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Show 58 RECONNAISSANCE IN THE UTE COUNTRY. several places. On the south the road is good and the descent is easy into Roman's Park, which is merely an extension of the San Luis Valley. The best grade on the northern approach is about 240 feet per mile. The route to the west extends by a first rate road on the west side of the park to Saguache and the Los Finos agency. To reach Fort Garland by this route, following down the margin of the park to Del Norte and thence east, is preferable to attempting the shorter line direct from Homan's Park through the sand- hills to the east end of the park. DONALD W. CAMPBELL, Assistant. APPENDIX A. Description of instruments and methods.- The instruments were theodolites by Alve, of Saint Louis, 5- inch limb, two verniers, reading to 20"; their telescopes were 8£", focal length 1&", aperture provided with a limb for reading vertical angles read oy a vernier to single minutes; these were fitted for use as stadia instruments by inserting vertical and cross hairs. There were three of the latter, giving two unequal intervals. For each wire interval a stadia rod wras graduated independently. Each rod was graduated by ascertaining the space covered on it at a distance of 1,000 feet, by the wire interval for which it was to be graduated, and subdividing this space with points for each five feet. The several rods were graduated to measure extreme distances of from 1,800 to 2,600 feet, and were read by the instrument-man. The stadia instruments served to determine the linear distances ; the direction of the line was kept by instrumental azimuths, the magnetic bearings being always read as checks. The azimuth was carried forward by taking back- sights and fore- sights at each station. The stadia rods served as signals for the back and fore sights, and the length of each course was read from each end when the fore and back sights were taken for azimuth, and the mean of the two readings used for the length. Whenever there was a marked difference of level between two consecutive stations, the angles of elevation or depression of the telescope was read at each statiou, and with the mean angle the horizontal distance was obtained by the aid of the valuable tables computed by Noble and Casgrain. The results obtained with these instruments were, as a whole, good, the closing being small even on loug lines, for instance, the two separate lines run from Pueblo to Fort Garland differed only thirty- eight hundredths of a mile from each other in a mean distance of 81.33 miles. Their chief defect was the smalluess of field and deficiency of power, making their use a severe task to the eyes and requiring an unnecessary number of sights in open country. It is thought that the same instruments, mounted with larger and more powerful telescopes, and used in conjunction with a double target-rod of a pattern similar to that known as the " New York" rod, and brightly painted for self- reading, on near sights, would give still better results than were obtained. There is no doubt that, in a rough, mouut-ainous country, carefully- made stadia- measurements are far more accurate than such as can be made by ordinary chaining with ordinary chain- men, and when the chain- men are very ordinary, as is too frequently the case, the superiority of the stadia is very great. |
