Eighteenth Annual Meeting. li 



The economic part of geological surveying is a department which cannot for 

 many reasons be done by a national organization; that must be done by the State 

 surveys, and the mineral beds, etc., be properly located and described. Information 

 relating to economic deposits must be furnished by the State surveys when demanded 

 by the people. The general survey makes topographic maps, places on them the 

 geologic formations, and discusses the relations of the iron, copper, coal, phosphates, 

 etc., to the formations. Then the State survey comes in and fixes the values of the 

 deposits, methods of development, and other questions of economic interest; upon 

 this basis many States are reorganizing their surveys. 



The surveying and map-making operations of the United States Government are 

 divided into three departments, as follows: 



I. The geodetic or coast survey. 



II. The geological survey — including, as a necessary preliminary, the topograph- 

 ical work. And 



III. The land surveys of the General Land Office. 



1. The geodetic or coast survey does that surveying and platting of the coast and 

 adjoining ocean which is necessary to make charts for the use of marines. This 

 work has been carried on for a number of years, and the two coasts of our country 

 are nearly completely charted. That is, the land and coast maps are nearly finished, 

 but there is a continual need of the study of the ocean — ^the hydrographic work. 



2. The geological survey has been referred to, and its work is familiar to every 

 one. Its importance may be noted in the fact that the mineral products of the 

 United States amount to )^450,000,000 annually. Surely there should be a scientific 

 basis for this industry, and the topographic work is also important, in that it gives 

 us accurate maps which are of use for many purposes. 



Both geodetic and topographic surveying are first begun by the measuring of base 

 lines. These base lines are scattered about 200 miles apart throughout the country, 

 depending on favorable sites. They are four or five miles in length, and are meas- 

 ured many times, to secure the greatest possible accuracy, astronomic and tele- 

 graphic methods being used to obtain the latitude and longitude exactly. From 

 these base lines the triangulation is expanded, the first triangles being small, those 

 more remote much larger, the sides sometimes measuring thirty to fifty miles. The 

 intervening country is then triangulated, to locate all objects desired to be noted on 

 the map. and the extent of the measuring and the scale of the map determine the 

 details of the work. The main difference between a geodetic and topographic sur- 

 vey is in the fact that the former is by far the most minute and exact, being 

 primarily made for the purpose of ascertaining the shape of the surface of the 

 earth. For this its methods are very much more refined than the topographic 

 methods, which are intended for map-making only, which is a very different thing. 

 There is no need, in the latter, of determining the location of a point within less 

 than ten feet in 1,000, for such error would not show on an ordinary map. But in 

 geodesy the error must not be one-tenth of that, for, by multiplying, it would be- 

 come very serious. Geodesy is valuable also in cadastral surveying, or the bounding 

 of private estates and properties, in that it provides unchangeable astronomical 

 data. 



The base line from which the triangulation of Kansas is now being carried on is 

 located in southwest Missouri, and the adjoining three States. This is one of the 

 five great base lines the geological survey has located on the national domain, and it 

 would seem to become us to seize the opportunity, while the survey is working within 

 our borders, to have the map made on a large scale, as other States have done, by 

 paying an additional amount for the extra expense of placing minute features on 

 the map. The United States survey, of course, locates all streams and all eleva- 



