Bulletin - United States Geological Survey, Issue 651 (Google eBook)

Front Cover
The Survey., 1917 - Geology
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Page 4 - The bottom is spread out to a width of 10 inches . in order to give a firm bearing on the earth. A bronze or aluminum bronze cap is riveted upon the top of the post.
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, at Washington, DC, for the...
Page 4 - II), 3f 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. The second form (F, PI.
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 is assumed that there is no difference...
Page 7 - Atlantic Ocean, the Gulf of Mexico, and the Pacific Ocean. The connection with tidal stations for bench marks in certain areas that lie at some distance from the seacoast 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 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 t%-inch steel dies on the tablets or post caps, to the left of the word
Page 7 - 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 286 - NORTHEAST BY TOLEDO, ST. Louis AND WESTERN RAILROAD, TO BROCTON. MATTOON QUADRANGLE. Lerna, 2 miles northeast of, 60 feet east of milepost "St. L. 125-T 326," 10 feet south of rail rack, in south end of terra cotta drain pipe; chiseled hole 721.39 Lerna, 3.01 miles northeast of, 40 feet north of track, 20 feet east of road; iron post stamped "708 1906" 708.589 Lerna, 3.99 miles northeast of, 250 feet northeast of milepost "St.
Page 7 - ... 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 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 great accuracy is desired they must extend over several years.
Page 91 - 684. 385 Londonderry, 2.7 miles northeast of, at northeast corner of road fork to north, in south face of foundation at southwest corner of Friends Church; aluminum tablet stamped "626 1906

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