- This sundial was constructed in 1969 on the top of a 10-foot round column on a 75-ton block of reinforced concrete by Heron Construction Co. to anchor an aerial tram cables spanning 2200 feet across the Royal Gorge. The column was tilted away from the cables and the station on the opposite side of the gorge, so the dial face is inclined about 4 degrees, sloping in a direction about 9 degrees west of due south.The original dial was designed by William L. Peterson of Time & Space LTD, Denver, CO (said to be a sundial expert by a newspaper article, but no further r information), and painted by a local sign painter, Ray Hawes.
On the original dial, hour lines were labeled with Roman numerals from V to VIII, with 15-minute marks between. The dial was properly laid out with hour lines extending from the corners of the wide gnomon with corresponding noon gap. Look carefully at the historic photographs and you will see that the morning hours before VI and evening hours after VI properly go to the opposite gnomon foot corner. Some time shortly after construction, after many complaints about the dial being "an hour off," a plaque was added to explain that "The operation of the universe pays no heed to man-made laws or 'daylight saving' time." See the inscription for full text.
Wood boards were placed between the tram cables and the concrete bollard (with the sundial drawn on top). In an annual inspection in 2011, the Colorado Passenger Tramway Safety Board (CPTSB) discovered that the wood was rotting. The Royal Gorge Bridge & Park constructed a metal building over the sundial to reduce exposure to the elements. The sun didn’t shine on the sundial again until after the 2013 Royal Gorge Fire when the building was removed. (See the enclosure below for greater detail).
The original gnomon -- two steel angles welded together -- was melted and twisted and the painted face of the dial severely damaged by a large wildfire in 2013, which also destroyed most of the park. The original tram was replaced with a gondola ride which no longer use this 75 ton bollard anchor. The gnomon was replaced and the face was repainted in 2015, but by 2023, it was badly deteriorated.
In June of 2024, the Park commissioned muralist Brandy Stone to repaint the dial. NASS member Roger Harris assisted in the line layout and painting. Brandy's new, modern sun face design was selected by Brooklyn Osborne, Marketing & Communications Manager and director of their "Art in the Park" program.
The restoration done in 2015 put the new gnomon up on a pedestal about 5 inches above the dial face. Unfortunately, this meant that the original hour lines were incorrect since gnomon shadows originate where they meet the dial face. The pedestal block extended the gnomon foot about 8 inches further south from the original hour line origins. This meant that the restored dial never showed the correct solar time except at noon. The gnomon on its pedestal cannot cast 6AM or 6PM shadows on the dial face, because the lowest section of gnomon that would cast those shadows is missing. The shadow of the pedestal does fall on the dial, however, but not where the VI lines would be. To avoid confusion the 6am and earlier hour lines and 6pm and later hour lines have been omitted, leaving an accurate solar time sundial showing shadows from VII in the morning to V in the afternoon.
The gnomon required a slight angle adjustment to match the site's latitude, but that was easily done by adjusting the mounting bolts. The angle was measured by hanging a small weight on a thread attached to the corner of the 16-inch side of a 16x24 framing square: With the 16-inch side sitting on the edge of the gnomon, when the thread crossed the 24-inch side at 20-5/32 inches, the gnomon was very close to the required angle of 38.45 degrees. The slope of the face complicates this dial, and measurements for the hour lines taken from a 3D model based on the approximated slope and direction proved to be less accurate than desired. Therefore, all dial lines (including quarter- and half-hour lines) were marked at the precise solar times shown by an Android phone app called TpSol. This app calculates Local Apparent Time based on GPS coordinates, and it calculates the Equation of Time as a continuous function which varies slightly during the day, whereas published tables typically show the EoT at noon on each day. The left edge of each painted line is the precisely marked time line, so the readings from this dial are most accurate when the left edge of the gnomon's shadow in the morning or the right edge in the afternoon first falls directly on the left edge of a line. This was done because it is easier to judge that alignment accurately rather than discerning when the shadow falls precisely on the center of a 5/8-inch wide black line. At solar noon, the 7-inch wide shadow falls directly between the noon gap lines. The slightly southwest orientation of the slope causes the dial to be slightly asymmetric, but not enough to be noticeable.
Now the sundial is now nicely landscaped and appeals to visitors. In addition to the sundial a Water Clock is located just behind the Visitor Center. This Water Clock, the only one of its kind in Colorado, is a replica of the original, which kept time for 30 years before the Royal Gorge Fire in 2013.
|
1969-01-17 New Tram Anchor.pdf 2167.323 KBytes
