The weights are then put on, the front weight first, the clips being placed over the studs on the breast-plate. The back weights are then put on, and the clip lashings over the hooks on the helmet, and the two are secured to the diver's body by means of the lashing from the back weight, which is passed round the waist, through the thimble beneath the front weight, and tied to the other end of the lashing at the back weight. When the signalman is sure that all is right, and that the diver understands all the signals, he gives the word _Pump_, and screws the centre bull's-eye into the helmet securely; this done, he takes hold of the life line and "pats" the top of the helmet, which is the signal for the diver to descend. _Signals employed._--The signalman is the responsible person, and must be very vigilant all the time the diver is down; occasionally he will give one pull on the life line, and the diver should return the signal by one pull signifying "all right;" if the signal be not returned, the diver must be hauled up, but if the diver wishes to work without being interrupted by signal, he gives one pull on the line, independently, for "All right; let me alone." If the signalman feels any irregular jerks, such as might be occasioned by the diver falling into a hole, he should signal to know if he is all right, and if he does not receive any reply, he should haul him up immediately. If the diver from any cause is unable to ascend the ladder, and wishes to be pulled up, he gives four sharp pulls on the life line. If while being hauled up the diver gives one pull, it signifies "All right; don't haul me any more." The diver should be hauled up slowly and steadily. If the signalman wishes the diver to come to the surface, he gives four sharp pulls on the line, on which the diver should answer "All right," return to the foot of the ladder, and signal to be hauled up. _One_ pull on the air-pipe signifies that the diver wants more air. _Two_ pulls on the life line and _two_ pulls on the air-pipe in rapid succession, signify that the diver is foul and cannot release himself, and requires the help of another diver; on receiving such a signal, no attempt should be made to haul the diver to the surface. The above signals are to be invariably used; but other signals may be arranged as is most convenient for any particular work, as a great variety can be made with the life line and air-pipe. The diver can communicate with the surface by means of a slate. Further information on this subject, especially with regard to the foregoing diving apparatus, will be found in Messrs. Siebe and Gorman's "Manual for Divers." FOOTNOTES: [Footnote V: In wrought iron there is always some residual magnetism; there is therefore no necessity to start the magnetism with a permanent magnet.] [Footnote W: Siemens' unit.] CHAPTER XI. ELECTRICITY.