Behold the Night Clock, a 17th Century Flame-Lit Clock

iStock // BarrySheene
iStock // BarrySheene

In this video from the British Museum, we see a "night clock" designed circa 1675. What's a night clock? Well, it's a grandfather clock designed to be read in the dark. It accomplishes this feat using fire.

This night clock features an unusual face that rotates numbers into position, rather than relying on rotating hands. That moving face allows the numbers to be cut out, such that light can shine through them, making the hours' numerals visible in the dark. (There are also little notches for minutes.)

The troubling design feature is that the face was originally illuminated by an oil lamp crammed inside the clock's case, behind the face. The case is made of wood.

In this video, British Museum curator Oliver Cooke notes that because of this fire-and-wood combo, there are only about five English night clocks still in existence. This model has had its oil lamp replaced by a modern electric light, hopefully preserving it for future generations.

Step back in time to an era when reading the time in the dark meant a real risk of burning your clock up:

The Palos Verdes Blue: The Beautiful Butterfly That Wasn't Extinct After All

U.S. Fish and Wildlife Service, Wikimedia // Public Domain
U.S. Fish and Wildlife Service, Wikimedia // Public Domain

Terrible extinction news frequently makes the headlines, but sometimes, conservationists declare defeat too early. The Palos Verdes blue (Glaucopsyche lygdamus palosverdesensis) is one such example: Presumed extinct in 1983 after it seemed to vanish from its habitat in California's Palos Verdes Peninsula, it was discovered flitting among the grass in San Pedro again 11 years later.

Aside from coming back from the edge, the butterfly is notable for fuzzy wings that look brownish when closed, but a stunning silvery blue once they open up. Today it's still listed as threatened, but there's a captive breeding program to help make sure the beautiful species never goes missing again. Learn more—and see the butterfly up-close—in the video from Great Big Story below.

Why Cutesy Names Are the Most Effective Way of Getting Your Cat's Attention


When you were naming your cat, you probably didn’t consider your feline friend’s hearing range. But according to Vancouver, Canada-based veterinarian Uri Burstyn, you probably should have—at least if you want your cat to pay attention when you talk to it.

According to Dr. Uri, the name he goes by in his adorable YouTube videos, Felix isn’t a great cat name. Nor is Garfield. But Fluffy? A great choice.

Cat ears are finely attuned to high-pitched noises. Since most of their prey communicate at high frequencies—think mouse squeaks and bird chirps—cats are not as good at hearing low-frequency sounds. Ideally, you want your cat’s name to end in a high frequency, since that’s the kind of sound cats hear best and naturally pay attention to.

For human speech, that basically means that it should end in an “eeeee” sound rather than a consonant. Grumpy Cat? A bad name. Just “Grumpy?” Perfect. That's why "kitty kitty" works pretty well to get a cat to pay attention or come toward you. It's a squeaky sound.

Luckily, many nicknames in English tend to end in an ie or a y, so you probably already have a cat-friendly name for your pet waiting in the wings. Now you know why your cat is more likely to respond to your high-pitched, baby-voiced nicknames than its full name.

Enjoy Dr. Uri's explanation, and his helpful demonstration with his noble friend Lancelot, in the video below.