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He invented what he called
"sheet asphalt pavement." Today, nearly all of the paved roads in
the world are made from the material that de Smedt first used more
than 135 years ago. Nothing too exciting about that, but there's an
interesting story about one of the pioneers in the road-building
industry.
The first roads were built in modern-day Iraq in approximately
4000 B.C., using stones as the main ingredient. As you can imagine,
roads made of stone tend to be pretty rough. Asphalt-based roads, on
the other hand, are processed from crude oils and result in smooth
roads.
In the late 1700s, three Scottish engineers pioneered the
building of smooth roads. We focus on a man named John Metcalfe in
this story. Metcalfe was born in Knaresborough, Scotland (that's
pronounced "Knaresborough") in 1717.
Dolly Benson was the only woman that John had ever loved. Her
parents had arranged for her to be married, but not to John, who was
out of town at the time. When he returned, he found out about her
upcoming marriage, so he went to see her the night before the
wedding. Climbing the wall of her home, he proposed to her, and they
eloped. It was exactly the same way you've heard of in other stories
-- he put a ladder up to her bedroom window and asked her to marry
him. So off they went, and they lived happily ever after with the
four kids they had together.
There's more to John Metcalfe's story, though, than his
relationship with Dolly.
He had served as a guide through Knaresborough Forest. Nothing
out of the ordinary here, until you find out more about him.
He joined the British army and was even in a battle. Again,
nothing out of the ordinary here, until you find out a little more
about him.
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Metcalfe began his road-building career in 1765 when he built a
simple three-mile road connecting two towns. By 1790, he had built
180 miles of roads in Yorkshire, England (which is where Yorkshire
pudding comes from). His major contribution to road-building was in
his method of using three layers, which consisted of large stones
for the base, road material such as smaller rocks and earth in the
middle, and a layer of gravel on top. His roads allowed the
rainwater to drain off better than on roads built by his
predecessors.
Metcalfe became the first road builder to build a road over a
marsh. Nothing out of the ordinary here, until you find out more
about him.
You see, Metcalfe built his roads despite the fact that he was
blind! He caught smallpox when he was 6 years old, causing him to
lose his sight.
I mentioned earlier that there were three Scottish engineers who
pioneered the building of smooth roads. What about the other two?
Thomas Telford was the first to raise the center of the roads to
allow rainwater to drain down the sides. He also figured out how
thick the stones would have to be -- this was before the invention
of asphalt-paved roads -- to handle the weight of horses and buggies
that were used back then.
The other Scottish engineer, John McAdam, mixed the stones with
tar to create a smooth road. His roads became known as "tarmacadam
roads" and were used until the 1870s, when they were replaced with
asphalt roads.
This is where the word "tarmac" comes from.
[Paul Niemann]
Paul Niemann may be reached at niemann7@aol.com. You can learn
more about Invention Mysteries by visiting the official
Invention Mysteries website.
Copyright Paul Niemann 2006
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