A Whistle Test

I had my eyes set on the tarnished copper whistle slung over my chest! Resting along the sunlit brick planter ledge, I pulled the red lanyard over my cap and set the metal cylinder flat against the rough mortar. Inside the little chamber, a tiny dried pea of gravel was jammed tight near the air slit. Time to fix it! I grabbed a stiff pine needle from the dark soil, knelt down, and carefully picked at the gritty obstruction. Pop! Out tumbled the pebble. I raised the whistle to my mouth with both gloved hands and blew with all my might! A sharp, triumphant tweet echoed down the alley walls!