Lesson 8: Global Engineering Practices

History of Standards and Practices

Let's begin with measurement. Currently the entire world uses metric measures except for some notable examples (i.e. U.S.A., Liberia, Burundi, Rwanda, Yemen & Myanmar). In some cases countries have partially switched to metric. For example, Canada still uses the term acre to describe land, but describes it in metric terms. Sports, such as football, still use the yard of measure and many products will list unit weight in both metric and imperial units as many products are exported to the United States.

Each system of measurement was based on units that had practical and significant meaning within the culture, but were unique to given regions. Initially each unit had different meaning. For example, in Britain the length of different measures was determined from the physical measurements of a monarch. A yard was the distance from the sternum to the tip of the fingers. A cubit (in case you wish to rebuild the Noah's ark) was the length of a forearm to fingertip with a span being from the wrist to fingertip. If you were measuring depth of water, a fathom was 18 handbreadths (side-to-side) not be mistaken for hand lengths (or span). While each of these were practical measures in a day and age without tape measures. Trades people only worked on local projects and the trade was often passed from father to son. This kept the units fairly close, but not always. However, they did allow trades people to work and function.

As industrialization occurred, more parts were manufactured and sent to fit into existing projects. A more uniform and consistent measurement system was needed. This allowed for parts to be manufactured in a less expensive way and allowed trades people to focus more on using these materials for projects rather than having to manufacture the material prior to using it. These standards required an alignment of many items as one technology was used less and another was adopted to a greater extent. An example of this is the gauge used for railroad tracks. The distance between rails used several measures adopted from previous technologies such as the Imperial Rome Chariots or Wagon Wheel spacing.

Gauges are varied depending on where they were used. For example trams and mines used a narrower gauge (1.067 m or 3 feet 6 inches compare to a standard gauge of 1.435 m or 4 feet 8.5 inches). The smaller gauge adapted better to specific circumstances and allowed for cost savings as they were less expensive to build. However, they became inconvenient as cars built for one gauge would not work on another this would require goods from one train to be unloaded and transferred to the other train. It is easy to see how this added time and expense of unloading and reloading, not to mention the added potential of damage or lost product.

Two examples of further standardization are described in the stories of Eli Whitney and Joseph Whitworth:

Eli Whitney

Eli Whitney promoted and popularized the idea of interchangeable parts. He was awarded a contract from the United States government to produce 10,000 muskets. This took a complex process of one person building the entire musket to breaking the manufacture of the muskets into a series of simple operations. These operations contributed to the assembly of the final product. To do this each part had to meet specific standards, so the muskets could be assembled and similar parts were interchangable.

Joseph Whitworth

In England, Joseph Whitworth endorsed standardization to achieve interchangeability of parts. He introduced the standard screw threads in England. He also developed the formula for the Whitworth system of threads. This made a common, often used, part in manufacturing uniform and interchangeable. It not only simplified construction of machines, but it also simplified the repair of machines.