conversations.from: human
conversations.value: What could be a title for a book about with the genre: New, Used & Rental Textbooks, Humanities?
conversations.from: assistant
conversations.value: A title for this book could be 'A History of Engineering in Classical and Medieval Times'
conversations.from: human
conversations.value: Provide the first five paragraphs for this book.
conversations.from: assistant
conversations.value: A History of Engineering in Classical and Medieval Times
  In Islam the great centres of population were (and are) based in river valleys and depend upon irrigation for their agriculture. Obviously, these centres had running water, and as we have seen, water-mills were a common feature of Muslim society. Transport, either by water or by pack-train was fairly cheap, and there seems to have been no difficulty in moving large quantities of flour over long distance, for example from Egypt to the Hejaz or from Upper Mesopotamia to Baghdad. Certainly, there were some areas in the Muslim world which could have benefited from the use of post-mills — the Syrian coastlands and parts of North Africa in particular. The fact that these mills were not introduced to those regions cannot be easily explained, but the shortage of suitable heavy timber may have been the most important inhibiting factor.
  One of the most complex and sophisticated astronomical instruments made before modern times is also one of the earliest known. The Antikythera Mechanism, so called because of its discovery as part of the cargo of a sunken vessel in 1900 near the island of Antikythera (between Crete and Kythera), was probably made in Rhodes about 87 BC. The find consisted of a number of pieces of bronze, much corroded, but clearly showing gear-wheels and parts of inscriptions. Professor Derek de Solla Price, of Yale University, after 20 years of research, has been able to produce a convincing reconstruction of the mechanism, which is identified as a geared calendar of astonishing complexity.6 The general plan of all the gearing is shown in Figure 10.2. The gears, all of bronze with teeth cut to equilateral triangles, were mounted on either side of a main bronze plate. It has not yet been possible to identify all the functions of the mechanism, but it is very probable that the contrate wheel A turned the main wheel, and that one rotation of the latter represented a solar year, this being the main input into the instrument. A very interesting part of the mechanism is a differential turntable, the purpose of which may have been to produce as output a function of the Metonic cycle. Other outputs were the positions of the sun and the moon, and the risings and settings of the circuit of notable fixed stars through the cycle of years and months. The Antikythera Mechanism, to quote Price:
  It is worthy of notice that this mechanical technology, not only in the construction of instruments, but also in the fields of water-raising, horology and automata, was not a product of classical Greece, but of the Hellenistic culture with its intellectual centre in Alexandria. As we see in the two final chapters, Arabic scholars, by translating the works of writers such as Ptolemy, Hero and Philo, were instrumental in the transmission of this tradition to Europe. And from the foundation of the Hellenistic writings, they produced their own tradition of fine mechanical technology.
  This transmission is exemplified by a geared calendar attributed to the astronomer Abu Sa'īd al-Sizjī. It was described by al-Biruni in a treatise written in the second quarter of the eleventh century.8 This is not so complex as the Antikythera instrument, although Muslim skills in astronomy and metalwork would certainly have been equal to the construction of such a calendar. As usual, however, we can only record what has survived. Al-Bīrūnī's calendar consists of eight gear-wheels installed on a circular brass plate (Figure 10.3a). Wheels 1 and 2, 3 and 7, 4 and 8 are each single units, soldered together concentrically, as shown in Figure 10.3b. Figure 10.3c shows wheel 7, which is the volvelle for the moon's phases; it has two silvered circles, and its rim, inside the teeth, is divided into 59 divisions. The main plate has a rim, over which a circular lid is fitted. The axles from wheels 1, 5 and 6 pass through holes in this lid. An alidade on the axle of wheel 1 moves round a scale divided into the days of the week. Pointers on the axles of wheel 5 (moon) and wheel 6 (sun) move around scales divided into the twelve signs of the Zodiac, each sign being subdivided into 30 degrees (not shown on Figure 10.3d). The hole for the moon's phases is the same diameter as the silvered circles on wheel 7, so that as the latter rotates the moon's shape changes daily; one rotation of the wheel corresponds to two lunations. The small hole to the left of the centre-line of the large hole shows the day of the lunation marked on the rim of wheel 7.
  These numbers give a synodical month of 29½ days and a sidereal month of 28 days. During a complete rotation of wheel 6, wheel 1 rotates 52.35 times, equivalent to 366.42 days. Over a period these slightly inaccurate figures would have produced distortions in the calendar, and we must assume that it was reset from time to time, probably by moving the pointers relative to their axles. Al-Bīrūnī says that the wheels on his calendar are like those fitted to the backs of astrolabes. Geared astrolabes have survived in a very few cases, but the survivors are later than the time of al-Bīrūnī.9 His remark, however, assures us that they were in use at an earlier date.
conversations.from: human
conversations.value: Provide three more paragraphs.
conversations.from: assistant
conversations.value: In the preceding two chapters, simulation of celestial and biological behaviour was discussed, together with the mechanical, hydraulic and pneumatic means used to impart motion to these simulations. In water-clocks, as in mechanical clocks, these two types of representation were often combined, and an equal, or even greater, attention was paid to methods of producing, controlling and transmitting energy. Water-clocks are therefore of crucial importance in the history of mechanical engineering, and not simply for their contribution to the development of the mechanical clock. This is not meant to imply, however, that machines should be considered only in their relation to an evolutionary process, but also as satisfying creations in their own right. The mechanical clock is still an interesting, important (and often beautiful) machine, even though it is now being superseded by electronic timepieces.
  The earliest type of water-clock was the simple outflow clepsydra, an earthenware vessel with a hole in its side, near the base. It was in use in Egypt and Babylonia before 1500 BC and the oldest surviving example, from Egypt, is dated about 1380 BC. This had a scale of hours graduated upon its inside, which must have been drawn by observation so that allowance was automatically made for the decrease in the rate of discharge as the water-level fell. Attempts were made to minimise the effects of the steady decrease in the rate of discharge by tapering the profiles of the containers. The Oxyr-rhynchos Papyrus of the third century AD gives dimensions for the standard clepsydra: its profile was the frustrum of a cone having an upper radius of 12 fingers, a lower radius of 6 and a height of 18.3 It is virtually impossible, however, to make an outflow clepsydra in which the water-level falls equal distances in equal successive time intervals. With very large vessels having large orifices the condition can be approached by making the profile a parabola in which the height is a given function of the radius. For vessels of a manageable size, however, this does not work, because with small heads of water and small orifices the effects of viscosity come into play, and a straight-forward formula is no longer applicable.4
  An important development was the introduction of the inflow clepsydra, which probably came into use in Egypt a little later than the outflow type. At first this consisted of two vessels, an outflow clepsydra that discharged into a receiver having an hour-scale marked on its interior. Clearly, this was no more accurate than the simple outflow type, but the next innovation made it a much better timekeeper. The reservoir vessel was provided with an overflow pipe and a constant supply of water, flowing in at a greater rate than the outflow from the orifice. A constant head was therefore maintained in the reservoir. The water supply could be from a large vessel, a stream or the city mains. The inflow clepsydra was an important component in some of the sophisticated water-clocks of Hellenistic times and later. Before discussing these, however, we must turn our attention briefly to the East, to establish a frame for cross-reference.
conversations.from: human
conversations.value: Reverse the sentences.
conversations.from: assistant
conversations.value: Before discussing these, however, we must turn our attention briefly to the East, to establish a frame for cross-reference.. The inflow clepsydra was an important component in some of the sophisticated water-clocks of Hellenistic times and later. The water supply could be from a large vessel, a stream or the city mains. A constant head was therefore maintained in the reservoir. The reservoir vessel was provided with an overflow pipe and a constant supply of water, flowing in at a greater rate than the outflow from the orifice. Clearly, this was no more accurate than the simple outflow type, but the next innovation made it a much better timekeeper. At first this consisted of two vessels, an outflow clepsydra that discharged into a receiver having an hour-scale marked on its interior.4
  An important development was the introduction of the inflow clepsydra, which probably came into use in Egypt a little later than the outflow type. For vessels of a manageable size, however, this does not work, because with small heads of water and small orifices the effects of viscosity come into play, and a straight-forward formula is no longer applicable. With very large vessels having large orifices the condition can be approached by making the profile a parabola in which the height is a given function of the radius.3 It is virtually impossible, however, to make an outflow clepsydra in which the water-level falls equal distances in equal successive time intervals. The Oxyr-rhynchos Papyrus of the third century AD gives dimensions for the standard clepsydra: its profile was the frustrum of a cone having an upper radius of 12 fingers, a lower radius of 6 and a height of 18. Attempts were made to minimise the effects of the steady decrease in the rate of discharge by tapering the profiles of the containers. This had a scale of hours graduated upon its inside, which must have been drawn by observation so that allowance was automatically made for the decrease in the rate of discharge as the water-level fell. It was in use in Egypt and Babylonia before 1500 BC and the oldest surviving example, from Egypt, is dated about 1380 BC.
  The earliest type of water-clock was the simple outflow clepsydra, an earthenware vessel with a hole in its side, near the base. The mechanical clock is still an interesting, important (and often beautiful) machine, even though it is now being superseded by electronic timepieces. This is not meant to imply, however, that machines should be considered only in their relation to an evolutionary process, but also as satisfying creations in their own right. Water-clocks are therefore of crucial importance in the history of mechanical engineering, and not simply for their contribution to the development of the mechanical clock. In water-clocks, as in mechanical clocks, these two types of representation were often combined, and an equal, or even greater, attention was paid to methods of producing, controlling and transmitting energy.In the preceding two chapters, simulation of celestial and biological behaviour was discussed, together with the mechanical, hydraulic and pneumatic means used to impart motion to these simulations
conversations.from: human
conversations.value: Provide the last five paragraphs.
conversations.from: assistant
conversations.value: Rome , , , , , ; armament workers ; bridges ; masonry buildings –; Nero's 'Golden House' –; overshot wheel ; pilgrimages to ; ship-mills ; Trajan's column ; water-wheels
  Sasanid Iran , ; bridges ; grist milling ; intellectual activity –; irrigation , , –; roads –; technical achievements ; water mill
  Spain –, , , –; allocation f irrigation water ; bricks ; ams –, –; grist milling ; irrigation ; mines –; aper-mills
  Syria , , , , , ; bricks ; camels ; dams –; asonry ; ogival arches ; aper-mills ; postal service ; errace irrigation
  Vitruvius, , , –, , –; lifting machines –; list of quarries ; specifications: bricks –, sand , timber –; surveying instruments ; technical knowledge of ; water-clocks –; water-raising machines , –, , ; water-wheels , , ; waywiser –