De architectura

Greek house plan by Vitruvius

Vitruvius sought to address the ethos of architecture, declaring that quality depends on the social relevance of the artist's work, not on the form or workmanship of the work itself. Perhaps the most famous declaration from De architectura is one still quoted by architects: "Well building hath three conditions: firmness, commodity, and delight". This quote is taken from Sir Henry Wotton's version of 1624, and accurately translates the passage in the work, (I.iii.2) but English has changed since then, especially in regard to the word "commodity", and the tag may be misunderstood. In modern English it would read: "The ideal building has three elements; it is sturdy, useful, and beautiful."

Vitruvius also studied human proportions (Book III) and this part of his canones were later adopted and adapted in the famous drawing by Leonardo da Vinci (Homo Vitruvianus, "Vitruvian Man").

While Vitruvius is fulsome in his descriptions of religious buildings, infrastructure and machinery, he gives a mixed message on domestic architecture. Similar to Aristotle, Vitruvius offers admiration for householders who built their own homes without the involvement of an architect.[6][7] Vitruvius’s ambivalence on domestic architecture is most clearly read in the opening paragraph of the Introduction to Book 6.[8] Book 6 focusses exclusively on residential architecture but as architectural theorist Simon Weir has explained, instead of writing the introduction on the virtues of residences or the family or some theme related directly to domestic life; Vitruvius writes an anecdote about the Greek ethical principle of Xenia: showing kindness to strangers.[9]

Books VIII, IX, and X of De architectura form the basis of much of what is known about Roman technology, now augmented by archaeological studies of extant remains, such as the Pont du Gard in southern France. Numerous such massive structures occur across the former empire, a testament to the power of Roman engineering. Vitruvius's description of Roman aqueduct construction is short, but mentions key details especially for the way they were surveyed, and the careful choice of materials needed.

His book would have been of assistance to Frontinus, a general who was appointed in the late 1st century AD to administer the many aqueducts of Rome. Frontinus wrote De aquaeductu, the definitive treatise on 1st-century Roman aqueducts, and discovered a discrepancy between the intake and supply of water caused by illegal pipes inserted into the channels to divert the water. The Roman Empire went far in exploiting water power, as the set of no fewer than 16 water mills at Barbegal in France demonstrates. The mills ground grain in a very efficient operation, and many other mills are now known, such as the much later Hierapolis sawmill.

Vitruvius described many different construction materials used for a wide variety of different structures, as well as such details as stucco painting. Cement, concrete, and lime received in-depth descriptions, the longevity of many Roman structures being mute testimony to their skill in building materials and design.

He advised that lead should not be used to conduct drinking water, clay pipes being preferred. He comes to this conclusion in Book VIII of De architectura after empirical observation of the apparent laborer illnesses in the plumbum (lead pipe) foundries of his time. However, much of the water used by Rome and many other cities was very hard, soon coating the inner surfaces of the pipes, so lead poisoning was reduced.

Design for an Archimedean water-screw

Vitruvius related the famous story about Archimedes and his detection of adulterated gold in a royal crown. When Archimedes realized the volume of the crown could be measured exactly by the displacement created in a bath of water, he ran into the street with the cry of "Eureka!", and the discovery enabled him to compare the density of the crown with pure gold. He showed the crown had been alloyed with silver, and the king was defrauded.

Drainage wheel from Rio Tinto mines

Sequence of drainage wheels found in Rio Tinto

Vitruvius described the construction of the Archimedes' screw in Chapter 10, although did not mention Archimedes by name. It was a device widely used for raising water to irrigate fields and dewater mines. Other lifting machines mentioned in De architectura include the endless chain of buckets and the reverse overshot water-wheel. Remains of the water wheels used for lifting water have been discovered in old mines such as those at Rio Tinto in Spain and Dolaucothi in west Wales. One of the wheels from Rio Tinto is now in the British Museum, and one from the latter in the National Museum of Wales. The remains were discovered when these mines were reopened in modern mining attempts. They would have been used in a vertical sequence, with 16 such mills capable of raising water at least 96 feet (29 m) above the water table. Each wheel would have been worked by a miner treading the device at the top of the wheel, by using cleats on the outer edge. That they were using such devices in mines clearly implies that they were entirely capable of using them as water wheels to develop power for a range of activities, not just for grinding wheat, but also probably for sawing timber, crushing ores, fulling, and so on.

Ctesibius is credited with the invention of the force pump, which Vitruvius described as being built from bronze with valves to allow a head of water to be formed above the machine. The device is also described by Hero of Alexandria in his Pneumatica. The machine is operated by hand in moving a lever up and down. He mentioned its use for supplying fountains above a reservoir, although a more mundane use might be as a simple fire engine. One was found at Calleva Atrebatum (Roman Silchester) in England, and another is on display at the British Museum. Their functions are not described, but they are both made in bronze, just as Vitruvius specified.

Vitruvius also mentioned the several automatons Ctesibius invented, and intended for amusement and pleasure rather than serving a useful function.

Ruins of the hypocaust under the floor of a Roman villa: The part under the exedra is covered.

Vitruvius outlined 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 baths and villas. He gave explicit instructions on how to design such buildings so fuel efficiency is maximized; for example, the caldarium is next to the tepidarium followed by the frigidarium. He also advised 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 did not suggest it himself, his dewatering devices such as the reverse overshot water-wheel likely 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 and the Baths of Caracalla.

That Vitruvius must have been well practised in surveying is shown by his descriptions of surveying instruments, especially the water level or chorobates, which he compared favourably with the groma, a device using plumb lines. They were essential in all building operations, but especially in aqueduct construction, where a uniform gradient was important to provision of a regular supply of water without damage to the walls of the channel. He described the hodometer, in essence a device for automatically measuring distances along roads, a machine essential for developing accurate itineraries, such as the Peutinger Table.

In Book IV Chapter 1 Subsection 4 of De architectura is a description of 13 Athenian cities in Asia Minor, "the land of Caria", in present-day Turkey. These cities are given as: Ephesus, Miletus, Myus, Priene, Samos, Teos, Colophon, Chius, Erythrae, Phocaea, Clazomenae, Lebedos, Mytilene, and later a 14th, Smyrnaeans. Myus, the third city, is described as being "long ago engulfed by the water, and its sacred rites and suffrage". This sentence indicates, at the time of Vitruvius's writing, it was known that sea-level change and/or land subsidence occurred. The layout of these cities is in general from south to north so that it appears that where Myrus should be located is inland. If this is the case, then since the writing of De architectura, the region has experienced either soil rebound or a sea-level fall. Though not indicative of sea-level change, or speculation of such, during the later-empire many Roman ports suffered from what contemporary writers described as 'silting'. The constant need to dredge ports became a heavy burden on the treasury and some have speculated that this expense significantly contributed to the eventual collapse of the empire. Roman salt works in Essex, England, today are located at the five-metre contour, implying this was the coastline.[10][11] These observations only indicate the extent of silting and soil rebound affecting coastline change since the writing of De architectura.

The earliest evidence of use of the stereographic projection in a machine is in De architectura, which describes an anaphoric clock (it is presumed, a clepsydra or water clock) in Alexandria. The clock had a rotating field of stars behind a wire frame indicating the hours of the day. The wire framework (the spider) and the star locations were constructed using the stereographic projection. Similar constructions dated from the 1st to 3rd centuries have been found in Salzburg and northeastern France, so such mechanisms were, it is presumed, fairly widespread among Romans.