A Manual for Practical Surveyors: Containing Methods Indispensably Necessary for Actual Field Operations |
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Page 14
... course may then be taken in any direc- tion with the needle , as correctly as if free from the effects of local attraction . The following description of an instrument for surveying was received 14 A MANUAL FOR SURVEYORS .
... course may then be taken in any direc- tion with the needle , as correctly as if free from the effects of local attraction . The following description of an instrument for surveying was received 14 A MANUAL FOR SURVEYORS .
Page 19
... correctly . The circular plates are not graduated at their outer edges , but so as to be read within and at the bottom of the compass - box . To the upper plate is attached the wyes , or vees , which support the axis of the telescope ...
... correctly . The circular plates are not graduated at their outer edges , but so as to be read within and at the bottom of the compass - box . To the upper plate is attached the wyes , or vees , which support the axis of the telescope ...
Page 62
... correctly , as the sum of the nat . tangs . of the angles C D E and C D F , is to the nat . tang . of either of them , so is E F the sum of the seg ments EC and C F , to the segment corresponding to the angle used in the second term of ...
... correctly , as the sum of the nat . tangs . of the angles C D E and C D F , is to the nat . tang . of either of them , so is E F the sum of the seg ments EC and C F , to the segment corresponding to the angle used in the second term of ...
Page 80
... correctly as if the needle set- tled in its true position , for the needle must be equally affected when the bearings were noted . Remove to B , and take a back sight to A , noting its bearing , then direct the sights to C , and note ...
... correctly as if the needle set- tled in its true position , for the needle must be equally affected when the bearings were noted . Remove to B , and take a back sight to A , noting its bearing , then direct the sights to C , and note ...
Page 82
... correctly taken , be equal to four right angles , or 360 ° . If any of the angles are re - entering , the sum of the external diminished by the sum of the re - entering angles , will be equal to 360 ° . If the telescope be reversed ...
... correctly taken , be equal to four right angles , or 360 ° . If any of the angles are re - entering , the sum of the external diminished by the sum of the re - entering angles , will be equal to 360 ° . If the telescope be reversed ...
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Common terms and phrases
40 perches A E produced angles of deflection angular point back sight bearing of A B bring the sights bring the telescope centre pin circumferenter clamp the lower closing line correction course degrees difference of variation distance A C equal F B G feet Given A B internal angles kerfs last station let the needle line A B line C D line joining lines of survey lower plate magnetic magnetic bearings marked tree n¹ m¹ n³ m³ nier nonius compass nonius plate parallel perpendicular distance Place the instrument present bearing PROPOSITION quired random line right angles right line run a line run the line Set the instrument set the vernier sights to bear subtracted surveyor tance tang telescope to bear tion trapezoid traverse table tripod true bearing true line unclamp vernier to zero
Popular passages
Page 80 - All the interior angles of any rectilineal figure, together with four right angles, are equal to twice as many right angles as the figure has sides.
Page 17 - ... more than half through its thickness, and intersecting each other at right angles at the centre of the block...
Page 58 - A line which is to be established from the course only, should be re-run at nearly the same season...
Page 58 - It must, therefore, be a matter of uncertainty 'whether we have the correct bearing of the line, even when the change for years has been ascertained with the utmost care.
Page 57 - The variation of the magnetic needle in declination, is subject to much irregularity, in some instances increasing, in other decreasing, and some years having scarcely a perceptible motion.