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10       Chapter 1   EnginEEring as a DisCiplinE

                                             figure 1-2  Iron-smelting furnaces were used to soften iron core.
                                             The blacksmith could then hammer the iron into different shapes.

                                   Iron eventually replaced bronze as the primary metal used in toolmaking because
                               it was available in more areas and was cheaper to process. It could also be crafted into
                               sharper, longer-wearing tools, such as chisels and saws. As with bronze, the techniques
                               used to make iron varied in different parts of the world. People experimented with
                               temperatures and with the amounts of the various ores they used. They often devel-
                               oped these early technologies by trial and error, without an understanding of the
                               underlying scientific principles.

                       1.2.1   Key invenTions of early hisTory
                               During early history, people in different parts of the world used stone, bronze, and iron
                               for many of their needs. Tools gradually became more sophisticated and easier to use.
                                 People in colder climates had a greater need for warm clothing and shelter. People who
                               lived far from a river or lake wanted to be able to store water for later use. Over many
                               thousands of years, important inventions were developed to meet these different needs.
                                   Although many tools were used in similar ways throughout the world, the inven-
                               tions in a particular area often reflected the specific needs of those people. For exam-
                               ple, when horses were used as a form of transportation, the saddle was then invented
                               so riders could ride more comfortably.


                               About 10,000 years ago—in 8000  b.c.—the nomadic, hunter-gatherer way of life
                               changed. People learned how to grow their own food. They cultivated different types
                               of grains for food, such as wheat and barley. They became farmers who grew flax, which
                               provided fibers to make linen cloth. They invented the wheel and then vehicles with
                               wheels. They built roads and stone houses.
                                   The plow was first developed approximately 4000 b.c. This simple tool (Figure 1-3)
                               allowed farmers to turn over soil for planting more easily. It made farming much more
                               efficient. Soon, strong animals such as oxen were used to pull the plow. Farmers could

   Ch01_p007-046.indd   10                                                                                 2/9/16   3:27 PM
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