cross-in-square was the dominant architectural form of middle Byzantine
churches. Marking a decided departure from the oblong ground plan of the
basilica, it has been described as "a type of church that was, in its own way, perfect". The earliest extant example being the
Theotokos church in
Constantinople (907/908), its development can be traced back with a fair degree of certainty at least to the
Nea Ekklesia, consecrated in 880/881.
Pendentive dome: Generally speaking, a
pendentive is a construction solution which allows a circular
dome to be built atop a rectangular floor plan. While preliminary forms already evolved in
Roman dome construction, the first fully developed pendentive dome dates to the reconstruction of the
Hagia Sophia in 563. Devised by Isodorus the Younger, the nephew of the first architect
Isidore of Miletus, the in-circle design, with a maximum diameter of 31.24 m, remained unsurpassed until the
Florence Cathedral). The Hagia Sophia became the paradigmatic
Orthodox church form and its architectural style was emulated by
Turkish mosques a thousand years later.
Counterweight trebuchet: The earliest written record of the
counterweight trebuchet, a vastly more powerful design than the simple traction trebuchet, appears in the work of the 12th-century historian
Niketas Choniates. Niketas describes a stone projector used by future emperor
Andronikos I Komnenos at the siege of Zevgminon I 1165. This was equipped with a
windlass, an apparatus required neither for the traction nor hybrid trebuchet to launch missiles. Chevedden hypothesizes that the new artillery type was introduced at the
1097 Siege of Nicaea when emperor
Alexios I Komnenos, an ally of the besieging
crusaders, was reported to have invented new pieces of heavy artillery which deviated from the conventional design and made a deep impression on everyone.
hand-trebuchet (cheiromangana) was a
staff sling mounted on a pole using a
lever mechanism to propel projectiles. Basically a portable trebuchet which could be operated by a single man, it was advocated by emperor
Nikephoros II Phokas around 965 to disrupt enemy formations in the open field. It was also mentioned in the
Taktika of general
Nikephoros Ouranos (ca. 1000), and listed in the Anonymus De obsidione toleranda as a form of artillery.
Greek fire: The invention and military employment of
Greek fire played a crucial role in the defense of the empire against the
early onslaught of the Muslim Arabs. Brought to Constantinople by a refugee from Syria by the name of Kallinikos, the incendiary weapon came just in time to save the capital from the Muslim sieges of
717–718, which might have otherwise proven fatal to the Byzantine state.
Greek fire, referred to by Byzantine chroniclers as "sea fire" or "liquid fire", was primarily a naval weapon, used in ship-to-ship battle against enemy
galleys. The exact composition was a well-guarded state secret, to the point that modern scholars continue to debate its ingredients, but the main method of projection is fairly clear, indicating effectively a flame-thrower: The liquid mixture, heated in a
brazier and pressurized by means of a pump, was ejected by an operator through a
siphon in any direction against the enemy. Alternatively, it could be poured down from swivel
cranes or hurled in pottery grenades.
Greek fire held a fearsome reputation among Byzantium's numerous enemies who began to field – probably differently composed – combustibles of their own. It was, however, no wonder weapon, but dependent on favourable conditions such as a calm sea and wind coming from behind. When and how the use of Greek fire was discontinued is not exactly known. According to one theory, the Byzantines lost the secret due to over-compartmentalization long before the
1204 sack of Constantinople.
Grenades appeared not long after the reign of
Leo III (717–741), when Byzantine soldiers learned that Greek fire could not only be projected by flamethrowers, but also be thrown in stone and ceramic jars. Larger containers were hurled by
catapults or trebuchets at the enemy, either ignited before release or set alight by fire arrows after impact. Grenades were later adopted for use by
Muslim armies: Vessels of the characteristic spheroconical shape which many authors identify as grenade shells were found over much of the Islamic world, and a possible workshop for grenade production from the 13th century was excavated at the Syrian city of
Flamethrower: for ship-borne
flamethrowers, see Greek fire above. Portable hand-siphons were used in land warfare.
Fork: the fork was originally used as a utensil for picking up and eating food in the 7th century by the nobles of the Byzantine empire. It was later introduced to western Europe through the marriage of
Maria Argyropoulina to
Giovanni Orseolo. The story goes that during her wedding feast she used her personal two pronged golden fork to eat some food. The Venetians, having not known of the fork and eating with their hands, considered using the fork blasphemous, "God in his wisdom has provided man with natural forks—his fingers. Therefore it is an insult to him to substitute artificial metal forks for them when eating.” claimed one member of the clergy. She died of a disease a few years later which the Venetians claimed was the result of her disrespecting God with her fork. 
Corpus Juris Civilis: Under the reign of
Justinian the Great he initiated reforms that had a clear effect on the evolution of jurisprudence as his Corpus Juris Civilis became the foundation of the jurisprudence in the Western world.
Icons are images of holy beings such as
Mary and the
saints which, painted according to certain traditional rules, have been playing a pivotal role in
Eastern Orthodox Church veneration since its early days. The most distinctive Byzantine form are representations on portable wooden panels painted in the
Hellenistic techniques of
encaustic. Other varieties include (precious) metal
mosaic-style panels set with
tesserae of precious stones, gold, silver and
ivory. The use of icons was violently opposed during the
iconoclastic controversy which dominated much of Byzantium's internal politics in the 8th and 9th centuries, but was finally resumed by the victorious
iconodules. Only few early icons have survived the iconoclasm, the most prominent examples being the 6th–7th century collection from
Saint Catherine's Monastery.
Ship mill: The historian
Procopius records that
ship mills were introduced by
Belisarius during the
siege of Rome (537/538), initially as a makeshift solution. After the
Ostrogoths had interrupted the water-supply of the
aqueducts on which the city was dependant to run its
gristmills, Belisarius ordered riverboats to be fitted with mill gearing; these were moored between bridge piers where the strong current powered the
water wheels mounted on the vessel. The innovative use quickly found acceptance among
medieval watermillers, reaching
Paris and the
Frankish Realm only two decades later.
theory of impetus: The theory was introduced by John Philoponus, and it is the precursor to the concepts of inertia, momentum and acceleration.
Hospital: The concept of hospital as institution to offer medical care and possibility of a cure for the patients due to the ideals of
Christian charity, rather than just merely a place to die, appeared in Byzantine Empire.
conjoined twins: The first known example of separating conjoined twins happened in the Byzantine Empire in the 10th century. A pair of conjoined twins lived in Constantinople for many years when one of them died, so the surgeons in Constantinople decided to remove the body of the dead one. The result was partly successful as the surviving twin lived three days before dying. The fact that the second person survived for few days after separating him was still being mentioned a century and a half later by historians. The next recorded case of separating conjoined twins was 1689 in Germany.
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