By Shari Kaplan
The trebuchet, a medieval weapon with a 10-foot throwing arm, sent objects hurling through the air at Fisher Middle School recently, to the delight of a crowd of seventh-grade onlookers as well as the two brothers who built the portable machine of war.
The school was not under siege; it was the site of a demonstration by Los Gatans David Hembry, 14, and Daniel Hembry, 12, who created the mostly wooden trebuchet in their back yard over the past summer.
Inspired by an article in Scientific American magazine, the boys did some additional research on the Internet and came up with the plans for a scaled-down model of an authentic trebuchet, which looks similar to a catapult at first glance but operates under different mechanical principals. Its name is derived from the Old French verb trebucher, meaning "to stumble."
When a counterweight at the end of the weapon's arm is pulled rapidly, the scoop--in this case an old jai alai basket--attached to the other end flings forward, which launches ammunition through the air in arcs of varying trajectories.
David also shared with Fisher students a historical footnote about 16th-century Spanish explorer Hernán Cortés' use of a trebuchet. During an invasion of the Aztec Empire, Cortés apparently made a miscalculation somewhere, because the large rock he meant to launch flew straight up and then came straight down, smashing the trebuchet to pieces.
While perfecting their own calculations at home, the boys launched "artillery" as varied as water balloons, empty propane cylinders, a baseball bat, weeds and rotten fruit. The water balloons went the farthest--70 feet, according to their records. At Fisher, they used safer objects, such as tennis and soccer balls.
"This was one of the weapons used in the period we're studying; it fits right in with our curriculum. It's one thing to tell students about weapons, but David brings in the geography too," Fisher history teacher Barry Siebenthall said.
David, a Los Gatos High School freshman, broached the idea to Siebenthall, his former teacher, of demonstrating the trebuchet to the seventh-grade history classes, which are studying the Middle Ages.
"I was amazed to find that this is used in so many cultures. We didn't build this to teach anyone. We like things that go bang and we like to send things flying," David said, adding that the trebuchet was used by the Arab, Mongol and Chinese civilizations, as well as by Europeans.
Diane Hembry said she always encouraged her sons in their creative feats, sometimes turning the home into a science fair of sorts in the process. She says that hands-on projects like this give students a chance to learn that "in life, nothing is given to you in a set. You have to go out and make it."
This article appeared in the Los Gatos Weekly-Times, February 21, 1996.
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