The mains, consisting of 2000 megohm insulation of vulcanized rubber, covered with lead, we will lay about 12 inches under the turf in rough tarred-wood casing with a centra] rib, similar to that used inside buildings, only less ornamental. All cinders most be carefully removed before screwing on the cover. as they would set up an electrolytic action and eat away the lead. These lead-covered cables would be connected to the switchboard, and the lead covering must be stripped off for about 6 inches, before they make contact thereto. Also immediately on their entering the house at the other end, they should be similarly treated, and led into two single-pole cut-outs. By this arrangement the surface-leakage along the lead on to the cut-outs will be stayed, and these cables can at any time be isolated for testing.

From these two cut-outs in the house, we will proceed with ordinary 600 megohm wire to the first distributing board, and thence to the other distributing boards, at a limit of 5-ampere circuits, - that is to say, each circuit must not have more than 8 lamps, each taking .6 of an ampere.

Great care must be displayed in the selection and arrangement of the lamps and fittings. Commencing at the entrance, - if there is a lamp there, - great care must be taken, not only to place it entirely out of reach of actual water, but as far as possible to protect it from moist air, the latter being quite sufficient to cause the lamp to fail.

The carriage-drive lamp, if such should exist, we will supply by two lead-covered wires in a trough (similar to those previously described), running from two cut-outs in the house-cellar right up into the globe of the pedestal, which shouId be weatherproof, remembering to strip back the lead covering at each end for a few inches; and the switch we will place in the vestibule, so that a sen-ant can light the lamp without leaving the house.

The lamps in the hall should be provided with so-called "corridor" switches, one being in the hall, and the other on the landing upstairs, or in the master's bedroom, both these switches being of special construction, and for which special but simple wiring is necessary, so that the lamps can be lit or extinguished by either switch. Thus, at dusk, the lamps can be lit by a servant in the hall, and at night extinguished by the master after he has retired to his bedroom, without putting the switch in the hall out of action at all for the next day.

Corridor switches can also be fitted in bedrooms, one at the door immediately on entering, and one at the head of the bed.

In the drawing-room, connection wall-sockets are often required for portable lamps, and to prepare for all future demands it is as well to run a pair of wires right round the room on the wainscot or in the dado rail, to which to connect them without causing any damage.

With a little thought, switches and their wires can generally be entirely hidden if desired, and to effect this, a point to remember is that the wires can possibly be led to any point on the far side of the wall on which they are to be fixed. Given sufficient time and money, it is generally possible to wire a house without any of the casings being visible in the reception rooms, or the best bedrooms.

In selecting the course for the wires, water-pipes, which may burst, and troughs or baths, which may overflow, should be carefully avoided. Special care should be exercised in false roofs. In stables and along damp cellar walls, it is desirable to "pack out" the casing by small pieces of wood, driven in and standing about one inch from the wall, and to varnish the casings with shellac inside and out, back and front.

When the work is completed, we may find that the exhaust from the engine makes a distressing noise. In such a case, it must be turned into a pit, dug just outside the engine-room, about four feet square and deep, lined with fire-clay bricks, drained, flagged at the bottom, and filled with cobbles the size of a man's fist, or gradually diminishing in size towards the top to the size of walnuts. If the exhaust-pipe is turned into the bottom of this horizontally, and drilled with -inch holes all over its length in the pit, and the pit is roofed over, allowing a wind-space of about 12 inches between the roof and the ground-level, the trouble will be cured.

Sometimes the belt runs against the flange of the dynamo-pulley, persistently showing that it is out of line; this may perhaps be cured by simply "slewing" the dynamo round a little on its rails.

After testing the insulation, and all being found in order, we proceed to charge the cells. To take every precaution against a mistake, we connect to the two wires leading from the engine-room for such charging, two small wires, and with their other ends we connect each of them to a piece of lead about six inches long by two inches wide, or to a piece of lead tubing; each of these two pieces we fasten to a piece of wood, in order to keep them apart, and then stand them in a small jar of acid, having previously placed in the circuit of this small cell. which we have made, a 100-volt lamp. We now run the dynamo full speed to rive 135 volts as shown by the voltmeter, and reduce this with our shunt-resistance to 100 volts, at which pressure the lamp will allow only .6 of an ampere to pass through the jar. After a few minutes one of the lead plates will have turned brown, which will indicate that that wire is connected to the positive terminal of the dynamo. The positive terminal of each cell is painted red, and the negative black, and as the cells are being erected, red should be joined to black. When this has been done, the positive wire from the dynamo must be joined to the positive terminal of one of the end cells, and, having poured in the acid, we are ready for charging.

The following should be' the course adopted in charging. Before starting the engine we connect the voltmeter across the accumulators, with a small switch on the board for that purpose, and find they register 80 volts. This is very low, and the cells will never register bo low again, but being new they are absolutely discharged. We now start the engine, and run the dynamo at full speed, when, as we know, it will give 135 volts, but this we reduce with the resistance to 90 volts, or ten more than the cells give. We then close the cell-itch, and Bee by the ammeter that a few amperes are going into the cells Thus we have established the current without causing a sudden rush, and can now easily increase it as desired. To do so, we merely watch the ammeter, and as we reduce the resistance in the shunt-circuit and so raise the E.M.F., we see the current rise to 40 amperes, which we must not exceed. Indeed, with these new cells it will be best to charge at 30 for about ten hours, when we will proceed at the 40 amperes for the remaining twenty hours, for which time, at least, we expect to have to charge on this first occasion. Many sets of cells have been, ruined by being insufficiently charged in the first instance. The charging must be continued until all the cells boil, and turn quite opaque with "gasing". When these cells are charged, they will give at least 2 volts each, so that a "many-way" switch is provided, connecting (by a separate wire to each cell) the first few cells in the circuit; standing at the board when the charging is out, we can. therefore, connect the cells to the voltmeter as previously, and connect only such a number of cells to the circuit as will give 100 volts. Since, then, some of the cells are not working all the time, they do not require as much charging, and so these are provided also with a many-way switch. The operator with these two switches can charge and discharge as many of the cells as he wishes.

If the belt happens to come off the dynamo, or the engine to stop, the dynamo will have no power, and the cells will send a current into it, since they are connected to it - and a powerful current too, as, when we commenced to charge them, they had an E. M. F. of 80 volts. Of course the dynamo cut-outs would be fused, but to prevent this frequently happening, an automatic accumulator-switch is used, which closes the dynamo-circuit when it is of a superior E.M.F. to that of the cells, and opens it immediately it is of an inferior voltage to theirs.

All the wires from the cell-room, leading to the many-way switches, must be fitted with cut-outs in the cell-room, close against the cells, to prevent the slightest possibility of a short circuit.

We will notice, before leaving the engine-room, that printed instructions have been framed and hung up to instruct any attendant hereafter appointed in the management of the plant; and that a copper or brass oil-can has been provided for the dynamo, so that it may not be attracted by the magnetism (as it would be if of ordinary tinned iron) and drawn into the dynamo, perhaps doing 20 worth of damage, and that dynamo-lubricating and engine-lubricating oil has been provided, with a filter for cleaning it for use again; the second time, however, it should be used for the engine. And on entering the house, we will see that similar notices are hung in the servants' hall, to be there for many years after perhaps the present servants have left, pointing out that on any damp arising in the house from any of the causes described, the wires to that portion of the house are to be cut off at the distributing-board, by removing the two fuse-wires, until the damage is repaired.