Elements of Surveying: With the Necessary TablesJ. & J. Harper, 1830 - 306 páginas |
Dentro del libro
Resultados 1-5 de 43
Página 5
... 37 CHAPTER II . Of the Measurement and Calculation of Lines and Angles , To measure a Horizontal Line , Of the Theodolite , Problems , 39 40 40 52 CHAPTER III . CHAPTER IV . Page 69 69 Of the Instruments used Of the Content of Ground , 61.
... 37 CHAPTER II . Of the Measurement and Calculation of Lines and Angles , To measure a Horizontal Line , Of the Theodolite , Problems , 39 40 40 52 CHAPTER III . CHAPTER IV . Page 69 69 Of the Instruments used Of the Content of Ground , 61.
Página 6
... . Of Levelling , Of the Level , Of the Levelling Staves , 121 123 127 CHAPTER VIII . Of the Contour and Accidents of Ground , 134 CHAPTER IX . ELEMENTS OF SURVEYING . 1 1 1 1 INTRODUCTION , Of Surveying Harbours , 144 COYTENTE ,
... . Of Levelling , Of the Level , Of the Levelling Staves , 121 123 127 CHAPTER VIII . Of the Contour and Accidents of Ground , 134 CHAPTER IX . ELEMENTS OF SURVEYING . 1 1 1 1 INTRODUCTION , Of Surveying Harbours , 144 COYTENTE ,
Página 39
... ground , and also to measure as many angles as are required to render at least three parts of every triangle known ; and then , by the aid of trigonometry , the other sides and angles may be calculated . 80. Our attention , then , is ...
... ground , and also to measure as many angles as are required to render at least three parts of every triangle known ; and then , by the aid of trigonometry , the other sides and angles may be calculated . 80. Our attention , then , is ...
Página 40
... ground be too great to admit of measuring a whole chain at a time , a part of a chain only must be measured : the sum of all the horizontal lines so measured , is evidently the horizontal distance between the stations . 83. We come now ...
... ground be too great to admit of measuring a whole chain at a time , a part of a chain only must be measured : the sum of all the horizontal lines so measured , is evidently the horizontal distance between the stations . 83. We come now ...
Página 47
... ground : reverse the telescope , and turn the vernier plate 180 ° : now , if in elevating and depressing the telescope , the line of collimation passes through the two points before noted , the axis is horizontal . If it be found , by ...
... ground : reverse the telescope , and turn the vernier plate 180 ° : now , if in elevating and depressing the telescope , the line of collimation passes through the two points before noted , the axis is horizontal . If it be found , by ...
Otras ediciones - Ver todas
Pasajes populares
Página 57 - 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 15 - FRACTION is a negative number, and is one more than the number of ciphers between the decimal point and the first significant Jigure.
Página 15 - The characteristic of a number less than 1 is found by subtracting from 9 the number of ciphers between the decimal point and the first significant digit, and writing — 10 after the result.
Página 102 - The line so determined makes, with the true meridian, an angle equal to the azimuth of the pole star; and from this line the variation of the needle is readily determined, even without tracing the true meridian on the ground. Place the compass upon this line, turn the sights in the direction of It, and note the angle shown by the needle. Now, if the elongation at the time of observation...
Página 21 - The circumference of every circle is supposed to be divided into 360 equal parts called degrees, each degree into 60 equal parts called minutes, each minute into 60 equal parts called seconds.
Página 97 - But the star being at a distance from the pole equal to 1° 30' nearly. It performs a revolution about the pole in a circle, the polar distance of which is 1° 30': the time of revolution is 23 h. and 56 min. To the eye of an observer this star is continually in motion, and is due north but twice in 23 h. 56 min.; and is then said to be on the meridian. Now, when It departs from the meridian it apparently moves east or west for 5 h.
Página 100 - ... three inches square, be nailed to the lower edge of it, for the purpose of holding a candle. About twenty-five minutes before the time of the greatest eastern or western elongation of the pole-star, as shown by the tables of elongations, let the theodolite be placed at a convenient point and leveled. Let the board be placed about one foot in front of the theodolite, a lamp or candle placed on the shelf at its lower edge; and let the board be slipped up or down, until the pole-star can be seen...
Página 2 - An Act for the Encouragement of Learning, by securing the copies of Maps, Charts, and Books, to the authors and proprietors of such copies during the time* therein mentioned," and extending the benefits thereof to the arts of designing, engraving, and etching historical and other prints.
Página 100 - Let the board be placed about one foot in front of the theodolite, a lamp or candle placed on the shelf at its lower edge ; and let the board be slipped up or down, until the pole-star can be seen through the hole. The light reflected from the paper will show the cross hairs in the telescope of the theodolite. Then, let the vertical spider's line be brought exactly upon the pole-star, and, if it is an eastern elongation that is to be observed, and the star has not yet reached the most easterly point,...
Página 100 - ... to coincide with the vertical hair. Then mark the point directly under the theodolite; the line passing through this point and the staff makes an angle with the true meridian equal to the azimuth of the pole-star. From the table of azimuths, take the azimuth corresponding to the year and nearest latitude. If the observed elongation was east, the true meridian lies on the west of the line which has been found, and makes with it an angle equal to the azimuth. If the elongation was west, the true...