Phantom Cameras Used in Testing Grenades from 17th Century French Shipwreck Vision Research
Following the loss of the colony’s last ship, La Salle attempted to lead the settlers on foot to the nearest French settlement, thousands of miles away. While a scant few made it back to France, many succumbed to the elements, while La Salle himself was murdered by his own men. This historic event marked the end of the first permanent European settlement in Texas.
For more than 300 years, the wreckage of La Belle remained an afterthought.Then, in 1995, Texas state archaeologists discovered one third of the ship at Matagorda Bay, about 120 miles south of Galveston, marking one of the most important archaeological finds of the century. A major excavation was launched by the state of Texas using a large, steel structure called a cofferdam – which was built around the ship to enable seawater to be pumped out. Over the next year, Texas Historical Commission archaeologists recovered the entire shipwreck, including the hull of the ship, as well as an array of important artifacts. These artifacts included hundreds of thousands of glass beads, tons of musket shot, bronze hawk bells, and three bronze cannons that were meant to defend the colony from attackers. “Many of these artifacts were likely remnants of the colony’s secret goal – to steal the Spanish silver mines in northern Mexico,” said Eric Ray, La Belle researcher at the Corpus Christi Museum of Science and History in Corpus Christi, Texas.
Archaeologists also discovered a collection of ceramic pots that were sealed by cork and fabric. Inside each pot was a mass of degraded gunpowder and an iron grenade. The ceramic pots, dubbed “fire pots,” were of particular interest to Ray and his team because they represented an early form of hand grenade. The word “grenade” derives from the French word for a “small explosive shell.” While both ceramic and iron grenades are known from the archaeological investigation of other sites, the composite forms found at La Belle were unique, according to Ray. “There is only one historical reference to an iron grenade inside a ceramic pot,and it’s from a French armament treatise released the same year La Belle sailed. The action and effectiveness of this type of device were unknown, and we were intrigued. So, in order to learn more about how these grenades functioned, there was only one option for us – to build new ones.”
Faster Than the Speed of Sound
Ray joined forces with artists and sculptors at nearby Victoria College and Texas A&M University – Corpus Christi, and together, they began the undertaking of building new ceramic pots and iron grenades. After months of replicating the grenades, the research team was granted permission by the Corpus Christi Police Department to launch them at the local bomb range. In order to accurately analyze the explosive effects of the grenades, Ray had to invest time in cutting edge cameras that could capture images at ultra-high speeds. “We literally had fragments of iron and ceramic traveling at hundreds of miles per hour in all directions, faster than the speed of sound. We needed a method to record the explosion that would yield the most accurate results in helping us formulate an understanding of how the grenades operated,” he noted. With the sophisticated, powerful features of Vision Research’s Phantom v710 and v1610 high-speed cameras in tow, the team performed 11 grenade launching tests in two days, documenting significant information with the Phantom cameras as part of the study of La Belle.
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15 February 2012
