After infinite toil and innumerable failures, he had at length succeeded in establishing an intelligible system of what may here be described as photo-telegraphy, in which the rays of light passing between the earth and Mars were made to perform the functions of the electric wires in modern telegraphy.
His alphabet, so to speak, consisted of a hundred great electric suns disposed at equal intervals on the mountain peaks round the great oval of the Valley. These were in direct communication with the observatory of Aeria, which was situated at a height of sixteen thousand feet on Mount Austral, the highest of the two snow-capped peaks which stood at the southern end of the Valley.
A single switch key enabled him, when sitting by the huge telescope which embodied all the highest optical science of Aeria, to light and extinguish these brilliant globes as he chose, and it was by lighting and extinguishing them at certain intervals that he was able to transmit his signals to the Martian astronomer, who was waiting to receive them, and to reply to them by similar means across the gulf of thirty-four million miles which separates the two planets at their nearest approach to each other.
Momentous as were the events of the last few days, they were dwarfed to utter insignificance by the irregular and apparently meaningless recurrences of a tiny point of light in the centre of a great concave mirror situated at the base of the huge barrel of the telescope, through the side aperture of which Vassilis Cosmo was looking a few minutes before midnight on that memorable 12th of May.
The point of light appeared and vanished, and reappeared again at irregular intervals, which the astronomer noted on an automatic registering instrument beside him. The moment the flash appeared he pressed a button, which he held down till it disappeared, then he released it, waited till the flash reappeared, and repeated the operation so long as the signals came.
For nearly five hours he received and registered the signals recorded by his reflector in silence, broken only by the monotonous ticking of the clockwork which, working synchronously with the movements of the two orbs, kept the image of Mars exactly in the centre of the object-glass, and by the soft whirring of the registering instrument.
Never before had human eyes read such a message as he read, sitting that night in silence and solitude in his observatory amid the snows, far above the lovely valley in which his countrymen were still holding high revel.
Well might his hands tremble and his eyes grow dim with something more than long watching when he reversed the mechanism of the register and a narrow slip of paper, divided by cross-lines into equal spaces a tenth of an inch long, issued from a slit in one end, and began to run slowly over a revolving drum.
On the tape was a series of straight black lines running longitudinally along it. They were of unequal length, and divided from each other by unequal spaces. Before the exact import of the message could be gained the length of each of these lines, and that of the space which separated it from the next, had to be accurately measured, but Vassilis knew his own code so perfectly that he had been able to read the general drift of the communication that had been sent along the light-rays from the sister world by approximately guessing the duration of the flashes and the intervals between them.
Day was beginning to dawn by the time the long tape had been unrolled and pinned down in equal lengths on a board for measuring. For more than five hours he had not uttered a syllable or even an exclamation, although he had received from another world what appeared to be tantamount, not only to his own death-sentence, but to that of the whole human race.