In 1987, the residents of Wilkinsburg, Pa., prepared to dig up a time capsule that had been buried in the last century. But no one could remember where it was.

In 1976, during the American bicentennial, a cross-country wagon train collected the signatures of a reported 22 million Americans to be buried at Valley Forge, Pa. But when President Ford arrived for the sealing ceremony, someone had stolen the capsule from an unattended van. It remains missing.

In 1939, MIT engineers deposited a brass time capsule beneath an 18-ton magnet used in a new cyclotron. No one has figured out how to retrieve it.

(Thanks, Luke.)

The editor of the Milford (Del.) Beacon, was shown, a few days go, a coin — a composition of copper and brass — found on the farm of Mr. Ira Hammond, about two miles from that place. It is over 600 years old, bearing, date 1178; on one side is a crown, and upon the other the words ‘Josephus, I D J-PO RT-ET-AL G-REX,’ very legible, and the work well executed. This coin is about two hundred years older than the discovery of America, and the question very naturally arises, where did it come from?

— Scientific American, 6:250, 1851

UPDATE: Another mystery solved: A reader points out this entry in the U.S.
Bureau of the Mint catalogue of coins and tokens:

Gold
16. Meia dobra, 1768. (R). 6*Jy.
JOSEPHUS.I.D.G. – PORT. ET.ALG.REX.
Laureated bust, draped, to right; below, R 1758. Rev. Garnished shield
of arms of
Portugal, crowned. Edge, wreath. 32 mm. ; 216 grs.

Probably Scientific American‘s correspondent discovered a Portuguese coin from the 18th century and misread the date. (Thanks, John.)

Being the paper of record brings with it some odd responsibilities. On March 10, 1975, the New York Times inadvertently published the wrong dateline in its Late City editions, officially dating the day’s news “March 10, 1075.”

Modern readers would understand that this was a simple typo, of course, but the editors grew concerned that future historians might be confused to discover a Times issue from the Middle Ages. So the following day’s issue contained a historic correction:

In yesterday’s issue, The New York Times did not report on riots in Milan and the subsequent murder of the lay religious reformer Erlembald. These events took place in 1075, the year given in the dateline under the nameplate on Page 1. The Times regrets both incidents.

Paradoxically, a shadow can go even faster than light! We can [cast a shadow] first at one star and then toward another star. We can take two stars more or less the same distance from Earth, such as Acrux in the Southern Cross and Bellatrix in Orion (both are 360 light-years away from us). We point the flashlight at Acrux and then we make the beam slide slowly toward Bellatrix. Three hundred sixty years later, the shadow … (which will at this point have become huge and very fast) will reach Acrux, and just a few seconds later it will be at Bellatrix, after having crossed one quarter of the vault of the sky far faster than the speed of light. Can shadows do things that are physically impossible?

— Roberto Casati, Shadows, 2000