of current, a magnetic amplifier network energized by said relaxation oscillator and responsive to said signal producing means to produce voltages varying in phase in accordance with the polarities of said signals, a pair of electronic tubes each having an input circuit and an output circuit, means operatively connecting said input circuits to said magnetic amplifier network for selectively energizing said input circuits in accordance with the phases of said voltages, means operatively connected to said output circuits for firing the mine when both of said input circuits are energized within a predetermined period of time, and means connected to the output circuit of the first tube to be energized for momentarily rendering the other of said tubes inoperative.

19. In a submarine mine for damaging a vessel, the combination of a mine comprising means responsive to the magnetic field adjacent said vessel as the vessel moves through the water for producing signals of opposite polarities in accordance with changes in the magnetic field, a relaxation oscillator for generating intermittent pulses of current, a magnetic amplifier network energized by said relaxation oscillator and responsive to said signal producing means to produce voltages varying in phase in accordance with the polarities of said signals, a pair of electronic tubes each having an input circuit and an output circuit, means operatively connecting said input circuits to said magnetic amplifier network for selectively energizing said input circuits in accordance with the phases of said voltages, a condenser connected across said output circuits, means for charging said condenser, means operatively connected to said output circuits for firing the mine when both of said input circuits are energized within a predetermined period of time, and means in series with said condenser for mementarily rendering one of said tubes inoperative when the condenser is discharged by operation of the other of said tubes.

20. In a device of the character disclosed, the combination of an output circuit including a first gaseous discharge device having a control grid and adapted to be rendered conducting when the voltage on the control grid is increased by a predetermined amount above an initial bias potential thereon, second and third gaseous discharge devices, means for rendering the second discharge device conducting, means adapted to be rendered effective as the second discharge device is rendered conducting to apply a first voltage to said control grid which exceeds a predetermined value for a predetermined interval of time, means for rendering the third discharge device conducting, and means adapted to be rendered effective as the third discharge device is rendered conducting to apply a second voltage to said control grid which is additive with respect to said first voltage applied thereto whereby the voltage on the grid is increased by said predetermined amount to render said first discharge device conducting when said second voltage is applied to the grid during said interval of time.

21. In a device of the character disclosed, the combination of an output circuit including a first gaseous discharge device having a control grid, means for rendering said first discharge device conducting to close said output circuit when the voltage on said control grid is increased by a predetermined amount above an initial bias potential thereon, means for applying said initial bias potential to the control grid, second and third gaseous discharge devices, means for rendering the second discharge device conducting, means for rendering the third discharge device conducting, means adapted to be rendered effective as the second discharge device is rendered conducting to apply a first voltage to said control grid which maintains the potential thereon in excess of a predetermined value for a predetermined interval of time, and means adapted to be rendered effective as the third discharge device is rendered conducting to apply a second voltage to said control grid which is additive wiTh respect to said first voltage and adapted to increase the voltage on the grid by said predetermined amount to render said first discharge device conducting when said second and third devices are rendered conducting successively within said interval of time.

22. In a device of the character disclosed, the combination of an output circuit including a first gaseous discharge device having a control grid, means for rendering said first discharge device conducting to close said circuit when the voltage on the control grid is increased by a predetermined amount above a predetermined value, a pair of gaseous discharge devices, means for rendering said pair of discharge devices conducting selectively, means adapted to be rendered effective as either one of said pair of discharge devices is rendered conducting to apply a first voltage to said control grid which maintains a potential thereon in excess of said predetermined value for a predetermined interval of time, and means adapted to be rendered effective as the other of said pair of discharge devices is rendered conducting during said interval of time to apply a second voltage to the control grid which is additive with respect to said first voltage thereon and increases the potential on the grid by said predetermined amount whereby the first discharge device is rendered conducting.

23. In a device of the class described, the combination of a pair of energy storage devices, means for gradually storing energy therein, means for selectively and substantially instantaneously discharging energy from said storage devices, a circuit, means responsive to discharging of one of said storage devices for applying an energy pulse to said circuit, means responsive to discharging of the other of said storage devices within a predetermined time after discharging of the first of said devices for applying an energy pulse to said circuit which is additive with respect to said first-named pulse applied thereto, means for closing said circuit when the additive energy pulses applied thereto exceeds a predetermined value, and electroresponsive means in said circuit adapted to be operated as the circuit is closed.

24. In a device of the class described, the combination of a pair of energy storage devices, means for gradually storing energy therein, means for selectively and substantially instantaneously discharging energy from said storage devices, a circuit, means responsive to discharging of energy from a first of said storage devices for applying an energy pulse to said circuit of a time diminishing amplitude determined by said storing means, means responsive to discharging of energy from the other of said storage devices for applying a second energy pulse to said circuit which is additive with respect to the first pulse applied thereto, means for closing said circuit when the additive energy pulses exceed a predetermined value greater than either of the pulses applied to said circuit, and electroresponsive means actuated upon closing of said circuit.

25. In a device of the class described, the combination of a pair of condensers, means for gradually charging said condensers, means for selectively and substantially instantaneously discharging said condensers, a circuit, means responsive to discharging of a first of said condensers for applying a voltage pulse to said circuit of a time diminishing amplitude determined by said charging means, means responsive to discharging of the other of said condensers for applying a second voltage pulse to said circuit which is additive with respect to the first pulse applied thereto, means responsive to the additive potential applied to said circuit for closing said circuit upon the application of said second pulse thereto when less than a predetermined charge has been placed on said first condenser, and electroresponsive means operated in response to closure of said circuit.

26. In a device of the class described, the combination of a pair of condensers, means for gradually charging said cOndensers, a pair of electronic tubes, means including said tubes for selectively and substantially instantaneously discharging said condensers, a circuit, means responsive to discharging energy from a first of said condensers for applying a potential pulse to said circuit of a time diminishing amplitude determined by said charging means, means responsive to discharging of the other of said condensers for applying a second potential pulse to said circuit which is additive with respect to the first pulse applied thereto, and electroresponsive means adapted to be actuated when the additive potential applied to said circuit exceeds a predetermined value which is greater than the maximum amplitude of either of the pulses applied to said circuit.

27. In a mine firing control circuit of the character disclosed, the combination of a control circuit including a normally nonconducting electron discharge device having a control electrode, a pair of normally non-conducting gaseous discharge devices, means for rendering said pair of devices conducting selectively, means controlled by operation of one of said devices for applying a voltage pulse of predetermined duration upon said control electrode, and means controlled by operation of the other of said devices for applying to said control electrode a voltage pulse which is additive with respect to said first pulse applied thereto thereby to render said electron discharge device conducting when the additive voltage exceeds a predetermined value.

28. In a mine firing control system of the character disclosed, the combination of means including a transformer having a secondary winding for generating electric impulses of opposite polarity across said secondary winding in accordance with the magnetic signature of a vessel moving with respect to the mine, a pair of electron discharge devices each having a cathode, an anode defining a main gap with said cathode and a control electrode defining a control gap with said cathode, circuit means for connecting the main gaps of said devices in parallel, a normally charged condenser connected in parallel with said main gaps, circuit means including a portion of said secondary winding and connected across the main anode and control anode of one of said devices, and circuit means including the remaining portion of said secondary winding and connected across the main anode and control electrode of the other of said devices, said devices being rendered conducting selectively in accordance with the polarity of impulses appearing across said secondary winding, said condenser being discharged through either of said main gaps as the device individual thereto is rendered conducting, and said condenser providing a reference voltage for impulses generated by the secondary winding whereby the value of an impulse applied to the control electrode of one of the devices is effectively reduced when the other of the devices is rendered conducting.

29. In a mine firing control system of the character disclosed, the combination of a pair of normally non-conducting electron discharge devices each having a cathode, an anode defining a main gap with said cathode and a control electrode defining a control gap with said cathode, circuit means for connecting the main gap of said devices in parallel, a normally charged condenser connected in parallel with said main gaps and adapted to be discharged through either of the gaps as either of the devices individual thereto is rendered conductive, means including a transformer having a secondary winding for generating across the secondary winding a voltage impulse having successive positive and negative values in accordance with the magnetic signature of a vessel moving with respect to the mine, means for applying across the control gaps of said devices fixed bias potential of insufficient value to render said devices conducting, circuit means including one end of said secondary winding and connected across the anode and control electrode of one of said devices for elevating the biAs potential thereon to a value rendering said device conducting in response to the positive value of the impulse appearing across said secondary winding, circuit means including the other end of said secondary winding and connected across the main anode and control electrode of the other of said devices for depressing the bias potential thereon in response to the positive value of said electrical impulse, the potential of said condenser serving as a reference voltage for said electrical impulse whereby the negative value thereof is suppressed upon discharge of the condenser as one of said devices is rendered conductive in response to the positive value of the impulse thereby to prevent operation of the other of said devices in response to the negative value of the impulse, circuit means controlled by said electron discharge devices for developing additively a voltage whose value is controlled by the time spaced relation of successive operations of the devices, and a mine firing circuit operatively connected to said last named circuit means and arranged to be operated by said additive voltage when the additive voltage reaches a predetermined value.