The Seconds Pendulum

An interesting historical fact from these MIT notes: Christiaan Huygens proposed defining the meter conveniently as the length of a pendulum that produces a period of 2 seconds. A pendulum’s period is

\displaystyle  T = 2\pi \sqrt{\frac{l}{g}},

so, using Huygens’ standard of T = 2s for 1 meter,

\displaystyle  g = \frac{4\pi ^{2}\times 1\ \textup{meter}}{4s^{2}} = \pi ^{2}ms^{-2}.

“So, if Huygens’s standard were used today, then g would be π2 by definition.”


Dutch Anabaptist Dirk Willems had made good his escape from prison in 1569 when a pursuing guard fell through the ice of a frozen pond and called for help.

When Willems turned back to rescue him, he was recaptured, tortured, and executed.

Podcast Episode 342: A Slave Sues for Freedom

In 1844 New Orleans was riveted by a dramatic trial: A slave claimed that she was really a free immigrant who had been pressed into bondage as a young girl. In this week’s episode of the Futility Closet podcast we’ll describe Sally Miller’s fight for freedom, which challenged notions of race and social hierarchy in antebellum Louisiana.

We’ll also try to pronounce some drug names and puzzle over some cheated tram drivers.

See full show notes …

Nowhere Man

In 1819, as a riposte to David Hume’s skepticism of the Gospel history, Richard Whately published Historic Doubts Relative to Napoleon Bonaparte:

‘But what shall we say to the testimony of those many respectable persons who went to Plymouth on purpose, and saw Buonaparte with their own eyes? must they not trust their senses?’ I would not disparage either the eyesight or the veracity of these gentlemen. I am ready to allow that they went to Plymouth for the purpose of seeing Buonaparte; nay, more, that they actually rowed out into the harbour in a boat, and came alongside of a man-of-war, on whose deck they saw a man in a cocked hat, who, they were told, was Buonaparte. This is the utmost point to which their testimony goes; how they ascertained that this man in the cocked hat had gone through all the marvellous and romantic adventures with which we have so long been amused, we are not told.

“Let those, then, who pretend to philosophical freedom of inquiry, who scorn to rest their opinions on popular belief, and to shelter themselves under the example of the unthinking multitude, consider carefully, each one for himself, what is the evidence proposed to himself in particular, for the existence of such a person as Napoleon Buonaparte: — I do not mean, whether there ever was a person bearing that name, for that is a question of no consequence; but whether any such person ever performed all the wonderful things attributed to him; — let him then weigh well the objections to that evidence, (of which I have given but a hasty and imperfect sketch,) and if he then finds it amount to anything more than a probability, I have only to congratulate him on his easy faith.”

The whole thing is here.

An Old Friend

Finland’s Raahe Museum contains the oldest surviving diving suit in the world, “The Old Gentleman,” an outfit of calf leather that could sustain a man long enough to inspect the bottom of a sailing vessel.

Museum conservator Jouko Turunen made a copy in 1988. Pleasingly, he called it The Young Gentleman.

The River Witham Sword

This 13th-century double-edged sword, possibly of German manufacture, was found in the River Witham, Lincolnshire, in 1825. Inlaid in gold wire along one of its edges is a curious inscription:


It’s been speculated that this is a religious invocation, but its full meaning is not clear. In 2015 the British Library invited readers to offer their thoughts, but no conclusive solution was reached. Medieval historian Marc van Hasselt of Utrecht University says it may be the product of a sophisticated workshop that made swords for the elite, as similar blades have been found throughout Europe. “These similarities go so far as to suggest the same hand in making the inscriptions. However, their contents are still a mystery, regardless of their origins.”

Podcast Episode 341: An Overlooked Bacteriologist,_Calcutta,_1894_Wellcome_L0037329.jpg
Image: Wikimedia Commons

In the 1890s, Waldemar Haffkine worked valiantly to develop vaccines against both cholera and bubonic plague. Then an unjust accusation derailed his career. In this week’s episode of the Futility Closet podcast we’ll describe Haffkine’s momentous work in India, which has been largely overlooked by history.

We’ll also consider some museum cats and puzzle over an endlessly energetic vehicle.

See full show notes …


The Massachusetts Archives holds a 1775 bill from Paul Revere for “self and horse.”

It covers the period April 21-May 7, starting three days after the midnight ride. The provisional state government paid it.

“It seems at first blush incongruous, but then again, it’s not,” Massachusetts secretary of state William F. Galvin told the Bangor Daily News. “Even a revolutionary horse needs to be fed, not to mention Paul Revere himself.”

The Presidents’ Tree

In August 1865, Maryland farmer Samuel M’Closky Fenton carved this grid into an American beech in Takoma Park:

  	N L O C N I L M L I N C O L N
	L O C N I L M A M L I N C O L
	O C N I L M A H A M L I N C O
	C N I L M A H A H A M L I N C
	N I L M A H A R A H A M L I N
	I L M A H A R B R A H A M L I
	L M A H A R B A B R A H A M L
	I L M A H A R B R A H A M L I
	N I L M A H A R A H A M L I N
	C N I L M A H A H A M L I N C
	O C N I L M A H A M L I N C O
	L O C N I L M A M L I N C O L
	N L O C N I L M L I N C O L N

He intended it as a memorial to Abraham Lincoln, who had been assassinated that April. Starting at the central A and following a jagged path toward any of the corner Ns will spell out the fallen president’s name.

Fenton also carved the name of every American president to date. In 1948 the tree was enclosed in an iron fence and dedicated “as a living memorial to men who gave their lives for their country in the war of 1861-1865.”

Podcast Episode 340: A Vanished Physicist

In 1938, Italian physicist Ettore Majorana vanished after taking a sudden sea journey. At first it was feared that he’d ended his life, but the perplexing circumstances left the truth uncertain. In this week’s episode of the Futility Closet podcast we’ll review the facts of Majorana’s disappearance, its meaning for physics, and a surprising modern postscript.

We’ll also dither over pronunciation and puzzle over why it will take three days to catch a murderer.

See full show notes …