“Living People Often Meet.”
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. |