LESSON 5: MEASUREMENTS OF ANGLES & DIRECTION

Question 1

_____ lies in a vertical plane passing through a fixed point of reference and through the observer’s position.

Answer 1

MERIDIANS

Question 2

Known as the astronomic or geographic meridian. This line passes through the geographic north and south poles of the earth and the observer’s position.

Answer 2

TRUE MERIDIAN

Question 3

Fixed line of reference which lies parallel with the magnetic lines of force of the earth.

Answer 3

MAGNETIC MERIDIAN

Question 4

Fixed line of reference parallel to the central meridian of a system. It is assumed that all meridians are parallel straight lines.

Answer 4

GRID MERIDIAN

Question 5

Arbitrary chosen fixed line of reference which is taken for convenience.

Answer 5

ASSUMED MERIDIAN

Question 6

Unit of angular measurement which uses the sexagesimal system.

Answer 6

DEGREE

Question 7

Unit of angular measurement which uses the centesimal system.

Answer 7

GRAD

Question 8

Unit of angular measurement which is commonly used in military
operations.

Answer 8

MIL

Question 9

Unit of angular measurement which is referred to the natural unit of
angle.

Answer 9

RADIAN

Question 10

North point of the true meridian. It is portrayed in the direction of the actual location of Earth’s north geographic pole.

Answer 10

TRUE NORTH

Question 11

The point is established by means of a magnetized compass needle when there are no local attractions affecting it.

Answer 11

MAGNETIC NORTH

Question 12

The point which is established by lines on a map which are parallel to a selected central meridian.

Answer 12

GRID NORTH

Question 13

The point is used to portray the location of any arbitrarily chosen north point.

Answer 13

ASSUMED NORTH

Question 14

Angles between adjacent lines in a closed polygon.

Answer 14

INTERIOR ANGLES

Question 15

Angles between a line and the prolongation of the preceding line.

Answer 15

DEFLECTION ANGLES

Question 16

Angles measured clockwise from the preceding line to the succeeding line.

Answer 16

Angles to the right

Question 17

The acute horizontal angles between the reference meridian and the line. A quadrant system is used to specify where a line may fall under to.

Answer 17

BEARINGS

Question 18

Any line on the surface of the earth may be defined by two directions which differ from each other by exactly 𝟏𝟖𝟎°.

Answer 18

Forward and Backward Bearings

Question 19

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.

Answer 19

AZIMUTHS

Question 19

The _______ of the instrument has a horizontal circle that is graduated from 0 to 90 degrees in each quadrant.

Answer 19

COMPASS BOX

Question 20

The _______ usually is fixed along the index mark on the north graduation of the circle

Answer 20

LINE OF SIGHT

Question 21

The ______ is of magnetized tempered steel balanced at its center on a jeweled pivot so that it swings freely in a horizontal position.

Answer 21

MAGNETIC NEEDLE

Question 22

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

Answer 22

Magnetic Declination

Question 23

This variation is usually neglected when observing magnetic directions.

Answer 23

Daily Variation/Diurnal Variation

Question 24

Also known as yearly variation It usually amounts to only less than 1 minute of arc and thus considered negligible.

Answer 24

Annual Variation/Annular Variation

Question 25

A slow, gradual, but unexplainable shift in the position of the earth’s magnetic meridian over a regular cycle

Answer 25

Secular Variation

Question 26

Uncertain in character and cannot be predicted as to amount or occurrence. At high altitudes, they usually amount to a degree or more.

Answer 26

Irregular Variation

Question 27

________ are most likely to occur during magnetic storms and disturbances associated with sunspots, and when auroral displays occur.

Answer 27

Irregular variations

Question 28

A chart or a map which shows lines connecting points where the magnetic declination of the compass needle is the same at a given time

Answer 28

ISOGONIC CHART

Question 29

Lines connecting point of zero magnetic declination.

Answer 29

AGONIC LINES

Question 30

Any deviation of the magnetic needle of a compass from its normalpointing towards magnetic north.

Answer 30

LOCAL ATTRACTION

Question 31

A characteristic phenomenon of the compass needle to be attracted downward from the horizontal plane due to the vertical component of the earth’s magnetic field

Answer 31

MAGNETIC DIP

Question 32

Type of compass that is designed for military use. It has a magnetic needle whose north point is luminous. Other points and markings on the crystal are also luminous for reading in darkness

Answer 32

LENSATIC COMPASS

Question 33

Type of compass that is Used earlier for running limited plane surveys of reasonable accuracy. It is now used for forest surveys in retracing old land surveys.

Answer 33

SURVEYOR’S COMPASS

Question 34

Type of compass that is like a surveyor’s compass, but it has no sight vanes. The line of sight is set up by a combination of a peep sight and a slotted vane.

Answer 34

PLAIN POCKET COMPASS

Question 35

Type of compass that has graduations on a rotating card and moves with the needle. Two short sighting devices are provided, and magnetic bearings are read by means of a prism at the same instant that the compass is sighted along the line.

Answer 35

PRISMATIC COMPASS

Question 36

Type of compass that is made of aluminum or some metal which does not affect the magnetic needle. It is best suited for forestry surveys as well as for geological and other exploratory surveys.

Answer 36

FORESTER’S COMPASS