Elements of Surveying and Leveling

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A. S. Barnes & Company, 1883 - 564 páginas
 

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Página 22 - The location must be distinctly marked on the ground so that its boundaries can be readily traced. All records of mining claims hereafter made shall contain the name or names of the locators, the date of the location, and such a description of the claim or claims located by reference to some natural object or permanent monument as will identify the claim. On each claim located after the tenth day of May, eighteen hundred and seventy-two, and until a patent has been issued therefor, not less than...
Página 18 - The circumference of every circle is supposed to be divided into 360 equal parts called degrees, and each degree into 60 equal parts called minutes, and each minute into 60 equal parts called seconds, and these into thirds, fourths, &c.
Página 181 - Being on a horizontal plane, and wanting to ascertain the height of a tower, standing on the top of an inaccessible hill, there were measured, the angle of elevation of the top of the hill 40°, and of the top of the tower 51° ; then measuring in a direct line 180 feet farther from the hill, the angle of elevation of the top of the tower Cway 33° 45' ; required the height of the tower.
Página 5 - Turn the instrument on its spindle so as to bring the solar lens to be adjusted in the direction of the sun, and raise or lower the adjuster on the declination arc, until it can be clamped in such a position as to bring the sun's image as near as may be between the equatorial lines on the opposite silver plate, and bring the image precisely into position by the tangent of the latitude arc or the leveling-screws of the tripod.
Página 7 - The declination of the sun, given in the Ephemeris of the Nautical Almanac, from year to year, is calculated for apparent noon at Greenwich, England. To determine it for any other hour at a place in the...
Página 8 - Allowance being made for refraction, the line of sights will indicate the true meridian ; the observation may now be made, and the flag-man put in position. When a due east and west line is to be run, the verniers of the horizontal limb are set at 90°, and the sun's image kept between the lines as before. The Solar Compass being so constructed that when the sun's image is in position the limb must be clamped at...
Página 9 - Caution as to the False Image. In using the compass upon the sun, if the revolving arm be turned a little one side of its proper position, a false or reflected image of the sun will appear on the silver plate in nearly the same place as that occupied by the true one. It is caused by the reflection of the true image from the surface of the arm, and is a fruitful source of error to the inexperienced surveyor. It can, however, be readily distinguished from the real image by being much less bright, and...
Página 25 - C' (89) (90) (91) (92) (93) 112. In any plane triangle, the sum of any two sides is to their difference as the tangent of half the sum of the opposite angles is to the tangent of half their difference.
Página 9 - THE logarithm of a number is the exponent of the power to which it is necessary to raise a fixed number to produce the given number...
Página 12 - ... after noon is so nearly that of the meridian that it may be called and allowed as the same. When the table is used, it must be borne in mind that when the declination is north, or + in the table, the refraction is to be added ; when the declination is south, or — , the refraction must be subtracted. It will be noticed that...

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