Trebuchets, Distilled Spirits, Stern-mounted Rudder

   Trebuchets: A trebuchet is kind of like a sling. David used a sling to protect his sheep like other shepherds. David also used his sling to kill Goliath. A trebuchet is much, much bigger than a normal sling and could do more damage. Men would shoot heads, rocks, and dead bodies out of a trebuchet. The Chinese invented the trebuchet.

   Distilled Spirits: Distilled spirits are alcohol. Ancient people used water wheels to bring energy to the city. Some water wheels needed aqueducts, but they were expensive. So they invented the vertical windmill. It brings power to the city. Instead of using the water wheel they used the vertical windmill.

   Stern-mounted Rudder: The stern-mounted rudder made it easier for sailers to sail large ships. This means it was less expensive to ship cargo.