300s BC

Astronomy

Hellenic astronomers in Alexandria build an observatory that employs large tools for measuring small angles between stars. See also 1008 ce Astronomy.

Romans and Hellenic Greeks begin to add flower gardens to the inner courts of their Mediterranean-type houses. The concept of a garden was introduced by the Persians and had been unknown previously in Greece and Rome.

The Adena people build the Great Serpent Mound in the Ohio valley, a mound in the shape of a serpent holding an egg in its mouth. The mound, measured along the body of the serpent, is 328 m (1254 ft) long.

Parts of the Great Wall of China are built by various warlords during the Warring States Period. See also 214 bce Construction.

Pytheas [b. Greece, c. 330] sails into the Atlantic Ocean and observes much higher tides than in the Mediterranean Sea. He reports that tides are controlled by the Moon. See also 1687 ce Earth science.

Dicaerchus of Messina (Sicily) [b. c. 355 bce], a student of Aristotle's, develops a map of Earth that is on a sphere. It has lines of latitude based correctly on the lines where the noonday Sun is at a given angle on a particular day. See also 380 bce Communication; 116 ce Communication.

The turkey is domesticated in Mexico.

The Chinese Book of the Devil Valley Master contains the first known reference to a lodestone's alignment with Earth's magnetic field. The lodestone is called a "south-pointer" although it was evidently used for divination, not for finding south. See also 1050 bce Transportation; 83 ce Tools.

The Chinese invent cast iron. See also 200 bce Materials. (See essay.)

Mohist writings in China describe the first known use of poison gas in warfare. The Mohists were followers of Mo-Tzu, a fifth-century bce Chinese philosopher.

The Museum is built in Alexandria, a home for scholars and artists of all types, but essentially the center of Hellenistic mathematics.

Euclid writes his Elements, 13 books that prove all that was known of geometry and numbers in his time, deducing the entire body from a small set of axioms and five postulates. Modern writers have criticized some of the axiomatic bases of the Elements, but the conclusions are still accepted as a consistent approach to geometry. See also 430 bce Mathematics.

In Central America the Maya develop a place-value system based on 20, with separate symbols for ones and fives. The Maya may be the first to introduce a symbol for zero. See also 500 bce Construction.

In China numerals are used for a place-value system based on ten. The Chou suan ching, among the oldest mathematics classics from China, is written. See also 540 bce Mathematics.

Before this time, the Chinese develop the first magic squares. These are arrays of numbers chosen so that the sum of the rows, columns, and diagonals are all the same number. The first, known as the lo shu and said to have been observed on a turtle's shell, is the following array (which adds to the "magic" number 15):

      4     9     2

      3     5     7

      8     1     6

See also 880 ce Mathematics.

Herophilus [b. Chalcedon (Istanbul), c. 335 bce, d. c. 280 bce] dissects the human body. He is believed to be the first to do so publicly. He claims the brain is the center of the nervous system. See also 500 bce Biology.

Epicurus argues that organs develop through exercise and weaken when not used.

Aineias the Tactician describes the portcullis, a gate overlaid with iron (later entirely of iron) that can be lowered at the entrance to a fortress to prevent attackers from gaining entrance.

A type of sundial known today as the hemicycle of Berosus is invented. It is a bowl with lines on its inner surface to mark the daylight hours when the shadow of a horizontal projection (gnomon) falls on them. For correct solar time, the hemicycle must be level and face due south. See also 700 bce Tools.

The screw is invented for fastening and other uses but is little used since all screws must be made by hand at this time. See also 60 ce Tools.

Convex lenses are introduced in Carthage (Tunisia). See also 3000 bce Tools; 1020 ce Physics.

The Chinese invent a form of harness that is pushed by a horse's chest instead of a horse's throat, a great improvement that was not to be adopted in the West until the eighth century ce. See also 4000 bce Transportation.

400s BC · 300s BC · 200s BC
Decades of the 300s BC:
390s BC · 380s BC · 370s BC · 360s BC · 350s BC · 340s BC · 330s BC · 320s BC · 310s BC · 309–300 BC

300s BC may refer to:

• The period from 399 BC to 300 BC, almost synonymous with the 4th century BC
• 309–300 BC, rarely

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