Patent GB-190022224-A (GB)
Title: An Improved Method of Warning Ships of the Proximity of Rocks and other Dangerous Obstructions.
Inventor: DAFT LEO
Filed: 1900-12-06
Granted: 1901-12-06
Abstract: 22,224. Daft, L., and Williams, A. Dec, 6. Signals, marine and ship.-Relates to electrical apparatus for warning ships of the proximity of rocks, islands, headlands, &c. The rock or other obstruction is wholly or partially surrounded by a submerged conductor r, which is connected by insulated conductors l<1> to one terminal of a source of high-tension electricity, such as an ordinary induction coil, the other terminal of which is earthed, preferably near the centre of the obstruction. In the arrangement shown in Fig. 1, the conductors l<1> and the earth plate p are connected to a condenser c, and to the circuit l<2> of a coil a, which consists of a single winding of thin sheet copper, the layers of which are separated by a continuous sheet of insulating-material, such as paraffined paper. The circnit l<2> of the coil includes a make-and-break contact d, e, a battery b, and a key k, which is operated by hand, or by clockwork &c., to produce variations in the potential of the conductor r. To improve the effectiveness of the contact made by the lever d, a cylindrical receptacle h, having an annular chamber partially filled with mercury, is mounted between stop-rings g on the lever. The Provisional Specification also states that granulated metal may be employed in the receptacle h, and that a loosely-mounted counterweight may be employed as an alternative. The apparatus on the ship comprises two insulated submerged plates 3, 4, arranged preferably at the bow and stern, and connected to a relay adapted to close a local circuit, through bells or visible signals, or both. If the ship approaches the conductor r, as shown at x, Fig. 1, the variations in the potential of the conductor cause a current through the plates 3, 4 to close the relay, and so to actuate the signals. If the vessel is passing the obstruction so that the plates 3, 4 are about equidistant from the conductor r, no effect is produced on the relay. In such a case, an indication may be given by employing a second relay apparatus adapted to operate distinctive signals, and connected to two lateral submerged plates 3<1>, 4<1>. If the vessel comes within the zone of the conductor r, as at y, Fig. 1, both relays and both sets of signals will be operated. Fig. 2 shows a special and preferred form of relay. The relay armature 11, which completes the signalling-circuit 24, 25 at the contact 13, or the circuit 22, 23 at the contact 12, is carried by the pivoted rectangular coil 10 mounted between the pole-pieces 9 of the permanent magnet 5. A cylindrical block 8 of soft iron lies within the coil, and is secured to the poleplate 7. The armature 11 is normally held in median position by the permanent magnet 16, which has a screw adjustment 15 to enable the sensitiveness of the armature to be regulated. The magnet 16 is provided with a coil 14, adapted to weaken its magnetism, and so to increase the sensitiveness without moving the magnet. The coil 14 may be in series or in parallel with the coil 10. It is shown in series, and can be short-circuited by inserting a plug in the socket 21. It may also be divided into a number of sections, which may be connected to a multiple commutator so as to enable all or any of the sections to be employed.