The Antikythera calculating mechanism
It is the first calculating machine in history.
It was used to determine and forecast important astronomical and calendar
events. Its remains were found accidentally by sponge divers in 1900 in the
eminent shipwreck off the island of Antikythera. Its manufacture dates from
around 120 B.C. and it is probably the product of a Rhodian laboratory, which
developed the tradition of Archimedes' "Sphere-Making", with its
direct inspirators being Hipparchus or Posidonius. It consisted of indicators,
scales and at least thirty-five cooperating gear wheels that were moved by a
handle. At the front it had a circular scale of the 365 days with the
possibility of adding one additional day every four years. At the back it had
the spiral scales of the Metonic and Saros cycles and also the Callippic cycle,
the "Exeligmos" cycle and the Athletic Games cycle. With the rotation
of the handle, and consequently the choice of a date on the front scale of 365
days the remainder indicators give us all available astronomical information on
this (e.g. position and phase of the moon, matching solar-lunar calendar,
etc.). Reversely, if the operator of the mechanism brings the indicator to some
particular astronomical or calendar events, (e.g. an eclipse of the moon or a
performance of the Olympic Games) he can see the date that this will happen in
the future or happened in the past. Solla De Price and Michael Wright were the
most important researchers of this mechanism. This reconstruction reflects the
constructional opinion of the exhibitor that was based on the new data from the
International Study Team of the Antikythera Mechanism.
SOURCES: "The Antikythera Mechanism
Research Project"
The astrolabe of Ptolemy
It was an exceptional astronomical instrument
which depicted the celestial sphere and was used for the measurement of
geographic length (longitude) and width (latitude) of the observed stars from
any part of the Earth but also reversely as locator of place (GPS) and also for
the measurement of the Sun – Moon distance.
It consisted of seven concentric interlocking
rings. The 7th ring (exterior) was fixed in the level of the meridian and it
had four marks that defined the horizontal and vertical. The 6th was graduated
and it turned freely in the level of the meridian with points 0ο and 90ο to
represent the equator and the pole respectively and it was placed in the
direction of the earth axis.
The 5th was turned in the direction of the Sun.
The 4th was articulated in the earth axis and observed the daily rotation of
the astral sphere. The 3rd was graduated and was articulated to the precedent
at a distance of approximately 66ο from the poles. It was placed in the
ecliptic zodiac; it had the names of the star signs (zodiacs) and was used for
the reading of geographic lengths of stars.
The 2nd was graduated, turned round a vertical
axis in the level of the ecliptic and was used for the reading of geographic
width of stars. Finally, the 1st ring (internal) had the aiming device.
SOURCES: "Ptolemy, Mathematical
Syntaxis", "Pappus of Alexandria, Annotation in the Books 5 and 6 of
the Mathematical Syntaxis".
The dioptra of Heron
It was an amazing surveying instrument which
was suitable for the precise measurement of horizontal, vertical and angular
distances between two celestial or terrestrial points. With repetitive use of
the instrument it was possible "in geography to chart islands and seas, in
astronomy to calculate the distances of stars and forecast eclipses, in
building to execute complicated structural work...".
It consisted of a stand which had a horizontal
toothed base that could be rotated with the help of an endless screw. A precise
system of aiming (theodolite) could be placed on the base which consisted of a
vertical calibrated semicircular disc that could be turned in precision with
the help of an endless screw and of horizontal calibrated disc. This disc was
placed at the edge of the semicircular disc and had a crisscross turning aiming
device. The operator of the instrument could aim any point in space and mark
his angle position.
Alternatively, a dumpy level system could be
placed on the base which consisted of two vertical glass connected pipes with
water that were used for the determination of horizontal level. It also
consisted of a regulated with precision aiming device.
The system had as requisite two calibrated
rules that each one had a device for its vertical position and a sliding black
- white disc that played the role of the target. The operator of the instrument
could aim two random points at which the two calibrated rules were placed and
calculate their hypsometric difference.
In the solving of topographic problems, with
the use of the dioptra, Heron applies the alignments, the multiple verticality
and the proportions of the sides of similar triangles. It is however certain
that at least in the calculation of astronomical sizes the protractors of the
dioptra were used precisely as in the astrolabes.
SOURCES: "Heron of Alexandria, On
Dioptra".
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