... screw or tympanum The Cofferdams were built, so the laborers could erect the piers without going under water. First the piles of the Cofferdam, a piece of wood sharpened like a pencil, were driven into the riverbed, then pumped. When the pumping was finished, each pier stood on a foundation of tar covered piles and was constructed of carefully cut stones on the inside. The mortar used between the stones contained pozzolana, a volcanic ash. When the piers reached a height of ... the use of the keystone block. The force was directed down on to the top of the keystone. Because of its shape...

• Word Count: 1593
• Approx Pages: 6
• Has Bibliography
• Grade Level: High School

... a device called an Archimedean screw or tympanum The Cofferdams were built, so the laborers could erect the piers without going under water. First the piles of the Cofferdam, a piece of wood sharpened like a pencil, were driven into the riverbed, and then pumped. When the pumping was finished, each pier stood on a foundation of tar covered piles and was constructed of carefully cut stones on the inside. The mortar used between the stones contained pozzolana, a volcanic ... through the use of a keystone block. The force was directed down on to the top of the keystone. Because of its shap...

• Word Count: 1601
• Approx Pages: 6
• Has Bibliography
• Grade Level: High School