ting, along the road to
the corral, of posts, furnished with glass insulators, and intended to
support the wire. A few days after, the wire was extended, ready to
produce the electric current at a rate of twenty thousand miles a
second.

Two batteries had been manufactured, one for Granite House, the other
for the corral; for if it was necessary the corral should be able to
communicate with Granite House, it might also be useful that Granite
House should be able to communicate with the corral.

As to the receiver and manipulator, they were very simple. At the two
stations the wire was wound round a magnet, that is to say, round a
piece of soft iron surrounded with a wire. The communication was thus
established between the two poles, the current, starting from the
positive pole, traversed the wire, passed through the magnet which was
temporarily magnetised, and returned through the earth to the negative
pole. If the current was interrupted the magnet immediately became
unmagnetised. It was sufficient to place a plate of soft iron before
the magnet, which, attracted during the passage of the current, would
fall back when the current was interrupted. This movement of the plate
thus obtained, Harding could easily fasten to it a needle arranged on
a dial, bearing the letters of the alphabet, and in this way
communicate from one station to the other.

All was completely arranged by the 12th of February. On this day,
Harding, having sent the current through the wire, asked if all was
going on well at the corral, and received in a few moments a
satisfactory reply from Ayrton. Pencroft was wild with joy, and every
morning and evening he sent a telegram to the corral, which always
received an answer.

This mode of communication presented two very real advantages;
firstly, because it enabled them to ascertain that Ayrton was at the
corral, and secondly, that he was thus not left completely isolated.
Besides, Cyrus Harding never allowed a week to pass without going to
see him, and Ayrton came from time to time to Granite House, where he
always found a cordial welcome.

The fine season passed away in the midst of the usual work. The
resources of the colony, particularly in vegetables and corn,
increased from day to day; and the plants brought from Tabor Island
had succeeded perfectly.

[Illustration: THE ENGINEER AT WORK]

The plateau of Prospect Heights presented an encouraging aspect. The
fourth harvest had been admirabl