(x)
changes position. The tenor of the article, (which does deal with the problem of the fluctuating course of the Komadugu Yobe), leads one to believe that the definition of this east-west alignment should be based on the river mouth, whatever its position, rather than the latitude value quoted at the time. Publication of series 1501 sheet ND 33-9 will show whether this is the view the US DMA Topographic Center has adopted.
1501 sheet ND 33-10. In the south of the sheet, at 13°05′N, a change has taken place due to the establishment of the Nigeria-Chad-Cameroon tri- junction by an Anglo-French exchange of notes on 9 January 1931. This is a change to a part of the 1910 Agreement boundary lying beyond the present-day Nigeria-Niger boundary.
All the above 1501 sheets are edition 1, and the Map Preparation Guides produced by the then U.S. Army Map Service state that the international boundaries are taken from the I.G.N. Carte de l'Afrique de l'Ouest, at 1:200,000 scale, together with overlays to be used as guides for location. (These overlays are not available at MRLG). However, the Nigeria-Niger boundary does not correspond exactly with the French map since some degree of generalisation has been introduced.
3. The 1.G.N. Carte de l'Afrique de l'Ouest shows the boundary as far east as 13°E, except sheet ND-32-X (9°E-10°E), on which no boundary is shown. The maps have most of the frontier beacons marked and numbered, fieldwork having been carried out in 1954-62. However, although agreeing well with most of the 1907-08 demarcation line, the French mapping, being the basis for international boundaries on the 1501 series sheets, also shows all the deviations listed in paragraph IV. 2, (see note 12). The following comments are related to the sub-paragraph headings in paragraph IV. 2:
(i)
Spot height 381 shown as a frontier pillar. (Sheet ND-31-XII).
(ii)
New turning points established by this deviation are not shown by boundary pillars, but a motorable track follows the new boundary just inside Nigeria. (Sheet ND-32-VII).
(iii) The new irregular boundary is not shown by boundary pillars. (Sheet
ND-32-VII).
(iv) Boundary pillar 65 seems to be a replacement one, since it is shown as
lying on the new alignment. (Sheet ND-32-VIII).
(v)
(vi)
The new alignment is shown in greater detail than on the 1501 sheet; this deviation occurs in relatively densely settled country where a straight-line boundary would almost certainly be unsatisfactory. (Sheet ND-32-IX).
Diché is shown in Niger, instead of Nigeria as in the 1907-08 demarcation, but this settlement appears to be the Angua Dala of the 1907-08 maps and the 1501 sheet. In any case a settlement appears to have been shifted to the Niger side of the boundary since 1907-08. (Sheet ND-32-IX).
(vii)
The French map does not show a boundary at these points.
(viii))
(ix)
There are no French 1:200,000 sheets east of 13°E, where these changes occur.
(x)
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