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Watch as a selection of history's most gruesome projectile weapons are tested for their accuracy and deadliness.

Introducing the bone-crunching, flesh-tearing series that takes an alternative look at ancient weaponry.

Climate experts examine what effect each rise of 1ºC could have on the world.

This time the Planet Mechanics are tackling one of the world’s biggest problems, traffic pollution.

Now it’s time for Dick and Jem to proudly reveal their new thoroughbred delivery vehicle to the expectant new owners.

The next morning, and the whole bike has to be stripped down to get to the heart of the problem.

The next morning and the Planet Mechanics’ eco-workshop is up and running. Dick and Jem are in the south of England on their...

Dick and Jem have come to this scrap heap to collect an old vehicle to recycle.

So they’re building a moped powered by fresh air. They’ll replace the petrol engine with an air motor and the gas tanks...

Fortunately they still have the oil they made earlier. So it’s time for the ultimate test: will that oil fire up the grain...

A few weeks later, Dick and Jem are back and can’t wait to see how much the gas tank has risen.

To drive the press, they’re salvaging this scrap lawnmower and will convert its petrol engine to run on biogas.

Although the tank seems leak proof, Dick and Jem are taking no chances with their potentially explosive gas plant. They’ve...

Andy has tipped them off about a tank. They could fill this with cow slurry and use it as a digester to make biogas.

Grain can’t be stored if it’s too wet. Trouble is the average British summer means crops sometimes have to be harvested...