But there was no need for Sir John to be relieved; the mitrailleuse was soon silent. The Makololos were struck with consternation, and had sought shelter from the torrent of grape-shot, having retired under the flanks of the fort, leaving the plateau strewn with numbers of their dead.
In this instant of respite the Colonel and Strux regained the donjon, and there, collecting themselves to a composure as complete as if they were under the dome of an observatory, they kept a constant eye upon their telescope, and scanned the peak of Volquiria. When, after a short period of rest, the yells of the Makololos made them aware that the combat was renewed, they only persevered in their determination, and resolved that they would alternately remain to guard their invaluable instrument.
The combat, in truth, had been renewed. The range of the mitrailleuse was inadequate to reach all the natives, who, uttering their cries of mortal vengeance, rallied again, and swarmed up every opening. The besieged, protected by their fire-arms, defended the breaches foot by foot; they had only received a few scratches from the points of the assagais, and were able to continue the fight for half an hour with unabated ardour.
Towards half-past eleven, while the Colonel was in the thick of the fray, in the middle of an angry fusillade, Matthew Strux appeared at his side. His eye was wild and radiant: an arrow had just pierced his hat and quivered above his head.
"The signal! the signal!" he cried.
The Colonel was incredulous, but ascertaining the correctness of the welcome announcement, discharged his rifle for the last time, and with an exuberant shout of rejoicing, rushed towards the donjon, followed by his intrepid colleague. There, kneeling down, he placed his eye to the telescope, and perceived with the utmost delight the signal, so long delayed and yet so patiently expected.
It was truly a marvellous sight to see these two astronomers work during the tumult of the conflict. The natives had by their numbers forced the enclosure, and Sir John and the bushman were contending for every step. The Europeans fought with their balls and hatchets, while the Makololos responded with their arrows and assagais.
Meanwhile the Colonel and Strux intently continued their observations, and Palander, equally composed, noted down their oft-repeated readings. More than once an arrow grazed their head, and broke against the inner wall of the donjon. But their eye was ever fixed on the signal, and reading the indications of the vernier, they incessantly verified each other's calculations.
"Only once more," said Strux, sliding the telescope along the graduated scale. An instant later, and it would have been too late for any observations, but the direction of the light was calculated to the minutest fraction of a second; and at that very instant an enormous stone, hurled by a native, sent the register flying from Palander's hands, and smashed the repeating-circle.
They must now fly in order to save the result which they had obtained at the cost of such continuous labour. The natives had already penetrated the casemate, and might at any moment appear in the donjon. The Colonel and his colleagues caught up their guns, and Palander his precious register, and all escaped through one of the breaches. Their companions, some slightly wounded, were ready to cover their retreat, but just as they were about to descend the north side of the mountain, Strux remembered that they had failed to kindle the signal. In fact, for the completion of the survey, it was necessary that the two astronomers on Mount Volquiria should in their turn observe the summit of Mount Scorzef, and were doubtless anxiously expecting the answering light.