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OFFICE OF THE CHIEF OF ENGINEERS,
SIR: Lieut. George M. Wheeler, Corps of Engineers, has sent to this office a report embodying the results from the astronomical observations made at Cheyenne, Wyoming Territory, and Colorado Springs, Colorado Territory.
As this report contains information of value to officers engaged upon explorations, surveys, and reconnaissances in the western country, I have respectfully to recommend that it be printed at the Government Printing-Office, and that five hundred copies be furnished on requisition from this office.
Very respectfully, your obedient servant,
A. A. HUMPHREYS, Brigadier-General and Chief of Engineers.
Hon. W. W. Belknap,
Secretary of War.
Approved by the Secretary of War, February 14, 1874.
H. T. CROSBY, Chief Clerk.
UNITED STATES ENGINEER OFFICE,
GEOGRAPHICAL AND GEOLOGICAL EXPLORATIONS AND SURVEYS
WEST OF THE IOOTH MERIDIAN,
Washington, D. C., February 9, 1874.
SIR: I have the honor to forward herewith a report embodying the results from the astronomical observations made at Cheyenne, Wyoming Territory, and Colorado Springs, Colorado Territory. They are typical stations for the years 1872 and 1873, although not selected because of probable errors that are a minimum.
Attention is invited to the methods employed and the order of sequence in reporting the results.
Uniformity of plan seems to be a matter of so great importance in the prosecution of astronomical work in the western interior that the one now in use is submitted for consideration as a step at least in this direction.
Minor features of the methods are still to be perfected; yet the errors of starplaces, from observation, and those known as instrumental, have now become reduced to such small and nearly equable values, that it seems desirable that some general and uniform plan should be adopted for the report at least, if not for the manner of conducting the observations.
The present one is submitted with extreme diffidence, and will probably demand certain changes in the light of future experience.
At Colorado Springs a heavy stone monument and observing-pier, with meridianmarks, have been established.
The same has been done at the greater number of the other points occupied as main field-stations in the years 1871, 1872, and 1873.
These meridian-lines may serve various purposes in checking future surveys in adjacent areas.
Very respectfully, your obedient servant,
Brig. Gen. A. A. HUMPHREYS,
GEO. M. WHEELER, Lieutenant of Engineers, in Charge.
Chief of Engineers, United States Army.
NOTE. The results from the observations made during the field-seasons of 1871, 1872, and 1873, at the remaining primary stations, twenty-two in number, will appear in Volume II of the Reports of the Survey, as proposed in the Annual Report of the Chief of Engineers for 1873, Appendix EE.
ORDER OF SEQUENCE
MAIN OR PRIMARY FIELD-STATIONS.
Longitude by Telegraph; Latitude by Zenith Telescope, (Talcott's method.)
1. Geographical position of station.
2. Physical-geography details; especially all physical peculiarities.
3. Meteorological conditions, both general and special; the latter while observations were made.
4. Description of observatory; including personnel of party, name of telegraphoperator, and name of telegraph-company whose wire has been employed.
5. Description of instruments used..
6. Points with which connections were made; nights of observation, and observers; also name of computer or computers.
7. Tabulation of stars used, and number of observations.
8. Instrumental values; circumstances of telegraphic communication, i. e., length
of circuit, number of batteries, repeaters, &c.
9. Uniform tables of time-reductions at receiving-station.
10. Uniform tables of time-reductions at sending-station.
11. Grouping of series of exchange-signals, including means of single and serial results.
12. Personal equation.
13. Probable error by least squares.
14. Resulting longitude.
15. Reduction of the latitude-observations properly grouped, with discussion of results.
16. Resulting astronomical co-ordinates.
ABBREVIATIONS AND SIGNS.
a, b, c,
azimuth, level, and collimation corrections.
A, B, C, azimuth, level, and collimation factors.
Tobserved time reduced to the mean of wires and corrected for rate.
4. Tresulting error of the chronometer after the mean of the wires is corrected for rate and level.
4T, adopted mean error of chronometer.
4Terror of the chronometer.
v = difference between mean final correction of chronometer and 4T.