Rome Part I: Early Roman Architecture - History of Architecture | ARCH 3115, Study notes of History of Architecture

Download Rome Part I: Early Roman Architecture - History of Architecture | ARCH 3115 and more Study notes History of Architecture in PDF only on Docsity! 30 Session 9: ROME PART I: EARLY ROMAN ARCHITECTURE NAMES AND TERMS Aeromancy: divination by looking for signs in the sky such as flocks of birds over a particular area. Agrimensor: the Roman surveyor responsible for laying out an Urbs quadrata or grid city. Amphitheater: a Roman theater in the round (usually oval) in which large audiences gathered to be entertained by circus-like spectacles and gladiatorial combat. Atrium: in Roman domestic architecture an inner court open to the sky and surrounded by the roof. Caldarium: the hot bath in a Roman bath house. Castrum: a Roman military camp. Cavea: the hollow of a Greek or Roman theater. Corinthian order: a tall slender order with a capital representing leaves of the acanthus plant, said to have originated in Corinth (not far from Mycenae) in the Greek Peloponnesus. This order was much used by the Romans for temples. Frigidarium: the cold bath in a Roman Bath house. Frontality: in architectural contexts, the alignment of facades at right angles rather than obliquely to the viewer's line of sight. Hypocaust: an under floor heating system used in Roman baths. Impluvium: the pool that collected rainwater in a Roman parastyle courtyard. Insulae: 'islands', apartment blocks for the poor in Roman cities Mundus: a hole dug at the intersection of the founding Cardo and Decumanus in which the first fruits of the harvest were placed as an offering to the spirits of the dead. Pomerium: the circular ditch plowed to define the limit of the city in the traditional Roman founding ceremony. Roman concrete: an unreinforced building material consisting of a cement bonding agent with aggregates of various kinds of stone from heavy to light, depending upon the structural need. Romulus and Remus: The mythical twins who founded Rome April 21, 753 BC. Sulla: early Roman dictator who used his army to stage a coup d'etat. Tablinum: in the Roman house, a room with one side open to the atrium or central courtyard. Templum: the sky divided into four imaginary quadrants for the purposes of aeromancy. Tepidarium: in the Roman baths, the bath of moderate (tepid) temperature Tiber: The City of Rome's main river. Triclinium: the dining room in a Roman house. Urbs Quadrata: a Roman city on the gridiron plan in which every north/ south street is a Cardo and every east/west street is a Decumanus Vesuvius: volcanic mountain responsible for burying Pompeii and Herculaneum under between 13 and 20 feet of mud and ash on August 24, 79 AD. BUILDINGS AND PLACES Herculaneum: Two story house with balcony above Pompeii: House of the Vettii The Forum Amphitheater, c 80 BC Bakery (Pistrinum) Baths 31 BUILDINGS AND PLACES (cont.) Rome: Forum Boarium: Temple of Fortuna Virilis, c. 100 BC Forum Boarium: Tholos (round temple) c. 200 BC Baiae (Near Naples): Thermal Baths (first large concrete dome) c. 40 BC Nimes France: Maison Caree Praeneste: Temple of Fortuna c. 80 BC Sperlonga: Grotto of the Emperor Tiberius (AD 14-37) ISSUES FOR LECTURE 9 THAT MAY BE COVERED ON THE EXAM Note: Please remember that these questions are only meant as a guide for study. Actual sample questions from previous exams of the kind you will be taking are given in the section below this one. 1. Explain in detail the objects and rituals involved in founding a traditional Roman city. 2. What events connected with Pompeii lead to the beginnings of something approaching the modern 33 Session 10: ROME PART TWO: ROMAN IMPERIAL ARCHITECTURE NAMES AND TERMS Apse: a half-cylinder (exedra) covered by a half-dome above. The Art of Memory: in Roman times, the use of the parts of a complex building as an aid to memorizing a speech for public delivery. Augustus: (Gaius Octavianus, 63 BC—AD 14) First Roman emperor (27 BC—AD 14) Grandnephew of Julius Caesar. Basilica: A roman meeting hall used in public administration, sometimes with an apse containing a statue of the emperor. Forum (plural = fora): the Roman transformation of the Greek agora, containing temples, civic buildings such as law courts libraries, prisons, and sometimes markets. Gladiator: a man hired to fight other men or animals with a sword and other weapons (from the Latin gladius = sword) Hadrian: (Publius Aelius Hadrianus AD 76-138) Roman emperor 117— 138 AD) responsible for the construction of the Pantheon. Hannibal: (247-c to 183 BC) Carthaginian general who crossed the Alps to invade Roman Italy in 281 BC. Jack arch: a straight, entirely horizontal arch in which the arch action is achieved just by the wedge shape of the bricks or stones that comprise it. Oculus: the circular opening in the center of a dome. Pax Romanum: the Roman Peace initiated by Augustus, which lasted 200 years. Pozzolana: a type of volcanic sand mixed with lime, rubble aggregate, and water to make mortar or Roman concrete Pompey the Great: (Gnaeus Pompeius Magnus, 106-48 BC) Roman general. Later a member of the First Triumvirate with Marcus Crassus and Julius Caesar. Relieving arch: an arch built into the solid portion of a wall to distribute laterally the load placed upon it by the wall above the arch. Rhetoric: the art of persuasive speaking. Sulla: (Lucius Cornelius Sulla Felix, 138-78 BC) Used his army to achieve a coup d'etat and became one of the first dictators of Rome (82-79 BC) The Tetrarchy: group of four Roman rulers established by the emperor Diocletian ()after a period of internal instability and vulnerability to invasion Trajan: (Marcus Ulpius Trajanus c. AD 53-117) Roman general and statesman; Roman emperor (98-117 AD) BUILDINGS AND PLACES The Imperial Fora, Rome (46 BC-117 AD) Trajan's Forum, AD 107-112 Forum of Augustus c. BC Roman Aqueduct, Segovia Spain Colosseum, Rome (AKA The Flavian Amphitheater) 69-79 AD Domus Aurea of Nero, Rome, AD 64. Pantheon, Rome AD 121+ Hadrian's Villa, Tivoli (a day's ride from Rome) AD 118+ Roman Theater, Orange France, 1st century BC. 34 Roman Baths: Baths of Caracalla, AD 212-216. Baths of Diocletian AD 298-306. Hippodrome (Circus Maximus), Rome AD 311. Porta Nigra, Trier, Germany (Roman gate) c. 3rd century AD. Aula Palatina, Trier, Germany, early 4th century AD. Timgad, Roman colonial city on the South Algerian Step, c. AD 100. ISSUES FOR LECTURE 10 THAT MAY BE COVERED ON THE EXAM Note: Please remember that these questions are only meant as a guide for study. Actual sample questions from previous exams of the kind you will be taking are given in the section below this one. 1. What geometry appears to have been employed in the layout of Roman Imperial Fora? 2. What might the character of Roman roads express about the Roman habitus or basic approach to life? 3. What was the art of memory and how was it related to Roman architecture? 4. What activities were typically associated with the Roman forum? 5. How did the Roman amphitheater (Colosseum) differ from the Roman theater (Theater at Orange)? 6. What activities were typically associated with the Roman baths? 7. How was Roman concrete used in the dome of the Pantheon in Rome? 8. What connection might there be between the symbolism of the dome in Nero's Domus Aurea and the Roman Pantheon? 9. Describe the main structures of Hadrian's Villa and their symbolism. 10. What activities took place in the Hippodrome and what political role did it play? 11. List and describe five features of Roman architecture which were incorporated in Christian religious architecture after the Edict of Milan 12. What made the shift from Republican to Imperial government necessary for the Roman empire? 13. How did the shift from Republican to Imperial government affect Roman architecture? 14. "Greek architecture was an architecture of place, whereas Roman architecture was an architecture of space." Discuss. 15. What did the Roman pantheon symbolize, and how were the recesses in the coffers adjusted to contribute to that symbolism? 35 SAMPLE QUESTIONS FROM PREVIOUS EXAMS FOR LECTURE 10 15. This structure is known as the_______________; it is______________. not be persecuted, deprived of property, or abused in any way. Christianity was made the official religion of the Roman Empire by the emperor Theodosius I in 382 CE. Eucharist: the ritual commemoration of Christ's Last Supper. Flying buttress: a support for a wall which stands free of the wall to which it is connected only by arches. Justinian and Theodora: Byzantine Emperor and empress (reigned 527- 565). Liturgy: the form and order of worship in a Christian church. Narthex: the entry porch of a basilican church, from which nonmembers might watch the service. Presbytery: the governing body of the church consisting of the minister and elders. Theoderic: Ostrogothic King of Italy who made Ravenna his capital in 493. Transept: a hall built across the main axis of the nave of a Christian basilica. BUILDINGS & PLACES Christian House, Dura Europos, 240-256 AD The Catacombs of the Via Latina, Rome 4th c. AD Basilica at Trier, Germany, 4th c. AD St. Peter's Basilica (Old St. Peter's) Rome, c. 320. Orthodox Baptistery, Ravenna, Italy, c. 450 AD S. Apollinare in Classe (Classe is the Ravenna seaport), consecrated 549. S. Vitale, Ravenna, consecrated 548. Mausoleum of Galla Placidia, Ravenna, 425 AD Hagia Sophia, Constantinople, 532-537. 37 ISSUES FOR LECTURE 11 THAT MAY BE COVERED ON THE EXAM Note: Please remember that these questions are only meant as a guide for study. Actual sample questions from previous exams of the kind you will be taking are given in the section below this one. 1. In what type of building did the early Christians (before the Edict of Milan) worship? Why? 2. What were the catacombs and how were they used by early Christian communities? 3. In what ways did early Christians venerate martyrs to their faith? What was the significance of burial close to the tomb of a martyr? 4. Why was the martyrium unsatisfactory as a church form for Christian congregational services, and how was this problem solved in early Christian church architecture? 5. How did Christianity differ from the traditional Roman state religion? 6. Prior to the Edict of Milan, why were the Christians persecuted by the Romans? 7. What physical characteristics of Roman and Early Christian mosaics gave them the sparkle and glow for which they are so well known? 8. In what ways can Hagia Sophia be interpreted as an image of the cosmos? 9. What were some of the geographical, cultural, political, and military reasons that led Constantine to found a new capital for the Roman Empire at Byzantium? 10. What features of Roman architecture were adapted to and incorporated in the early Christian church? 11. Early Christian architecture may be thought of in terms of shaping space around ritual. Discuss. 12. Discuss the concept of anagogicus mos in light of the following quotation from Procopius, the Emperor Justinian's court historian: "Whenever one enters this church (Hagia Sophia) to pray, he understands at once that it is not by any human power or skill, but by the influence of God, that this work has been so finely wrought. And so his mind is lifted up toward God and exalted, feeling that He cannot be far away, but must especially love to dwell in this place which He has chosen." 38 SAMPLE QUESTIONS FROM PREVIOUS EXAMS FOR LECTURE 11 19. Even though you have not seen this Early Christian building located in Rome before, you can tell from this perspective section that it must have been ____. 1. a mausoleum 2. a basilica 3. a baptistery 4. a market 20. The eight windows in the drum under the dome comprise what is known as___________ 1. a clerestory 2. a lantern 3. a skylight 4. an oculus 1. What are the basic rules of the Islamic religion, and how do they shape the architecture of the mosques in which this religion is observed? 2. Why are there no representational images in some examples of Islamic architecture? 3. What is the basic form of the mosque and in what building is it thought to have originated? 4. What are some of the variations of the mosque form? 5. For Muslims, what is the significance of Mecca, and what important artifact is found there? 6. Draw a diagram of a typical urban center in an Islamic city and label the component structures. 7. From what is the shape of the Taj Mahal derived? 8. Explain what the centering for a vault is and some of the techniques used by the folk builders of the Islamic world to construct vaults without centering. 9. Describe the process by which an Islamic muqarnas vault is designed and laid out on site. 10.What do we miss if we study only the architectural monuments of a culture and ignore its folk architecture? 11. Is there a distinction between architecture and building, and if there is, what is it? 12. What symbolic connections are there between the Roman concept of founding a city and the circular plan for the city of Baghdad? 13. What evidence is there that there may have been communication between the masons of Europe and those of the Muslim world? 41 SAMPLE QUESTIONS FROM PREVIOUS EXAMS FOR LECTURE 12 This cut-away perspective shows the Great Mosque at Qairawan Tunesia.which dates from about 862 A.D. Please answer the following questions about it. 21. The tower structure under the letter ‘A’ is known as: 1. a minbar 2. a mirab 3. a minaret 4. a musette 22. The structure marked ‘E’ is called a__________and indicates the direction of____________. 1. mirab, Mecca 2. minbar, the Imam 3. minaret, Mecca 4. muazin, Mecca 23. After entering the courtyard (or atrium), the person who has come to pray would next seek out the_________, which would be located_________________, where they would remove___________. 1. garden, near the courtyard, their head covering. 2. Imam, in the dikka, their shoes. 3. Muazin, in the minaret, their weapons. 4. cleansing pool, under the dome above the letter ‘C’, their shoes. 24. The prayer room is _____________which is especially suited to the Islamic understanding of prayer because_____________. 1. a long narrow space, prayer is an intensely visual experience for Muslims. 2. a hypostyle hall with a bare floor, for Muslims, prayer is a direct communication with Allah. 3. a carpeted hypostyle hall, Muslims pray with their eyes closed, and prayer is not a visual experience.. 4. a carpeted hypostyle hall, Muslims pray with their eyes open, but prayer is not a visual experience. 42 Session 13: ARCHITECTURE OF INDIAN ASIA NAMES AND TERMS Brahma: The creator god in the Hindu religion Brahman: in the Hindu religion, the incognizable center of being, without attributes and without differentiation. Also the name given to the Hindu priest (sometimes anglicized as Brahmin). Caste system: traditional, Indian society was divided into five castes: (1) Shudra: the agriculture/labor caste [may build 3.5 floors]; (2) Vaishya, the trading caste [may build 5 floors]; (3) Kshatriya, the warrior caste [may build 5.5 floors]; (4) Bramins: the priest and ruling class [may build 7.5 floors]; (5) Kings [may build 8.5 floors]. gnomon: the vein on a sundial, a column or other device used to indicate the time of day or the east-west axis by means of shadows. karma: in Buddhism, the doctrine of cause and effect: what you do in this life determines in what form your soul will be incarnated in the next temple. 4. the paramasayika-mandala, a Buddhist temple. 29. As in many other cultures, the result of following this process is that man-made structures are seen as ___________the____________. 1. created by, gods. 2. created by, structure of the world 3. different from, structure of the world 4. analogous to, structure of the world. 44 30. This structure is a_______________located on _________. 1. Hindu rock temple, Java. 2. Hindu stupa, Celebes. 3. Buddhist stupa, Java 4. Buddhist rock temple, Borneo 31. The various levels have stories from the life of__________ carved on their walls. 1. Brahma 2. Christ 3. Shiva 4. Buddha 32. The top level contains a series of hollow____________ containing meditating______________. 1. stupas, Brahmas 2. stupas, Buddhas 3. bells, Shivas 4. bells, Brahmas 33. By ascending this structure one___________________. 1. recreates the Hindu vision of cosmogenesis. 2. duplicates the path that Shiva followed to enlightenment. 3. duplicates the path that the Buddha followed to enlightenment. 4. unwinds time back to the primordial act of creation. 45 Session 14: MAYA ARCHITECTURE IN MEXICO AND GUATEMALA NAMES AND TERMS Aztec: a member of an advanced Indian civilization in what is now Mexico before the conquest by Cortez in 1519 Books of Chilam Balam: A Maya chronicle dating to 495 AD but written much later. Ceiba tree: a tall straight tree sacred to the Maya who regard it as the World Tree or axis mundi—the prop that holds up the sky and the place where humans communicate with the gods. Cenote: a large natural well-like source of water for the Maya formed by the drainage of surface water into caverns with the consequent collapse of the cavern roof due to erosion and leaching. Chac: a Maya rain god Chacmool (or Chac Mool): A Maya reclining figure looking over its left shoulder and having a kind of tray or vessel for offerings upon its chest. It has been interpreted as a heavenly messenger taking the blood-gifts of humans to the gods (Kubler). Others say that they are attendants of the rain god Tlaloc, and that the trays are for catching rain (Nicholson). Corbeling: formation of a vault-like structure by progressively cantilevering two stacks of stones until they touch at the top, leaving an open space below. Cortez, Hernando: (1485-1547) explorer and conqueror of Mexico De Soto, Hernando: (c1500-42) explorer in America; discovered the Mississippi River. Hero Twins (Hunapu and Xbalanque) in some ways comparable to Romulus and Remus in the Founding of the City of Rome, the Hero Twins of the Maya Popol Vuh repeatedly outwit the Xibalbans, the Lords of the Underworld (evil and darkness). Maize God: one of the chief gods in the Maya pantheon, associated with the sun and the most basic food of the Maya people Maya Glyphs or hieroglyphics or glyphs: the Pre-Columbian Maya writing system. Maya: member of an advanced Indian civilization found in Yucatan, Chiapas, British Honduras and N. Guatemala. They had a sophisticated system of hieroglyphic writing for which about half of the characters are now translated. monogenesis: the theory that Homo sapiens developed in just one place (probably Africa) and spread from there over the rest of the world including to the American continent, perhaps via the Bering Strait. Compare with polygenesis. Pakal: one of the major rulers at Palenque. Pizarro, Francisco: (1474-1541) conqueror of Peru. Popol Vuh The book of the Maya creation myth. Psychoduct: a tube connecting a tomb to a temple through which the soul(s) of the deceased were throught to gain access to the world of the living. Quetzalcotl: In incarnate form, which he is supposed to have assumed at a certain moment in history, a great lawgiver and civilizer, inventor of the calendar or Book of Fate. He was a compassionate king who could scarcely bear to hurt anything. Otherwise, the great plumed bird- serpent; the life god. LOCATIONS Note: In Maya languages, the stress is almost always on the last syllable in a word. X is pronounced "sch" and z = "s." Antigua: the old capital city of Guatemala Chich' en Itza: Maya city in Yucatan (Mexico) Copan: Maya site in Honduras Iximche: Maya site in Guatemala Kabah: Maya site in Yucatan famous for the Codz Poop, a temple covered with sculpted faces. Palenque: Maya city in Chiapas (Mexico) Las Sepulturas: residential suburb of the Maya site of Copan (Honduras) Tikal: Maya site in Guatemala Uxmal: Maya city in Yucatan 2. watering, Xibalba. 3. baptizing, his rebirth as a Christian. 4. watering, the daytime sun. 38.This view of the Great Plaza at the Maya site of Tikal in Guatamala shows how the Maya may have used_____________to lay out their cities in conformity with___________. 1. trigonomentry, the geometry of their concept of the universe. 2. a surveyor’s transit, the Pythagorean theorem. 3. the 3-4-5 right triangle, the geometry of their concept of the universe. 4. the 3-4-5 right triangle, the Pythagorean theorem. 39. In Pre-Columbian times Maya city centers were_____. 1. More densely covered with vegetation than we see them today. 2. Completely free of trees and vegetation. 3. Planted much as we see them today. 4. Planted with elaborate gardens. 40. The prototype structure for the Maya temple house appears to have been: 1. the Maya palace. 2. the Aztec temple. 3. the cenote. 4. the Maya traditional house. 48 Session 15: EARLY MEDIEVAL EUROPE AND THE CAROLINGIAN RENAISSANCE NAMES AND TERMS Alric: king of the Visigoths who sacked Rome in 410 St. Benedict: (c. 480-547); author of the Benedictine Rule and founder of the monastic community at Montecassino, Italy in 520AD. chapter house: building attached to the church in which monastic community affairs were administered and the Benedictine Rule was read on a daily basis. Carolingian: of Charlemagne or his period. (also Carolinian) Charlemagne: Charles The Great, King of the Franks From 771-814; crowned Emperor in 800 by Pope Leo III. Franks: Germanic tribe which established a kingdom in northern and western France. St. Patrick: (385-461) reputedly established the monastic tradition in Ireland in 432. Ottonian: of the three major emperors (Ottos I, II and III), 962 to 1002. Pepin; king of the Franks from 754 to 771. Father of Charlemagne Visigoths: Germanic tribe that established a kingdom in Spain westwork: the west end of a Carolingian or Romanesque church, consisting of a low entrance hall and above it a room open to the nave. BUILDINGS AND ARTIFACTS DISCUSSED Cluny: Benedictine monastery in western France 909-1120 Lindisfarne Gospels, c. 700 Palatine Chapel, Aachen, 805 Plan of St. Gall, Switzerland c. 819 Torhalle: (gate hall), Lorsch, Germany, after 774 The Abbey of Saint-Requier, Centula, northern France, dedicated 799 St. Stephen at Corvey an der Weser (Germany) 873-85 St. Michel’s Hildesheim, Germany 1001-33 Kaiserdom, Speyer, Germany 1030-61 ISSUES FOR LECTURE 15 THAT MAY BE COVERED ON THE EXAM Note: Please remember that these questions are only meant as a guide for study. Actual sample questions from previous exams of the kind you will be taking are given in the section below this one. 1. What is the meaning of the term ‘Middle Ages’ or ‘medieval’? What is the meaning of ‘Renaissance’? How did the terms originate and why were they used? 2. In what sense were the Middle ages a “dark age”? 3. Where and how did Christian monasticism originate? What was the role of St. Benedict in the monastic movement? 4. What kinds of people became monks and nuns? 5. What is the relationship between Charlemagne’s Palatine Chapel at Aachen and the church of San Vitale in Ravenna? 49 6. What influence did Charlemagne’s Chapel at Aachen have upon church architecture? 7. Draw a plan of a typical Carolingian or Romanesque basilican church and label the parts. Be sure to include the narthex or porch, the nave with its side aisles, the crossing, the transept, the apse, the westwork, the main or high altar 8. In what ways did Charlemagne promote a rebirth of classical culture in his empire? 9. What sort of relationship did Charlemagne establish with Pope Leo III and how did he do it? What did this relationship enable him to accomplish? 10. What was the “westwork” of a church and what did it symbolize? 11. What attitude toward the surrounding world environment does Carolingian architecture express? NO SAMPLE QUESTIONS FROM THE EXAMS ARE AVAILABLE FOR LECTURE 15 AT THIS TIME. Romanesque church? 3. What sorts of things were collected as relics? 4. Explain how a Romanesque vault or arch works structurally. 5. What reasons (give at least three) were there to cover the church space with stone vaults rather than a timber roof? 6. Why did people undertake pilgrimages; when they did, where did they go and what did they see? 7. Where did the money come from to build pilgrimage churches? 8. Using a specific example such as the piano, the automobile, and the Romanesque basilica, discuss the process of development which artifacts typically undergo over time. Does this development represent a process of gradual perfection or just change? How can you tell? 9. Discuss the symbolism of the typical Romanesque tympanum. What is the politics and economics of this symbolism? 10. It has been said that all the features of the Gothic cathedral occur separately in the Romanesque basilicas. Can you site specific examples which would prove this? 11. From an expressive standpoint, what would you say is the basic feeling conveyed by French, English, and Spanish Romanesque churches? SAMPLE QUESTIONS FROM PREVIOUS EXAMS FOR LECTURE 17 12. This view of the vaults at St. Etienne (1064-1134) in Caen, France shows that it: 1. has a four-part vault system 2. has a six-part vault system 3. has a two-part vault system 4. has a five-part vault system 13. One wall pier has a single engaged column, while the other has three, because: 1. there was a change in architectural style 2. an error was made 3. different teams of workers built each. 4. the one with three gets more vault thrust 14. The reason there are arches on only one side of the clerestory windows is that 1. there wasn’t enough room on the other side 2. the clerestory windows are off center 3. there is more vault thrust on that side 4. there is less vault thrust on that side 15. From this arrangement of vaults and openings, one can 15. From this arrangement of vaults and openings one can infer that: 1. the vaults were retrofitted at a later date 2. the vaults collapsed at some time 3. the vaults are made of brick rather than stone 4. the ribs were too weak to achieve arch action 45. This plan and section of Saint Philibert at Tournus, France (950-1220) show it to have_________. 1. radiating chapels, 2. a longitudinal barrel vault, 3. a crypt above ground, 4. fan vaults 46. The curved passageway at the East end is known as a ______________. 1. ambo, 2. chevet, 3. chevrolet, 4. narthex 47. This structure made it possible for pilgrims to ____________ without interrupting church services. 1. arrive late, 2. talk softly, 3. buy gifts, 4. view the church relics 48. The space over the vaulted West entry is _____________ . 1. a narthex, 2. an atrium, 3. a westwork chapel, 4. an ambo 49. The vaults at Saint Philibert are unusual in that they are _______________ . 1. transverse, 2. barrel vaults, 3. groin vaults, 4. five in number rather than four 50. A probable structural reason for this vault arrangement is that it _______________ . 1. makes the vaults shorter, 2. eliminates the lateral thrust on the nave walls, 3. makes the vaults lighter, 4. eliminates the thrust on the end walls