Recherches sur les instruments les méthodes et le dessin Topographiques

Abstract

IN the first part of the second volume of his exhaustive treatise on topography, Colonel Laussedat treats of “iconométrie” and “métrophotographie”—two branches of the art which are but little studied in British military schools. He commences by tracing the evolution of the photo-theodolite from the primitive forms of the camera obscura and the camera lucida; and not the least instructive part of this volume is to be found in the careful analysis of those principles of perspective which are the governing principles of all methods of reducing a field of observation to its horizontal plan, whether for the purpose of topography or of plan drawing. He shows that the camera lucida is an instrument which (in France at any rate) has proved of immense value in the hands of the military engineer. Some excellent examples are given by Colonel Laussedat of the practical use that has been made of this instrument in the construction of accurate geometrical views of fortifications, with the object of obtaining precise plans of the same, on the principle which was first advocated by Beautemps-Beaupré, and which is fully explained by the author. It is curious that an English invention (it was invented in 1804 by Wollaston) should have been applied to so much greater practical purpose in France than it ever has been in England.

Recherches sur les instruments les méthodes et le dessin Topographiques.

By Colonel A. Laussedat. Tome ii. Part i. Pp. 198. (Paris: Gauthier-Villars et Fils, 1901.)