Dionysodorus
Encyclopedia
Dionysodorus of Caunus was an ancient Greek
mathematician
.
writes that Dionysodorus was from Caunus, not to be confused with another Dionysodorus from Pontus
who was mentioned by Strabo
.
Dionysodorus is remembered for solving the cubic equation by means of the intersection of a rectangular hyperbola
and a parabola
. Eutocius credits Dionysodorus with the method of cutting a sphere into a given ratio, as described by him. Heron
mentions a work by Dionysauras entitled On the Tore, in which the volume of a torus
is calculated and found to be equal to the area of the generating circle multiplied by the circumference of the circle created by tracing the center of the generating circle as it rotates about the torus's axis of revolution. Dionysodorus used Archimedes
' methods to prove this result.
It is also likely that this Dionysodorus invented the conical sundial
. Pliny says that he had an inscription placed on his tomb, addressed to the world above, stating that he had been to the centre of the earth and found it 42 thousand stadia
distant. Pliny calls this a striking instance of Greek vanity; but this figure compares well with the modern measurement.
Greeks
The Greeks, also known as the Hellenes , are a nation and ethnic group native to Greece, Cyprus and neighboring regions. They also form a significant diaspora, with Greek communities established around the world....
mathematician
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....
.
Life and work
Little is known about the life of Dionysodorus. Pliny the ElderPliny the Elder
Gaius Plinius Secundus , better known as Pliny the Elder, was a Roman author, naturalist, and natural philosopher, as well as naval and army commander of the early Roman Empire, and personal friend of the emperor Vespasian...
writes that Dionysodorus was from Caunus, not to be confused with another Dionysodorus from Pontus
Pontus
Pontus or Pontos is a historical Greek designation for a region on the southern coast of the Black Sea, located in modern-day northeastern Turkey. The name was applied to the coastal region in antiquity by the Greeks who colonized the area, and derived from the Greek name of the Black Sea: Πόντος...
who was mentioned by Strabo
Strabo
Strabo, also written Strabon was a Greek historian, geographer and philosopher.-Life:Strabo was born to an affluent family from Amaseia in Pontus , a city which he said was situated the approximate equivalent of 75 km from the Black Sea...
.
Dionysodorus is remembered for solving the cubic equation by means of the intersection of a rectangular hyperbola
Hyperbola
In mathematics a hyperbola is a curve, specifically a smooth curve that lies in a plane, which can be defined either by its geometric properties or by the kinds of equations for which it is the solution set. A hyperbola has two pieces, called connected components or branches, which are mirror...
and a parabola
Parabola
In mathematics, the parabola is a conic section, the intersection of a right circular conical surface and a plane parallel to a generating straight line of that surface...
. Eutocius credits Dionysodorus with the method of cutting a sphere into a given ratio, as described by him. Heron
Heron
The herons are long-legged freshwater and coastal birds in the family Ardeidae. There are 64 recognised species in this family. Some are called "egrets" or "bitterns" instead of "heron"....
mentions a work by Dionysauras entitled On the Tore, in which the volume of a torus
Torus
In geometry, a torus is a surface of revolution generated by revolving a circle in three dimensional space about an axis coplanar with the circle...
is calculated and found to be equal to the area of the generating circle multiplied by the circumference of the circle created by tracing the center of the generating circle as it rotates about the torus's axis of revolution. Dionysodorus used Archimedes
Archimedes
Archimedes of Syracuse was a Greek mathematician, physicist, engineer, inventor, and astronomer. Although few details of his life are known, he is regarded as one of the leading scientists in classical antiquity. Among his advances in physics are the foundations of hydrostatics, statics and an...
' methods to prove this result.
It is also likely that this Dionysodorus invented the conical sundial
Sundial
A sundial is a device that measures time by the position of the Sun. In common designs such as the horizontal sundial, the sun casts a shadow from its style onto a surface marked with lines indicating the hours of the day. The style is the time-telling edge of the gnomon, often a thin rod or a...
. Pliny says that he had an inscription placed on his tomb, addressed to the world above, stating that he had been to the centre of the earth and found it 42 thousand stadia
Stadion (unit of length)
The stadion, Latinized as stadium and anglicized as stade, is an ancient Greek unit of length. According to Herodotus, one stade is equal to 600 feet. However, there were several different lengths of “feet”, depending on the country of origin....
distant. Pliny calls this a striking instance of Greek vanity; but this figure compares well with the modern measurement.