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 magnetized, and returned through the earth to the negative pole.  If the current was interrupted, the magnet immediately became unmagnetized.  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.

The plateau of Prospect Heights presented an encouraging aspect.  The fourth harvest had been admirable and it may be supposed that no one thought of counting whether the four hundred thousand millions of grains duly appeared in the crop.  However, Pencroft had thought of doing so, but Cyrus Harding having told him that even if he managed to count three hundred grains a minute, or nine thousand an hour, it would take him nearly five thousand five-hundred years to finish his task, the honest sailor considered it best to give up the idea.

The weather was splendid, the temperature very warm in the day time, but in the evening the sea-breezes tempered the heat of the atmosphere and procured cool nights for the inhabitants of Granite House.  There were, however, a few storms, which, although they were not of long duration, swept over Lincoln Island with extraordinary fury.  The lightning blazed and the thunder continued to roll for some hours.