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.”

In a Word

n. a lover of books

Created by Slovakian artist Matej Kren, the Idiom Installation in Prague’s municipal library seems to present an infinite tower of books, thanks to some conveniently placed mirrors.

It debuted at the São Paulo International Biennial in 1995 and moved permanently Prague in 1998.

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 …

Road Games

Statistics textbooks sometimes ask: Suppose you’re driving on the highway and adjust your speed so that the number of cars you pass is equal to the number that pass you. Is your speed the median or the mean speed of the cars on the highway?

The expected answer is that it’s the median speed, since the number of cars traveling more slowly than you is equal to the number traveling faster. But California State University mathematician Larry Clevenson and his colleagues wrote in 2001, “This certainly is true of the cars that you see, but that isn’t what the problem asks, and it isn’t the correct answer.”

Surprisingly, they found that the correct answer is the mean. “If you adjust your speed so that as many cars pass you as you pass, then your speed is the mean speed of all the other cars on the highway.” Details at the link below.

(Larry Clevenson et al., “The Average Speed on the Highway,” College Mathematics Journal 32:3 [2001], 169-171.)

Jacob’s Ladder
Image: Wikimedia Commons

In 1829, engineer J.W. Hoar built a cable railway up the side of Ladder Hill in Jamestown, Saint Helena, in the South Atlantic, to carry cargo up the 40-degree incline to Ladder Hill Fort. After 40 years, termite damage forced the closure of the railway, but the associated staircase remains open to intrepid tourists.

The fastest recorded ascent to date was made by Scotland’s Graham Doig in 2013. He climbed the 699 steps in 5 minutes 16.78 seconds.


From a letter by Phillips Brooks to a friend on the death of his mother, Nov. 19, 1891:

May I try to tell you again where your only comfort lies? It is not in forgetting the happy past. People bring us well-meant but miserable consolations when they tell us what time will do to help our grief. We do not want to lose our grief, because our grief is bound up with our love and we could not cease to mourn without being robbed of our affections.

Choosing Sides

shekatkar image

Temple University anthropologist Wayne Zachary was studying a local karate club in the early 1970s when a disagreement arose between the club’s instructor and an administrator, dividing the club’s 34 members into two factions. Thanks to his study of communication flow among the members, Zachary was able to predict correctly, with one exception, which side each member would take in the dispute.

The episode has become a popular example in discussions of community structure in networks, so much so that scientists now award a trophy to the first person to use it at a conference. The original example is known as Zachary’s Karate Club; the trophy winners are the Zachary’s Karate Club Club.

(Wayne W. Zachary, “An Information Flow Model for Conflict and Fission in Small Groups,” Journal of Anthropological Research 33:4 [1977], 452-473.) (Thanks to Snehal Shekatkar for the image.)


In the Middle Ages, before the advent of street lighting or organized police forces, fortified cities and towns used to discourage vandals by closing their gates and laying chains across their roads, “as if it were in tyme of warr.” Historian A. Roger Ekirch writes that Nuremberg “maintained more than four hundred sets [of chains]. Unwound each evening from large drums, they were strung at waist height, sometimes in two or three bands, from one side of a street to the other … [and] Paris officials in 1405 set all the city’s farriers to forging chains to cordon off not just streets but also the Seine.”

In some cities, residents who’d returned home for the night were required to give their keys to the authorities. A Paris decree of 1380 reads, “At night all houses … are to be locked and the keyes deposited with a magistrate. Nobody may then enter or leave a house unless he can give the magistrate a good reason for doing so.”

(From Jane Brox, Brilliant: The Evolution of Artificial Light, 2010.)

Waste Not, Want Not

In 1929, Indiana Bell bought the Central Union Telephone Company of Indianapolis. Central Union’s headquarters building at that time was more than 20 years old and inadequate to the new company’s needs, but rather than demolish it, architect Kurt Vonnegut Sr. (father of the novelist) proposed moving it out of the way.

Over the course of a month, the 10,000-ton building was shifted 52 feet south, rotated 90 degrees, then shifted another 100 feet west. Amazingly, this was all accomplished while the building was open and operating — customer telephone service was never interrupted, and the building’s gas, heat, electricity, and water operated continuously throughout the move.

A new headquarters was built on the old site, and the shifted building stood in its new position until 1963.

The Bishop Problem

rolling die puzzle

What is the minimum number of bishops needed to occupy or attack all squares on an 8 × 8 chessboard?

Click for Answer