But before night we encamped in the shelter of the mountains; the chiah, which grew in abundance around us, enabled us to kindle fires, and a salutary reaction took place in the spirits of the troops. According to a common practice of mine, I invited to supper the man whose life I had saved by frightening him into exertion. After swallowing a glass of warm wine, well sugared, and spiced with tincture of cinnamon, he licked his lips, sucked the edges of his glass, and said: 'Thank ye, doctor; but for you I should have been dead,' with a naivete which I can never forget, and which even now mingles pleasing associations with the thoughts of those days of suffering. The next day nearly 200 of the men were affected with partial or total blindness. Some had merely a sensation like fatigue of the visual organs, with heaviness, watering, and inflammation of the conjunctive membrane. But with others the pain was acute, the eye much inflamed, and the cornea covered with minute ulcerations. Those who were more slightly affected, marched like persons enveloped in a cloud of smoke, and trying to see their way out of it; they took a few steps with their eyes shut, then half opened them with evident pain to reconnoitre the ground before them, and quickly closed them again. But many had for the time wholly lost their sight; they stumbled on the tufts of halfa, and rolled on the ground, so that we were obliged to hoist them on the cacolets. The general, in a state of much uneasiness, called a council of such members of the military corps of health as were found in his column. Some were of opinion that this epidemic was occasioned by the sudden cold, others that it was attributable to the smoke of the chiah; but the truth is, that, both before and after this period, we had experienced nearly as great extremes of heat by day and cold by night without any such consequences, and that some, who had not approached the chiah fires were as severely affected as those who had. It was concluded, with every appearance of reason, that the real cause was the dazzling light reflected from the snow during our march on the 20th of April. I recollect one artilleryman, who was conducting his gun, when suddenly, as the sun broke out afresh, he stopped, rubbed his eyes, turned his head in every direction, and exclaimed: 'I cannot see; I am quite blind!' Although we had not expected snow in the plains of Sahara, the general had anticipated the effects of the reflection of light from the sand, and the possibility of small particles of it getting into the eyes; and with this view each man had been provided with a green gauze veil. But the soldier dislikes anything out of his regular routine as much as the most ignorant peasant; so when the order was given that these veils should be worn,[3] the soldiers wore them to be sure--in their pockets. I insisted that each man should fasten his on his helmet, and this, too, was done; but it was allowed to fly like