Appendix. Colophon

The animals on the cover of The Ruby Programming Language are Horned Sungem hummingbirds (Heliactin bilophus). These small birds are native to South America, living mainly in Brazil and Bolivia. They prefer dry, open habitats such as grasslands, and they avoid dense or humid forests.

Hummingbirds have the fastest wingbeat of all birds, and the Horned Sungem is capable of 90 wingbeats per second. (Contrast that with the vulture, the slowest of all birds, capable of just 1 wingbeat per second.) Because hummingbirds are so fast and light, they are able to hover in mid-air by rapidly flapping their wings. They can also fly backward (the only birds who can do so) in order to keep position as they drink nectar from flowers. Their long, thin bills allow them to reach deep within blossoms. Fittingly, the Portuguese word for hummingbird is beija-flor, or “flower kisser.” The English word, of course, comes from the hum made by its fast-moving wings.