Popular Science Monthly/Volume 38/April 1891/Scientific Jottings in Egypt
|SCIENTIFIC JOTTINGS IN EGYPT.|||
THE following pages record impressions and observations made in the spring of 1889, during a brief sojourn in the Nile Valley, and a more deliberate study of the Sinaitic Peninsula. In discussing one's experience on a journey the weather claims early notice. In February, at the hotel in Cairo, the thermometer ranged from 60° at 8 a. m. to 78° at 3 p.m.; but on the Nile steamer much greater extremes were noted, 54° at midnight (February 19th) to 87° at 2.30 p. M. (February 9th). In the shade the heat was rarely oppressive.
The temperature in the desert in March was favorable to the traveler's comfort, with rare exceptions; the thermometer ranged from about 60° to 80° in twenty-four hours at the sea-level, and from 48° to 75° at the elevation of about five thousand feet.
The highest evening temperature was on March 17th, after the khamsin had blown all day—at 7 p. m., 84°. The lowest temperature observed was on March 20th, in camp about three thousand feet above the sea—at 6.30 a. m., 33°. (In February, 1874, Rohlf noted in the Libyan Desert a minimum temperature of 23°.) In considering the physiological effects of these temperatures one must remember the extreme dryness of the atmosphere in the desert.
My first experience in Egypt was calculated to give the impression that it is a rainy country, for I saw two showers in three days. In passing through the Suez Canal (January 31st), a heavy shower, lasting half an hour, drove the passengers to shelter, and a brilliant rainbow delighted beholders. Two days later, rain again fell at night in Cairo, making the dirty streets more nasty still. Of course this experience was exceptional, as rain is a rarity in Cairo. Authorities give the rainfall at Alexandria as about eight inches per annum, and at Cairo about 1·2 inch, while in Upper Egypt the precipitation of moisture is far less; there are adults who say they have never seen rain.
I noticed, on the other hand, unmistakable signs of recent rains, such as dried mud-puddles, rain-drop prints, etc., at several points, near Cairo, east of Thebes (Wadi Bab-el-Molook), and in the peninsula of Sinai, and I was impressed with the belief that more rain falls in Egypt than is usually supposed. A local shower passing over a sandy, gravelly region, makes but little impress on it; and there is no corps of trained observers, outside of Cairo and Alexandria, to record the phenomenon. On visiting the Khedivial Astronomical Observatory just out of Cairo, I was cordially received by the director, Mr. T. Esmatt, a graduate of the École Polytechnique of Paris, and for three years an assistant in the Naval Observatory at Washington. I take pleasure in mentioning his politeness and courtesy, but I can not omit pointing out a weakness : he took me to the roof of the building to see the meteorological instruments, and I noted that the rain-gauge was quite full of water; this again gave me reason to regard Egypt as a rainy country. (The last shower fell one month previously.)
During my journey in the desert (March 13th to April 8th) rain fell three times in my vicinity : twice the fall was insignificant, lasting only two or three minutes, but on March 19th rain fell abundantly in Wadi Feirân, from 7.15 a. m. to 9.30 a. m. Heavy mists had obscured the peaks bordering this extensive valley nearly all the preceding day; the temperature during this rainfall was 52º, elevation about nineteen hundred feet.
That heavy falls of rain and even of snow occur in December and January in the Sinai region, is reported by many travelers; in the defile of Nakb-el-Hawi (five thousand feet), crossed by pilgrims en route for the sacred mountain, the winter rains make veritable torrents; in 1867 the water rose to such a height in the valley adjoining, Wadi Selâf, as to wash away a camp of Bedouins, causing a loss of forty lives and of numerous cattle (Baedeker). Captain Palmer describes also a sudden precipitation so copious as to fill the bottom of Wadi Feirân to the depth of several feet, causing the party to seek high ground. That the Oasis of Feirân was once the site of a village of anchorites and monks sufficiently important to become an episcopal see, is known to students of history; this was in the second to the sixth century a. d. A few cut stones, the capital of one column, and ruined sites, alone remain to indicate the locality.
Powerful winds sweep across the plains and through the valleys of Arabia Petræa, with a violence and continuity that I have not elsewhere experienced. In the spring months the prevailing wind in the desert is from the north and northwest, down the gulf. This wind is a cool one, but it occasionally veers around to the south and becomes oppressively hot. In April and May this south wind, called khamsîn, blows unremittingly for days together, scorching the traveler's skin and filling the orifices in his head with a very fine dry dust. Khamsîn is from an Arabic word meaning fifty, so called from a mistaken notion that it blows for a period of fifty days before the summer solstice.
In the Nile Valley, north winds prevail during the heated period of eight months, and southern winds during the rest of the year; these being in the opposite direction from the winds in the region of the Red Sea.
I witnessed three characteristic sand-storms at localities far apart and under varied circumstances. On February 15th, when riding a donkey through Thebes Nileward, a powerful west wind arose in the afternoon, blowing before it fine dust from the Libyan Desert. Words fail to describe the discomfort of such a sandstorm; the fine dust seems able to penetrate everything except perhaps an unbroken egg, and it is quite impossible to escape from it; to prevent suffocation, I borrowed from a fellah a coarse yet closely woven blue outer garment and wrapped my head up. Donkeys did not seem to enjoy the phenomenon any better than the Bedouins, and they shrank from its blast as well as the travelers. After crossing to Luxor in a boat, we found the residents in the large hotel much inconvenienced by the penetrating dust, although the building is screened by a handsome garden.
My second experience was in Cairo itself. On March 6th a northwest, and consequently a cool, wind blew dust from the adjoining desert into the city with such power as to obscure the usually brilliant sun during an entire day. Residents of Cairo said that the sand-storm was the severest in twenty-five years, and of an unusual character—being accompanied by a low temperature instead of the scorching khamsîn.
I experienced a third sand-storm in the desert of Sinai, on the plain of El Markha; it was accompanied by a scorching south wind, and the drying effects on the skin and the capital orifices produced greater discomfort than the suffocating dust and cutting sand; my party could do nothing but sit in silence on our camels, facing the storm, and the poor animals forgot to snatch at the tufts of scanty shrubs, as is their custom. In the evening the fierce wind very nearly overturned our tents in spite of extra stays, and at dinner every course was seasoned with the all-penetrating dust. The temperature at 7 p. m. was abnormally high, 84º; just twenty-four hours later it fell to 58º, the wind having meanwhile veered around to the north, bringing with it heavy mists.
Before dismissing the subject of climate, I wish to testify to the invigorating, delightful air in the desert; it has a bracing quality that enables one to expend much energy without fatigue. From about 1 to 3 p. m. the glare of the sun is often great, and shade is a comfort; but the constant breeze, sometimes rather too strong, tempers the heat. I suspect, too, that the air is very free from disease-germs.
In the journey from Suez to Sinai by the ordinary caravan route, one crosses undulating plains, limestone and sandstone hills, and eventually reaches bold granitic mountains, rising to the height of eight thousand feet. Each of these regions is furrowed by wadis, or dry water-courses, which present very different aspects in the three divisions named. The first fifty-two miles of the journey, occupying about two days and a half, as camels travel, cover an arid, sterile plain about ten miles wide from the low range of limestone hills on the east, Et Tîh, to the gulf on the west. This plain, like that of El Gâa, to the south, rises gradually from the sea to the foot-hills, and is undulating toward its southern end. It is crossed by broad, shallow wadis, running east and west, which were perfectly dry at the time of my visit; Wadi Werdan, the largest, is depressed but a foot or two below the level of the plain, and is approximately three miles in width at about six miles from the point where it enters the sea.
The most extensive plain on the western side of the peninsula is that of El Gâa, which is about eighty miles long and fifteen wide at its widest point. From the sea-coast to the mountains bordering it on the east it rises nearly one thousand feet, but so gradually as to deceive the eye and appear level. It is crossed by many shallow wadis, and its northern half is separated from the sea by a range of limestone hills (Jebel-el-Araba) reaching a height of sixteen hundred feet. When the plain was covered by the sea, this range was probably an island, or series of islands. The plain is rarely broken by hills, the sharp-pointed Krên Utûd, conspicuous from a distance, being an exception. I crossed the monotonous desolate waste, from the mouth of the beautiful Wadi Es-Sleh to Tor (or Tûr), on the gulf, a distance of about fifteen miles, and noted scarcely a dozen tufts of plants; water is absolutely wanting. North of Tor, however, and east of Jebel-elAraba, are palm-gardens that extend for several miles in a narrow belt; and these date-'bearing trees owe their existence to several saline springs occurring at intervals, some of which were quite warm. On this sterile plain the characteristics of a desert are seen in perfection : the level expanse is not too broad to conceal the lofty mountains on the east, nor to prevent glimpses of the blue sea on the western horizon; the floor is a firm, hard surface, made up of a compact mixture of gravel and coarse sand, so hard indeed that camels make no impress on it with their broad feet. At some places the surface pebbles are of many shades of brown, intermingled with black and white, and these are so closely laid and regularly distributed as to resemble a mosaic pavement, but of course a patternless one. The surface particles are generally coarser than those immediately beneath; they are chiefly limestone, sometimes of coralline limestone, intermingled with flint and other varieties of amorphous quartz. Many of the pebbles show on their surface beautifully regular pittings and furrows carved out by the wind-driven sand. The fine-grained sand has all been lifted high in air by the powerful winds, whirled away, and dropped into depressions or on the lee sides of hills. Hundreds of acres have no surface stones larger than an ostrich-egg; no water whatever is found in this region, much less any signs of vegetable or animal life, rarely even a passing bird.
On this desolate plain, when overtaken by night, one place is as good (or bad) as another for pitching the tents, unless perhaps a small hillock is reached, which may serve as a partial shelter from the gales that sometimes threaten to overturn the canvas.
In the region of extensive plains, the wadis, or dried-up watercourses, being depressed but little, closely resemble them. The floor of the wadi hardly differs from that of the plain, except when a torrent has swept before it large bowlders and deposited them irregularly in its bed. The sorting power of the water, however, is noticeable, as also the well-defined vertical walls, perhaps only a few inches deep, excavated at the point of lowest level. On the margins, too, of the wadis of the plain, and at points protected from the full force of the winter floods, several varieties of green shrubs grow in widely separated tufts. I often remarked mud-cracks, apparently of recent date; but these indications of water probably remain undisturbed in this desolate region for a considerable period, perhaps for several seasons.
In the limestone hills these wadis take the form of cañons, having nearly vertical walls, sometimes hundreds of feet high—as in Wadi Tayyibeh. The regular erosion on their sides produces, often, picturesque effects, as at Ras Abu Zanîmeh.
In the granitic district the wadis form V-shaped valleys, broken by narrower ones entering at right angles, and bounded by bold peaks many thousand feet above the beholder. In the beds of these wadis are scattered specimens of the rocks of the surrounding country; often bowlders of great size testify to the violence of the torrents during the winter months, especially in Wadi Feiran.
The absolute dependence of the population of Egypt upon the Nile is a familiar fact, discussed from the time of Herodotus to the present day. The proposed reopening of Lake Mœris in the Fayoum district, for irrigating the Delta, has been fully explained to the Academy by one of our members, Mr. F. Cope Whitehouse, its enthusiastic advocate.
The conditions of occurrence of water in the desert are perhaps less familiar. Not only is water scarce, but when obtained a large proportion of it is practically unpotable, being saturated with saline matter to such an extent that the soil in the vicinity is white with efflorescent salts of soda, magnesia, and lime. The "bitter waters" of Marah are not exceptional. The longest journey that I made without meeting good drinking-water was on the return from Tor to Suez, a distance of about one hundred and fifty miles, occupying six and a half days. On this route we passed a well in Wadi Gharundel where camels and Bedouins slaked their thirst, and our water-barrel was replenished with water for washing; but had we not been supplied with sweet water from the Nile, brought down to Tor on a boat from Suez, we should have fared badly in this respect. At the time of my visit all wells were admittedly very low, and in some places entirely dried up; so I saw the region in its most arid aspect.
Good water, flowing from springs and running short distances—say a quarter of a mile before sinking into the thirsty soil—is found in Wadi Feirân and in Wadi Tarfa. In the former place, many date-palms and even barley-fields make a charming oasis; at the latter, palms, canes, and tamarisks line the babbling brook, as it may truly be named, but the oasis is not extensive. North of Tor, on the gulf, are flowing springs of warm and saline water, not very palatable, but admirably adapted to the culture of date-palms, of which there are many thousands. The best drinking-water in the region that I have visited is on the flanks of Sinai. There are four wells within the monastery walls, one without, and others in the Leja Valley and vicinity.
In Wadi Es-Sleh, the romantic gorge southwest from Sinai, I discovered a cold and sweet sulphur spring, agreeable to the palate. It issues in the center of the wadi, at a point two hours' journey east of its mouth, and flows a short distance, depositing characteristic bluish sulphur on its borders. It was this latter that first attracted my attention. This spring is not mentioned in Baedeker's guide-book, generally so accurate.
The total absence of ponds and lakes is a marked feature in the physical geography of the peninsula of Sinai. Rain does at times fall in abundance, but it rushes precipitately down the wadis into the seas which bound it on two sides. Yet there is evidence of the existence of lakes at some earlier period. In Wadi Feirân, banks of earth sixty to one hundred feet high rest on the mountain-sides, especially in the angles of the valley, showing clearly the former existence of a lake, the barrier of which was probably near Hererât. I noticed also, at the point where the Wadi Es-Sleh enters the plain of El Gâa, unmistakable signs of an ancient lake. The wadi emerges suddenly from the mountain-range, and a circular depression from thirty to fifty feet deep, with a perfectly level sandy bottom and bounded by nearly vertical gravel cliffs, now marks the bed of a small lake.
The uninhabitability of the peninsula is due to its sterility rather than to its climate. Its sterility is due, I imagine, more to the unequal annual distribution of the water than to its absence, and, should the population warrant it, storage-dams, easily constructed in the narrow granite-walled wadis, would to a great degree remedy this defect. Perhaps at some future day, when a crowded world thrusts its surplus population into regions now hardly regarded as habitable, Arabia Petræa will bloom like a garden. Granite and limestone furnish valuable soil-ingredients, and the climate is not unfavorable to semi-tropical cultivation.
The flora and fauna of the desert have been often described, yet I imagine that much remains to be studied; the variety, beauty, and fragrance of the shrubs and flowers which the traveler meets in the most forbidding and unexpected spots were to my unprepared mind a remarkable feature. In March I gathered dandelions and daisies at Wadi Useit, also "butter and eggs"; in Wadi Tayyibeh, near saline water, spearmint; and in Wadi Feiran, on the hillsides, sorrel.
The oases with their date-palms, tarfa (or tamarisk) yielding manna, seyâl (or acacia) yielding gum arabic, gharkad shrubs, and thickets of tall reeds, are veritable islands of fertility in an ocean of desolation. At the monastery, cypresses, oranges, peaches, and vines are cultivated, although five thousand feet above the sea-level.
Naturalists enumerate a number of large animals that live in the oases of the desert, among them the gazelle, ibex, jackal, and fox. I met with the head of a gazelle and numerous horns of ibexes, and in Wadi Es-Sleh a Bedouin suddenly appeared with two little half-tamed ibexes about fourteen days old; my traveling companion bought them, but they were unable to withstand the novelty of camel-riding, and, though kindly cared for, died within a few days. Their skins were preserved. I noted on the journey a large field-mouse, a small light-yellow snake two and a half feet long, and a peculiar kind of lizard (?). At Assouan I killed an intensely energetic scorpion, and at many places noted chameleons basking in the sun. Of the numerous and curious fish in the Red Sea, I can only say that some of them proved to be excellent food.
Insects were rarely seen in the desert, and only in the neighborhood of water, or in the oases. I observed red and black ants, one large caterpillar, very few flies, many black beetles leaving behind them well-defined tracks as they crawled over the fine-grained sand, a few moths, a bee, a grasshopper, many spiders, a lady-bug (so called), gnats near the sea-coast, and my traveling companion noted fleas. Mosquitoes, so abundant in Cairo were not seen nor heard. Twice large birds sailed high above our heads. This is the total of animal life met with in my four weeks' journey, excepting camels, goats, one lamb (which we ate), one donkey (at Tor), a dozen cats (at the monastery), several Bedouins, two Russian ladies, two German philologists, two Irish theologians, three enterprising Americans, and twenty-nine lazy monks.
- Abstract of a paper read to the New York Academy of Sciences, February 24, 1890, and condensed by the author from the Transactions, vol. ix, p. 110.