Bulletin of the United States Geological Survey

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Page 4 - The office adjustment of the notes and the reduction to mean sea-level datum may so change some of the figures that the original markings are 1 or 2 feet in error. It is assumed that engineers and others who have occasion to use the bench-mark elevations will apply to the Director of the United States Geological Survey...
Page 4 - I), 3^ inches in diameter and one-quarter inch thick, having a 3-inch stem, which is cemented in a drill hole in solid rock in the wall of some public building, a bridge abutment, or other substantial masonry structure.
Page 36 - Bs of the Coast and Geodetic Survey at Olney. Illinois, a square cut at the base of one of the columns of the north face of the court house. The elevation now accepted is 486.117 feet above mean sea level as determined by the 1907 adjustment. The leveling was done in 1907 by Mr. Henry Biicher, levelman.
Page 4 - The numbers stamped on the bench marks described in the following pages represent the elevations to the nearest foot as determined by the levelman. These numbers are stamped with...
Page 24 - Quadrangles. The elevations in the following list are based upon an aluminum tablet at the southeast corner of the Jefferson County Court House at Steubenville, Ohio, marked "716 STEUBENVILLE. ' ' The elevation of this is accepted as 714.729 feet above mean sea level and was determined from the Army Engineers bench mark "67 A...
Page 19 - The leveling was done in cooperation with the State, and the bench marks are stamped with the State name. There is doubt as to the marking of some of the bench marks. WEINGARTEN QUADRANGLE.
Page 4 - This level is not the elevation determined from the mean of the highest and lowest tides, nor is it the half sum of the mean of all the high tides and the mean of all the low tides, which is called the half-tide level. Mean sea level is the average height of the water, all stages of the tide being considered. It is determined from observations made by means of tidal gages placed at stations where local conditions, such as those due to long, narrow bays, rivers, and like features, will not affect...
Page 7 - It is determined from observations made by means of tidal gages placed at stations where local conditions, such as long, narrow bays, rivers, and like features, will not affect the height of the water. To obtain even approximately correct results these observations must extend over at least one lunar month, and if accuracy is desired they must extend over several years. At ocean stations the half-tide level and the mean sea level usually differ but little. It...
Page 7 - Mexico, or the Pacific Ocean. The connection with tidal stations for bench marks in certain areas that lie at some distance from the sea coast is still uncertain, and this fact is indicated by the addition of a letter or word to the right of the word "datum
Page 4 - The bottom is spread out to a width of 10 inches in order to give a firm bearing on the earth.

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