Inhabitants.

PLATE IV.Ruins of Um Eleiga. Gebel Abu Dahr in the Background.Ruins in Wadi Shenshef.Besides those at the mining camps and stations, there are some other extensive collections of ruins in the district, two of the most considerable being at Shenshef and Bir Meneiga. Theruins at Shenshef(seePlate IV) are in part those of well-built houses, furnished with doors and windows, formed of slabs of fissile quartzose schist, quarried in the neighbouring hills. There are wells at Shenshef, but apparently no mines; the presence of watch towers on the hills, and the peculiar situation of the place, suggest that it may have been a slave dealer’s stronghold where slaves were herded till they could be shipped from Berenice. The better houses may have been those of the overseers, while the ruder hovels accommodated the slaves, and sentinels at the watch towers prevented any attempt at escape. Theruins at Bir Meneiga, though extensive, are very rude, and probably only represent a camping ground near the springs. A large rubble enclosure near Abraq springs has been thought by Purdy[54]to have been a hunting station of the Ptolemies.In many places there aremarks and drawings on the rocksnear roads. These are frequently spirited representations of animals, among which the ostrich is often seen. At the Galt el Aguz, near the watershed at the head of one of the branches of Wadi Garara, the drawings are accompanied by rude Greek inscriptions. At Abu Saafa, one of the springs issues from a niche cut in the sandstone, having a carved cornice with the remains of a Greek inscription on it.Another class of remains are found scattered over the area in the form ofcylindrical rubble piles, four metres in diameter and from one to two metres high. The natives consider these to be tombs of pre-Arab date.OfArab tombsin the area, the most considerable is that of Sheikh Shadli, near Gebel Abu Hamamid, a view of which is shown onPlate V.It is a well-built tomb of several domes, inhabited by a Moorish guardian. A yearly pilgrimage is made to this place by the Ababda Arabs, who hold the memory of Shadli in high veneration. The next largest tomb is probably that of Sheikh Hamid, near Abraq springs. Near the nose of Ras Benas is a large sheikh’s tomb, where sailors perform their devotions, and smaller tombs of the same type, built of drift-wood, are to be seen at other points near the coast. Cemeteries of small Arab graves exist near every well and spring.Inhabitants.The South-Eastern Desert of Egypt is inhabited by nomad Arabs of the various Ababda and Bisharin tribes.[55]Ababda (Ashabab and Meleikab) occupy the country north of Muqsim and Bir Shalatein, while Bisharin (Hamedorab, Kurbeilab, Koatil, and Balgab) inhabit the country to the south.[56]Only guesses are available as to their numbers, but it is not probable that they comprise so much as one inhabitant for each five square kilometres. A casual journey through the country would lead one to think that it was inhabited to an even less degree, but the Arabs mostly camp in selected narrow wadis out of sight of the traveller. They are a people of good physique, hardy, intelligent, and fair workers if once their employer knows how to handle them. They share, however, in the universal Bedouin dislike to protracted regular work; after a few months of regular routine, even the semi-nomad routine of a survey-expedition, they experience strong desires for their own independent roaming life, and it is impossible to retain them for longer periods. Many of the Ababda who are settled near the Nile have lost their true desert character, and on desert expeditions men of this class are far less satisfactory than nomads; they do not know the country, but fear the desert and are continually desirous of returning to the valley. The better desert guides, on the other hand, love the wilderness, and they have a perfectly marvellous geographic instinct. The skeleton on which they arrange their knowledge is always the system of drainage. Ifa map of their country is laid before them, and a few points named to them, they will delight in tracing out and naming all the wadis and peaks. But they have very vague ideas of proportion, and can only read a map when it is laid on the ground in its true orientation with respect to the meridian. The Ababda are generally regarded as the best type of Egyptian desert Arab, while my experience of the Bisharin of the Elba district is that they are superior, in industry, intelligence, truthfulness, and orderliness, to the Ababda.[57]It is, however, necessary either to understand the Bishari tongue, or to have men who can interpret into Arabic, as the great mass of the Bisharin understand only their own language, which is quite different from Arabic.[58]Education is very backward, but there is akuttab(elementary school) at Halaib, where instruction in Arabic reading and writing is given to boys. All the Arabs are of course Moslems, but they are not at all fanatical.PLATE V.Tomb of Sheikh Shadli.Bir Shadli.The manner of life of the Arabs is very simple. Most of the men have only a single cotton wrap about their middle, though some wear the ordinary galabia and cotton drawers. Their camps are rude tents of matting about two metres in diameter, but the men commonly sleep in the open, sheltering themselves from winds by their camel saddles, covered only with their cotton wrap, which they spread over their entire bodies, including their heads. They wear no head covering, having heavy “mops” of curled black hair plentifully supplied with mutton fat. Their food consists almost entirely of milk and meat, of which their flocks and herds give them a plentiful supply; they eat but little bread, but they are fond of a kind of gruel of flour and water, and of dates, which are imported from ArabiaviaSuakin. Only a few of them smoke tobacco, and that generally in soapstone pipes which they carve out for themselves. Intoxicants are unknown amongst true desert Arabs. For arms, they carry swords and knives, seldom fire-arms. Of their tribal customs, I saw but little; Linant de Bellefonds gives an interesting account of them in his “L’Etbaye.” On festive occasions, camel-racing and dancing are favourite amusements.Slavery appears to be non-existent at present, for in the course of my twenty months’ wanderings I received no complaint under this head, as I should almost certainly have done had any oppressive servitude existed.Languages.My own study of the Ababda and Bishari tongues has been mainly confined to their geographical terms. The Ababda nowadays almost all speak Arabic, and most of their place-names are either Arabic or closely akin to it. A marked feature of their tongue is a fondness for diminutives. Thus we haveSellimandSeleim,HafafitandHefeifit,Faraid, andFereyid,WadiandWadai, in each of which the second of the pair is a diminutive formed by vowel-change, generally accompanied by a change in the placing of the stress. The commonest special geographical terms in Ababda country are:erf, a ridge;rod, a tributary wadi;talet, a small tributary wadi;kab, a watershed or pass;hamrat, a (red) granite mountain;zergat, a black mountain;galt, a rock basin containing rain water; andmegal, a small water hole. Thus we have such names asHamrat Selma,Zergat Naam, and so on, the name often giving a clue to the nature of the rock.As soon as one passes into Bisharin country the change in the nature of place-names is very striking. The definite article is no longerel, buto,u,ei,e(masc.), andto,tu,tei,ti(fem.). Many place-names end inaiandoi. The principal geographical terms are:kwan, a wadi;da-aiyob, a depression from which there is no drainage outlet;aweibandriba, a mountain;kulet, a hill;megwel, a water hole;adar, red;hadal, black;sotai, green;eire, white;sarara, deep;salala, rather deep (applied to wells). Hence we get such combinations as:Hadal Aweib Meisah, the black mountain near Wadi Meisah;Eir Arib, the white (granite) rock;Sarobi Kwan, the wadi where the Sarob plant (Capparis sodada) grows;Bir Sararat Seyet, the deep well in Wadi Seyet, and so on. A mountain calledadaris generally of red granite, while one calledhadalis usually diorite or serpentine.Asotriba, the green mountain south of Gebel Elba, receives its name from the vegetation on it.Industries.The principal industries carried on by the desert Arabs are the rearing of camels, sheep and goats, especially the first-named. The Bisharin devote much attention to camel-breeding, and supply many animals annually to the Coast Guard Administration. Their camels are very superior animals, and need to be hardy in order to negotiate the steep mountain passes of their country. Sheep and goats can be bought cheaply in the south, and are driven in to Aswân for sale at the higher rates there prevailing. It is common to find a flock of hundreds of sheep being watered at wells such as Bir Abu Hashim and Qoleib on the route to Kom Ombo; but many animals drop and die on the weary march from well to well.Charcoal burning has been practised, especially in the Ababda country, but is not much carried on now; this industry deserves strong opposition, for it only impoverishes the country, and theseyaltrees are few enough for the support of camels in years of drought.In recent years some employment has been found for the Arabs by prospectors for mining companies, both as miners and for camel-transport, and they are occasionally, as in the present expedition, employed on Government work.For the information of future travellers, it may be worth while to mention the prices paid for local labour on the survey expeditions. The men and animals were all the best obtainable of their particular class, and the prices include saddles and fodder for camels, their own provision of water and food for the men, and, in the case of sheikhs, postmen, and guides, their riding camels and fodder:—Mills, per day.[59]Responsible sheikhs in charge of all Arabs200Skilled guides (also employed as beacon builders)150Postmen journeying regularly to and from the Nile Valley150Baggage camels, each to carry 300 pounds’ load, with one driver to every two camels, the drivers to act as general labourers at a camp and to collect wood and water and to carry supplies up the mountains when required120Riding camels120Porters70 to 80A small amount of agriculture is practised in the Wadi Di-ib, slightly south of the Sudan frontier, but there is none actually withinthe district here described. My camels were fed for some time ondurra(Indian corn) brought from Wadi Di-ib.A little fishing is carried on near Berenice and at Mersa Shab and Halaib, but only for the food of the fishermen, who subsist almost entirely on it, and thus recall theIchthyophagesof Ptolemy. When I had abundance of excellent fish at Shab and Halaib, I noticed that but few of my Bisharin cared to partake of what was to me a very welcome change of diet.Halaib is the only permanent village, and even it is merely a miserable collection of wooden huts and tents, where trade is confined to dates, fat, corn, sugar, and such like necessaries; supplies are brought by boat from Suakin and sold to the local Arabs.Communications.There are numerous camel-roads connecting the various wells with each other and with the Nile, the principal of which are indicated onPlate III(p. 26). The most usual starting points from the valley are Edfu, Kom Ombo, Aswân, Dakka, and Berber. The roads lie mostly along wadis, and are far from being very direct, being necessarily so chosen as to pass water supplies and to avoid very steep places. From Aswân or Kom Ombo, Berenice can be reached in about seven or eight days by luggage camels, and the roads are fairly good; water is least scarce on the Kom Ombo road, which takes advantage of the wells of Qoleib and Abu Hashim. Between any two wells, there are generally several possible roads. The one taken by any particular traveller is naturally that which his guides happen to know best, or that along which the most camel food is to be found at the time; hardly any two Europeans have journeyed by precisely the same road. A “road” in desert parlance is only a track by which camels have passed at some time or other; there is nothing of the nature of amaderoad, even along the ancient routes mentioned in the Antonine Itinerary; and the tracks are sometimes obliterated by sand. Since the opening up of Port Sudan, the Elba district is most easily reached from that place, whence it is about 340 kilometres distant, by two roads of nearly equal length, one skirting the coast and the other more inland; the latter passes good wells at about twodays’ intervals.[60]To reach Elba from the valley, a camel journey of more than 500 kilometres is necessary whether Aswân, Dakka, or Berber be the starting point. The ports of Berenice, Shab, and Halaib are only touched occasionally and irregularly by coasting boats and Coast Guard steamers. News is passed orally among the wandering Arabs with remarkable rapidity, but naturally it frequently gets somewhat modified in transit.Government.The geographical frontier between Egypt and the Sudan is the 22nd parallel of north latitude. But for administrative purposes it has been found convenient to consider all Bisharin Arabs as under the Sudan Government, and all Ababda under that of Egypt. The administrative frontier therefore runs between the districts of the two main tribal divisions, along a zigzag line from Gebel Muqsim,viaGebel Um el Tiur el Foqani, Gebel Niqrub el Foqani, and Bir Meneiga, to Bir Shalatein on the coast.[61]A territory of some 16,000 square kilometres in the extreme south-east corner of Egypt is thus placed for purposes of government under the Sudan mudiria of Berber, under which arrangement a moawin and small police force are maintained in the fort of Halaib. The remainder of the area is administered by the Egyptian mudir of Aswân. In Egypt, the Arabs are not taxed except in respect of any lands they may own in the Nile Valley. In the Sudan a tax is levied on each tribe in return for police protection and other advantages; the tax is paid very willingly, for the Bisharin are less poor than the Ababda, and thoroughly appreciate the advantage of good government, while they have unbounded faith in the justice of Anglo-Egyptian officials in settling their disputes. One of the incidents which most strongly impressed itself on my remembrance during my travels in the district was the meeting near Gebel Korabkansi of an English inspector from Berber, to whom a number of Bisharin Arabs engaged in disputes stated their rival claims quietly and reasonably, both sides having the utmost confidence that the judgment given would be just and fair. In Egypt,the Arabs are less friendly in their feelings towards the government, and prefer to settle their differences among themselves; a circumstance no doubt due to the fact that Egyptian governors have had their hands full with matters connected with the valley, and have had no time to become acquainted with Bedouin ideas and customs, while the Arabs, independent for centuries and very poor, are afraid of misunderstanding and taxation. It would, I think, be unfair to tax the true desert Arabs of Egypt, even to the moderate extent which is done for the Arabs of the Sudan, for their country is much more barren than that of the Bisharin, and their sources of income are consequently fewer. In a year of little or no rainfall, there is not enough vegetation to feed their animals, so that many are lost, and the only way a tax could be raised at such times would be by cutting down trees for charcoal; but, as already mentioned, any encouragement of the charcoal industry would soon impoverish the country still further, the thorny acacia trees being the principal reserve camel food in rainless years. That so many Ababda are settled in and near the Nile Valley is possibly in part due to their having been driven from the desert by the growing scarcity of trees consequent on the prosecution of the charcoal industry in the past.[33]The mountains and hills will be found described in fuller detail inChapter VI.[34]The altitudes refer to the highest points of the groups.[35]This is the altitude of Shendib, the highest of the group in Egypt; but the peaks of Asotriba, which is part of the same mass lying within the Sudan, rise considerably higher.[36]In the map onPlate I,I have shown the watershed crossing directly from Gebel Soaorib across the high intervening mountains to Gebel Is, which is how it appeared to me from my station on Hadal Aweib Meisah. But Mr. Morrow Campbell’s map (referred to onp. 15) shows the heads of Wadi Soaorib to extend further west than I could see them; and if this is correct, as it probably is since Mr. Morrow Campbell doubtless approached the watershed more closely than I did, the watershed between Gebel Soaorib and Gebel Is lies further west than I have shown it on Plate I. In drawing the wadis on the geological and tribal maps on PlatesXXandXXVI,I have shown the westward extension of the heads of Wadi Soaorib according to Mr. Morrow Campbell.[37]The wadis will be found described at length in ChaptersIVandV.[38]See theRed Sea and Gulf of Aden Pilot, published by the Admiralty.[39]See my short paper on the meteorology of the Berenice district inSurvey Notes, Sept. 1907, p. 325.[40]I have given short accounts of some of these phenomena inSurvey Notes, April 1907, p. 219, and in theCairo Scientific Journal, May 1908, p. 206.[41]D’Anville,Mémoires sur l’Egypte. p. 234.[42]SeeBarronandHume,Topography and Geology of the Eastern Desert, Central Portion. Cairo, 1902. pp. 98-104.[43]Schweinfurth, inPetermann’s Mittheilungen, 1865.[44]For a fuller description of the water-sources of the region,seeChapter VII.[45]For a fuller account of the geology,seeChaptersVIIItoXI,and the geological map onPlate XX.[46]Suess,The Face of the Earth. Miss Sollas’ translation. Vol. I. Oxford, 1904. p. 376.[47]Lib. III, 12-14.[48]SeeDunn,Notes on the Mineral Deposits of the Anglo-Egyptian Sudan, published by the Sudan Government. Khartoum, 1911. p. 15.[49]For a plan of the temple and notes on its inscriptions,seeGolénischeff, Une Excursion à Bérénice,Recueil de Travaux. XIII (1891). pp. 75-96.[50]Macalister,Geog. Journal. Vol. XVI (1900). p. 546.[51]Op. cit.Golénischeff gives sketch plans of the stations.[52]The Empire of the Ptolemies.London, 1895. p. 130.[53]Diodorus(I. 49) probably greatly exaggerated the value of the produce of the mines.SeeUhlemann,Handbuch der gesammten aegyptischen Alterthumskunde, Zweiter Theil, Leipzig, 1857, pp. 148-151, where a very clear account, mainly derived from Diodorus, is given of the mining methods used by the ancients.[54]Bulletin Soc. Khéd. de Géogr.1886. p. 443.[55]According to Mr. Bramly (The Anglo-Egyptian Sudan. 1905. p. 91) the Bisharin are not true Arabs, and are of Hamitic descent.[56]Regarding the geographical boundaries of the different tribes,seeChapter XII.[57]Schweinfurth did not have the same experience in 1864; but one speaks as one finds. Schweinfurth was reluctant to pass judgment, not knowing the language, and possibly in the interval since 1864 the people have improved.[58]On the Bishari language,seeAlmkvist,Die Bishari-sprache, Upsala, 1881-1885;Reinisch,Die Bedauye-sprache in Nordost-Africa, Wien, 1893; andReinisch,Wörterbuch der Bedauye-sprache, Wien, 1895.[59]The millieme is practically equivalent to an English farthing.[60]For a detailed description of this road,seeChapter XIII.[61]Arrêté of the Ministry of Interior, Egypt, June 25, 1902.CHAPTER III.SURVEYING METHODS AND PRINCIPAL GEOGRAPHICAL RESULTS.Triangulation.Base-Lines—The triangulation was commenced by measuring a base line[62]near Gebel Muelih by means of a 100-metre steel tape, which had been previously standardised at the Khedivial Observatory. A level tract having been selected, in such a position as to afford easy connection with points already triangulated from the Nile Valley, a line about two and a half kilometres long was ranged out, along which wooden pegs were driven flush with the ground at 100-metre intervals. The inequalities of the ground between the pegs were levelled off by tiny embankments and cuttings, so as to enable the tape to lie flat. On each peg was nailed a zinc plate having a millimetre scale running in the direction of the line. In measuring, the tape was laid on the ground, stretched to a constant tension by a spring balance at each end, in such manner that its end marks fell on the zinc scales, and readings were simultaneously taken on the scales at the two ends. Temperatures were taken in several places along the tape by mercurial thermometers. The operation of measurement was carried out in the early morning, so as to avoid any large difference of temperature between the ground and the air. The levels of the pegs were found by spirit levelling. After correction for the initial error of the tape, temperature, stretch, and inclination, the true length of the base-line reduced to sea-level was found, as the mean of two separate measurements at different tensions, to be 2,482·280 metres. The azimuth of the line was found by observations ofPolarisat elongation to be 30° 30′ 6″ E. of N. The geographical position of the west end of the line was found by triangulation-connexion with the Nile Valley by Mr. Villiers Stuart to be latitude 24° 53′ 36″·7 N., longitude 34° 4′ 17″·9 E.A second connexion to a base-line was made near Gebel Um Harba, where a base had been previously measured by Mr. Villiers Stuart in the course of his triangulation of the western part of the desert. In this case the connexion was not made to the actual base-line, but to another main line tied directly on to it. The data at this point of connexion from the two triangulations afforded a useful check on the accuracy of the work, and were as follows:—From Mr. Stuart’s triangulation.From my triangulation.Difference.Latitude N.23° 36′ 55″·023° 36′ 55″·60″·6Longitude E.34° 30′ 38″·134° 30′ 37″·60″·5Length of line to Dagalai beacon13,170·2 metres.13,167·9 metres.2·3 metres.Reconnaissance for triangulation pointswas carried out simultaneously with the triangulation itself. The distance of likely looking peaks was determined either by intersecting them from distant stations, or by special small triangulations from short bases, and such selection made as seemed most likely to secure well shaped figures and a good command of surrounding country. As a rule, the highest summits were selected as main (occupied) stations, while all other prominent peaks and other features were fixed by intersection from two or more main stations. The form adopted for the main triangulation net was a series of quadrilateral figures with diagonals, combined with centric polygons, all the angles of the figures being generally measured. The average length of side was about thirty-five kilometres.Beacons.—Main stations were marked by wrought-iron beacons, consisting of two lengths of stove piping about 15 centimetres diameter by 1½ metres long, the upper length fitting into a faucet made by splaying out the lower tube. Near the top of the tube were affixed four sheet iron wings, bolted on to angle iron cleats. A conical cairn of stones was built up round the tube, nearly up to the wings, so that the beacon when erected was about three metres high, two metres in diameter across the base of the cairn, and about a metre wide across the wings. The beacons were taken down while a station was being occupied, and replaced on leaving.Intersected points were sometimes marked with a beacon or cairn, but in general the peaks were simply bisected from several stations, as it was found that this gave sufficiently accurate results.Measurement of Horizontal Angles.—Angles were measured with a 6-inch theodolite furnished with reading microscopes graduated to 10″ and permitting of reliable estimations to 1″. The angles between main points were read on four arcs to eliminate circle errors. Intersected points were observed on one arc only. The average error of closure of main triangles was 3″·3.Field Computation and Plotting of Triangulated Points.—The triangles were computed by the ordinary method, but the angles were rounded off to 10″ to enable the sines to be taken direct from the logarithmic tables, and the logarithms were only taken to five places. The length of the sides having been thus found, the geographical positions were found by the ordinaryL M Zcomputation, using, however, only two latitude terms and 5-place logarithms, while azimuths were only taken out to the nearest 10″. The abbreviated form of computation used will be best illustrated by an example:—[63]Computation of Position of△No. 260 from No. 275.l=20042 m.275⎰⎱φ=23° 55′30″·6Z=64° 29′ 20″E of N.λ=34° 54′36″·9Logl=4·30194Logl2=8·604Log cosZ=1·63416Log sin2Z=1·911B2·51194C=9·0532·44804=1·568dφ,1stterm=+ 280″·6Logl=4·301942ndterm=−0″·4Log sinZ=1·95545dφ=280″·2A′=2·50948=4′40″·2=2·76687φ=23° 55′30″·6Log cos φ′=1·96072φ′=24°0′10″·8=2·80615dλ=640″·0Whence=10′40″·0260⎰⎱φ′=24°0′10″·8λ=34° 54′36″·9λ′=35°5′16″·9λ′=35°5′16″·9In the above, it will be noticed that the azimuth is always noted as so much east or west of north or south. If this convention be adopted, one may consider the first term ofdφas always +, and the second term will be + if the azimuth contains the word south,—if it is from the north, while the totaldφis to be added or subtracted according as one is going north or south. A somewhat similar convention is adopted in neglecting the sign ofdλtill the actual addition or subtraction is made. It was found in the field that this method prevented any mistake of sign, while being much simpler to work than one involving angles greater than 90°.The geographical coordinates thus found were plotted directly on to the plane-table sheets, on which the graticule at 10′ intervals was the first thing drawn. The odd minutes and seconds were first converted into minutes and decimals, and then into kilometres by multiplying by the factors appropriate to the latitude, so that the plotting could be done by the ordinary scale of kilometres. To avoid difficulties of paper-shrinkage, as many points as possible were plotted at the time of drawing the graticule, and in general the points had to be plotted as far ahead as possible for controlling the traversing and sketching.Astronomical Observations.—Astronomical checks on the triangulation were obtained by observations of latitude at certain selected main stations 60-120 kilometres apart, and by azimuth observations for certain main lines.The method used forlatitudewas that of observing the times of equal altitudes of three or more stars, selected as near to the meridian[64]as possible. This method presents great advantages over the usualPolarisand circummeridian altitudes, in that the observations are more easily made, and yield much more accurate results, because uncertainties in refraction are largely eliminated and the errors of circle graduation are not involved, the altitudes not being read at all.[65]The theodolite used was the same as was employed in triangulation,and the times were taken by a half chronometer watch, preferably one marking sidereal time with a rate which could be considered negligible during the hour or so occupied by the observation. The first star taken was usuallyPolaris, and the vertical circle was left clamped at its altitude. For the other stars, any dislevelment was corrected by touching up the levelling screws just before the instant of observation; this was found better, than taking bubble readings and correcting for slight difference of altitude.The method which I found best in the field for reducing the observations differs somewhat from that described by Chauvenet. Assuming approximate values for the latitude and watch error, I first calculated the altitude of each star from the formulasinh= sin φ sin ε + cos φ cos δ costIf the assumed latitude and watch error were correct, all the stars would give the same value forh. If not, each star would give an equation of the formh+ cosAdφ+ cos φ sinAdT−h0= 0whereAis the star’s azimuth,dφthe required correction to the assumed latitude,dTthe required correction to the assumed watch times, andh0the true altitude common to the three stars. The values of cosAand cos φ sinAwere calculated from the ordinary formulasinA=cos δ sintcoshby four-place logarithms (using the approximate values for φ,t, andh, since these are quite sufficiently accurate for the purpose) and inserted into the three star-equations.[66]By then solving the three simultaneous equations fordφ, the required correction to the assumed latitude was at once obtained.As the method is one not usually treated of in books on practical astronomy, I give on the following pages the reduction of an observation worked out in full.Latitude by Equal Altitudes of Three Stars.Station on Gebel Um Heshenib. January 30, 1906.Approximateφ=24°20′50″N.„λ=34°51′0″E.Sidereal watch U. and C. 30811, approximately 2m22sfast on L.S.T., rate negligible.Observed times of equal altitudes by watch:—Polaris3h33m54s·2αColumbæ34240·8εCanis majoris42435·8Polaris.Watch time3h33m54s·2Watch fast222·0L.S.T.33132·2Star’s R.A.1259·1t2623·1= 31° 35′ 46″·5 W. of meridian.φ = 24° 20′ 50″log sin1·6151769δ = 88° 48′ 33″·1log sin1·99990621·6150831log cos δ2·3177Nat. (1)0·4121764log sint1·71932·0370φ = 24° 20′ 50″log cos1·9595488log cosh1·9560δ = 88° 48′ 33″·1log cos2·3176870log sinA2·0810t= 31° 35′ 46″·5log cos1·9303179log cos φ1·95952·04052·2075537Nat. =0·011Nat. (2)0·0161270Nat. (1)0·4121764log cosA1·99990·4283034Nat. =1·000log sinh1·6317515h=25° 21′ 35″·8Whence the equation forPolarisis

PLATE IV.Ruins of Um Eleiga. Gebel Abu Dahr in the Background.Ruins in Wadi Shenshef.

PLATE IV.

Ruins of Um Eleiga. Gebel Abu Dahr in the Background.

Ruins in Wadi Shenshef.

Besides those at the mining camps and stations, there are some other extensive collections of ruins in the district, two of the most considerable being at Shenshef and Bir Meneiga. Theruins at Shenshef(seePlate IV) are in part those of well-built houses, furnished with doors and windows, formed of slabs of fissile quartzose schist, quarried in the neighbouring hills. There are wells at Shenshef, but apparently no mines; the presence of watch towers on the hills, and the peculiar situation of the place, suggest that it may have been a slave dealer’s stronghold where slaves were herded till they could be shipped from Berenice. The better houses may have been those of the overseers, while the ruder hovels accommodated the slaves, and sentinels at the watch towers prevented any attempt at escape. Theruins at Bir Meneiga, though extensive, are very rude, and probably only represent a camping ground near the springs. A large rubble enclosure near Abraq springs has been thought by Purdy[54]to have been a hunting station of the Ptolemies.

In many places there aremarks and drawings on the rocksnear roads. These are frequently spirited representations of animals, among which the ostrich is often seen. At the Galt el Aguz, near the watershed at the head of one of the branches of Wadi Garara, the drawings are accompanied by rude Greek inscriptions. At Abu Saafa, one of the springs issues from a niche cut in the sandstone, having a carved cornice with the remains of a Greek inscription on it.

Another class of remains are found scattered over the area in the form ofcylindrical rubble piles, four metres in diameter and from one to two metres high. The natives consider these to be tombs of pre-Arab date.

OfArab tombsin the area, the most considerable is that of Sheikh Shadli, near Gebel Abu Hamamid, a view of which is shown onPlate V.It is a well-built tomb of several domes, inhabited by a Moorish guardian. A yearly pilgrimage is made to this place by the Ababda Arabs, who hold the memory of Shadli in high veneration. The next largest tomb is probably that of Sheikh Hamid, near Abraq springs. Near the nose of Ras Benas is a large sheikh’s tomb, where sailors perform their devotions, and smaller tombs of the same type, built of drift-wood, are to be seen at other points near the coast. Cemeteries of small Arab graves exist near every well and spring.

The South-Eastern Desert of Egypt is inhabited by nomad Arabs of the various Ababda and Bisharin tribes.[55]Ababda (Ashabab and Meleikab) occupy the country north of Muqsim and Bir Shalatein, while Bisharin (Hamedorab, Kurbeilab, Koatil, and Balgab) inhabit the country to the south.[56]Only guesses are available as to their numbers, but it is not probable that they comprise so much as one inhabitant for each five square kilometres. A casual journey through the country would lead one to think that it was inhabited to an even less degree, but the Arabs mostly camp in selected narrow wadis out of sight of the traveller. They are a people of good physique, hardy, intelligent, and fair workers if once their employer knows how to handle them. They share, however, in the universal Bedouin dislike to protracted regular work; after a few months of regular routine, even the semi-nomad routine of a survey-expedition, they experience strong desires for their own independent roaming life, and it is impossible to retain them for longer periods. Many of the Ababda who are settled near the Nile have lost their true desert character, and on desert expeditions men of this class are far less satisfactory than nomads; they do not know the country, but fear the desert and are continually desirous of returning to the valley. The better desert guides, on the other hand, love the wilderness, and they have a perfectly marvellous geographic instinct. The skeleton on which they arrange their knowledge is always the system of drainage. Ifa map of their country is laid before them, and a few points named to them, they will delight in tracing out and naming all the wadis and peaks. But they have very vague ideas of proportion, and can only read a map when it is laid on the ground in its true orientation with respect to the meridian. The Ababda are generally regarded as the best type of Egyptian desert Arab, while my experience of the Bisharin of the Elba district is that they are superior, in industry, intelligence, truthfulness, and orderliness, to the Ababda.[57]It is, however, necessary either to understand the Bishari tongue, or to have men who can interpret into Arabic, as the great mass of the Bisharin understand only their own language, which is quite different from Arabic.[58]Education is very backward, but there is akuttab(elementary school) at Halaib, where instruction in Arabic reading and writing is given to boys. All the Arabs are of course Moslems, but they are not at all fanatical.

PLATE V.Tomb of Sheikh Shadli.Bir Shadli.

PLATE V.

Tomb of Sheikh Shadli.

Bir Shadli.

The manner of life of the Arabs is very simple. Most of the men have only a single cotton wrap about their middle, though some wear the ordinary galabia and cotton drawers. Their camps are rude tents of matting about two metres in diameter, but the men commonly sleep in the open, sheltering themselves from winds by their camel saddles, covered only with their cotton wrap, which they spread over their entire bodies, including their heads. They wear no head covering, having heavy “mops” of curled black hair plentifully supplied with mutton fat. Their food consists almost entirely of milk and meat, of which their flocks and herds give them a plentiful supply; they eat but little bread, but they are fond of a kind of gruel of flour and water, and of dates, which are imported from ArabiaviaSuakin. Only a few of them smoke tobacco, and that generally in soapstone pipes which they carve out for themselves. Intoxicants are unknown amongst true desert Arabs. For arms, they carry swords and knives, seldom fire-arms. Of their tribal customs, I saw but little; Linant de Bellefonds gives an interesting account of them in his “L’Etbaye.” On festive occasions, camel-racing and dancing are favourite amusements.

Slavery appears to be non-existent at present, for in the course of my twenty months’ wanderings I received no complaint under this head, as I should almost certainly have done had any oppressive servitude existed.

My own study of the Ababda and Bishari tongues has been mainly confined to their geographical terms. The Ababda nowadays almost all speak Arabic, and most of their place-names are either Arabic or closely akin to it. A marked feature of their tongue is a fondness for diminutives. Thus we haveSellimandSeleim,HafafitandHefeifit,Faraid, andFereyid,WadiandWadai, in each of which the second of the pair is a diminutive formed by vowel-change, generally accompanied by a change in the placing of the stress. The commonest special geographical terms in Ababda country are:erf, a ridge;rod, a tributary wadi;talet, a small tributary wadi;kab, a watershed or pass;hamrat, a (red) granite mountain;zergat, a black mountain;galt, a rock basin containing rain water; andmegal, a small water hole. Thus we have such names asHamrat Selma,Zergat Naam, and so on, the name often giving a clue to the nature of the rock.

As soon as one passes into Bisharin country the change in the nature of place-names is very striking. The definite article is no longerel, buto,u,ei,e(masc.), andto,tu,tei,ti(fem.). Many place-names end inaiandoi. The principal geographical terms are:kwan, a wadi;da-aiyob, a depression from which there is no drainage outlet;aweibandriba, a mountain;kulet, a hill;megwel, a water hole;adar, red;hadal, black;sotai, green;eire, white;sarara, deep;salala, rather deep (applied to wells). Hence we get such combinations as:Hadal Aweib Meisah, the black mountain near Wadi Meisah;Eir Arib, the white (granite) rock;Sarobi Kwan, the wadi where the Sarob plant (Capparis sodada) grows;Bir Sararat Seyet, the deep well in Wadi Seyet, and so on. A mountain calledadaris generally of red granite, while one calledhadalis usually diorite or serpentine.Asotriba, the green mountain south of Gebel Elba, receives its name from the vegetation on it.

The principal industries carried on by the desert Arabs are the rearing of camels, sheep and goats, especially the first-named. The Bisharin devote much attention to camel-breeding, and supply many animals annually to the Coast Guard Administration. Their camels are very superior animals, and need to be hardy in order to negotiate the steep mountain passes of their country. Sheep and goats can be bought cheaply in the south, and are driven in to Aswân for sale at the higher rates there prevailing. It is common to find a flock of hundreds of sheep being watered at wells such as Bir Abu Hashim and Qoleib on the route to Kom Ombo; but many animals drop and die on the weary march from well to well.

Charcoal burning has been practised, especially in the Ababda country, but is not much carried on now; this industry deserves strong opposition, for it only impoverishes the country, and theseyaltrees are few enough for the support of camels in years of drought.

In recent years some employment has been found for the Arabs by prospectors for mining companies, both as miners and for camel-transport, and they are occasionally, as in the present expedition, employed on Government work.

For the information of future travellers, it may be worth while to mention the prices paid for local labour on the survey expeditions. The men and animals were all the best obtainable of their particular class, and the prices include saddles and fodder for camels, their own provision of water and food for the men, and, in the case of sheikhs, postmen, and guides, their riding camels and fodder:—

A small amount of agriculture is practised in the Wadi Di-ib, slightly south of the Sudan frontier, but there is none actually withinthe district here described. My camels were fed for some time ondurra(Indian corn) brought from Wadi Di-ib.

A little fishing is carried on near Berenice and at Mersa Shab and Halaib, but only for the food of the fishermen, who subsist almost entirely on it, and thus recall theIchthyophagesof Ptolemy. When I had abundance of excellent fish at Shab and Halaib, I noticed that but few of my Bisharin cared to partake of what was to me a very welcome change of diet.

Halaib is the only permanent village, and even it is merely a miserable collection of wooden huts and tents, where trade is confined to dates, fat, corn, sugar, and such like necessaries; supplies are brought by boat from Suakin and sold to the local Arabs.

There are numerous camel-roads connecting the various wells with each other and with the Nile, the principal of which are indicated onPlate III(p. 26). The most usual starting points from the valley are Edfu, Kom Ombo, Aswân, Dakka, and Berber. The roads lie mostly along wadis, and are far from being very direct, being necessarily so chosen as to pass water supplies and to avoid very steep places. From Aswân or Kom Ombo, Berenice can be reached in about seven or eight days by luggage camels, and the roads are fairly good; water is least scarce on the Kom Ombo road, which takes advantage of the wells of Qoleib and Abu Hashim. Between any two wells, there are generally several possible roads. The one taken by any particular traveller is naturally that which his guides happen to know best, or that along which the most camel food is to be found at the time; hardly any two Europeans have journeyed by precisely the same road. A “road” in desert parlance is only a track by which camels have passed at some time or other; there is nothing of the nature of amaderoad, even along the ancient routes mentioned in the Antonine Itinerary; and the tracks are sometimes obliterated by sand. Since the opening up of Port Sudan, the Elba district is most easily reached from that place, whence it is about 340 kilometres distant, by two roads of nearly equal length, one skirting the coast and the other more inland; the latter passes good wells at about twodays’ intervals.[60]To reach Elba from the valley, a camel journey of more than 500 kilometres is necessary whether Aswân, Dakka, or Berber be the starting point. The ports of Berenice, Shab, and Halaib are only touched occasionally and irregularly by coasting boats and Coast Guard steamers. News is passed orally among the wandering Arabs with remarkable rapidity, but naturally it frequently gets somewhat modified in transit.

The geographical frontier between Egypt and the Sudan is the 22nd parallel of north latitude. But for administrative purposes it has been found convenient to consider all Bisharin Arabs as under the Sudan Government, and all Ababda under that of Egypt. The administrative frontier therefore runs between the districts of the two main tribal divisions, along a zigzag line from Gebel Muqsim,viaGebel Um el Tiur el Foqani, Gebel Niqrub el Foqani, and Bir Meneiga, to Bir Shalatein on the coast.[61]A territory of some 16,000 square kilometres in the extreme south-east corner of Egypt is thus placed for purposes of government under the Sudan mudiria of Berber, under which arrangement a moawin and small police force are maintained in the fort of Halaib. The remainder of the area is administered by the Egyptian mudir of Aswân. In Egypt, the Arabs are not taxed except in respect of any lands they may own in the Nile Valley. In the Sudan a tax is levied on each tribe in return for police protection and other advantages; the tax is paid very willingly, for the Bisharin are less poor than the Ababda, and thoroughly appreciate the advantage of good government, while they have unbounded faith in the justice of Anglo-Egyptian officials in settling their disputes. One of the incidents which most strongly impressed itself on my remembrance during my travels in the district was the meeting near Gebel Korabkansi of an English inspector from Berber, to whom a number of Bisharin Arabs engaged in disputes stated their rival claims quietly and reasonably, both sides having the utmost confidence that the judgment given would be just and fair. In Egypt,the Arabs are less friendly in their feelings towards the government, and prefer to settle their differences among themselves; a circumstance no doubt due to the fact that Egyptian governors have had their hands full with matters connected with the valley, and have had no time to become acquainted with Bedouin ideas and customs, while the Arabs, independent for centuries and very poor, are afraid of misunderstanding and taxation. It would, I think, be unfair to tax the true desert Arabs of Egypt, even to the moderate extent which is done for the Arabs of the Sudan, for their country is much more barren than that of the Bisharin, and their sources of income are consequently fewer. In a year of little or no rainfall, there is not enough vegetation to feed their animals, so that many are lost, and the only way a tax could be raised at such times would be by cutting down trees for charcoal; but, as already mentioned, any encouragement of the charcoal industry would soon impoverish the country still further, the thorny acacia trees being the principal reserve camel food in rainless years. That so many Ababda are settled in and near the Nile Valley is possibly in part due to their having been driven from the desert by the growing scarcity of trees consequent on the prosecution of the charcoal industry in the past.

[33]The mountains and hills will be found described in fuller detail inChapter VI.[34]The altitudes refer to the highest points of the groups.[35]This is the altitude of Shendib, the highest of the group in Egypt; but the peaks of Asotriba, which is part of the same mass lying within the Sudan, rise considerably higher.[36]In the map onPlate I,I have shown the watershed crossing directly from Gebel Soaorib across the high intervening mountains to Gebel Is, which is how it appeared to me from my station on Hadal Aweib Meisah. But Mr. Morrow Campbell’s map (referred to onp. 15) shows the heads of Wadi Soaorib to extend further west than I could see them; and if this is correct, as it probably is since Mr. Morrow Campbell doubtless approached the watershed more closely than I did, the watershed between Gebel Soaorib and Gebel Is lies further west than I have shown it on Plate I. In drawing the wadis on the geological and tribal maps on PlatesXXandXXVI,I have shown the westward extension of the heads of Wadi Soaorib according to Mr. Morrow Campbell.[37]The wadis will be found described at length in ChaptersIVandV.[38]See theRed Sea and Gulf of Aden Pilot, published by the Admiralty.[39]See my short paper on the meteorology of the Berenice district inSurvey Notes, Sept. 1907, p. 325.[40]I have given short accounts of some of these phenomena inSurvey Notes, April 1907, p. 219, and in theCairo Scientific Journal, May 1908, p. 206.[41]D’Anville,Mémoires sur l’Egypte. p. 234.[42]SeeBarronandHume,Topography and Geology of the Eastern Desert, Central Portion. Cairo, 1902. pp. 98-104.[43]Schweinfurth, inPetermann’s Mittheilungen, 1865.[44]For a fuller description of the water-sources of the region,seeChapter VII.[45]For a fuller account of the geology,seeChaptersVIIItoXI,and the geological map onPlate XX.[46]Suess,The Face of the Earth. Miss Sollas’ translation. Vol. I. Oxford, 1904. p. 376.[47]Lib. III, 12-14.[48]SeeDunn,Notes on the Mineral Deposits of the Anglo-Egyptian Sudan, published by the Sudan Government. Khartoum, 1911. p. 15.[49]For a plan of the temple and notes on its inscriptions,seeGolénischeff, Une Excursion à Bérénice,Recueil de Travaux. XIII (1891). pp. 75-96.[50]Macalister,Geog. Journal. Vol. XVI (1900). p. 546.[51]Op. cit.Golénischeff gives sketch plans of the stations.[52]The Empire of the Ptolemies.London, 1895. p. 130.[53]Diodorus(I. 49) probably greatly exaggerated the value of the produce of the mines.SeeUhlemann,Handbuch der gesammten aegyptischen Alterthumskunde, Zweiter Theil, Leipzig, 1857, pp. 148-151, where a very clear account, mainly derived from Diodorus, is given of the mining methods used by the ancients.[54]Bulletin Soc. Khéd. de Géogr.1886. p. 443.[55]According to Mr. Bramly (The Anglo-Egyptian Sudan. 1905. p. 91) the Bisharin are not true Arabs, and are of Hamitic descent.[56]Regarding the geographical boundaries of the different tribes,seeChapter XII.[57]Schweinfurth did not have the same experience in 1864; but one speaks as one finds. Schweinfurth was reluctant to pass judgment, not knowing the language, and possibly in the interval since 1864 the people have improved.[58]On the Bishari language,seeAlmkvist,Die Bishari-sprache, Upsala, 1881-1885;Reinisch,Die Bedauye-sprache in Nordost-Africa, Wien, 1893; andReinisch,Wörterbuch der Bedauye-sprache, Wien, 1895.[59]The millieme is practically equivalent to an English farthing.[60]For a detailed description of this road,seeChapter XIII.[61]Arrêté of the Ministry of Interior, Egypt, June 25, 1902.

[33]The mountains and hills will be found described in fuller detail inChapter VI.

[34]The altitudes refer to the highest points of the groups.

[35]This is the altitude of Shendib, the highest of the group in Egypt; but the peaks of Asotriba, which is part of the same mass lying within the Sudan, rise considerably higher.

[36]In the map onPlate I,I have shown the watershed crossing directly from Gebel Soaorib across the high intervening mountains to Gebel Is, which is how it appeared to me from my station on Hadal Aweib Meisah. But Mr. Morrow Campbell’s map (referred to onp. 15) shows the heads of Wadi Soaorib to extend further west than I could see them; and if this is correct, as it probably is since Mr. Morrow Campbell doubtless approached the watershed more closely than I did, the watershed between Gebel Soaorib and Gebel Is lies further west than I have shown it on Plate I. In drawing the wadis on the geological and tribal maps on PlatesXXandXXVI,I have shown the westward extension of the heads of Wadi Soaorib according to Mr. Morrow Campbell.

[37]The wadis will be found described at length in ChaptersIVandV.

[38]See theRed Sea and Gulf of Aden Pilot, published by the Admiralty.

[39]See my short paper on the meteorology of the Berenice district inSurvey Notes, Sept. 1907, p. 325.

[40]I have given short accounts of some of these phenomena inSurvey Notes, April 1907, p. 219, and in theCairo Scientific Journal, May 1908, p. 206.

[41]D’Anville,Mémoires sur l’Egypte. p. 234.

[42]SeeBarronandHume,Topography and Geology of the Eastern Desert, Central Portion. Cairo, 1902. pp. 98-104.

[43]Schweinfurth, inPetermann’s Mittheilungen, 1865.

[44]For a fuller description of the water-sources of the region,seeChapter VII.

[45]For a fuller account of the geology,seeChaptersVIIItoXI,and the geological map onPlate XX.

[46]Suess,The Face of the Earth. Miss Sollas’ translation. Vol. I. Oxford, 1904. p. 376.

[47]Lib. III, 12-14.

[48]SeeDunn,Notes on the Mineral Deposits of the Anglo-Egyptian Sudan, published by the Sudan Government. Khartoum, 1911. p. 15.

[49]For a plan of the temple and notes on its inscriptions,seeGolénischeff, Une Excursion à Bérénice,Recueil de Travaux. XIII (1891). pp. 75-96.

[50]Macalister,Geog. Journal. Vol. XVI (1900). p. 546.

[51]Op. cit.Golénischeff gives sketch plans of the stations.

[52]The Empire of the Ptolemies.London, 1895. p. 130.

[53]Diodorus(I. 49) probably greatly exaggerated the value of the produce of the mines.SeeUhlemann,Handbuch der gesammten aegyptischen Alterthumskunde, Zweiter Theil, Leipzig, 1857, pp. 148-151, where a very clear account, mainly derived from Diodorus, is given of the mining methods used by the ancients.

[54]Bulletin Soc. Khéd. de Géogr.1886. p. 443.

[55]According to Mr. Bramly (The Anglo-Egyptian Sudan. 1905. p. 91) the Bisharin are not true Arabs, and are of Hamitic descent.

[56]Regarding the geographical boundaries of the different tribes,seeChapter XII.

[57]Schweinfurth did not have the same experience in 1864; but one speaks as one finds. Schweinfurth was reluctant to pass judgment, not knowing the language, and possibly in the interval since 1864 the people have improved.

[58]On the Bishari language,seeAlmkvist,Die Bishari-sprache, Upsala, 1881-1885;Reinisch,Die Bedauye-sprache in Nordost-Africa, Wien, 1893; andReinisch,Wörterbuch der Bedauye-sprache, Wien, 1895.

[59]The millieme is practically equivalent to an English farthing.

[60]For a detailed description of this road,seeChapter XIII.

[61]Arrêté of the Ministry of Interior, Egypt, June 25, 1902.

SURVEYING METHODS AND PRINCIPAL GEOGRAPHICAL RESULTS.

Base-Lines—The triangulation was commenced by measuring a base line[62]near Gebel Muelih by means of a 100-metre steel tape, which had been previously standardised at the Khedivial Observatory. A level tract having been selected, in such a position as to afford easy connection with points already triangulated from the Nile Valley, a line about two and a half kilometres long was ranged out, along which wooden pegs were driven flush with the ground at 100-metre intervals. The inequalities of the ground between the pegs were levelled off by tiny embankments and cuttings, so as to enable the tape to lie flat. On each peg was nailed a zinc plate having a millimetre scale running in the direction of the line. In measuring, the tape was laid on the ground, stretched to a constant tension by a spring balance at each end, in such manner that its end marks fell on the zinc scales, and readings were simultaneously taken on the scales at the two ends. Temperatures were taken in several places along the tape by mercurial thermometers. The operation of measurement was carried out in the early morning, so as to avoid any large difference of temperature between the ground and the air. The levels of the pegs were found by spirit levelling. After correction for the initial error of the tape, temperature, stretch, and inclination, the true length of the base-line reduced to sea-level was found, as the mean of two separate measurements at different tensions, to be 2,482·280 metres. The azimuth of the line was found by observations ofPolarisat elongation to be 30° 30′ 6″ E. of N. The geographical position of the west end of the line was found by triangulation-connexion with the Nile Valley by Mr. Villiers Stuart to be latitude 24° 53′ 36″·7 N., longitude 34° 4′ 17″·9 E.

A second connexion to a base-line was made near Gebel Um Harba, where a base had been previously measured by Mr. Villiers Stuart in the course of his triangulation of the western part of the desert. In this case the connexion was not made to the actual base-line, but to another main line tied directly on to it. The data at this point of connexion from the two triangulations afforded a useful check on the accuracy of the work, and were as follows:—

Reconnaissance for triangulation pointswas carried out simultaneously with the triangulation itself. The distance of likely looking peaks was determined either by intersecting them from distant stations, or by special small triangulations from short bases, and such selection made as seemed most likely to secure well shaped figures and a good command of surrounding country. As a rule, the highest summits were selected as main (occupied) stations, while all other prominent peaks and other features were fixed by intersection from two or more main stations. The form adopted for the main triangulation net was a series of quadrilateral figures with diagonals, combined with centric polygons, all the angles of the figures being generally measured. The average length of side was about thirty-five kilometres.

Beacons.—Main stations were marked by wrought-iron beacons, consisting of two lengths of stove piping about 15 centimetres diameter by 1½ metres long, the upper length fitting into a faucet made by splaying out the lower tube. Near the top of the tube were affixed four sheet iron wings, bolted on to angle iron cleats. A conical cairn of stones was built up round the tube, nearly up to the wings, so that the beacon when erected was about three metres high, two metres in diameter across the base of the cairn, and about a metre wide across the wings. The beacons were taken down while a station was being occupied, and replaced on leaving.

Intersected points were sometimes marked with a beacon or cairn, but in general the peaks were simply bisected from several stations, as it was found that this gave sufficiently accurate results.

Measurement of Horizontal Angles.—Angles were measured with a 6-inch theodolite furnished with reading microscopes graduated to 10″ and permitting of reliable estimations to 1″. The angles between main points were read on four arcs to eliminate circle errors. Intersected points were observed on one arc only. The average error of closure of main triangles was 3″·3.

Field Computation and Plotting of Triangulated Points.—The triangles were computed by the ordinary method, but the angles were rounded off to 10″ to enable the sines to be taken direct from the logarithmic tables, and the logarithms were only taken to five places. The length of the sides having been thus found, the geographical positions were found by the ordinaryL M Zcomputation, using, however, only two latitude terms and 5-place logarithms, while azimuths were only taken out to the nearest 10″. The abbreviated form of computation used will be best illustrated by an example:—[63]

Computation of Position of△No. 260 from No. 275.

In the above, it will be noticed that the azimuth is always noted as so much east or west of north or south. If this convention be adopted, one may consider the first term ofdφas always +, and the second term will be + if the azimuth contains the word south,—if it is from the north, while the totaldφis to be added or subtracted according as one is going north or south. A somewhat similar convention is adopted in neglecting the sign ofdλtill the actual addition or subtraction is made. It was found in the field that this method prevented any mistake of sign, while being much simpler to work than one involving angles greater than 90°.

The geographical coordinates thus found were plotted directly on to the plane-table sheets, on which the graticule at 10′ intervals was the first thing drawn. The odd minutes and seconds were first converted into minutes and decimals, and then into kilometres by multiplying by the factors appropriate to the latitude, so that the plotting could be done by the ordinary scale of kilometres. To avoid difficulties of paper-shrinkage, as many points as possible were plotted at the time of drawing the graticule, and in general the points had to be plotted as far ahead as possible for controlling the traversing and sketching.

Astronomical Observations.—Astronomical checks on the triangulation were obtained by observations of latitude at certain selected main stations 60-120 kilometres apart, and by azimuth observations for certain main lines.

The method used forlatitudewas that of observing the times of equal altitudes of three or more stars, selected as near to the meridian[64]as possible. This method presents great advantages over the usualPolarisand circummeridian altitudes, in that the observations are more easily made, and yield much more accurate results, because uncertainties in refraction are largely eliminated and the errors of circle graduation are not involved, the altitudes not being read at all.[65]The theodolite used was the same as was employed in triangulation,and the times were taken by a half chronometer watch, preferably one marking sidereal time with a rate which could be considered negligible during the hour or so occupied by the observation. The first star taken was usuallyPolaris, and the vertical circle was left clamped at its altitude. For the other stars, any dislevelment was corrected by touching up the levelling screws just before the instant of observation; this was found better, than taking bubble readings and correcting for slight difference of altitude.

The method which I found best in the field for reducing the observations differs somewhat from that described by Chauvenet. Assuming approximate values for the latitude and watch error, I first calculated the altitude of each star from the formula

sinh= sin φ sin ε + cos φ cos δ cost

If the assumed latitude and watch error were correct, all the stars would give the same value forh. If not, each star would give an equation of the form

h+ cosAdφ+ cos φ sinAdT−h0= 0

whereAis the star’s azimuth,dφthe required correction to the assumed latitude,dTthe required correction to the assumed watch times, andh0the true altitude common to the three stars. The values of cosAand cos φ sinAwere calculated from the ordinary formula

sinA=cos δ sintcosh

by four-place logarithms (using the approximate values for φ,t, andh, since these are quite sufficiently accurate for the purpose) and inserted into the three star-equations.[66]By then solving the three simultaneous equations fordφ, the required correction to the assumed latitude was at once obtained.

As the method is one not usually treated of in books on practical astronomy, I give on the following pages the reduction of an observation worked out in full.

Latitude by Equal Altitudes of Three Stars.

Station on Gebel Um Heshenib. January 30, 1906.

Sidereal watch U. and C. 30811, approximately 2m22sfast on L.S.T., rate negligible.

Observed times of equal altitudes by watch:—

Polaris.

Whence the equation forPolarisis

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