elem surv finals

Meridian

a fixed reference line or direction which lies in a vertical plane passing through a fixed point of reference and through the observer's position

true meridian

known as the astronomic or geographic meridian

true meridian

it is the generally adapted reference line and surveying practice which passes through the geographic north and south poles of the earth and the observer's position

magnetic meridian

fixed line of reference which lines parallel with the

magnetic lines of force of the earth

magnetic meridian

this meridian has its direction defined by freely suspended magnetic needle of a compass held at the observer's position

grid meridian

fixed line of reference which lies parallel to the central meridian of a system of plane rectangular coordinates and is only applicable do plane surveys of limited extent

assumed meridian

arbitrarily chosen fixed line of reference which is taken for convenience

2000

the distance of the magnetic poles away from the actual location of the geographic poles of the earth

magnetic declination

horizontal angle and direction by which the needle of a compass deflects from the true meridian at any particular locality

local attraction

any deviation of the magnetic needle of a compass from its normal pointing towards the magnetic north

interior angles

angles between the adjacent lines in a closed polygon

deflection angles

angles between line and the prolongation of the preceding line

bearing

direction of a line, usually acute

forward bearing

when bearing offline is observed in the direction in which the survey progresses

back bearing

when bearing of the same line is observed in an opposite direction

azimuth

the ___ is its direction has given by the angle between the meridian and the line measured in a clockwise direction from either the north or south branch of the meridian

brunton compass

one of the most versatile and widely used aas it combines the features of a prismatic compass, sighting compass, hand level and clinometer

brunton compass

suitable and sufficiently accurate for preliminary and exploratory surveys, etc. requiring only low degrees of precision

lensatic compass

consists of an aluminum case containing a magnetic dial balanced on a pivot a hinge cover with a sighting wire hinged eyepiece and sighting slot

lensatic compass

design for military use such as in reconnoitering, determining directions and other uses where magnetic azimuths are required

Surveyor's Compass

has a compass box containing a graduated circle, 2 sight vanes, a magnetic needle and two clamping screws

surveyor’s compass

popularly used earlier for running limited plane surveys of reasonable accuracy but is now commonly used for forest surveys

plain pocket compass

similar to the surveyors compass except it has no sight vanes

plain pocket compass

small hand instrument used for obtaining roughly the bearing of a line used in reconnaissance and exploratory surveys

prismatic compass

widely used by sailors for navigation at sea

forester’s compass

another type of pocket compass usually made of aluminum or any material which does not affect the free movement and positioning of the magnetic needle

forester’s compass

widely used in forestry surveys as well as for geological and other similar exploratory surveys

transit compass

similar to the surveyors compass only it is mounted on the upper plate of the transit

transit compass

used to check horizontal angles and directions measured or laid off and is also used for orienting the transit with a magnetic meridian