This is my summary of lessons two through four. In lesson two, I studied the invention of the suspension bridge. Ancient bridges such as the ones the Romans built were strong, but very heavy. They consumed lots of materials, and required much labor to build. Other cultures built simpler suspension bridges using vines, and later upgraded to metal chains and planks of wood. However, these ancient bridges had one main problem: they weren’t very stable, so pedestrians were about the limit on how much the long bridge could hold up. Then, James Finley came along.

James Finley combined Roman arch bridges with the simple rope bridges to invent an efficient but strong bridge. Finley was a friendly Irish immigrant who got involved in politics. Because of this, he helped in modernizing Pennsylvania’s road system. Finley spent years experimenting with different bridge designs to find the most efficient one.

Once Finley finally invented the modern suspension bridge design, bridges required far less materials to build a bridge just as stable as older designs. Suspension bridges use tall towers to support the bridge by connecting them with with cables. These cables take the strain off the bridge, enabling it to carry a load far heavier than the bridge itself.

Then, in lesson three, I studied the invention of the fire hydrant. Before the fire hydrant was invented, pipes with water flowing through them were positioned underground instead. Fire fighters had to dig a large hole into the ground and puncture holes in these pipes during a fire, and the water contained in them would fill the hole the firefighters dug. Then, the firefighters would form a bucket brigade to put out the fire. After the fire was put out, wooden plugs would have to be installed to keep the water from continuously flowing out of the pipes.

This wasn’t too terrible, but it could take time. A replacement was needed for the pipes, and it came in the form of the fire hydrant. The fire hydrant, invented by Friedrich Gaff, is basically a large iron fire plug that can be opened to release a strong jet of water. The main benefit of the fire hydrant is that it provides a quick, convenient way to put out fires, giving the fore less time to grow and cause damage.

Next, in lesson four, I learned about the invention of the locomotive. Richard Trevithick was born in England, where he grew up among miners. He was fascinated by the steam engines that pumped water out of the mines every day. Trevithick was also interested in the experiments of his neighbor- William Murdock- was making with high-pressure steam engines.

Trevithick built the first locomotive from a small high-pressure steam engine based on his mining experiment. Locomotives contain boilers, which convert water into steam. The steam then powers pistons used to move the locomotive. They can tow heavy carts filled with either human passengers or goods.