This book is about a machine that has affected every aspect of our lives.This book is about a simple machine that has impacted our lives.

The wheelbarrow is perhaps one of the simplest and most useful tools in the history of mankind. Most people never think about where it comes from, as they see it everywhere on construction sites and in gardens today. Its invention has a history of about two thousand years back to the ancient China.

The earliest reliable evidence for the wheelbarrow dates back to the Han Dynasty (1st and 2nd century AD) in China. A mural from Sichuan Province, from around 118 AD, shows a single-wheeled cart that is being pulled by a human. These images are the earliest visual evidence for this device. The archaeological evidence is supported by written references that come from the same time period, indicating that the wheelbarrow was already in use by it.

The invention is traditionally credited to Chinese military strategist Zhuge Liang, who lived during the Three Kingdoms period (early 3rd century AD). He is said to have invented a very efficient means of conveying military supplies, the "wooden ox" or "gliding horse" cart. Historians have speculated whether these were genuine wheelbarrows or a new type of transport because of the simplicity of the wheels, but the ubiquity of the device in logistics and manual work of early Chinese society has left no doubt about its importance.

The ingenious part of the Chinese wheelbarrow was not its structure, but rather its wheel placement. In contrast to later European designs, the Chinese designs usually oriented the large central wheel at the bottom of the load. This placed the entire load directly on the axle of the wheel, and thus it carried very little load for the person pushing. A simple engineering feat that enabled a single worker to move loads which would have needed more than one to move.

The wheelbarrow was invented in China, but didn't come to Europe until the Middle Ages, about 1,000 years later. The earliest clear depictions by Europeans are from the beginning of the 13th century in manuscripts and stained glass windows from France and England. European designs preferred a smaller wheel at the front of the barrow that would move the weight to the operator but give a greater ability to manoeuvre the barrow in confined areas, like building sites and mines.

It is unclear how the wheelbarrow got from East to West. Other historians believe that the idea was brought to Europe through trade routes between Asia and Europe. Some speculate that it could have been a rediscovery. A millennium is a long time for transmitting the tradition, but direct transmission is a possibility even if it is not easy to prove.

However, the impact of the wheel barrow on human labour cannot be disputed. It eliminated the physical burden of building, farming and mining activities over countless centuries and cultures. Back then there was no machinery and hauling heavy loads was done exclusively on foot, using one's back and arms. The wheelbarrow made a dramatic change to that equation, providing many times the capacity of a single worker.

It is still in use today in much the same form in which it was found in medieval Europe, and it is an excellent design solution to the problem that it was designed to solve.