For years, bearing burdens


Wheelbarrows: As gardening season wraps up, a look at the history of the extraordinary yet simple machine.

September 28, 2002|By William Amelia | William Amelia,SPECIAL TO THE SUN

Over the coming weeks, countless gardeners will be parking their wheelbarrows for the season, saying a silent thank you for its labor-saving efficiency that made many of the hard jobs in the garden a lot less onerous.

The daunting labor and heft that often come with gardening - the amateur at work on a stone wall, for example - are testimony to the wheelbarrow's value. With practice one soon becomes a believer, for the wheelbarrow is an extraordinary tool. Ubiquitous and affordable, it is a garden help-mate worthy of the highest praise as well as the honor of the acclaimed poet William Carlos Williams' memorably iconic line, "So much depends upon a red wheelbarrow. ... "

Wheelbarrow users will attest that it is a dependence that endures, from the earliest dogged days of its invention centuries ago to the present. Its evolution is a long and labored one that, you might say, was pushed across those centuries. But once it was developed, wheelbarrow users have been forever dependent upon it, though perhaps unaware of its global history or of one particular genius who helped get it rolling.

Before the wheelbarrow, there was the handbarrow, a primitive tool of the Middle Ages usually made to the measure of the sacks to be piled on it. It had four handles and was carried by two men, each using the two handles at their end and the strength of their limbs. For the times, it was a practical and useful tool.

The handbarrow traces its evolution from the curious long-shaped sack trolley, a handbarrow crudely fitted with a wooden wheel at each corner. Predating the wheelbarrow, the sack trolley is shown in 14th-century illustrations being effectively used by laborers on the docks. Throughout the ages, its uses never diminished; a slightly modernized version of the sack trolley can still be seen in use on railway platforms today.

The single achievement that improved the lot of the laborer was the earliest emergence of the wheel, when primitive rollers were placed under the dragging ends of burden-laden shafts. But it was the barrow's single wheel - an addition of pure genius - that transformed the handbarrow, primarily a muscle-driven tool, into the wheelbarrow, a device using the labor-saving laws of mechanics.

Most sources attribute the use of a single wheel to the inspiration of Leonardo da Vinci who added it to the ancient handbarrow. It was a better developed wheel than the crude disc used on the sack-trolley. In his genius, da Vinci inserted it at the forward end of the barrow in place of one of the men, converting the simple box with shafts at either end into a new tool. Much later, the push cart evolved, a larger, less mobile vehicle with two forward wheels.

Evidence exists that a crude form of the wheelbarrow was used in England in the early 14th century, a full century before the da Vinci invention. This ancient wheelbarrow had no supporting legs beneath its tray and rested on the ground. Its single wheel was placed under the center of the boxy structure, diminishing the lever effect. The European wheelbarrow, which came much later, had its wheel positioned far forward, which maximized the lever effect.

Though the wheelbarrow's origin can be debated and its chronology may be uneven in the Western mind, its mechanics are scientific certainties. Da Vinci understood the elements of lever mechanics: lever, fulcrum and load.

A lever - like the labor-saving pulley - is a simple machine: a lever bar exerts a force to move a load by turning on a pivot or fulcrum.

Archimedes, the Greek mathematician, supposedly remarked, "Give me a place to stand and I will move the earth."

Giulio Parigi's wall painting in the Uffizi Gallery in Florence, Italy, illustrates this. In the painting, a man who seems to be suspended in the universe is holding a long staff; he has positioned the other end of the staff beneath the Earth, around the South Pole, obviously levering the globe.

We use a wheelbarrow as a second-class lever, in that the closer the load is to the wheel, the less force you need to move it. And the longer the handles of the wheelbarrow, the less force required to lift a given load. In terms of the lever, the wheel's axle is the fulcrum; the handles take the effort and the load is placed between them. The effort travels a greater distance and is less than the load.

Less lever mechanics, a typical encyclopedia description of the wheelbarrow goes something like this: A shallow open box made from wood, plastic or metal for moving small multiple loads. It has a single rubber wheel in front forming a tripod with two legs in back and two wooden or steel shafts with handles for raising the vehicle off its legs and pushing or pulling it.

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