16. After the insulation test is taken, it is to be worked out thus--The same deflection at the 15th minute’s reading will be obtained with the same battery through resistance, and a shunt to the galvanometer. The amount of resistance multiplied by multiplying power of the shunt, and galvanometer multiplied by the length of the Cable, will give the G. p. R. pr. nt. 17. The copper resistance of the Cable will be taken after 5 minutes’ electrification. 18. No change in the instruments, wires, or connections (other than the batteries, if necessary), to be made on any account, unless such instruments, &c., become defective--any necessary change to be made as quickly as possible. 19. Should the rolling of the ship generate a magnetic current of sufficient strength to embarrass the signals, a stronger current for the signals will be put on on shore, and a shunt used with the galvanometer on board, notice to the shore to put on more power will be given by one current of 5 minutes, commencing Z to E, and 5 reversals of 1 minute’s duration. 20. The iron earth of the Cable will be used both on board and on shore--other earths, however, to be in readiness for use, if necessary. 21. Full particulars of every test and every occurrence in the testing-room to be entered in journal, together with the name of the electricians on duty, and the time of their coming on and going off duty. 22. After the end is landed, should signals fail, the paying-out system to be resumed until signals are re-established. 23. In case of a minute fault appearing, such as will partially affect the signalling, but which will not stop the communication entirely, notice will be given to shore to reduce battery power. Such notice will be given at the 50 minutes, by sending 5 reversals of 1 minute each, commencing Z to E, and 1 current of 5 minutes’ duration. 24. A proper supply of lamps, glasses, oil, and wicks; instrument ink and instrument paper, in sufficient quantities; paraffin, wicks, and spare lamp-glasses for the instrument lamps; lamp-brushes, tools, sulphate of copper, stationery, &c., to be always ready for use. 25. No person except those on duty, and the engineers and the officers authorised by the Atlantic Telegraph Company, to be allowed in the instrument room on any pretence. 26. The batteries to be kept in an efficient state, especially those for sending reversals--their force taken periodically, and if any variety occur, they must be renewed, or brought up to the original force. 27. Supplies of every material needful for such purpose to be in constant readiness. 28. The actual end of the Cable to be brought to the instrument tables, and well insulated. SHIP’S SIGNALS.