percussion drill การใช้

• You must use special percussion drill bits for this operation.
• In 1849, Couch's assistant, Joseph W . Fowle, filed a patent caveat for a percussion drill of his own design.
• The commissioned stonemason used percussion drills to get the iron pins out that held the pieces of the granite together.
• The percussion drill is designed to go down to and collect cemented ice samples for an onboard miniaturised laboratory called ProSPA.
• The first " percussion drill " was made in 1848 and patented in 1849 by Jonathan J . Couch of Philadelphia, Pennsylvania.