In July 1808, 100 kilometers east of the Montana Rockies, Lewis and Clark wrote, “We have repeatedly heard a strange noise coming from the mountains. … It is heard at different periods of the day and night … and consists of one stroke only, or of five or six discharges in quick succession. It is loud and resembles precisely the sound of a six-pound piece of ordnance.”

They were leading the first overland expedition of the United States territory, so it wasn’t a cannon. The sounds have never been explained.

In 1658, French admiral Etienne de Flacourt reported a curious legend among the natives of Madagascar. They described a creature, called tretretretre, that was as big as a 2-year-old calf, with a round head, a human face and ears, an ape’s feet, a short tail, and frizzy fur.

That description matched nothing on the island, so the Europeans dismissed it. But since then, fossils have been unearthed of a giant lemur, Megaladapis, that may explain the myth. It had been thought to become extinct thousands of years ago, but now zoologists think it may have survived into the sixth century, when humans came to the island, and entered their folklore.

A few Megaladapis may even have survived into the 16th or 17th century, so perhaps Flacourt was witnessing the birth of a legend.

Testimony given by James Device against his grandmother, Elizabeth Sothernes, in a trial for witchcraft, Lancaster, England, April 27, 1612:

THE sayd Examinate Iames Deuice sayth, that about a month agoe, as this Examinate was comming towards his Mothers house, and at day-gate of the same night, Euening. this Examinate mette a browne Dogge comming from his Graund-mothers house, about tenne Roodes distant from the same house: and about two or three nights after, that this Examinate heard a voyce of a great number of Children screiking and crying pittifully, about day-light gate; and likewise, about ten Roodes distant of this Examinates sayd Graund-mothers house. And about fiue nights then next following, presently after daylight, within 20. Roodes of the sayd Elizabeth Sowtherns house, he heard a foule yelling like vnto a great number of Cattes: but what they were, this Examinate cannot tell. And he further sayth, that about three nights after that, about midnight of the same, there came a thing, and lay vpon him very heauily about an houre, and went then from him out of his Chamber window, coloured blacke, and about the bignesse of a Hare or Catte. And he further sayth, that about S. Peter’s day last, one Henry Bullocke came to the sayd Elizabeth Sowtherns house, and sayd, that her Graund-child Alizon Deuice, had bewitched a Child of his, and desired her that she would goe with him to his house; which accordingly she did: And therevpon she the said Alizon fell downe on her knees, & asked the said Bullocke forgiuenes, and confessed to him, that she had bewitched the said child, as this Examinate heard his said sister confesse vnto him this Examinate.

Sothernes died in prison as her trial approached, but her family barely outlived her. James, his mother, and his sister also confessed to witchcraft and were executed on Aug. 18.

Older than the pyramids, Ireland’s Newgrange lay lost for millennia until workers uncovered it while looking for building stone in the late 1600s.

No one knows who built it or why, but each year at the winter solstice the sun shines directly along a special passage into a chamber at its heart.

Oscar Wilde wrote, “The true mystery of the world is the visible, not the invisible.”