The Engineering Profession
Engineering is one of the oldest occupations in history. Without the skills included in the broad field of engineering, our present-day civilization never could have evolved. The first toolmakers who chipped arrows and spears from rock were the forerunners of modern mechanical engineers. The craftsmen who discovered metals in the earth and found ways to refine and use them were the ancestors of mining and metallurgical engineers. And the skilled technicians who devised irrigation systems and erected the marvellous buildings of the ancient world were the civil engineers of their time. One of the earliest names that has come down to us in history is that of Imhotep, the designer of the stepped pyramid at Sakkara in Egypt about 3000 BC.
Engineering is often defined as making practical application of theoretical sciences such as physics and mechanics. Many of the early branches of engineering were based not on science but on empirical information that depended on observation and experience rather than on theoretical knowledge. Those who devised methods for splitting the massive blacks that were needed to build Stone-henge in England or the unique pyramids of Egypt discovered the principle of the wedge by trial for the pyramids were probably raised into place by means of ramps of earth that surrounded the structures as they rose; it was a practical application of the inclined plane, even though the concept was not understood in terms that could be quantified or expressed mathematically.
Quantification has been one of the principal reasons for the explosion of scientific knowledge since the beginning of the modern age in the sixteenth and seventeenth centuries. Another important factor has been the development of the experimental method to verify theories. Quantification involves putting the data or pieces of information resulting from experimentation into exact mathematical terms. It cannot be stressed too strongly that mathematics is the language of modern engineering.
Since the nineteenth century both scientific and practical application of its results have escalated. The mechanical engineer now has the mathematical ability to calculate the mechanical advantage that results from the complex interaction of many different mechanisms. He or she has new and stronger materials to work with and enormous new sources of power. The Industrial Revolution began by putting water and steam to work；since then machines using electricity, gasoline, and other energy sources have become so widespread that they now do a very large proportion of the work of the world.
One result of the rapid expansion of scientific knowledge was an increase in the number of scientific and engineering specialities. By the end of the nineteenth century not only were mechanical, civil, and mining and metallurgical engineering established but the newer specialities of chemical and electrical engineering emerged. This expansion has continued to the present day. We now have, for example, nuclear, petroleum, aerospace, and electronic engineering. Within the field of each engineering there are subdivisions. For example, within the field of civil engineering itself, there are subdivisions；structural engineering, which deals with permanent structure； hydraulic engineering which is concerned with systems involving the flow and control of water or other fluids ； and sanitary or enviromental engineering, which involves the study of water supply, purification, and sewer systems. The major subdivision of mechanical engineering is industrial engineering which is concerned with complete mechanical systems for industry rather than individual machines.
Another result of the increase in scientific knowledge is that engineering has grown into a profession. A profession is an occupation like law, medicine, or engineering that requires specialized, advanced education; indeed, they are often called the "learned professions". Until the nineteenth century, engineers generally were craftsmen or project organizers who learned their skills through apprenticeship, on-the-job training, or trial and error. Nowadays, many engineers spend years studying at universities for advanced degree. Yet even those engineers who do not study for advanced degrees must be aware of changes m their field and those related to it.
Thus, the word engineer is used in two ways in English. One usage refers to the professional engineer who has a university degree and education in mathematics, science, and one of the engineering specialities. Engineer, however, is also used to refer to a person who operates or maintains an engine or machine. An excellent example is the railroad locomotive engineer who operates a train. Engineers in this sense are essentially technicians rather than professional engineers.