INTRODUCTION IT WAS at Venice. The lofty windows of the ancient Ducal Palace of the Speranzi opened upon the Grand Canal. The orb of night was mirrored in the waters by a furrow of silver spangles, and the immensity of the sky stretched over the towers and cupolas. When the musicians borne by the gondolas had turned the corner of the canal to glide towards the Bridge of Sighs, their last choruses vanished in the night, and Venice seemed to go to sleep in that profound silence known to no hive of humanity but the Queen of the Adriatic. This Venetian silence was untroubled save by the cadenced beats of the old clock, and perhaps I should not have appreciated the whole depth of the universal muteness but for the regular oscillation of that apparatus designed for measuring time. The continuous “tick-tock” marked out the silence, and, curiously enough, seemed to intensify it. Seated in the embrasure of the high window, I contemplated the shining disc of the Moon enthroned in an azure sky filled entirely with its light, and I remembered that this luminary of the night, so tranquil and calm in appearance, moved a thousand yards in space at each beat of the clock. This fact struck me for the first time with a certain force, perhaps on account of the enveloping solitude. Gazing upon the lunar globe, in which I could distinguish with the naked eye the ancient seas and geographical outlines, I bethought myself that it was still perhaps inhabited by beings organised differently from ourselves who can live in an extremely rarefied atmosphere; but what struck me even more forcibly was its rapid revolution round the Earth, at the rate of 1,000 yards at each beat of the clock, making 38 miles a minute, 2,280 an hour, 53,800 a day, or 1,500,000 miles for each lunar month.