THE ELEVATIONS OF CERTAIN DATUM-POINTS ON THE GREAT 

 LAKES AND RIVERS AND IN THE ROCKY MOUNTAINS. 



By James T. Gardner, Geogr.upher. 



IITTEODUCTIOJ}'. 



As tbe field of labor of the United States geoloj^ical and geograpliical 

 surveys of the Territories now lies in Colorado, the following work was 

 undertaken for the purpose of determining the elevation of Denver, 

 which is at present the base from which all altitudes in the Territory 

 are measured. The height of Denver above the sea had been vari- 

 ously reported at from 5,043 feet to 5,303 feet, and the spirit-level 

 lines of the K. P. and U. P. E. E.s seemed to differ nearly 200 feet. 

 Believing that any such large discrepancies between spirit-level lines 

 must be due to false reports and errors in joining the different links 

 of these long chains to the sea, 1 determined to reconstruct all pos- 

 sible lines of levels from the ocean to the Eocky Mountains, using only 

 official reports by engineers, and checking them by personal examina- 

 tion of their note-books and working profiles wherever practicable. 

 For this purpose I visited the railroad-engineer offices at Denver, 

 Omaha, Lawrence, Kansas City, Saint Louis, Chicago, Cleveland, ISTew 

 York, and Philadelphia, examining not only the completed i)rofi!es and 

 the original notes from which they were made, but making, also, such 

 corrections as then seemed necessary to unite the lines of diti'erent 

 companies. Several of the most important profiles were lost in the 

 Chicago fire, and of one of these, that of the C, A,, & St. L. E. E., no 

 record is left. Profiles of the C. & N. W. and of the C, E. L, & P. E. E.s 

 had been sent to the geological survey of Iowa, and had been published; 

 these have now to be used instead of the originals. 



For many years, various Departments in Washington have been 

 gathering railroad and canal profiles. Mr. Nicholson, the topographer 

 of the Post-Ofiice Department, deserves especial mention for his long- 

 continued activity in this important work under the Smithsonian Insti- 

 tution. Lately, the office of the Chief Signal-Officer of the United States 

 Army has compiled all of this material, with a large collection of their 

 own from original sources, and carefully arranged and indexed it. In 

 the 1871 and 1872 reports of the Chief Signal-Officer, Gen. Albert J. 

 Myer, he speaks of Lieut. Henry Jackson, acting signal-ofiicer and 

 assistant, as having vigorously prosecuted this department of the work. 

 The collection comprises over one thousand profiles and reports from 

 original sources; and efforts are being made to render it so complete, 

 as to the profiles and their connections, that the elevation of every 

 town on railroad or canal shall be well determined. The civil engineers 

 of this country cannot render a greater service to geographiwd science 

 than to send to the United States Signal-Office copies of railroad and 

 canal profiles. Some of the most important problems in the meteor- 

 ology of the country are dependent for their solution upon our exact 

 knowledge of the elevations of the observing-statious; and these must 



