35·8 + 1·000 dφ − 0·011 dT − h0 = 0 (1)

α Columbæ.

Watch time 3h 42m 40s·8
Watch fast 2  22 ·0
L.S.T. 3  40  18 ·8
Star’s R.A. 5  36  15 ·6
t 1  55  56 ·8 = 28° 59′ 12″·0 E. of meridian.
φ = 24° 20′ 50″ log sin 1·6151769
δ = 34°  7′ 45″·7 log sin 1·7490118
1·3641887
Nat. (1) 0·2313070 log cos δ 1·9179
log sin t 1·6854
φ = 24° 20′ 50″ log cos 1·9595488 1·6033
δ = 34°  7′ 45″·7 log cos 1·9179112 log cos h 1·9560
t = 28° 59′ 12″·0 log cos 1·9418753 log sin A 1·6473
1·8193353 log cos φ 1·9595
Nat. (2) 0·6596830 1·6068
Nat. (1) 0·2313070 Nat. = 0·404
0·4283760
log sin h 1·6318196 log cos A 1·9523
Nat. = 0·896
h = 25° 21′ 51″·1

Whence the equation for α Columbæ is

51·1 − 0·896 dφ + 0·404 dT − h0 = 0 (2)

ε Canis majoris.

Watch time 4h 24m 35s·8
Watch fast 2  22 ·0
4  22  13 ·8
Star’s R.A. 6  54  57 ·1
t 2  32  43 ·3 = 38° 10′ 49″·5 E. of meridian.
φ = 24° 20′ 50″ log sin 1·6151769
δ = 28° 50′ 52″·7 log sin 1·6834857
1·2986626
Nat. (1) 0·1989128
φ = 24° 20′ 50″ log cos 1·9595488
δ = 28° 50′ 52″·7 log cos 1·9424561 log cos δ 1·9424
t = 38° 10′ 49″·5 log cos 1·8954602 log sin t 1·7911
1·7974651 1·7335
Nat. (2) 0·6272853 log cos h 1·9560
Nat. (1) 0·1989128 log sin A 1·7775
0·4283725 log cos φ 1·9595
log sin h 1·6318215 1·7370
Nat. = 0·546
h = 25° 21′ 51″·5
log cos A 1·9034
Nat. = 0·801

Whence the equation for ε Canis majoris is

51·5 − 0·801 dφ + 0·546 dT − h0 = 0 (3)

Collecting the equations of the three stars, we have

35·8 + 1·000 dφ − 0·011 dT − h0 = 0 (1)
51·1 − 0·896 dφ + 0·404 dT − h0 = 0 (2)
51·5 − 0·801 dφ + 0·546 dT − h0 = 0 (3)

By solving these equations for dφ, we find

dφ = + 6″·5

whence the latitude is found to be

24° 20′ 56″·5

It may be remarked that the above process was considerably shortened when it was possible to get a pair of observations on the same south star both east and west of the meridian, instead of on two separate south stars. In that case the watch error was found at once from the difference between the star’s R.A. and the mean of the two observed times, and the latitude could be found from two equations instead of three. The condition for this modification of the method was that a nautical almanac star could be found culminating at an altitude slightly greater than that of Polaris at a time convenient for the observation. It is not advisable to select a star which would give too long an interval between the equal east and west altitudes. The best results are obtainable when the interval between the two observations of the south star is about an hour, and when Polaris is near its transit. Under such circumstances the watch correction is obtained quite nearly enough for a good latitude; for, as Gauss[67] pointed out, “the essential condition is not so much that the precise instant when the star reaches a supposed place should be noted, as that at the time which is noted the star should not be sensibly distant from that place.”

The following table shows the latitudes found by observation and triangulation at the various points. It may be remarked that the method used for latitude determination was liable to observational errors of 2″ or so, as well as to errors of possibly more than double that amount due to plumb-line deflection among the mountains,[68] so that the observed latitudes were only taken as checks to prevent any gross error in triangulation being overlooked, and not for any determination of the figure of the earth, for which latter purpose more elaborate observations would have been necessary.

Point. Lat. observed. Lat. computed from Triangulation. Difference computed-observed.
West Peg, Muelih Base 24° 53′ 40″·3 24° 53′ 36″·7 − 3″·6
Beacon on Gebel Um Heshenib 24° 20′ 56″·5 24° 20′ 49″·2 − 7″·3
 „  „ Hill near Gebel Selaia 23° 55′ 33″·2 23° 55′ 30″·6 − 2″·6
 „  „ Berenice Temple 23° 54′ 39″·5 23° 54′ 40″·3 − 0″·8
 „  „ Gimeida Hill 22° 46′ 33″·2 22° 46′ 29″·4 − 3″·8

Azimuths were determined in the usual manner[69] by elongations of close circumpolar stars, Polaris or 51 Cephei being usually selected. The azimuth mark used was an ordinary Egyptian shamadan (candlestick with spring feed) with a glass globe, placed at a distance of one to two kilometres, with its foot firmly bedded in sand and stones to prevent any motion. The azimuths observed at the different stations are shown in the following table:—

Station of Observation. Point to which Azimuth is given. Azimuth observed.
Peg at West end of Muelih Base Peg east end of base 33° 30′  6″ E. of N.
Beacon on Gebel Um Heshenib Beacon on Gebel Hamata 45° 15′ 34″ E. of S.
 „  „ Hill near Gebel Selaia  „  „ Abu Gurdi 25° 30′ 35″ N. of E.
 „  „ Berenice Temple  „  „ Kalalat 61° 10′ 31″ W. of S.
 „  „ Gimeida Hill  „  „ Hamra Dom  6° 14′ 46″ E. of S.
Centre of Halaib Fort  „  „ Elba 83° 25′  0″ W. of S.

The observed azimuths, unlike the observed latitudes, were more accurate than the results of triangulation, repetition having shown them to be reliable within 2″ or 3″, an error of which magnitude would soon be surpassed in the process of continuing a chain of azimuths with the unadjusted values of the angles of the triangles, which were the only values possible to be used in the field. On arriving at an azimuth station, therefore, a fresh chain of azimuths was begun from the results of the observation, and continued to the next station where astronomical observations were undertaken. The accumulated azimuth error was, however, never found to exceed 10″ in any chain, a quantity which could not sensibly affect the computed positions of points for plotting on the maps.

Connexion with the Sudan Surveys.—At the south end of the area, connexion was made to a number of points triangulated by the Sudan Surveys, but as the Sudan triangulation was commenced as an independent piece of work from an observed latitude and a telegraphically determined longitude, the connexion affords no check on the accuracy of the triangulations. The difference found between my positions and those of the Sudan Surveys was practically constant for all the Sudan points connected, and amounted to 3″·5 in latitude and 26″ in longitude[70]; these figures represent the errors in the assumed latitude and longitude of the starting point of the Sudan Surveys, and will be employed as corrections to the Sudan positions now that a complete chain of triangulation connects Berber with the Mediterranean.

Levels of Triangulation Points.—The altitudes above sea-level of all triangulation points were determined by vertical angular measurements carried out at the occupied stations, an actual sea-level datum being obtained by including rocks awash in the sea among the triangulated points. To secure constancy of atmospheric refraction as far as possible, vertical angles were always read in the middle of the day, where the change of refraction is slowest. For the occupied stations, refraction and curvature were eliminated by reciprocal observations. For intersected points the formula h = d tan θ + 1 − k2rd2 was used, the value of d tan θ being first found by five-figure logarithms and then that of the curvature and refraction correction 1 − k2rd2 by means of the very convenient “Universal” slide rule of Nessler.[71] The value of k found from a discussion of the first few reciprocal observations was found to be very nearly 0·13, corresponding with the mean of European determinations, and this value for the coefficient was employed throughout the work for intersected points.[72] For obtaining the correction 1 − k2rd2 by the slide rule, a mark R was scratched at 1210[73] on the lower scale of the slide; by bringing this mark R opposite to the distance (in kilometres) on the lower scale (or, where the logarithm of the distance was more convenient, by bringing the mark vertically under that logarithm on the log scale of the rule by means of the cursor) the correction could be read off directly on the lowest fixed scale opposite the end-graduation of the slide. Usually four or five values for the altitude of a single point were obtained from a corresponding number of stations, and the mean taken; the various values generally agreed within two metres.

The constant combination of vertical angular measurements with horizontal ones was of great service from another point of view from that of providing altitude data for the maps. It frequently happened that a peak observed at one station could not be identified among a number of similar peaks visible at another station. When this trouble arose, the vertical angles offered a way out of the difficulty. Vertical and horizontal angles were read off to a number of likely-looking peaks; on working out the triangles to the nearest minute of the observed angles, the distance of each peak was obtained on the assumption that it was the one required. Then to find which of the several peaks was the correct one, the elevations were worked out, assuming the distances correct; in only one case would the level agree from the two stations, and this obviously discriminated the peak required. The working out of the triangles for this purpose could be done with sufficient accuracy in a very few minutes by means of the slide rule, and many points were thus saved from rejection consequent on misidentification.

Checks on absolute level were frequently obtained by observing depression angles to the sea horizon, using the formula θ = 107·8 √ h , where θ is in seconds of arc and h is the altitude in metres. But for high stations the horizon is so distant that very small variations in refraction cause rather large errors in the result, so that this method only furnished a rough check.

Summary of Triangulated Positions.

The following tables give the geographical positions and altitudes above sea-level of all points triangulated, arranged in order of diminishing latitude, i.e., from north to south. The list includes the points fixed within the Sudan for connexion with the Sudan Surveys. Stations occupied are indicated by an asterisk against the number of the point. It will be noticed that in some cases several different mountains bear the same name though widely distant from each other; also that where a single mountain mass possesses several peaks or summits, each of these has been fixed separately.

Summary of Triangulated Positions.

Field Number of Point. Name. Mark. Latitude N. Longitude E. Altitude Metres.
° ′ ″ ° ′ ″
21 G. Hamrat Wogud cairn. 25 9 34 34 20 0 1,103
29 G. Iteima „ 25 8 1 34 11 13 849
* 204 G. Igli „ 25 4 6 34 36 16 975
* 26a G. Atut „ 25 0 56 34 23 49 908
* 203 Erf el Fahid „ 25 0 5 34 11 52 579
14 G. Hagar Dungash „ 24 59 12 34 2 33 815
* 218 G. Sukari „ 24 56 50 34 42 50 476
216 G. Um Tundeba summit. 24 55 48 34 47 29 550
* 202 Muelih base E. peg. 24 54 44 34 5 7 406
219 Isolated hill near sea summit. 24 54 23 34 54 21 190
* 201 Muelih base W. peg. 24 53 37 34 4 18 398
19 G. Muelih cairn. 24 52 44 34 0 37 707
* 225 Kurdeman mines „ 24 52 35 34 41 35 525
71 Marwot Rod el Ligah „ 21 51 31 34 8 21 514
206 G. Mudergeg summit. 24 51 0 34 22 1 885
205 G. Hangalia „ 24 50 29 34 38 43 1,241
* 215 G. Ghadir cairn. 24 50 9 34 47 22 636
* 32a G. Nugrus „ 24 48 34 34 35 47 1,505
* 25 G. Migif „ 24 47 23 34 27 30 1,199
* 214 G. Allawi „ 24 46 42 34 49 39 515
211 G. Zabara „ 24 45 21 34 41 53 1,361
224 G. Lewewi „ 24 44 38 34 46 39 654
212 Ridge near G. Zabara N. end. 24 43 48 34 40 56 1,104
221 Hill near sea summit. 24 42 31 35 3 15 —
208 G. Hamrat Selma „ 24 41 58 34 20 58 761
210 Peak in G. Hafafit cairn. 24 40 44 34 37 8 722
240 Wadi Gemal island N. end. 24 40 45 35 9 6 0
* 223 G. Sikait cairn. 24 39 55 34 48 5 771
213 G. Um Moghar summit. 24 39 16 34 41 5 860
24a G. Abu Khrug cairn. 24 38 57 34 16 19 870
20 G. Sufra beacon. 24 38 42 34 4 13 690
241 Wadi Gemal island S. end. 24 38 38 35 10 36 0
207 G. Nahud N. cone. 24 35 36 34 22 14 662
* 209 Peak in G. Hafafit beacon. 24 35 32 34 45 22 744
* 222 Madaret Um Gamil „ 24 34 52 34 56 28 454
226 G. Abu Had summit. 24 34 12 34 36 6 633
242 Low spur of coast tip. 24 33 47 35 10 2 0
235 G. Um Regeba summit. 24 33 36 34 42 29 571
233 G. Nahud S. cone. 24 33 35 34 20 11 662
239 Low spur of coast tip. 24 28 43 35 10 58 0
247 G. Um Suerab summit. 24 26 50 34 42 33 1,024
231 G. Um Sueh „ 24 26 45 34 54 30 781
236 G. el Abiad „ 24 26 27 34 48 56 892
* 227 G. Abu Hegilig „ 24 26 16 34 58 32 607
237 G. Um el Abbas „ 24 26 11 34 56 33 697
232 G. Nukheira „ 24 25 58 34 32 53 876
73 G. Um Goraf cairn. 24 25 33 34 18 28 —
252 G. Durunkat centre. 24 23 43 34 45 51 924
274 S. end of low sandy island — 24 22 41 35 22 56 0
255 G. Um Sedri S. peak of twin. 24 22 0 34 41 3 970
234 G. el Heda summit. 24 20 56 34 30 11 862
248 G. Sarobi (S. peak) „ 24 20 50 35 9 0 471
* 228 G. Um Heshenib beacon. 24 20 49 34 50 53 1,135
243 G. Hefeiri summit. 24 20 22 35 1 21 612
246 G. Khulla „ 24 19 43 34 38 42 978
253 G. Tarfawi N. end of ridge. 24 18 46 34 55 54 1,363
251 G. Marasan summit. 24 17 34 34 44 56 1,261
249 G. Abu Ghusun „ 24 16 1 34 58 17 1,389
245 G. Metawit „ 24 15 51 34 31 48 741
* 230 G. Abu Hamamid beacon. 24 14 41 34 47 38 1,747
250 G. Um Usher summit. 24 14 11 34 53 21 1,487
259 G. Um Hasidok „ 24 12 45 34 54 46 1,497
* 229 G. Hamata beacon. 24 12 17 35 0 16 1,978
258 G. Abarun summit. 24 11 20 34 50 18 1,602
257 G. Abu Argub „ 24 11 1 34 45 43 1,609
75 G. Hamrat Mukbud cairn. 24 9 53 34 23 17 890
254 G. Ras el Kharit peak. 24 9 25 35 1 55 1,661
261 G. Khashir summit. 24 9 14 35 4 50 1,565
262 G. Ras el Kharit peak. 24 9 2 35 0 28 1,564
* 256 G. Kahfa beacon. 24 8 18 34 38 55 1,018
* 399 Hill near Bir Qoleib beacon. 24 8 6 33 42 46 355
400 Bir Qoleib clay basin. 24 6 36 33 41 20 239
287 G. el Anbat summit. 24 5 12 34 54 58 788
263 G. Mikbi S. end of ridge. 24 4 54 35 4 49 1,388
276 G. Um Huk cairn. 24 4 41 35 15 34 517
279 G. Um Sellim E. peak. 24 3 52 35 9 51 947
320 Peak N. of Berenice summit. 24 3 41 35 26 30 276
264 G. Egat peak. 24 3 40 35 3 32 1,277
273 G. Egat summit. 24 2 52 35 2 29 1,422
280 G. Abu Ghalqa cairn. 24 1 7 35 16 47 561
* 260 G. Abu Gurdi beacon. 24 0 11 35 5 17 1,562
288 G. Derhib summit. 24 0 8 35 1 29 1,160
* 315 Hill near Berenice beacon. 24 0 4 35 30 37 196
268 G. el Homur summit. 23 58 54 34 55 16 731
289 G. Um Gunud cairn. 23 57 46 35 12 10 989
* 339 Limestone hill on Ras Benas beacon. 23 57 16 35 43 10 187
271 G. Selaia summit. 23 57 14 34 52 13 787
* 317 Hill on Ras Benas beacon. 23 56 40 35 39 44 193
* 316 Limestone peak, Ras Benas „ 23 56 36 35 36 9 189
* 338 Hill on Ras Benas cairn. 23 56 1 35 40 53 197
291 G. Aidab summit. 23 55 52 35 13 38 848
270 Hill near G. Selaia „ 23 55 46 34 53 58 623
* 275 Low hill near G. Selaia beacon. 23 55 30 34 54 37 563
278 G. Geneina peak near N. end. 23 54 56 34 47 45 548
336 G. Um Maiat N. end. 23 54 45 35 13 35 928
* 313 Berenice Temple beacon. 23 54 39 35 28 26 8
290 Marwot Elemikan summit. 23 54 14 35 6 8 648
319 Peak N. of G. Kalalat „ 23 54 10 35 13 55 870
334 Hill near Wadi Mindeit „ 23 53 57 35 22 0 —
340 Sheikh’s tomb at Ras Benas centre. 23 53 50 35 47 13 3
341 Tip of Ras Benas sandy point. 23 53 42 35 47 5 0
266 G. Abu Derega summit. 23 53 38 34 59 13 831
335 G. Um Maiat S. end. 23 53 34 35 14 48 842
333 High range N. of G. Kalalat N. end. 23 53 3 35 15 1 875
77 G. el Nekeiba cairn. 23 52 34 34 22 10 570
330 Hill near Wadi Kalalat summit. 23 52 29 35 22 18 328
318 G. Um Maiat central peak. 23 52 24 35 15 36 821
332 High range N. of G. Kalalat S. end. 23 51 59 35 16 29 762
331 G. Kalalat minor peak. 23 50 48 35 15 51 743
294 N. end of Mukawar Island — 23 50 47 35 48 31 0
293 G. Batoga central peak. 23 50 7 35 20 46 802
329 G. Kalalat N. peak. 23 49 57 35 17 6 1,080
294a S. end of Mukawar Island — 23 49 53 35 48 19 0
314 G. Batoga (S. peak) beacon. 23 49 37 35 21 9 785
* 282 G. Kalalat „ 23 49 9 35 17 36 1,125
328 G. Batoga minor peak. 23 48 57 35 22 47 413
353 Minor peak of G. Kalalat S. one of pair. 23 47 37 35 18 46 894
355 G. Um Hegilig summit. 23 47 13 35 14 32 966
327 G. Dibag NW. peak. 23 46 47 35 21 23 517
308 G. Dibag SE. peak. 23 46 40 35 22 4 544
* 265 G. Dahanib beacon. 23 45 44 35 11 10 1,270
* 269 G. Um Bisella „ 23 45 34 34 57 39 824
* 277 G. Zergat Naam „ 23 45 28 34 40 34 823
345 G. Reyan N. peak. 23 45 20 35 17 50 740
346 G. Reyan S. peak. 23 44 7 35 17 20 863
* 343 Hill near Shenshef ruins beacon. 23 44 5 35 22 40 290
292 Erf el Gemal W. end of ridge. 23 43 37 34 52 10 673
272 G. Hagar el Fil summit. 23 43 5 34 42 3 845
281 G. Shut „ 23 42 35 35 16 59 930
398 Bir Abu Hashim principal well. 23 41 56 34 4 26 320
* 397 Hill near Bir Abu Hashim beacon. 23 41 44 34 3 33 386
348 Hill near W. Salib Abiad summit. 23 41 5 35 7 3 703
325 G. Um Etli central peak. 23 39 54 35 23 22 795
384 G. Abu Husenat summit. 23 39 45 35 1 15 725
326 G. Um Etli W. peak. 23 39 32 35 21 52 844
324 G. Um Etli E. peak. 23 39 26 35 23 53 764
295 G. Hendusi sharp peak. 23 39 15 34 58 44 678
344 G. Um Akra beacon. 23 37 58 35 16 41 1,050
* 385 Ruins of Um Eleiga „ 23 37 20 35 3 5 599
302 Peak near G. Abu Dahr summit. 23 37 16 35 6 44 840
* 79 Um Harba beacon. 23 36 56 34 30 38 688
356 G. Um Akra S. peak. 23 36 35 35 16 58 970
347 G. Hindia summit. 23 36 27 35 13 39 873
337 Zeberged Island central peak. 23 36 16 36 11 42 238
* 267a G. Abu Dahr beacon. 23 36 8 35 5 46 1,131
305 G. Abu Sieiyil summit. 23 35 16 35 1 4 833
321 G. Faraid peak. 23 34 8 35 23 18 1,131
323 G. Faraid „ 23 33 29 35 21 50 1,341
361 Hill S. of G. Abu Dahr summit. 23 33 28 35 4 42 912
322 G. Faraid highest peak. 23 33 7 35 22 10 1,366
342 G. Faraid „ 23 31 53 35 22 46 1,068
360 Hill S. of G. Abu Dahr summit. 23 31 43 35 5 15 772
362 Hill S. of G. Abu Dahr „ 23 31 37 35 2 49 793
359 Hill S. of G. Abu Dahr „ 23 31 17 35 6 22 784
* 285 G. Faraid peak. 23 30 53 35 20 25 1,259
* 85 G. Um Khafur beacon. 23 29 54 34 29 19 560
357 G. Faraid minor peak. 23 29 35 35 17 30 862
286 G. Faraid “The Bodkin.” 23 28 58 35 20 35 1,232
350 G. Faraid outlying peak. 23 28 39 35 17 35 875
351 G. Faraid peak. 23 28 35 35 16 31 954
352 Granite peak near Wadi Rahaba summit. 23 27 48 35 13 15 697
349 G. Faraid outlying peak. 23 27 14 35 19 5 904
297 G. Orga beacon. 23 26 21 35 8 17 682
363 Hill near Wadi Rahaba summit. 23 26 18 35 12 38 506
* 296 G. Abraq beacon. 23 25 19 34 46 48 667
365 Hill near Wadi Rahaba summit. 23 25 2 35 11 42 536
389 G. Faraid minor peak. 23 24 57 35 24 42 585
358 G. Faraid peak. 23 22 39 35 22 19 916
395a G. Abraq „ 23 22 26 34 50 18 699
395 G. Abraq „ 23 22 19 34 50 4 705
* 87 G. Awamtib beacon. 23 20 59 34 26 39 793
* 299 G. Um Tenedba „ 23 19 48 35 10 40 656
368 Hill near G. Um Tenedba summit. 23 18 43 35 12 36 555
* 390 Plateau near Abu Saafa beacon. 23 18 40 34 48 30 639
307 G. Saalek peak E. side. 23 18 18 34 31 10 753
* 354a G. Fereyid beacon. 23 17 29 35 22 48 612
394 G. Hodein „ 23 16 20 34 53 25 695
380 G. Hodein corner of scarp. 23 16 18 34 52 5 718
304 Peak W. of G. Um Reit summit. 23 15 26 34 30 14 805
306 Peak W. of G. Um Reit „ 23 15 23 34 31 47 837
366 Hill near Wadi Rahaba „ 23 15 4 35 16 25 420
* 300 G. Um Reit beacon. 23 15 4 34 34 17 857
* 298a G. Harhagit „ 23 14 35 35 12 52 542
393 G. Tibatib summit. 23 12 41 35 1 28 396
387 Hill near Wadi Hodein „ 23 12 24 35 16 51 383
396 Granite peak near Wadi Rahaba „ 23 11 11 35 20 35 355
392 Rock in sea (level datum). 23 10 55 35 35 57 0
310 Isolated hill west of G. Etresia summit. 23 10 35 34 25 23 703
388 Hill near Wadi Hodein „ 23 10 33 35 16 32 309
423 G. Kala „ 23 10 3 34 45 49 808
503 G. Etresia E. summit. 23 9 24 34 30 43 1,037
303 Hill E. of G. Etresia summit. 23 9 15 34 32 23 922
* 375a G. Anfeib beacon. 23 8 24 34 59 19 705
364 Hill NE. of G. el Anbat summit. 23 8 0 35 21 46 359
* 386 Close to Bir Shalatein beacon. 23 7 57 35 36 23 13
502 G. Etresia summit. 23 7 53 34 31 24 1,038
407 G. Kala „ 23 7 42 34 42 58 846
311 Isolated hill north of G. Shigigat „ 23 7 16 34 24 39 901
425 G. Kala „ 23 7 11 34 42 37 783
424 G. Kala „ 23 6 51 34 42 30 739
501 G. Etus „ 23 6 19 34 29 53 997
* 367a G. el Anbat beacon. 23 6 5 35 19 27 390
312 G. Shigigat conspicuous peak. 23 5 37 34 23 39 1,023
406 G. Kala summit. 23 5 16 34 42 19 629
500 G. Aqab el Negum „ 23 3 26 34 27 20 1,149
496 G. Natetiai peak. 23 3 8 34 21 0 1,022
499 Peak near Aqab el Negum summit. 23 2 43 34 26 3 998
498 Peak near Aqab el Negum „ 23 2 22 34 25 36 979
497 Peak near Aqab el Negum „ 23 1 56 34 25 42 974
495 G. Natetiai peak. 23 0 49 34 22 7 1,164
373 G. Niqrub el Tahtani high pinnacle. 23 0 42 35 0 58 828
373a G. Niqrub el Tahtani beacon. 23 0 39 35 0 53 829
* 369a G. Beida „ 23 0 14 35 16 54 716
494 G. Natetiai peak. 22 59 35 34 22 22 977
508 Peak in S. part of G. Feg summit. 22 58 45 34 20 29 885
391 G. Humariai „ 22 58 38 35 9 36 563
382 Hill S. of Wadi Beida „ 22 58 10 35 12 58 631
507 Peak in S. part of G. Feg „ 22 58 2 34 19 15 836
381a Hill S. of Wadi Beida „ 22 57 30 35 16 53 631
379 G. Mismih „ 22 56 56 34 45 32 599
381 Hill S. of Wadi Beida „ 22 56 47 35 17 3 615
510 Conical hill „ 22 54 48 34 40 27 504
* 401 G. Kolaiqo beacon. 22 54 13 35 24 35 320
* 374 G. Niqrub el Foqani „ 22 51 29 34 56 49 1,078
509 G. Waqif summit. 22 51 21 34 38 57 556
466 Tree at Mersa Shab centre. 22 50 56 35 47 3 1
419 G. Um el Kalala N. peak. 22 50 23 34 44 14 672
506 G. Sheyenit „ 22 50 13 34 18 23 853
505 G. Sheyenit S. peak. 22 49 58 34 18 15 887
415 G. Um el Kalala „ 22 49 26 34 44 18 655
418 Hill close to Bir Madi beacon. 22 47 46 35 1 39 556
* 408 G. Meneiga „ 22 47 35 35 11 7 1,032
* 402 G. Meneiga highest point. 22 47 31 35 10 57 1,092
430 Hill near Wadi Tikosha summit. 22 46 29 35 20 11 443
* 410 Gemeida hill beacon. 22 46 29 35 37 49 123
437 Hill SSE. of Bir Meneiga summit. 22 45 58 35 13 3 987
434 Peak near Wadi Ti Ilak „ 22 44 36 35 17 54 774
376 G. Shabih highest peak. 22 44 26 34 50 21 1,117
527 G. Mishbih NW. summit. 22 44 21 34 41 23 1,321
378 G. Mishbih beacon. 22 44 18 34 41 20 1,316
440 Ridge near head of W. Shellal el Gharbi high point. 22 44 15 35 12 18 1,092
447 Qrein Salama summit. 22 44 5 35 24 32 354
435 Peak near Wadi Ti Ilak „ 22 44 4 35 17 46 849
431 Hill N. of Wadi Muqur „ 22 43 55 35 18 52 670
414 G. el Naga smaller hill. 22 43 32 34 27 22 747
91 G. Seiga cairn. 22 43 31 34 16 16 905
377 G. Mishbih E. peak. 22 43 28 34 42 39 1,311
526 G. Mishbih peak. 22 42 52 34 41 27 1,353
413 G. el Naga N. peak. 22 42 42 34 27 46 787
445 G. Tueiwi summit. 22 42 40 35 5 56 836
* 403 G. Gerf high point on ridge 22 42 15 35 11 43 1,339
427 G. Gerf minor summit. 22 42 13 35 13 32 1,327
* 370 G. Gerf beacon. 22 42 6 35 12 16 1,419
412 G. el Naga S. peak. 22 42 0 34 28 25 827
436 Peak near Wadi Muqur summit. 22 41 58 35 18 22 778
493 G. Mishbih S. peak. 22 41 44 34 42 41 988
432 Peak near Wadi Muqur summit. 22 41 40 35 17 35 962
383 G. Muqur „ 22 41 31 35 16 50 1,058
433 Hill near Bir Sararat Seyet „ 22 41 16 35 0 57 797
426 Peak near Wadi Diqdib summit. 22 41 6 35 14 30 1,258
438 Peak near Wadi Qadiloi „ 22 41 3 35 17 54 911
429 Peak near Wadi Eirahimib „ 22 40 51 35 9 55 1,227
371 G. Shweib „ 22 40 43 34 43 57 914
428 Peak near Wadi Eirahimib „ 22 40 38 35 10 29 1,327
531 Mt. near Bir Baaneit „ 22 40 1 35 18 15 909
404 G. Gerf minor summit. 22 39 59 35 10 7 1,318
405 G. Korabkansi „ 22 39 39 35 0 44 1,052
446 G. Korabkansi N. peak. 22 39 35 34 59 32 1,176
614 G. Hamra Dom „ 22 39 34 35 38 19 326
439 Peak near Wadi Diqdib summit. 22 39 17 35 16 11 1,028
* 372 G. Korabkansi beacon. 22 39 16 34 59 55 1,230
420 Peak near Wadi Difoteb cairn. 22 39 11 35 10 21 1,298
* 417 G. Hamra Dom beacon. 22 39 6 35 38 42 388
450 Tibansi Tikam Ankwei summit. 22 39 5 35 32 11 345
475 Peak near Wadi Sherefa „ 22 38 20 35 11 42 1,344
411 G. Hamra Dom central peak 22 38 2 35 39 12 381
473 Hill near Wadi Um Saha summit. 22 37 54 35 17 56 926
532 Hill near Wadi Um Saha „ 22 37 53 35 17 56 932
444 G. Dreb peak. 22 36 54 35 6 20 1,139
615 G. Hamra Dom S. peak. 22 36 48 35 39 36 317
443 G. Dreb peak. 22 36 41 35 7 0 1,148
442 G. Dreb „ 22 36 40 35 7 46 1,137
476 G. Dreb „ 22 36 16 35 9 15 1,176
478 G. Dreb „ 22 36 10 35 8 21 1,224
477 G. Dreb „ 22 36 1 35 8 56 1,191
504 G. Kulyeit summit. 22 35 50 34 16 38 724
441a G. Dreb peak. 22 35 18 35 8 24 1,293
533 Kilia Arib summit. 22 35 2 35 18 46 647
441 G. Dreb peak. 22 35 0 35 8 36 1,288
535 G. Dreb „ 22 34 15 35 9 42 1,095
534 Tibashoi Tomakolat summit. 22 33 4 35 19 40 464
* 449a Kolmanab hill beacon. 22 32 26 35 53 36 137
566 Hill near Wadi Ibib summit. 22 32 2 35 37 36 459
619 Point near Kolmanab — 22 31 55 35 52 40 110
612 G. Medarai minor peak. 22 31 23 35 13 5 1,103
520 G. Medarai summit. 22 30 58 35 12 5 1,299
610 G. Medarai minor peak. 22 30 56 35 14 37 922
485 G. Anweiyib N. summit. 22 30 22 34 53 42 871
* 567a G. Eqrun (W. summit) beacon. 22 30 10 35 37 9 473
567 G. Eqrun SE. summit. 22 30 0 35 37 18 468
665 Adar Aweib Um Bishtit summit. 22 29 28 35 33 2 455
577 Granite hill „ 22 29 19 35 54 6 143
522 G. Medarai S. peak. 22 29 8 35 12 4 1,114
528 G. Anweiyib summit. 22 29 5 34 53 32 864
587 G. Um Rasein N. peak. 22 28 52 35 20 44 791
* 416 G. Um Rasein beacon. 22 28 12 35 20 19 909
* 575 Einiwai hill „ 22 27 50 35 57 59 138
521 G. Abu Hireiq N. summit. 22 27 39 35 14 58 1,116
609 Hill near Wadi Merdiyeb summit. 22 27 21 35 15 51 856
613 Tahaqayet „ 22 26 47 35 40 23 432
596 Hill near Wadi Odruk „ 22 26 47 35 18 42 639
595 Hill near Wadi Odruk „ 22 26 25 35 19 17 615
582 Granite hill „ 22 26 23 35 56 20 155
592 Near Wadi Odruk peak. 22 26 9 35 20 9 627
523 G. Abu Hireiq highest point. 22 25 57 35 14 39 1,319
581 Osnei hill summit. 22 25 38 35 50 42 251
455 Hill near Bir Um Bishtit „ 22 25 14 35 33 19 634
472 Mt. near Wadi Abu Hireiq „ 22 24 43 35 16 13 1,256
611 G. Adatalob Hadal beacon. 22 24 38 35 48 22 381
451 Titailibab summit. 22 24 32 35 38 52 593
459 G. Orgem NW. peak 22 24 31 35 31 1 779
576 G. Orgem SE. peak. 22 24 21 35 31 11 775
488 G. Anweiyib NW. summit. 22 24 16 34 49 46 884
471 Mt. near Wadi Abu Hireiq summit. 22 23 56 35 16 41 1,226
486 G. Anweiyib SE. summit. 22 23 37 34 51 25 921
664 Hill S. of Titailibab summit. 22 23 26 35 39 5 554
422 G. Abu Hodeid beacon. 22 23 18 35 14 9 1,482
572 G. Adatalob Adara summit. 22 23 1 35 49 58 385
603 Near Wadi Tikraneib peak. 22 22 57 35 18 38 732
454 G. Meis-heit-ar summit. 22 22 37 35 34 44 717
470 Mt. near Bir Abu Hodeid „ 22 22 31 35 17 33 1,074
479 G. Mansur Diab „ 22 22 28 35 10 49 1,091
469 Mt. near Bir Abu Hodeid „ 22 22 10 35 17 51 1,078
457 Hill near head of Wadi Qidmib „ 22 22 3 35 32 42 738
583 G. Tishushi Tiboki minor summit. 22 22 0 35 57 12 284
647 Abu Hodeid Oqla summit. 22 21 29 35 17 51 992
492 G. Um el Tiur el Tahtani „ 22 21 26 34 34 46 783
666 G. Meis-heit-ar „ 22 21 15 35 34 48 721
580 G. Tishushi Tiboki highest point. 22 21 14 35 55 46 359
* 569a Ti Keferiai beacon. 22 21 0 35 49 47 494
598 G. Hamra Tit SW. peak. 22 20 6 35 20 44 642
461 G. Qidmib summit. 22 19 55 35 30 45 1,037
* 456 O Shakafa „ 22 19 44 35 34 42 751
597 G. Geror NE. summit. 22 19 31 35 52 4 434
462 G. Qidmib summit. 22 19 13 35 30 23 1,108
464 G. Qidmib „ 22 19 4 35 29 18 1,070
463 G. Qidmib „ 22 18 49 35 30 15 1,099
616 G. Geror high point. 22 18 37 35 50 18 510
584 G. Qidmib summit. 22 18 18 35 29 20 1,089
453 Adar Aqdeib summit. 22 18 6 35 37 51 736
490 G. Um el Tiur el Foqani „ 22 17 56 34 41 14 946
602 G. Geror summit. 22 17 51 35 50 55 516
649 G. el Sela peak. 22 17 37 36 14 17 433
487 G. Hadal Derqa summit. 22 16 40 35 9 55 1,108
* 460 Hadal Aweib Meisah beacon. 22 16 39 35 31 55 1,224
650 G. el Sela peak. 22 16 32 36 12 59 560
491 G. el Adraq summit. 22 16 22 34 35 3 770
421 Qara Saba „ 22 16 7 35 41 34 778
601 G. Um Seleim „ 22 15 58 35 21 35 1,098
480 G. Hadal Derqa SE. peak. 22 15 50 35 10 59 1,090
585 Hadal Aweib Meisah minor summit. 22 15 48 35 30 10 1,092
604 G. Leqaq summit. 22 15 40 35 20 8 1,192
512 G. Heianai NW. summit. 22 14 40 35 1 30 1,007
668 G. Hamida minor summit. 22 14 34 35 46 13 583
620 Qash Amir beacon. 22 14 31 36 12 20 724
651 G. Sul Hamid highest peak. 22 14 16 36 4 53 572
568 G. Balatitda summit. 22 13 56 35 58 5 592
513 G. Hilwit Hasium NE. peak. 22 13 50 35 14 38 1,037
468 G. Adar Qaqa summit. 22 13 47 35 19 0 1,606
482 G. Heianai SE. summit. 22 13 41 35 3 11 1,256
618 G. Hamida minor summit. 22 13 36 35 46 47 701
608 G. Adar Qaqa „ 22 13 33 35 19 21 1,542
448 G. Hamida summit. 22 13 32 35 46 33 754
* 458 Halaib Fort centre of top. 22 13 25 36 38 56 8
556 G. Elba peak near Bir Kansisrob. 22 13 21 36 22 23 820
652 Hill E. of G. Balatitda peak. 22 13 20 35 59 43 491
555 Karam Elba summit. 22 13 13 36 25 40 586
525 G. Shanaiyet „ 22 13 4 34 49 43 907
653 Hill near Wadi Warabeit „ 22 13 4 35 50 12 511
676 G. Elba peak near Wadi Yahameib. 22 13 2 36 20 54 935
662 G. Balatitda minor summit. 22 12 56 35 57 44 493
489 G. el Hateib summit. 22 12 44 34 43 18 854
674 Hill near Wadi Siamtit summit. 22 12 42 36 13 10 507
516 G. Hilwit Hasium SW. peak. 22 12 30 35 13 14 952
669 Mt. south of Hadal Aweib Meisah summit. 22 12 21 35 30 40 1,072
481 G. el Arib „ 22 12 15 35 8 32 1,112
579a G. Um Ein beacon. 22 11 52 35 39 4 901
667 Hill near head of Wadi Warabeit summit. 22 11 40 35 47 6 651
467 G. Soaorib „ 22 11 33 35 20 13 1,469
* 536 G. Elba beacon. 22 11 27 36 20 52 1,428
621 G. Elba minor peak. 22 11 16 36 23 44 1,102
675 G. Elba „ 22 11 10 36 20 35 1,394
483 G. Heleikonti summit. 22 11 7 34 57 59 1,151
573 G. Warabeit „ 22 11 1 35 47 52 794
518 G. Soaorib „ 22 10 54 35 17 48 1,397
* 571 Adar Aweib beacon. 22 10 50 35 54 0 620
538 G. Elba minor peak. 22 10 17 36 19 34 1,217
606 G. Soaorib summit. 22 10 14 35 21 25 1,349
98 G. Muqsim cairn. 22 10 11 34 1 12 825
589 Mt. near Wadi Baueiwai summit. 22 10 10 35 30 45 1,266
537 G. Elba highest point. 22 10 3 36 21 52 1,435
617 G. Mashushenai summit. 22 9 54 35 49 45 634
605 G. Soaorib peak. 22 9 50 35 21 45 1,383
678 G. O Sir Eirab summit. 22 9 24 36 20 56 842
677 Hill near W. O Sir Hadal „ 22 9 7 36 15 56 724
519 Peak near Wadi Kirir „ 22 8 24 35 18 27 1,328
465 G. Soaorib „ 22 8 22 35 23 36 1,431
590 Mt. N. of Wadi Adar Ameit el Sharqi NE. peak. 22 8 16 35 31 2 1,294
670 Hill near Wadi Aqwem summit. 22 8 12 35 43 30 724
578 Hill near Da-aiyob Wushaq „ 22 7 45 35 44 8 833
681 G. Hanquf minor peak. 22 7 45 36 16 54 789
591 Mt. N. of Wadi Adar Ameit el Sharqi SW. peak. 22 7 12 35 29 54 1,299
682 G. Hanquf minor peak. 22 6 54 36 17 18 877
524 G. Um Reddam summit. 22 6 23 34 59 55 1,109
657 G. Miatit W. peak. 22 6 14 35 34 12 1,229
511 Mt. near G. Egat summit 22 5 53 34 53 1 985
484 G. Egat „ 22 5 39 34 52 15 1,145
586 G. Miatit SE. peak. 22 5 36 35 35 34 1,257
659 Mt. near Wadi Adar Ameit el Gharbi peak. 22 5 20 35 25 30 1,440
540 G. Hanquf N. peak. 22 4 52 36 18 45 1,397
452 Hill near W. Di-ib summit. 22 4 14 36 1 32 491
655 G. Suruk E. peak. 22 4 10 35 38 7 1,059
588 G. Suruk highest point. 22 3 50 35 35 28 1,327
673 Hill near G. Suruk peak. 22 3 46 35 40 16 846
656 G. Shendib „ 22 3 40 35 36 1 1,275
515 Mt. near G. Himeitra „ 22 3 17 35 17 52 1,134
685 G. Shendib „ 22 3 8 36 13 44 1,427
539 G. Shendodai highest peak. 22 3 1 36 25 31 1,529
672 Hill near G. Suruk peak. 22 3 0 35 40 25 847
661 G. Shiab „ 22 2 57 35 45 18 855
* 607 G. Hadarba beacon. 22 2 53 36 47 23 217
654 G. Shiab highest point. 22 2 51 35 44 7 987
517 G. Himeitra summit. 22 2 46 35 14 19 1,231
474 G. Is cairn on summit. 22 2 36 35 28 4 1,736
599 G. Is peak. 22 2 24 35 27 35 1,659
627 G. Shendodai S. peak. 22 2 12 36 25 22 1,395
684 Hill near G. Shendib summit. 22 2 12 36 9 6 601
600 G. Is peak. 22 2 11 35 26 56 1,594
671 Hill near G. Suruk „ 22 1 54 35 40 20 903
593 Mt. east of G. Is N. peak. 22 1 38 35 31 56 1,290
570 G. Hanquf highest point. 22 1 32 36 20 14 1,465
640 G. Shendib peak. 22 1 26 36 14 47 1,724
641 G. Shendib „ 22 1 8 36 14 59 1,698
594 Mt. east of G. Is S. peak. 22 1 2 35 31 11 1,474
642 G. Shendib peak. 22 0 51 36 15 0 1,696
543 G. Shendib beacon. 22 0 48 36 16 30 1,912
546 G. Shendib peak. 22 0 46 36 14 49 1,674
544 G. Shendib peak. 22 0 45 36 16 10 1,852
687 Hill near G. Shellal summit. 22 0 40 36 9 2 614
557 G. Shellal peak. 22 0 39 36 30 30 1,269
529 G. Shellal E. peak. 22 0 34 36 30 45 1,279
574 G. Shellal highest point. 22 0 15 36 29 40 1,409
545 G. Shendib peak. 21 59 56 36 17 6 1,863
547 G. Shendib „ 21 59 49 36 15 42 1,668
550 G. Shendib „ 21 59 8 36 14 16 1,565
645 G. Shendib „ 21 59 7 36 13 22 1,227
549 G. Shendib „ 21 59 6 36 14 40 1,525
644 G. Shendib „ 21 59 0 36 15 20 1,552
646 G. Shendib „ 21 58 58 36 13 11 1,196
660 Low hill near W. Shendib summit. 21 58 24 36 4 25 500
541 G. Qeda E. peak. 21 56 24 36 28 11 1,850
542 G. Qeda W. peak. 21 56 16 36 26 12 1,872
514 Hadal Aweib summit. 21 52 40 35 22 26 1,780
628 G. Asotriba highest point. 21 51 55 36 30 26 2,216
551 Eir Aweit peak. 21 50 30 36 22 48 1,715
552 Eir Aweit „ 21 49 56 36 23 1 1,678
564 G. Obkeik N. peak. 21 49 55 35 39 40 1,837
548 G. Asotriba S. peak. 21 49 30 36 30 40 2,082
565 G. Obkeik S. peak. 21 49 6 35 39 29 1,856
553 Eir Aweit highest peak. 21 47 57 36 22 40 1,853
554 Eir Aweit peak. 21 47 38 36 22 32 1,759
658 Adar It sharp peak. 21 47 1 36 19 14 1,170
409 beacon. 21 44 21 34 36 53 —
558 Arit peak. 21 40 26 36 22 50 1,529
559 Arit „ 21 39 25 36 22 32 1,772
663 Karai Awa summit. 21 39 18 36 10 21 1,056
562 Arit peak. 21 38 3 36 18 57 1,410
560 Arit highest peak. 21 36 51 36 23 27 1,810
563 Arit high peak. 21 36 1 36 19 52 1,727
561 Arit W. end of ridge. 21 35 50 36 22 48 1,532