pistons

"The wind displaces the papers on my desk, making a mess. "

"The royal herald sounded a trumpet to announce their arrival."

"The pencil holder was a cylinder, its smooth surface created by rotating a circle around its central axis. "

"I saw a movement in that grass on the hill."

"He built himself a cabin in a hollow high up in the Rockies."

"The ancient Romans used a powerful siege engine to break down the city walls. "

"They were all converts to Islam."

"The tadpole changed into a frog.   Stock prices are constantly changing."

"The violinist was a master of her instrument."

"Apply pressure to the wound to stop the bleeding."

"The inside of the building has been extensively restored."

"The student pressed the pencil against the paper to write neatly. "