3.4 Building the bridge The contract for the bridge was won by the firm of Charles de Bergue, and a contract signed on 8 May 1871, whereby the contractor undertook to have the bridge ready for traffic in three years at a price of £217 000. In the event the bridge was opened on 31 May 1878, by which time it had cost £300 000. Work started on the south bank of the Tay, with piers laid on to solid rock foundations. As the piers advanced into the estuary, foundations needed to be sunk onto the river bed, and cai
3.3 Description of the bridge An outline plan of the bridge shows the main piers on which the bridge was laid (Figure 10). To allow shipping to pass up the Tay to Perth, a height of about 88 feet was required between the bridge girders and the high water mark in the middle of the firth. On the south bank, at Wormit, the land rose steeply t
3.1 Overview The Tay Bridge disaster came towards the end of a period of intense development of the railway system in the UK. The bridge had materials that were well known. Cast iron was used for the columns and wrought iron for the trussed girders. The construction of the bridge was, at the time, the largest single engineering project in Britain, the Tay estuary being about two miles wide near Dundee, and the bridge was the longest in the world. In the shallower approaches in the estuary, con
2.2 Transportation disasters Movement of people and goods was one of the main outcomes of the industrial revolution in Britain in the late-eighteenth century, starting with canals, which were displaced gradually by railways. Industrialisation came through innovation in manufacture, especially the development of mass-produced materials such as cast-iron. While the material had been known and used since the Elizabethan period, it could only be made in small quantities by smelting iron ore with charcoal. The Darby fam
Introduction This unit starts by giving an overview of the two main categories of disasters: disasters of natural origin and disasters of human origin. It then analyses the Tay Bridge disaster, which was caused by mechanical failure. Inevitably, human factors emerge as important in many major disasters. They may involve the failure by engineers, designers or managers to recognise faults in safety-critical products, or managers overriding the design team for other reasons – such as keeping to a dea
Acknowledgements The content acknowledged below is Proprietary (see terms and conditions) and is used under licence. Grateful acknowledgement is made to the following sources for permission to reproduce material in this unit: This video extract is from Coast Se
Video Materials
Introduction This unit focuses on the Forth Road Bridge that connects Edinburgh with Fife. This suspension bridge continues to face a number of problems regarding its deteriorating condition. The short video included in this unit illustrates some of the major structural issues facing bridges and examines some of the proposed changes to the use of the Forth Road Bridge to help increase its lifespan. This material is from our archive and is an adapted extract from Author(s):
3.4 Compact cassettes The use of magnetic tape for home use has always been somewhat problematic. Whilst it offers several advantages over discs, being capable of high-quality sound, substantially free from surface noise and able to make personal recordings, tape never became so popular as to make any serious inroads into the sales of discs. Why should this be the case? The answer is one of convenience, for magnetic tape has always been difficult to handle compared with discs – threading the tape through the mac
3.1 Introduction I've an opera here you shan't escape – on miles and miles of recording tape. Flanders, M. and Swann, D. (1977) ‘The Song of Reproduction’ from The Songs of Michael Flanders and Donald Swann, London, Elm Tree Books and St George's Press, p. 99 Sounds, pictures, measurement data, financial statistics, personal details, etc. can all be recorded and stored on magnetic media, i.e. m
2.6 Turning the handle The owners of the original hand-cranked gramophones were instructed that the standard velocity for ‘seven-inch plates’ was about 70 revolutions per minute. The owner was also warned that failure to turn the plate at the correct speed would lead to a lowering of the pitch if turned too slow, or a raising of the pitch if turned too fast. It is doubtful if true reproduction of the recorded sound was ever achieved by the owners of these machines! A better power source was needed and as electr
2.5 Making multiple copies Berliner was aware that Edison had problems duplicating cylinders. Initially copies were made from a master cylinder using a mechanical engraving process. Unfortunately this method caused the master cylinder to wear out after making just a few copies, so performers had to be asked to record several masters to ensure enough cylinders could be duplicated. An improved recording system allowed multiple master cylinders to be made by feeding several recording phonographs from one horn, but the cyl
2.4 Cutting the groove The vertical (up-and-down) cutting method, which was nicknamed ‘hill-and-dale’, shown in Figure 9(a) was invented by Edison. The lateral (side-to-side) motion developed by Berliner is shown in Author(s):
Module team
Academic staff
Dr Alec Goodyear (course chair) Professor Nicholas Braithwaite Jan Kowal Dr Tony Nixon Dr Sally Organ Robin Harding (critical reader) James McLannahan (critical reader) Dr Martin Rist (critical reader) Dr George Weidmann (critical reader) Peta Jellis (course manager) P
T356 course team
External assessor
3.1 Protein diversity Of course, our bodies can't just be made up of squidgy bubbles of phospholipid, or we would collapse in a heap on the floor! Stiffer frameworks, both inside and outside the cells, also exist and help to define shape and add strength. These frameworks are formed largely from structural proteins, a class of polymeric materials that form fibres and filaments to provide mechanical support for cells and tissues. Structural proteins are made inside cells but are often then moved into the spa
Introduction This unit examines how self-assembled structures based on lipids and proteins provide a framework for cellular processes. This unit is an adapted extract from the Open University course Engineering small worlds: micro and nano technologies
(T356).
6 Radiation All the primary vibrators we discussed in the previous section can to some extent communicate vibrations to the surrounding air and hence radiate sound. However, some radiate sound better than others. Air columns, for example, radiate sound quite well. Even though only around 1% of the energy possessed by a vibrating air column is radiated away, this is enough to produce a clearly audible note. Similarly, circular membranes and circular plates are also good sound radiators. They have a
5.15 Summary of Section 5 It is probably worth summarising some of the main points you should take away from this section on primary vibrators. The first thing to remember is that when an instrument is excited, it vibrates strongly at certain frequencies called natural (or resonance) frequencies. The reason for this is that standing waves are set up in the instrument's primary vibrator at these frequencies. The next thing to note is that some primary vibrators, such as a string or an air column, have natural frequenci
5.13.4 Pitches of notes produced by percussion instruments We have seen that none of the rectangular bar, the circular membrane and the circular plate have harmonically related natural frequencies. It may not surprise you to learn, therefore, that instruments containing these primary vibrators tend to produce notes that don't have a very well-defined sense of pitch. This is certainly true in the case of the cymbal, which has a circular plate as its primary vibrator. Whether a single cymbal is struck with a drumstick or two cymbals are crashed t
5.6 Vibrating air column You learned in the previous section that for standing waves to be set up on a string there must be reflection. A travelling wave reaches the end of the string and is reflected. This results in a second travelling wave, which moves back up the string in the opposite direction to the first wave. The two travelling waves interact to produce a standing wave. Standing waves are set up in an air column enclosed within a tube in a very similar way. Again there must be reflection. In this case,
5.2 Vibrating string: speed of wave propagation If standing waves are set up when two travelling waves moving in opposite directions interact, then how are standing waves set up on a string and why are they set up only at certain frequencies? To help answer these questions, I want you first to imagine a length of string that is fixed at one end and held in someone's hand at the other. Suppose the person holding the string flicks their end of the string in such a way that an upward pulse is sent along the string. As the pulse pa
