The Desert journey from Korosko is not an affair to be undertaken carelessly and without thoughtful preparation. The distance is about two hundred and fifty miles, and is traversed in eight days. It is necessary to carry water in goatskins all the way, as there is only one well or spring on the route, and the water from it is undrinkable by man, and only endurable by the powerful stomach of the camel. Of course, the supply was used very sparingly; washing, except in sand, was quite out of the question, and as none of the party had a fondness for the sand bath, they made no ablutions until reaching the Nile once more, except to moisten their eyes in the morning. The skins of water were distributed upon the camels, and each of the travelers had a small skin hanging at his saddle-bow for a daily supply. By the advice and example of the Doctor each of the boys had an extra skin of water hidden in his baggage, and its existence was carefully concealed from the Arab drivers. These fellows are inclined to improvidence, and had they known of this private provision they would have been certain to count it as part of the regular supply, and expect to draw upon it.

The heat of the Desert and the glare of the sun incline the traveler to thirst, and perhaps the knowledge of the necessity for economy is an additional incentive to it. Human nature has curious ways, and the desire for a thing generally increases in proportion to the difficulty of procuring it. Frank and Fred found that the fact of the scarcity of water, and the necessity of limiting their use of the precious fluid, increased their longing for it. At first, they yielded by taking occasional draughts, but very soon they decided upon the old expedient of chewing a bit of leather or some other hard substance, to create a flow of saliva to moisten their lips. With a little self-denial, aided by the above practice, they soon conquered their thirst, and were able to get along nearly as well as the Arabs who accompanied them. Frank intimated that the warmth of the water, and the flavor of goatskin which it soon acquired, had a material influence in lessening his desire for it.

The dreary waste of sand was partially relieved here and there by ranges of hills or low mountains, but they were barren as the rest of the Desert, and therefore made comparatively little variation in the landscape. There was not a cloud in the sky, and the sun poured its blistering rays upon the travelers during all the time it was above the horizon. In the morning and evening the heat was not intense, but in the middle of the day it was like the blast of a furnace.

At first, the jolting of the camels was disagreeable, but in a little while the boys became accustomed to it, and tried to believe they were enjoying themselves. The camels of easiest motion are selected for riding purposes, and the youths were fortunate in their animals, which had been chosen by Abdul. Frank had a very tall and powerful camel, while Fred was on one little more than two-thirds the size of Frank's. The two animals were friendly to each other, but not to their riders, and the boys soon abandoned the attempt to establish social relations with their beasts of burden. "You may possibly be on good terms with them after a while," said Abdul, "but you must be patient. You could hardly expect it under a fortnight, and we ought to be in Abu Hamed before that time. Most camels hate Europeans instinctively, but are docile with Arabs, just as mules are said to dislike Europeans and prefer the society of Africans."

On the second day of their journey Frank happened to look ahead, and to his great surprise saw a beautiful lake, surrounded by groves of trees.

He shouted to Frank, and then to the Doctor and Abdul, who were riding just behind them.

Abdul quickened the pace of his camel, and was soon at Frank's side.

"You told us there was no water on the road," said Frank, "and there is a lake right before us. I suppose it is filled with saltwater, and therefore doesn't count."

"Worse than saltwater," responded Doctor Bronson, who joined them. "It isn't water at all, but a mirage."

"Of course, it is," Frank exclaimed, with a laugh; "I ought to have known better than be deceived by it."

"You are not the first to be deceived by it," said Abdul, "and it has been the cause of many deaths on this very route. Men have wandered from the road, confident that they were on the borders of a lake or river, and have fallen exhausted to die on the ground. Colonel Long, in his account of his travels in Central Africa, tells of a regiment on its march from Korosko across this desert. The men saw these lakes of water formed by the mirage; deceived by the illusion and maddened by thirst, they broke from the ranks, in spite of the protests of their guide, and went in search of water. They found their error too late, as most of them perished of exhaustion and thirst."

"Look at the graves along the road, and the bleaching bones of the camels," said the Doctor, "and you will understand the perils of the journey over the desert."

It was as Doctor Bronson suggested; the way was marked by thousands of skeletons of the faithful beasts of burden that had fallen in the service of their masters; and here and there, at painfully frequent intervals, were the graves of men who had perished of thirst or of the excessive heat. Even if no other landmarks existed, these would be sufficient to indicate the road.

The evening journey was continued until a late hour, and the boys were surprised to find that the desert air, so scorching during the day, was of a chilliness suggesting frost at night. Doctor Bronson recalled to them their experience in India, where there was often a sensible change of temperature in going from sunshine into shadow, and said it was a noticeable feature of the desert that it did not retain at night any appreciable portion of the heat poured upon it during the day. "It is fortunate for man that such is the case," he added, "as the coolness of the night enables us to recuperate from the exhaustion of the sweltering temperature of daytime."

The wells or springs to which allusion has been made are about half way from Korosko to Abu Hamed. They are shallow pools of exceedingly bitter water, quite unfit for men to drink, but not injurious to camels. Doctor Bronson tasted the water, and said the bitterness was caused by sulphate of magnesia, commonly known as Epsom salts. Frank and Fred were curious to try it, but their curiosity was easily satisfied. A few drops on the tongue made a burning sensation, which did not show a disposition to go away immediately.

The tents were pitched a short distance from the wells and close to an encampment of Arabs, who were spending two or three days there to refresh their camels. Around some of the pools there was a little vegetation, but not enough to furnish a good meal for a hungry animal; there were a few stunted palms in the valley, and the lines on the sand showed that at some former time a river flowed there. The camels drank freely of the water, and evidently understood that they must lay in a supply for the rest of the journey to the Nile.

They left the wells early in the morning, and after a few hours found themselves on a broad, sandy plain, where the thermometer at two o'clock in the afternoon stood at 100°. It was the greatest heat they had found since leaving the Nile. Frank kept the record of the temperature, and reported to the Doctor each evening the result of his observations. In the morning it was chilly; the Arabs shivered in all their wrappings, and our friends sought shelter in their overcoats for the early part of the ride, but invariably laid them aside when the sun was a couple of hours above the horizon. By noon they were in their lightest garments, and so continued until evening, when the air grew cool again.

There was a daily variation of not far from forty degrees between the highest and lowest readings of the thermometer. The lowest record was 50°, and the highest 100°; but these did not occur on the same day. The boys were not slow to understand why the Doctor had made such a liberal provision of blankets, and were greatly obliged to him for his forethought.

As they approached the Nile, Frank and Fred vied with each other to get the first glimpse of the great river. The mirage was all around them, and the boys were several times deceived by it, until Abdul came to their assistance.

"I will give you a rule," said he, "by which you can always tell a real lake or river from an imaginary one. In a mirage the imaginary lake is of the same color as the sky above it, while the Nile is of a deeper blue. You will rarely, if ever, find the sky and water of the same hue when the sun is shining, and this is the only time when the mirage appears. With this simple rule in mind, you are not likely to be deceived."

While they were talking Fred made good use of his eyes, and suddenly pointed ahead to a little cleft in the line of rocky hills. There was a strip of blue which did not resemble the sky in color, and he felt certain it was the Nile.

"You are right," said Abdul, "and that is the Nile. We will make our camp tonight on its banks."

Soon a fringe of palm trees came into sight; the blue streak increased to a broad expanse of water, and the line of palms into a grove. Then they came among fields of beans and other green things, and before sunset they stood on the bank of the river, and drank freely of the water, which Ali brought them in a large bowl. It was a great improvement upon the warm and strongly flavored water which had been their only resource for eight long days, and they both declared it the sweetest draught they had ever taken.

"You can understand now, better than ever before," said the Doctor, "why the Arabs seem to worship the Nile, and why the ancient Egyptians regarded it as a divinity. Without it all this part of Africa would be like the desert we have just passed, and existence here would be impossible."

"And I understand, too," responded Fred, "why the Arab conception of Paradise abounds in rivers of never-failing water. Mohammed wrote from his own experience, as he lived among the deserts of Arabia."

An Arab merchant, with whom Abdul was acquainted, came to offer the shelter of his house to the strangers; but they preferred their tents, and told the dragoman to thank him for his offer and decline it. Frank proposed a swim in the river, which was seconded by Fred. Abdul suggested the possibility of an interview with a crocodile, and the swim was indefinitely postponed. Crocodiles are numerous in this part of the river, and in fact all the way from the second Cataract to the equatorial lakes. They are by no means timid, and the stranger should think twice before venturing into the river.

Abdul told the boys that it was not unusual for crocodiles to be counted by dozens on the sandbanks in the upper Nile; on one occasion he saw more than fifty together, and they did not show a disposition to slide into the water until he was within twenty yards of them. Sometimes, when boats were overturned in the river, the unfortunate victims of the upset were eaten by the hideous reptiles; and they occasionally came close to the bank and seized women or girls who were filling water jars from the stream.

Of course, the youths were seized with a desire to shoot a crocodile, and eagerly asked the Doctor if there would be an opportunity for a hunting expedition. Doctor Bronson said they would remain a day at Abu Hamed, and he had no objection to their trying their skill if the game could be found.

Abdul went in search of his merchant friend, and the business was soon arranged. There was a sandbank a little way up the river, where the crocodiles came out to sun themselves, and he thought they could get a shot or two by going there on the following morning.

Their sleep that night was disturbed by dreams of monster saurians. Frank waked with a start, under the impression that he was being swallowed feet foremost by a crocodile; he found, on coming to his senses, that the blankets had rolled away from his feet and allowed the cold air to fall on them, and it was the change of temperature that had given him the impression of being devoured. Fred dreamed of falling into the water from a boat, and finding himself where the river was full of hungry crocodiles; the reality was that he had rolled from his couch, and upset a water jar which Ali had placed ready for his use in the morning.

After breakfast they left for the crocodile hunt, the party consisting of Frank and Fred, with Ali, the latter going as interpreter. One of the camel drivers went along, and there were at least a dozen Arabs who followed, in the hope of earning or begging something from the young hunters.

When they reached the sandbank a single crocodile was seen by one of the Arabs, who pointed it out to the youths. A friendly dispute followed, to determine who should have the first shot, which would probably be the only one. The choice fell upon Frank, and, as soon as it was determined, he motioned the others to remain quiet while he crept slowly in the direction of the prize.

Armed with his rifle, he went slowly along the sand until within about sixty yards of the crocodile; at this moment the creature raised his head and looked around, but as Frank lay perfectly still the proximity of danger was not discovered. The reptile settled to sleep again, and when he had been lying quiet a couple of minutes Frank advanced as before.

The eye and the shoulder are the only vulnerable points of the crocodile. As the eye was closed its position was not easy to make out, and so Frank determined on shooting at the shoulder. He took deliberate aim and fired.

The crocodile gave one convulsive motion and stretched himself on the sand. Evidently Frank's shot had been well aimed.

The youth was about to run forward to examine his game, but was restrained by a shout from Ali, telling him to wait for the Arabs. They came up at the top of their speed.

"They say you must be careful," said Ali, "as the crocodile may not be dead. He will lie quite still awhile, and when you don't expect it, he thrashes his tail round and opens his jaws."

Thus cautioned, Frank went more slowly, accompanied by the rest of the party. To make the thing certain, Fred put a bullet through the crocodile's eye, and Frank added another from the opposite side. At each of these shots there was a slight movement of the creature's muscles, but nothing that appeared dangerous.

The boys told the Arabs they might do what they pleased with the carcass. It was of very little consequence, as the flesh is not fit to eat, but the skin and teeth can occasionally be sold to a traveler who desires to take home a trophy, and has not been fortunate in bagging any game of his own. While one of them went for a rope the rest sat down and waited; the boys followed their example, hoping another crocodile would show himself, and give Fred a chance to try his skill; but nothing appeared.

When the man returned with the rope, the party set at work to drag their prize to the solid ground. They were very cautious in approaching him, but finally managed to get the rope around his neck. As soon as they commenced pulling, the legs and tail began to move, the tail swinging from side to side in a way that would have been dangerous to anyone within its reach.

The men hauled away vigorously, and, despite the opposition of the crocodile, they soon removed him from the narrow strip of sand and had him safe on the main bank. A blow from a hatchet finished the work of the boys, and the crocodile lay dead on the ground. By means of the rope his length was ascertained, and then the youths returned to the village.

They told the story of their adventure to the Doctor, who measured the rope, and found that the crocodile was only a few inches short of fifteen feet long.

"It's a very good one," said Abdul, "but I've seen 'em eighteen or twenty feet long. The great fellows are no more dangerous than the smaller ones, as a crocodile ten feet long can drag a man under water and hold him there until he is drowned."

Abdul said that one day, while the men of Baker Pacha's party were working among some masses of reeds that the river had piled up, they felt something moving under their feet. They got away from the spot as soon as possible, and a moment afterward the head of a crocodile was thrust up from below. His body was tangled in the reeds, and before he could get free the men attacked him. He was unable to use his tail, and so was at their mercy; "and you may be sure," he continued, "nobody has any mercy for a crocodile. Besides, the men were Africans from the Sudan country, and, unlike the Arabs, they had no scruple in eating the flesh. They made short work of him, and had a good supper that night, in addition to the sport of killing their natural enemy."

Abdul said that the number of natives killed by crocodiles every year along the upper part of the Nile must be quite large. Every few days a death from this cause occurs in nearly every town or village. The careless habits of the people are greatly in the crocodile's favor, and he has no scruples about taking them as near his heart as the position of his stomach will permit. When a large crocodile is killed and dissected, the proof of his misdeeds is generally discovered, in the shape of anklets and other silver ornaments worn by his unfortunate victims, and which remain of course undigested.

The crocodile does not eat his game on the spot where he captures it; his habit is to drag it to a secluded place and take his time in devouring it. In this respect, he differs from his marine cousin, the shark, who bolts his prey at once, and then, like Oliver Twist, looks around for more.