Vehicle horn horn. Bicycles often have a classic "bulb horn", operated by squeezing a rubber bulb attached to a metal horn. Squeezing the bulb forces air through a steel reed located in the throat of the horn, making it vibrate, producing a single note. The flaring horn matches the acoustic impedance of the reed to the open air, radiating the sound waves efficiently, making the sound louder. Other types of horns used on bicycles include battery-operated horns (sometimes even car horns on 12-volt circuits are incorporated) and small air horns powered by a small can of compressed gas. Oliver Lucas of Birmingham,
A Sound Like Someone Trying Not to Make a Sound make a sound". The child wakes his father and describes the sound to him. The child believes that the sound comes from a "monster with no arms and legs", which "slides on its fur" and "pulls itself along on its teeth". The father and child discover that the sound is coming from the mice in the walls, and the child is comforted by his parent. The two return to sleep. A "Publishers Weekly" reviewer wrote that "In showing young readers that the things that go bump in the night are, in reality, not so scary, Irving succeeds in helping them