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. 



