Appendix I
A List of the Astronomically Determined Points in Air
The positions given in the following table have been collected from the record of the proceedings of the Foureau-Lamy Mission, from the list given on the second sheet of the “Carte de l’Air” prepared by the Mission Cortier and others on a scale of 1/500,000, and from the observations by the author. Two positions given in Lieut. Jean’s Les Touareg du Sud-Est are also included. The French longitudes have been converted into longitudes east of Greenwich by the addition 2° 20′ 14″.
The author’s observations were carried out with a three-inch transit theodolite by Cary and Porter, and were in all cases stellar sights. The latitudes were in all cases determined from pairs of north and south circum-meridian stars, or from altitudes of Polaris and one south star. The longitudes were determined by calculations based on local mean time derived from pairs of east and west stars, and chronometric differences from points which had previously been determined by French travellers. Where the author’s longitudes for points previously determined by French observers are also given, they are the result of chronometric differences from other points previously or successively visited. The author, however, has not used his own longitudes for determining intermediate points when French observations were available, and his co-ordinates in these instances are only reproduced for purposes of comparison.
The data for the Foureau-Lamy observations are described in the record of the proceedings of the expedition. The source of the positions given on the Cortier map is not stated. The data for Colonel Tilho’s positions are in the record of the delimitation of the northern boundary of Nigeria. The author’s computations are in the records of the Royal Geographical Society in London, where are also the original route reports and prismatic compass traverses made throughout the journey.
Where possible the author’s chronometric differences were checked by opening and closing a series of observations on points previously fixed by French observers. In one unfortunate case, however, the author’s watches stopped as a result of his camels going astray and the series was consequently broken. His watches again stopped at Auderas, where, however, he stayed a sufficient length of time to re-rate them. At this place a number of local mean time observations were taken over a long period.
The author’s longitude observations were carried out as follows:
| Series A | opened at Fanisau camp near Kano from a position supplied by the Survey school—closed at Tessawa— Dan Kaba (unreliable), intermediate position. |
| Series B | opened at Tessawa—not closed: Urufan-Gangara-Tanut, intermediate positions. |
| Series C | not opened—closed at T’in Wana: Termit—Teskar-Guliski, intermediate positions. |
| Series D | opened at T’in Wana—closed at Auderas. |
| Series E | opened at Auderas—watches rated—closed at Auderas. |
| Series F | opened at Auderas—closed at Auderas: Abarakan-Teginjir-Telia-Teloas, intermediate positions. |
| Series G | opened at Auderas—closed at Auderas: Aggata-Assode-Afis-Iferuan, intermediate positions. |
The author’s meteorological record, which was kept for nine months, has not been reproduced. It consists of daily maximum and minimum, actual (twice daily), and wet and dry bulb temperatures; aneroid readings; wind and rainfall, and sunset and sunrise notes. It is at any student’s disposal to consult.
The following abbreviations are used in the ensuing table:
F—Foureau; Ch—Chambrun (see Record of Foureau-Lamy expedition); R—Rodd; T—Tilho; C—Cortier’s Map of Air; J—Jean’s Touareg du Sud-Est.
| Place. | Area. | Latitude, north. | Longitude (east of Greenwich). | Authority. | |
|---|---|---|---|---|---|
| ° ′ ″ | ° ′ ″ | ||||
| Dan Kaba433 | Nigeria | 13-12-40 | 7-44-30 | R | |
| Tessawa | Tessawa | 13-45-20·5 | 7-59-12·6 | T | |
| 13-45-50 | 7-59-15 | R | |||
| Urufan | Tessawa | 14-04-50 | 8-06-25 | R | |
| Gangara | Damergu | 14-36-30 | 8-27-32 | F | |
| 14-36-42 | — | Ch | |||
| 14-36-50 | 8-25-40 | R | |||
| Tanut434 | Damergu | 14-58-20 | 8-47-50 | R | |
| Guliski | Damergu | 15-00-50 | 9-06-20 | R | |
| Teshkar | Elakkos | 15-07-40 | 10-35-10 | R | |
| Termit | Eastern Desert | 16-04-10 | 11-04-50 | R | |
| Abellama | Tegama-Azawagh | 16-16-32 | 7-47-19 | C | |
| Marandet | Tegama-Azawagh | 16-22-20 | 7-24-14 | C | |
| Ain Irhayen | Tegama-Azawagh | 16-26-40 | 7-55-22 | C | |
| Tabzagur | Tegama-Azawagh | 16-36-57 | 7-08-17 | C | |
| Tin Wana (T’in-Nouana) | S. Air | 16-42-32 | 8-25-19 | C | |
| 16-42-55 | 8-25-15 | R | |||
| In Gall | S.W. | Air | 16-47-08 | 6-54-15 | C |
| Tebehic | S. | Air | 16-47-32 | 8-21-14 | C |
| Eghalgawen | S. | Air | 16-48-21 | 8-31-19 | C |
| Agades (Post) | S. | Air | 16-59-19 | 7-57-15 | C |
| „ (T’in Shaman435) | S. | Air | 16-59-02 | (8-24-18) | J |
| Tin Dawin | S. | Air | 17-00-07 | 8-26-19 | C |
| Tin Taboraq | S. | Air | 17-01-50 | 8-08-19 | C |
| Tagidda N’Adrar | W. | Air | 17-04-13 | 7-22-21 | C |
| Anu Areran | W. | Air | 17-15-27 | 7-43-20 | C |
| Fagoshia | W. | Air | 17-16-01 | 6-57-17 | C |
| Tafadek | S. | Air | 17-23-32 | 7-55-19 | C |
| Tagidda N’T’isemt | W. | Air | 17-25-38 | 6-34-33 | C |
| Tinien | S. | Air | 17-26-54 | 8-09-02 | F |
| 17-26-24 | — | Ch | |||
| Idikel | W. | Air | 17-29-42 | 7-37-23 | C |
| Teloas-Tabello | E. | Air | 17-34-40 | 8-49-30 | R |
| Egeruen | S.W. | Air | 17-35-15 | 7-54-22 | C |
| Auderas436 | C. | Air | 17-37-50 | 8-19-00 | R |
| 17-38-00 | 8-18-14 | F | |||
| 17-37-48 | 8-19-30 | (C) | |||
| Telia | E. | Air | 17-47-30 | 8-49-20 | R |
| In Kakkan | W. | Air | 17-49-22 | 7-48-23 | C |
| In Abbagarit | Western Desert | 17-53-47 | 5-59-15 | C | |
| Tamet Tedderet | Western Desert | 17-54-04 | 6-36-18 | C | |
| Anu n’Ageruf | W. | Air | 17-54-46 | 7-24-22 | C |
| Aureran | C. | Air | 17-56-54 | 8-23-17 | F |
| 17-56-42 | — | Ch | |||
| Teginjir | C. | Air | 17-59-20 | — | R |
| Abarakan | C. | Air | 18-03-30 | 8-39-20 | R |
| Aggata | C. | Air | 18-09-00 | 8-26-40 | R |
| Ufa Atikin | W. | Air | 18-09-26 | 7-12-21 | C |
| In Allaram | Western Desert | 18-16-12 | 6-15-19 | C | |
| Tamadalt Tan Ataram | W. | Air | 18-16-23 | 7-49-18 | C |
| Afasto | W. | Air | 18-17-08 | 7-17-22 | C |
| Zilalet | W. | Air | 18-23-19 | 7-51-21 | C |
| Assode | C. | Air | 18-27-00 | 8-26-50 | R |
| Sidawet | C. | Air | 18-30-54 | 8-02-20 | C |
| Afis | N. | Air | 18-37-30 | 8-35-40 | R |
| Agellal | N. | Air | 18-43-02 | 8-07-17 | C |
| 18-43-00 | 8-10-02 | F | |||
| 18-43-00 | 8-07-14 | Ch | |||
| Faodet | N. | Air | 18-47-20 | 8-34-50 | R |
| Iferuan437 | N. | Air | 19-04-10 | 8-22-45 | R |
| 19-04-28 | 8-22-22 | C | |||
| 19-04-18 | 8-24-32 | F | |||
| 19-04-12 | 8-21-20 | Ch | |||
| 19-04-03 | 8-24-24 | J | |||
| Zurika | N. | Air | 19-14-35 | 7-50-15 | C |
| Uraren | Western Desert | 19-31-44 | 7-08-17 | C | |
| In Gezzam | Western Desert | 19-33-10 | 5-44-20 | C | |
Heights above Sea Level.438
| Iferuan | 681 | metres | (F) |
| 673 | „ | (C) | |
| Uraren | 485 | „ | (C) |
| Sidawet | 554 | „ | (C) |
| Agellal | 613 | „ | (C) |
| 604 | „ | (F) | |
| Auderas | 798 | „ | (F) |
| Agades (T’in Shaman) | 500 | „ | (F) |
| In Gezzam | 374 | „ | (C) |
| Zilalet | 557 | „ | (C) |
Note.—The exact positions of the observations in the same localities are not identical in the case of all observers, which accounts for some of the apparent discrepancies.
Notes
433The Dankaba observation is of somewhat doubtful accuracy.
434The Tanut longitude depends on only one stellar observation for L.M.T.
435Jean’s longitude for T’in Shaman, which is the site of the French post and therefore also of the rest-house where the Cortier observation was taken, differs so materially from the latter that it cannot be accepted. It is described (like the position he gives for Iferuan) as “d’après F. Foureau,” but I can find no record in the account of the proceedings of the Foureau-Lamy Mission to justify this statement.
436My camp at Auderas was situated about 400 yards east of the camp site which the Foureau-Lamy Mission occupied and where, therefore, Foureau’s observation was probably made. This difference accounts for the discrepancy in our longitudes. The Cortier map shows an astronomically fixed point at Auderas which, when measured on the copy in my possession, gives these co-ordinates, but they are not recorded in the table on the second sheet of the map, as are the other positions in Air. Foureau’s latitude is based upon five observations, one of which is appreciably smaller than the other four; if this result is omitted from the average, the latitude becomes even higher than it is given in the table.
437Foureau’s latitude for Iferuan is based upon five observations, one of which is appreciably higher than the other four; if this result is omitted the average practically coincides with my observation, which was taken on the identical spot.
438The altitudes obtained by me from boiling-point observations and aneroid readings are not given; they are numerous but have not been fully worked out.