Abstract
THE object of this volume is to provide travellers in little-known regions with information which will enable them to record particulars of service to geography concerning the land traversed. In the first chapter the methods are described for determining and representing approximately the route followed and the details of the surface, using a prismatic compass and an aneroid. The astronomical observations required to define positions along the route are then explained; and it is shown how the combination of these observations with the rough survey enables an approximately accurate representation of the journey to be laid down. The determination of heights and distances by levelling and triangulation are described in the third chapter, for the instruction of explorers who wish to make a detailed study of particular districts. The two temaining chapters deal with systems of projection for the conversion of the observations to maps, and the choice and transport of the instruments referred to in the text. The sextant is not included among the instruments, the astronomical observations being made with the theodolite instead. No instructions are given as to what to observe in natural history, geology, anthropology, or other sciences; hence, the volume is not to be compared in value with the “Hints to Travellers” published by the Royal Geographical Society. Nevertheless, as a clear and very elementary manual on surveying and practical astronomy for travellers who explore without having received a preliminary scientific training, the book may prove of service.
Manuel de l'Explorateur.
By E. Blim Rollet de l'Isle. Pp. vii + 260. (Paris: Gauthier-Villars, 1899.)
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Manuel de l'Explorateur. Nature 59, 5 (1898). https://doi.org/10.1038/059005b0
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DOI: https://doi.org/10.1038/059005b0