National Geographic : 1898 Jul
336 GEOGRAPHIC WORK OF GENERAL GOVERNMENT that part of the Atlantic traversed by the Gulf stream. It con ducts also magnetic observations for the determination of the direction, dip, and force of the earth's magnetism, and measures the force of gravity by means of the pendulum. It is carrying on accurate triangulation in the interior of the country, having already completed a belt across the continent from east to west, together with a large amount of similar work done in aid of state surveys. In addition to this triangulation in the interior, lines of accurate levels have been run over many thousands of miles. The results of this work' are published in the form of charts of the coast upon various scales, upon some of which the relief is represented by hachures, upon others by contours. These charts are sold at prices differing with the size of the chart. There are also published annual reports, in. which are contained papers upon geographic subjects pertaining to the work of the Survey. CORPS OF ENGINEERS, U. S. A . The War Department carries on a great variety of geographic work, mainly through its Corps of Engineers. By this office has been executed a complete survey of the shores of the Great Lakes and of the St Lawrence. The charts resulting from this survey are upon various scales, dependent upon the needs of navigators, and are sold at prices differing with the size of the chart. The Mississippi and Missouri River Commissions are in the nature of advisory boards to the Chief of Engineers. By the Mississippi River Commission that river has been mapped from its mouth far up into Illinois and the results published upon various scales, the largest being 1: 20,000, in contours; another on a scale of one mile to an inch, while the whole alluvial region of the Mississippi, from Cairo to the Gulf, has been issued in one large map, on a scale of four miles to an inch, in eight sheets. The Missouri River Commission has mapped that river from its mouth to the Three Forks, in Montana, publishing the maps upon various scales, ranging from one mile to an inch upward. The Engineer Corps has mapped also the Ohio river from Pittsburg to its mouth, the Arkansas, Red, White, and Yellow stone rivers. Copies of these maps can be obtained by applica tion to the Chief of Engineers. To this organization has been entrusted also the survey of parts of our international boundary.