Down the air return vent

Hans won a "Connect 4" type game at Bible Bingo last night. It was a small, cheap (in both senses of the word) game with 30 disks less than 1/2" diameter. After playing the game twice, Hans and Fritz decided it would be fun to drop them down the air return vent in the hall. We live in a 95 year old house. The main air return is a 1' x 2' conduit that drops down from the hallway floor, to almost the basement floor. We've lost a comb and a few other things down there accidentally, but this is the first intentional, fun, dropping incident that I have witnessed. Too bad I wasn't fast enough with the camera.