16. APPENDIX C. REPORT OF EDWARD P. AUSTIN, ASTRONOMICAL ASSISTANT.
The instruments employed were a sidereal chronometer by Negus, No. 1344; a mean solar chronometer by Hutton, No. 288; and a portable transit of 26-inch focus, and 1¾-inch aperture, by Würdemann, No. 16, which had been altered to convert it into a meridian instrument, similar to those introduced by the United States Coast Survey.
Observations at Carlin consist in observations for time and exchanges of telegraphic signals for difference of longitude with Washington, D. C., (United States Naval Observatory, J. R. Eastman, observer,) through Detroit, Michigan, (United States Lake Survey Observatory, O. B. Wheeler, observer,) on May 19, 23, and 24; and observations for latitude May 17, 25, 26, and 27.
At this place I was assisted by Mr. A. R. Marvine. The observations at this point consisted in observations for time, moon culminations for longitude, observations to determine the constants of the instrument, and observations for latitude. They lasted from July 21 to August 7.
I then repaired to Salt Lake City, Utah, to await the arrival of Mr. Marvine at Saint George, Utah, when observations were made for time, and signals exchanged between Salt Lake and Saint George, on September 13, 14, and 15.
The instruments used at Salt Lake were a mean-time chronometer, by Barrand, No. 22961; and a portable transit of 31 inches focal length, 2frac12;-inch aperture, by William Würdemann, No.19, which was firmly mounted on a sandstone pier, in the observatory erected in 1869 for the United States Coast Survey party; these instruments, and the observatory, being the property of Brigham Young, president of the Mormon church.
From the preliminary reductions, the probable error of a time determination with the instrument used at the stations from Carlin to Independence is from ±0.″02 to ±0.″04, and the probable error of a single pair observed for latitude is ±1.″37, giving the probable error of a result depending on thirty pairs ±0.″25; on fifty pairs ±0.″20. These values will be considerably reduced by the final computations.
The time determinations at Salt Lake, owing to the larger size and greater stability of the instrument, as well as the more favorable conditions for observing, give a probable error much less, being less than ±0.″01.