Byzantine Empire - 1350 and later in 1403

1. Undershot water wheel; 2. Overshot Water Wheel, 3. Water Mill Gears, 4. Water Gear Shaft.

1. Undershot water wheel; 2. Overshot Water Wheel, 3. Water Mill Gears, 4. Water Gear Shaft. Some early ideas leading to the thought of using water power to accelerate production over human labor animal labor.

1. Swing Beam Pump; 2.Double Bucket Wheel Pump; 3. Drum Pump; 4. Persian Wheel Pump.

1. Swing Beam Pump; 2.Double Bucket Wheel Pump; 3. Drum Pump; 4. Persian Wheel Pump.

These are four more pump types used in the Roman world. All these designs led to even more and better advancement in the modern day.

Tower and Gate of St. Paul, Island of Rhodes

The fortifications of the town of Rhodes are shaped like a defensive crescent around the medieval town and consist mostly in a modern fortification composed of a huge wall made of an embankment encased in stone, equipped with scarp, bastions, moat, counterscarp, and glacis. The portion of fortifications facing the harbor is instead composed of a crenelated wall. On the mole's towers and defensive forts are found.  The 'Tower and Gate of St. Paul' with the 'Post of France' is shown at the bottom of the drawing. The 'Gate of St. Paul 'gave access to the 'Mandraki Harbor.'

Dioptra of Heron

Drawing of a "Diopta by Heron," by Marcus Audens.

A dioptra (sometimes also named dioptre or diopter from Greek: διόπτρα) is a classical astronomical and surveying instrument, dating from the 3rd century BCE. The dioptra was a sighting tube or, alternatively, a rod with a sight at both ends, attached to a stand. If fitted with protractors, it could be used to measure angles.

Greek astronomers used the dioptra to measure the positions of stars; both Euclid and Geminus refer to the dioptra in their astronomical works. By the time of Ptolemy (2nd century CE), it was obsolete as an astronomical instrument, having been replaced by the armillary sphere.

It continued in use as an effective surveying tool. Adapted to surveying, the dioptra is similar to the theodolite, or surveyor's transit, which dates to the sixteenth century. It is a more accurate version of the "groma."

The dioptra may have been sophisticated enough, for example, to construct a tunnel through two opposite points in a mountain. There is some speculation that it may have been used to build the Eupalinian aqueduct. Called "one of the greatest engineering achievements of ancient times," it is a tunnel 1,036 meters (4,000 ft) long, "excavated through Mount Kastro on the Greek island of Samos, in the 6th century BCE" during the reign ofPolycrates. Scholars disagree whether the dioptra was available that early.

An entire book about the construction and surveying usage of the dioptra is credited to Hero of Alexandria (also known as Heron; a brief description of the book is available online; see Lahanas link, below). Heron was "one of history’s most ingenious engineers and applied mathematicians."

The dioptra was used extensively on aqueduct building projects. The screw turns on several different parts of the instrument made it easy to calibrate for very precise measurements

The dioptra was replaced as a surveying instrument by the theodolite.

Roman Groma

Chorbates #2

Chorbates #2 - Marcus Audens

Liechtenstein Castle

Liechtenstein Castle.
The Castle Of Liechtenstein

Ancestral castle of the princes of Liechtenstein

Hugo of Liechtenstein built the castle between 1130 and 1135, which came to be in possession of the Stadeck family by 1295, by use of a marriage contract.

The castle often changed hands between different royal families like the Dukes of Cilli and King Matthias Corvinius which granted Jan (Hans) Holuberzi the upkeep. The houses of Khevenhiller and Aichelberg owned the castle since 1592 including Prince Johann Josef the 1st of Liechtenstein, who acquired the castle from Prince Poniantovsky and returned the ownership of the houses of Liechtenstein in 1807, which is still current.

Monument of Romanic architecture

Major parts of the Romanic castle, originating from the first building phase circa 1130/1135, are still surviving and able to be visited. With this Romanic settlement, the castle today counts as one of the rare Romanic surviving secular buildings of the 12th century in Europe.

From 1508 to 1588 the castle was occupied by the Tyrolian house of Freisleben. In 1529 the castle was initially destroyed by the Osmanians and was rebuilt from 1533 – this leads to the loss and sale of the ownership of the castle in 1567.

The castle and ownership came into the possession of the Duke of Khevenhiller between 1592 and 1664 during which the castle was extensively extended under the Duke Franz Christoph Khevenhiller, Baron of Aichelberg. In 1664 his family tree was drawn up in which the background consisted of a rendition of the castle of Liechtenstein.

Alas, the castle was once again largely destroyed by the Osmanians in 1683 which rendered the castle almost completely uninhabitable. The Gothic entrance was allotted to the use of stables, until being razed to the ground in 1809.

Chorbates (leveling Instrument)

The 'Chorobates,' described by Vitruvius in Book VII of the Architecture, was used to measure horizontal planes and was especially important in the construction of aqueducts. Similar to modern spirit levels, the 'Chorobates' consisted of a beam of wood 6 m in length held by 2 supporting legs and equipped with 2 plumb lines at each end. The legs were joined to the beam by two diagonal rods with carved notches. If the notches corresponding to the plumb lines matched on both sides, it showed that the beam was level. On top of the beam, a groove or channel was carved. If the condition was too windy for the plumb bobs to work effectively, the surveyor could pour water into the groove and measure the plane by checking the water level.  Vitruvius instructs that the water level groove was to be "five feet long, one digit wide, and a digit and a half deep". By using two or more 'Chorobates,' established levelly, the vertical distance between instruments could be established by sighting along the depth of the uphill instrument, to a rod placed atop the lower 'Chorobates.'

Libella, Leveling Tool

Roman architects were skilled in this kind of leveling work, for which they used sophisticated tools. Besides the ordinary level (Libella), similar to the one used today by carpenters, they used devices such as a groma, chorobates, and dioptra.

Given the elementary means, materials en tools which were available, it is remarkable to see the precision with which the Roman aqueducts were laid out. The mean gradient of a Roman aqueduct was something between 0,15 - 0,30 %.

Additional resources

Another leveling instrument used by the Romans was the simple "Libella." It consisted of a frame in the shape of the letter A, with the addition of a horizontal bar on top (see photo). From the apex, a plumb line was suspended that coincided with a mark on the lower crossbar when the instrument was level. Other marks could have been added to indicate other slopes, but there is no evidence that this was done (Hauck, 1988:43).

Literature:

> Moreno (2004): Roman Surveying (from the Spanish Traianus website)
> M.J.T. Lewis (2001): Surveying Instruments of Greece and Rome

> O.A.W. Dilke (1971): Roman Land Surveyors

Roman military surveying, from YouTube

Greek Merchantman

Greek Warship

The Bark Provencale