SURVEYING INSTRUMENT Flashcards
(18 cards)
one of the best known of the measuring instruments
Astrolabe
invented by Hipparchus around 140BC and further improved by Ptolemy
Astrolabe
invented by Lippershey in 1607
Telescope
what kind of telescope did Galileo construct in 1609?
Refracting telescope
invented by Young and Draper in 1830
Transit
early surveying instruments used to measure and lay off angles and establish lines of sight by employing peep sights
Semicircumferentor
a board attached to a tripod which can be leveled or rotated to any desired direction
plane table
who perfected the dioptra?
Heron of Alexandria
leveled and measured horizontal and vertical angles. A copper tube supported on a standard that rotated in either a horizontal or vertical plane
dioptra
aligns and sights points. it has cross arms fixed at right angles and pivoted eccentrically upon a vertical staff
roman groma
short auxiliary scale placed alongside the graduated scale of an instrument. fractional parts of the smallest or least division of the main scale can be determined precisely without interpolation
Vernier
developed by the Greeks around 130BC. used for leveling, laying off right angles, and measuring horizontal and vertical angles
diopter
magnetic compass to determine the direction of lines and calculating angles between lines
compass
when was the compass widely used?
13th Century
invented by Sir Edmund Gunter in 1620 and used for taping distances. It is 66ft long and contains 100 links.
Gunter’s chain
how long was each link of the Gunter’s chain?
0.66ft long
designed for leveling work. It has a horizontal straight-edge 6m long with supporting legs, and a groove 2.5cm deep and 1.5m long on top
chorobates
measured time and meridian. first used by chaldeans about 4,000BC. a slotted palm leaf through which to sight and a bracket from which a plumb bob was suspended
merchet
