Development of Surveying Instruments Flashcards
consists of a board attached to a tripod and can be leveled or rotated to any direction
PLANE TABLE
invented by Hipparchus in 140 BC and further improved by Ptolemy. used to determine the altitude of stars
ASTROLABE
invented by Lippershey (1607) Only used in surveying
after the cross hairs for fixing the line of sight were introduced
TELESCOPE
invented by Young and Draper (1830) the universal surveying instrument
TRANSIT
used to measure and lay off angles and establish lines of sight by employing peep sights
SEMICIRCUMFERENTOR
invented by Heron of Alexandria
* used in leveling and
measuring horizontal and
vertical angles
DIOPTRA
for aligning or sighting points
* consists of cross arms with
suspended plumb lines fixed at
right angles and pivoted upon a
vertical staff.
ROMAN GROMA
used by Assyrians and Egyptians
* had an A-frame with a plumb
line suspended from its apex
* used to determine the
horizontal
LIBELLA
invented by Pierre Vernier, a short auxiliary scale placed alongside the graduated
scale of an instrument to determine the fractional
parts of the main scale without interpolating.
VERNIER
developed by Greeks in 130 BC. used for leveling, laying off right angles, and measuring horizontal and vertical angles.
DIOPTER
For determining direction of lines and calculating angles between lines. consists of a magnetized steel needle which points at the magnetic north
COMPASS
invented by Sir Edmund Gunter
(1620) used for taping distances
GUNTER’S CHAIN
for leveling work. consists of a horizontal straight- edge about 6 m long, a groove 2.5 cm deep and 1.5 m long on top.
CHOROBATES
for measuring time and meridian. used by Chaldeans in 4000 BC. consists of a slotted palm leaf through which into sight and a bracket from which a plumb bob was suspended
MERCHET
