Editing Vitruvius (section)

==Roman technology==
[[File:Archscrew2.jpg|thumb|200px|Drainage wheel from [[Rio Tinto (river)|Rio Tinto]] mines]]
Books VIII, IX and X form the basis of much of what we know about Roman technology, now augmented by archaeological studies of extant remains, such as the [[water mill]]s at [[Barbegal]] in France. The other major source of information is the {{lang|la|[[Naturalis Historia]]}} compiled by [[Pliny the Elder]] much later in {{circa|75&nbsp;AD}}.

===Machines===
The work is important for its descriptions of the many different machines used for engineering structures such as [[Hoist (device)|hoists]], [[Crane (machine)|cranes]] and [[pulley]]s, as well as war machines such as [[catapult]]s, ''[[ballistae]],'' and [[siege engine]]s. As a practising engineer, Vitruvius must be speaking from personal experience rather than simply describing the works of others. He also describes the construction of [[sundials]] and [[water clocks]], and the use of an [[aeolipile]] (the first [[steam engine]]) as an experiment to demonstrate the nature of atmospheric air movements (wind).

===Aqueducts===
His description of [[aqueduct (watercourse)|aqueduct]] construction includes the way they are surveyed, and the careful choice of materials needed, although [[Frontinus]] (a general who was appointed in the late 1st century AD to administer the many aqueducts of Rome), writing a century later, gives much more detail of the practical problems involved in their construction and maintenance. Surely Vitruvius' book would have been of great assistance in this. Vitruvius was writing in the 1st century BC when many of the finest [[Roman aqueducts]] were built, and survive to this day, such as those at [[Segovia]] and the [[Pont du Gard]]. The use of the [[inverted siphon]] is described in detail, together with the problems of high pressures developed in the pipe at the base of the siphon, a practical problem with which he seems to be acquainted.

===Materials===
He describes many different [[construction material]]s used for a wide variety of different structures, as well as such details as [[stucco]] painting. Concrete and [[Lime (material)|lime]] receive in-depth descriptions.

Vitruvius is cited as one of the earliest sources to connect lead mining and manufacture, its use in drinking water pipes, and its adverse effects on health. For this reason, he recommended the use of clay pipes and masonry channels in the provision of piped drinking-water.<ref>{{cite journal |author= Hodge, Trevor, A. |title= Vitruvius, Lead Pipes and Lead Poisoning |publisher= Archaeological Institute of America |volume= 85 |issue= 4 |date = October 1981|pages= 486–491 |jstor= 504874 |journal= American Journal of Archaeology |doi= 10.2307/504874 |s2cid= 193094209 }}</ref>

Vitruvius is the source for the anecdote that credits [[Archimedes]] with the discovery of the [[Archimedes' principle|mass-to-volume ratio]] while relaxing in his bath. Having been asked to investigate the suspected adulteration of the gold used to make a crown, Archimedes realised that the crown's volume could be measured exactly by its displacement of water, and ran into the street with the cry of'' [[Eureka (word)|Eureka!]]''

===Dewatering machines===
[[File:VitruviusTenBooksMHMorgan1914p295.gif|thumb|left|200px|Design for an Archimedean water-screw]]

He describes the construction of [[Archimedes' screw]] in Chapter X (without mentioning Archimedes by name). It was a device widely used for raising water to irrigate fields and drain mines. Other lifting machines he mentions include the endless chain of buckets and the [[reverse overshot water-wheel]]. Remains of the water wheels used for lifting water were discovered when old mines were re-opened at [[Rio Tinto (river)|Rio Tinto]] in Spain, [[Rosia Montana]] in Romania and [[Dolaucothi]] in west [[Wales]].{{cn|date=January 2023}} The Rio Tinto wheel is now shown in the [[British Museum]], and the Dolaucothi specimen in the [[National Museum of Wales]].

===Surveying instruments===
That he must have been well practised in surveying is shown by his descriptions of surveying instruments, especially the water level or ''[[chorobates]],'' which he compares favourably with the ''[[Groma surveying|groma]],'' a device using [[plumb line]]s. They were essential in all building operations, but especially in aqueduct construction, where a uniform gradient was important to the provision of a regular supply of water without damage to the walls of the channel. He also developed one of the first [[odometer]]s, consisting of a wheel of known circumference that dropped a pebble into a container on every rotation.

===Central heating===
[[File:Hypocaustum.jpg|thumb|right|220px|Ruins of the [[hypocaust]] under the floor of a Roman villa. The part under the [[exedra]] is covered.]]

He describes the many innovations made in building design to improve the living conditions of the inhabitants. Foremost among them is the development of the ''[[hypocaust]],'' a type of [[central heating]] where hot air developed by a fire was channelled under the floor and inside the walls of [[public bath]]s and [[villa]]s. He gives explicit instructions how to design such buildings so that [[fuel efficiency]] is maximised, so that for example, the ''[[caldarium]]'' is next to the ''[[tepidarium]]'' followed by the ''[[frigidarium]]''. He also advises on using a type of regulator to control the heat in the hot rooms, a [[bronze]] disc set into the roof under a circular aperture which could be raised or lowered by a [[pulley]] to adjust the ventilation. Although he does not suggest it himself, it is likely that his dewatering devices such as the [[reverse overshot water-wheel]] were used in the larger baths to lift water to header tanks at the top of the larger ''thermae'', such as the [[Baths of Diocletian]]. The one which was used in Bath of Caracalla for grinding flour.