Eighteenth annual report of the United States Geological Survey to the Secretary of the Interior, 1896-1897: Part I - Director's report, including triangulation and spirit leveling
During the fiscal year 1896-97 the organization of the Geological Survey as set forth in the Director's last report was continued without material change, and the field work of 1896 was largely a continuatoin of the previous season.
The most important change in the field work was rendered necessary by the legislation providing for the establishment of levels and permanent monuments and bench marks. The clauses of the act embodying this legislation, and a full statement of the reasons for it, were given in the Introduction to Part I of the Seventeenth Annual Report, pages 7 to 11, and the subject is again referred to further on in this report. The actual cost of the leveling and monuments for the year was somewhat greater than it will be another year, as the expense of training men and initiating the new methods- of survey will not have to be met hereafter. During the year 10,840 miles of levels were run and 1,820 bench marks were established.