The work upon the rock was tedious and exasperating in the extreme. The gneiss was of maddening hardness and obstinacy--“four times as tough as Aberdeen granite” was the general opinion. The Atlantic, pounding the rock continuously through the centuries, had faced it smoother than could any mason with his tools, yet had not left it sufficiently sound to receive the foundations. In the external layer, which the masons laboured strenuously to remove with their puny tools, there were cracks and crevices here and there. The stubborn rock played havoc with the finest chisels and drills, and clearing had to be effected for the most part by the aid of gunpowder. This powerful agent, however, could only be used sparingly and with extreme skill, so that the rock-face might not be shivered or shattered too severely. Moreover, the men ran extreme risks, for the rock splintered like glass, and the flying chips were capable of doing as much damage, when thus impelled, as a bullet. While the foundations were being prepared, and until the barrack was constructed, the men ran other terrible risks every morning and night in landing upon and leaving the polished surface of the reef. Five months during the summer was the working season, but even then many days and weeks were often lost owing to the swell being too great to permit the rowing-boat to come alongside. The engineer relates that the work was “a good lesson in the school of patience,” because the delays were frequent and galling, while every storm which got up and expended its rage upon the reef left its mark indelibly among the engineer’s stock-in-trade. Cranes and other material were swept away as if they were corks; lashings, no matter how strong, were snapped like pack-threads. Time after time the tender lying alongside had to weigh anchor hurriedly, and make a spirited run to its haven at Tyree. When the barrack was erected, the situation was eased somewhat, but then the hours became long. Operations being confined to the summer months, the average working day was from four in the morning until nine in the evening--seventeen hours--with intervals for meals; but the men were not averse to the prolonged daily toil, inasmuch as cessation brought no welcome relaxations, but rather encouraged broodings over their isolated position, whereas occupation served to keep the mind engaged. Twice the men had severe frights during the night. On each occasion a violent storm sprang up after they had gone to bed, and one or two ugly breakers, getting their blows home, shook the eyrie with the force of an earthquake. Every man leaped out of his bunk, and one or two of the more timid, in their fright, hurried down the ladder and spent the remaining spell of darkness shivering and quaking on the completed trunk of the lighthouse, deeming it to be safer than the crazy-looking structure which served as their home.