Unwinding the wire and bending the free end into the form of a rude hook, the man attached this last to the cord of his bedside lamp at a point, located by sense of touch, where a minute section of electric light wire had been left naked by defective insulation.

In 1851, Ruhmkorff constructed an induction coil so greatly improved, by the careful insulation of its secondary circuit, that he could obtain from it torrents of long sparks in ordinary air.

At a distance where the current has become weak because of the resistance of the wire and losses due to faulty insulation, it will still operate a delicate electro-magnet with a very light armature so arranged as to open and close a local circuit provided with suitable batteries.

Because the condition of my pipe and the imperfect insulation of my wires were such that it became necessary to stop trenching on this account alone, but, taken in connection with the advanced state of the season, when it was impossible to carry on my operations out of doors, I was compelled to stop any further trenching.

The sides have double boarding inside and outside the frames, with a layer of our excellent quilted seaweed insulation between each pair of boardings.