Meridiana by Jules Verne

It was now the ninth day since Zorn and Emery had started on their expedition. Their colleagues, detained on the summit of Mount Scorzef, began to give way to the fear that they had fallen into some irretrievable misfortune. They were all well aware that the young astronomers would omit nothing that lay in their power to ensure the success of their enterprise, and they dreaded lest their courageous spirit should have exposed them to danger, or betrayed them into the hands of the wandering tribes. They waited always impatiently for the moment when the sun sank behind the horizon, that they might begin their nightly watch, and then all their hopes seemed concentrated on the field of their telescope.

All through the 3rd of March, wandering up and down the slopes, hardly exchanging a word, they suffered as they had never suffered before; not even the heat and fatigues of the desert, nor the tortures of thirst, had equalled the pain that arose from their apprehensions. The last morsel of the ant-eater had been devoured, and nothing now remained but the insufficient nourishment afforded by the ants.