« PreviousContinue »
THE FIELD-SEASON OF 1873,
THE MAIN OR PRIMARY FIELD-STATION, COLORADO SPRINGS, COLORADO TERRITORY,
U. S. ENGINEER OFFICE, GEOGRAPHICAL AND GEOLOGICAL
EXPLORATIONS AND SURVEYS WEST OF 100TH MERIDIAN,
Washington, D. C., January 1, 1874.
SIR: There is presented herewith a report upon the astronomical observations taken by myself, and the party under my charge, at Colorado Springs, Colorado Territory, during the field-season of 1873.
GEOGRAPHICAL POSITION OF STATION.
Longitude 104° 49′ 15′′.10.
Latitude = 38° 49′ 41′′.67.
Colorado Springs is a town in El Paso County, Colorado Territory. It has been built up within five years, and has nearly fifteen hundred inhabitants, and the place promises to become one of considerable importance. During the summer-months the hotels (of which there are quite a large number) are filled with invalids, who flock here on account of the beautiful scenery and the salubrity of the climate. The track of the Denver and Rio Grande Railway passes around the town at a distance from the town-limits of about four thousand feet.
The astronomical point is situated between the town and the railroad, about six hundred and fifty feet distant from the latter, on a slight eminence near the freightdepot of the Denver and Rio Grande Railroad. The observations were conducted on a pier built of bricks, which was replaced two months later by a solid sandstone monument, furnished by Mr. S. G. Ward, of Pueblo.
This part of Colorado is not well watered, but the land where irrigated yields almost in every instance splendid harvests.
From the astronomical point there is a clear outlook to the north, south, and east. Looking west, prominent peaks and foot-hills of the Rocky Mountain range are seen running north and south; Pike's Peak, immediately west, being the highest, and Cheyenne Mountain the highest in the south-southwest. At the foot of Cheyenne Mountain there is a creek, the waters of which are brought, by means of ditches, to Colorado Springs. From the station the plains rise a little to the east, at the horizon say one hundred and fifty feet. In the southeast there is a hill about four hundred feet high, called Washington Mountain.
Colorado Springs is laid out regularly, the streets running east and west and north and south; the greatest extension is from north to south.
Generally speaking, it is inadvisable to have the astronomical station near the railroad-track; but in this case the trains ran only during the day, and the observations. were never affected by the vibrations of the ground.
The meteorological observations made at the station show great changes in temperature during the day. I have been told by several old residents that they never experienced a summer similar to that of 1873. The rainy period of the summer is looked for about the 1st of July, to last only a few days. This year it was noted that from July 28th to August 9th there was no day without rain, accompanied by thunder and lightning. The prevailing winds were from the northeast or southeast, commencing at 10 or 11 o'clock a. m., and increasing in force until 2 or 3 o'clock Then clouds came up from the southwest or west, bringing much rain, thunder, and lightning. It was generally clear again by 12 p. m.; but I found the air so very undulating, and the stars on that account so faint, that I was sometimes obliged to suspend the observations. It is probable that the temperature of the higher regions of the air was affected by the vicinity of the mountains, and after a rain changed very rapidly, while the lower strata remained under the same conditions.
The following table shows the general direction of the wind at 7 a. m., 2 p. m., and 9 p. m., giving the mean or prevailing direction of the wind for three hours before and three hours after the given time; also the estimated force of wind for the same time. The last column gives the general appearance of the sky, and needs no further explanation. It shows under what particularly unfavorable circumstances the observations were made:
DESCRIPTION OF OBSERVATORY AT COLORADO SPRINGS, COLORADO TERRITORY.
As soon as the monument was built, a solid framework, 8 by 10 feet, was constructed, and a large wall-tent put over it. There was an opening in the tent for the meridian-line; this was closed, when necessary, by a fly. During heavy winds the
tent was in danger of being blown away, and it was found necessary to nail the fly to the framework, while the tent itself was fastened to the stakes by strong iron wires. The entrance to the tent was from the west side, and was closed by ropes. In the northwest corner of the observatory a large box was used for a table. On it the switchboard and galvanic battery were placed; the chronometer being also placed there during the observations. The connection from the switch-board to the Western Union Telegraph office was made by a line 600 feet in length, supported by the framework of the tent and one telegraph-post 30 feet in height. A ground-wire was used after switching in the Western Union office to complete the circuit. In the northeast corner of the tent the chronograph was placed upon a solid and insulated framework. Wires for the connection of the chronometer and breaking-key were fastened to the tent-frame. The levels were also set on an insulated post in the southeast corner of the tent. For chairs I used two small boxes, one on the north and the other on the south side of the monument. In arranging and constructing the observing-tent I was assisted by C. D. Gedney and Privates J. Meier and J. Clancy, Battalion of Engineers. They also took the meteorological observations. Mr. G. T. Ellison, at that time in charge of the Western Union office, kindly assisted in sending the telegraphic signals.
DESCRIPTION OF INSTRUMENTS USED.
Observations were made by means of a combined transit-instrument number 28, made by Würdemann. Its focal length is three feet; radius of aperture, 23 inches; diameter of pivots, 1 inches. The diagonal eye-piece used had a magnifying-power of 40 diameters. This instrument was provided with two finding-circles, 3 inches in diameter, graduated to every twenty minutes, and reading to single minutes by means of the vernier. Another circle was affixed to the upper part of the tube, divided also also to twenty minutes, and having in the center a level used in latitude-observations for determining the change in the inclination of the horizontal revolving-base. Seven wires were placed in the focus for time-observations, besides one horizontal wire for latitude-observations. The equatorial intervals of the wires from mean of wires, clamp west, upper culmination, were:
One revolution of the micrometer-screw moved the horizontal-wire 62".12; the the value of one division of the striding-level, which was used at every station, was o'.75; the value of one division of the zenith-telescope level was 1".10. The chronograph used was similar to that used at the United States Naval Observatory invented by Professor William Harkness; the barrel being 8 inches in diameter and 24 inches long, and makes one revolution a minute. The chronograph worked very well when it was cleaned before commencing operations at a new station. It had but a single pen, which recorded clock-signals and those made by the observer.