The Frog Battery

Early experimenters in electricity sometimes dealt in frogs’ thighs. Dissecting a frog creates an “injury potential” in its muscles, which can then be arranged in series to produce a kind of biological battery. Carlo Matteucci strung together 12 to 14 half-thighs to make a “frog battery” strong enough to decompose potassium iodide; he was able to induce some effect even with living frogs.

Matteucci did similar work with eel, pigeon, and rabbit batteries. In 1803 Giovanni Aldini used a galvanoscope made of frogs to detect current in a circuit that ran from an ox’s tongue to its ear through Aldini’s own body. The mechanisms underlying these results weren’t always clearly understood, but they formed important early strides in bioelectrochemistry.

Maps and Symbols
Image: Wikimedia Commons

This map shows mountain symbols above a river symbol. Suppose that, in the part of the world that the map represents, there really are mountains in the location that the map indicates. But suppose that there are also mountains on the other side of the river — where no mountains are indicated on the map. Would we say that the map is inaccurate?

People tend to say yes — in general, if a marker appears on a map, then we tend to think that the absence of the marker reflects an absence of that feature from the corresponding location.

But this is very different from linguistic representation. “After all,” writes Rutgers philosopher Ben Bronner, “if I say that there are mountains north of the river, the accuracy of my assertion doesn’t depend on whether there are mountains south of the river.”

And suppose I drew a map on which some national capitals were indicated, but not all. We wouldn’t take this to mean that the absent capitals don’t exist, merely that the map is incomplete. So how can we make sense of the intuition?

(Ben Bronner, “Maps and Absent Symbols,” Australasian Journal of Philosophy 93:1 [2015], pp. 43-59.)

Image: Wikimedia Commons

The town of Bozouls in the south of France sits at the edge of a horseshoe-shaped canyon 300 feet deep, the product of 2 million years of erosion of the region’s limestone plateau by rivers and glaciers.

Because the outcrop at the center of the horseshoe is accessible only from the south, it makes an ideally defensible position, and a castle was built there in the 9th century, of which only ruins remain. In medieval times guards in towers monitored the approach 24 hours a day.

One historic building still survives: The 12th-century St. Faustus church sits right on the edge of the cliff, looking over the river.

A Shocking Experience

On a dry summer day in California, physicist Julius Sumner Miller was driving slowly near the desert when a friend overtook him on the left. The friend’s wife, in the passenger seat, reached out to hand him a package of gum. Their hands were no less than 3 inches apart when “a terrific discharge took place which possessed the classical physiological effects. The shock was momentarily disabling, as a three-inch spark in air can well be.”

Miller published an inquiry about this in the American Journal of Physics and received a reply from R.F. Miller of B.F. Goodrich in Ohio. The motion of the cars had built up charges of different amounts; Goodrich had found that the accumulated charges can (or could) increase greatly as the wheel rotates, and “as soon as the tread charges are far enough removed, they will find a lower resistance path through the rim to ground rather than around the tread,” charging the vehicle.

Even at the time the phenomenon was well known; in his original letter Miller noted that gasoline trucks were required by law to carry a dragging chain or strap. But “the question as to how great a charge may accumulate is difficult to answer.”

(Julius Sumner Miller, “Concerning the Electric Charge on a Moving Vehicle,” American Journal of Physics, 21:4 [April 1953], 316.)


The Treaty of Versailles contains a macabre clause:

ARTICLE 246. Within six months from the coming into force of the present Treaty, … Germany will hand over to His Britannic Majesty’s Government the skull of the Sultan Mkwawa which was removed from the Protectorate of German East Africa and taken to Germany.

Mkwawa was a tribal leader in German East Africa who opposed colonization. After his defeat in battle, the Germans had sent his skull to Berlin. When the United Kingdom inherited the colony after World War I, the British sought to return the skull to the Wahehe people, but there was some confusion as to its whereabouts. It wasn’t actually returned until 1954, when Tanganyika governor Sir Edward Twining tracked it down in the Bremen Museum. It now resides at the Mkwawa Memorial Museum in Kalenga, Tanzania.

(Thanks, Jon.)


A poignant little detail I found in Jay Scarfone and William Stillman’s The Wizardry of Oz: For the 1939 film version of The Wizard of Oz, MGM designated a flying monkey named Nikko to serve as the Wicked Witch’s familiar.

Unlike the other monkeys, Nikko has very small wings. An early script, dated July 5, 1938, explains that the Witch had clipped his wings to ensure his servitude.

In that script, it’s Nikko who presses the water bucket into Dorothy’s hands at the critical moment.

The Social Whirl

A problem by Russian mathematician Vyacheslav Proizvolov:

At a party each girl danced with three boys, and each boy danced with three girls. Prove that the number of girls at the party was equal to the number of boys.

Click for Answer

Primate Wanted

The ACLU found John Scopes by running a newspaper ad seeking a teacher willing to test the law about teaching human evolution in the classrooms of Tennessee. From the May 4, 1925, edition of the Chattanooga Times:

We are looking for a Tennessee teacher who is willing to accept our services in testing this law in the courts. Our lawyers think a friendly test case can be arranged without costing a teacher his or her job. Distinguished counsel have volunteered their services. All we need now is a willing client.

Scopes wasn’t a biology teacher but had filled in for one using a textbook that accepted evolution, and that was enough to set the “monkey trial” moving forward.

Strangely, the disputed textbook was the one that Tennessee required its high school teachers to use that year. Clarence Darrow later quipped in his autobiography, “It seems strange that the Dayton school board did not adopt the first and second chapters of Genesis as a modern textbook on biology.”


white house alterations

As the 19th century advanced, the White House began to seem increasingly cramped. In 1889, the centennial of the U.S. presidency, First Lady Caroline Harrison suggested adding an art wing to the east and an administrative wing to the west, with glass-enclosed palm gardens, plant conservatories, and a lily pond completing the quadrangle, creating a private inner courtyard (top). Congress shot it down.

In 1900 Army engineer Colonel Theodore Bingham offered his own plan, which would add a massive two-story cylindrical wing at each flank, with domes and lanterns patterned after those at the Library of Congress (middle and bottom). The project stalled with McKinley’s assassination.

In 1902 the architectural firm McKim, Mead and White finally renovated the mansion, doubling the size of the family living quarters and providing a new wing for the president and his staff. The modern White House still largely reflects this design.

Related: In 1947, when Harry Truman proposed building a balcony on the south face of the White House, critics raised a unique objection:

Some quarters in Washington are wondering, half in fun, if President Truman’s controversial balcony on the White House will make $20 bills inaccurate and outmoded. The $20 bill bears a picture of the south portico of the White House, where Mr. Truman has announced he wants to build his balcony. If that structure is added, the currency will be pictorially incorrect.

That’s from the Chicago Tribune, Feb. 1, 1948. “Treasury officials scoffed at the idea that the balcony might make it necessary to print a new issue of $20 bills. They agreed that the bureau of engraving and printing is proud of the accuracy of its currency engravings, but said there is a limit to accuracy.” But subsequent issues of the bill were quietly updated to reflect the new addition.$20-FRN-1928-Fr-2050-G.jpg