Category: Odd Science

Editor’s note: The images in this article are original editorial illustrations. They are not photographs of the University of Queensland apparatus or scientific evidence.

In a glass funnel at the University of Queensland, a black substance that looks solid has been conducting one of science’s slowest demonstrations since 1927. It can feel hard and even shatter under a hammer, yet given enough time it flows.

The substance is pitch, an extremely viscous fluid. In this experiment, “extremely” means that only nine drops have completed their descent in nearly a century. A tenth is still taking shape.

A lecture demonstration with no convenient ending

University of Queensland physics professor Thomas Parnell set up the apparatus in 1927. According to the university’s Physics Museum, he heated pitch, poured it into a sealed glass funnel, and then let it settle for three years. The funnel’s stem was cut in 1930, giving gravity a very long assignment.

The first drop took roughly eight years to fall. For the first several decades, another drop arrived about every seven to nine years. The eighth and ninth took longer, about 13 years apiece, according to a University of Queensland account of the ninth drop.

Why something hard can still flow

Viscosity is a fluid’s resistance to flowing. Water has relatively low viscosity; honey resists flow more strongly. The pitch in Parnell’s funnel sits at an almost comical extreme. The Physics Museum says estimates put it at about 100 billion times more viscous than water.

That number is an estimate for this sample and setup, not a universal constant for every material called pitch. Temperature matters greatly. The apparatus was created as a teaching demonstration rather than a tightly climate-controlled experiment. University records note that seasonal temperature changes affect the flow, and air-conditioning installed near the display helped slow later drops.

The experiment therefore makes a useful point without requiring pitch to fit neatly into everyday categories. On a human timescale, it seems solid. On the experiment’s timescale, its continuing deformation is unmistakable.

The drop that kept dodging its audience

The long waits created a second, accidental experiment: could anyone catch a drop at the decisive moment?

Former custodian John Mainstone repeatedly came close. University accounts say he missed the 1977 drop by a day and the 1988 drop after briefly leaving the display. In 2000, a webcam was watching—but a short power failure covered the crucial interval.

The ninth behaved differently. Instead of cleanly breaking free, it slowly touched the older drop beneath it in April 2014. The university used time-lapse images to study the contact, then replaced the crowded beaker so the experiment could continue. That intervention is one reason a simple drop count hides a messier history: “falling” has not always meant a dramatic, free-falling plop.

A record with an important qualifier

Guinness World Records recognizes the Queensland Pitch Drop Experiment as the longest-running laboratory experiment. That wording is best treated as a specific record title, not a claim that no older scientific apparatus or long-term observation exists anywhere. The University of Queensland also describes the piece as an ongoing teaching experiment and museum object.

The funnel still contains enough pitch for future drops. Predictions are necessarily loose because temperature, the changing amount of material, and the geometry of each forming drop affect the timing. The honest answer to “When will the tenth fall?” is the answer this apparatus has always demanded: keep watching.

What the experiment actually proves

• Pitch can behave like a hard solid during a quick test and still flow under sustained stress.
• Our everyday labels depend partly on the timescale of observation.
• A simple demonstration can become scientifically interesting in new ways when its surroundings and maintenance history affect the result.

It does not prove the common myth that old window glass sags because glass is a slow liquid. The pitch in this apparatus was selected precisely because it flows on a timescale that can be observed across years. The experiment’s weirdness is real enough without borrowing claims from unrelated materials.

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Sources

• University of Queensland Physics Museum: Famous Pitch Drop Experiment
• University of Queensland News: Pitch drop touches down—oh so gently
• University of Queensland: Explainer—the pitch drop experiment
• Guinness World Records: Longest-running laboratory experiment

In a glass case at the University of Oxford, a metal ball no bigger than a pea keeps making the same short trip. It touches one brass bell, crosses a narrow gap, touches a second bell, and heads back again. The mechanism was set up in 1840. Oxford’s Department of Physics says it still oscillates about twice each second.

The apparatus is usually called the Oxford Electric Bell or the Clarendon Dry Pile. Its longevity sounds like a perpetual-motion story, but it is nothing of the kind. The bell is an unusually frugal electrical machine: it uses high voltage, an extraordinarily small current, and a simple electrostatic shuttle to spend its stored energy almost grudgingly.

Two batteries, two bells, one restless ball

The visible arrangement is beautifully spare. Two tall dry-pile batteries stand side by side. Each connects to a brass bell, giving the bells opposite electrical charges. A metal sphere about four millimeters across hangs between them on a thread.

When the sphere touches one bell, it picks up that bell’s charge. Like charges repel, so the newly charged sphere is pushed away from the bell it has just touched. At the same time, it is attracted toward the oppositely charged bell. On contact with the second bell, its charge changes and the process reverses. The ball becomes a tiny courier, carrying charge back and forth while tapping the bells on every crossing.

A 2025 demonstration published in The Physics Teacher reproduced the principle with modern, readily available materials. The authors describe the motion as an electrostatic effect driven by charge on the battery terminals. Their replica helps confirm that the famous Oxford apparatus does not need a conventional motor or a large continuous current to keep the shuttle moving.

The trick is high voltage and almost no current

Most battery-powered devices draw enough current to do conspicuous work: heating a wire, turning a motor, lighting a screen. The Oxford bell has a much smaller assignment. Its clapper is light, the distance is short, and each trip transfers only a minuscule amount of charge.

In a history of Oxford’s Clarendon Laboratory, physicist A. J. Croft described the apparatus as operating at roughly 2,000 volts but only about one nanoampere. Those figures are estimates rather than a promise about its present output, but they capture the central point. Voltage measures electrical potential; current measures the flow of charge. The bell has plenty of the first and vanishingly little of the second.

That tiny current is why “still running” does not mean “free energy.” The batteries are continually surrendering stored chemical energy, just at a rate so low that the process has outlasted generations of laboratory equipment. Oxford estimates that the bells have been struck on the order of 10 billion times. The sound is muffled by the display case, so visitors see the motion rather than hear a 186-year concert.

What is inside the dry piles?

This is where documentation ends and informed reconstruction begins.

Oxford says the two battery columns are covered with an insulating layer of sulfur. Their exact internal construction remains unknown. Similar early nineteenth-century “dry piles” were assembled from large numbers of very thin metal-and-paper layers. The university’s exhibit notes that the Oxford piles may contain alternating foil and paper coated with manganese dioxide. Croft favored a related historical recipe involving roughly 2,000 pairs of zinc and “silvered” paper discs.

Those are plausible comparisons, not an inventory of the sealed Oxford batteries. The device cannot be opened without ending—or at least radically altering—the very long-running performance people want to understand. Its survival has therefore protected its mystery.

The word dry can also mislead. Croft argued that the pile would not work if it were absolutely moisture-free. In his account, the sulfur coating helped retain a small amount of water needed for the electrolyte while limiting leakage and unwanted chemical reactions. It is a sealed, slow electrochemical system—not a stack of perfectly dry inert wafers.

A three-year prediction that missed by two centuries

The apparatus carries a handwritten note saying it was “set up in 1840,” although Oxford records that it may have been constructed about 15 years earlier. Croft’s history reproduces an 1841 letter to Oxford physicist Robert Walker from instrument maker Francis Watkins. Watkins doubted that the residual power could keep the clapper moving for more than three or four years.

That was a reasonable expectation based on the instruments of the period. It was also spectacularly wrong. The sulfur seal, the enormous number of thin battery layers, the microscopic current draw, and the light electrostatic shuttle combined into a machine whose useful lifetime was far outside ordinary experience.

Why it is not perpetual motion

Oxford explicitly rejects the popular “perpetual motion” label. The bell has an energy source: its dry-pile batteries. Every swing dissipates a little energy through electrical resistance, air drag, sound, deformation, and friction at the suspension. Eventually the chemical potential will become too weak to move the clapper, or a mechanical part will fail first.

The uncertainty is not whether it will stop, but how and when. Croft thought the clapper might wear out before the electrochemical energy was exhausted. That, too, is a hypothesis. The sealed apparatus has made patience part of the experiment.

The weird lesson in the glass case

The Oxford Electric Bell lasts because it does almost nothing, extremely efficiently, for an extremely long time. It turns a tiny flow of charge into a visible rhythm and makes the difference between voltage, current, power, and energy impossible to ignore.

Its greatest mystery is also carefully bounded. The operation is understood. The broad family of battery technology is understood. What remains uncertain is the exact recipe inside two sealed nineteenth-century columns and which component will finally determine the ending. Until then, the little sphere keeps crossing the gap.

Sources

• University of Oxford Department of Physics: “Exhibit 1 — The Clarendon Dry Pile”
• A. J. Croft, Oxford’s Clarendon Laboratory, Appendix A: “The Oxford Dry Pile”
• Yu Che and Wangfeng Ding, “Replicating the Oxford Electric Bell: A simple high-voltage battery demonstration!” The Physics Teacher 63 (2025)

At the end of Antarctica’s Taylor Glacier, a rusty red-orange stain spills across blue-white ice toward Lake Bonney. The feature is called Blood Falls, but its color does not come from blood, and it is not a conventional waterfall. It is the visible outlet of an iron-rich, extremely salty liquid-water system hidden inside and beneath a glacier.

That alone is a puzzle. Taylor Glacier lies in the McMurdo Dry Valleys, one of Earth’s coldest and driest landscapes. A 2017 study described a mean annual air temperature around minus 17 degrees Celsius and limited surface melting. Yet geophysical surveys found a zone of liquid brine within the cold glacier feeding the intermittent discharge.

Salt and freezing help keep the water moving

Researchers used radio-echo sounding to map the brine rather than treating the red surface stain as the whole system. Their observations support a network of basal crevasses through which pressurized subglacial brine is injected into the ice and routed toward the terminus. The system is not an open cavern shaped like a giant underground lake; it is a distributed, salty hydrologic network.

Two physical effects help explain why liquid can persist. Dissolved salts lower water’s freezing point. Freezing also releases latent heat, providing localized warming. The 2017 paper concluded that elevated salinity and latent heat together allow the brine to remain mobile in subglacial and englacial environments even while the surrounding glacier stays cold.

The color develops when iron-rich brine reaches the surface and encounters oxygen. Iron compounds oxidize, producing the red-orange material that stains the ice. The result looks theatrical from a distance, but the chemistry is closer to rusting than bleeding.

A hidden habitat in cold, dark brine

Blood Falls is also important because the outflow has revealed a microbial community adapted to cold, darkness, high salinity, and little oxygen. NASA’s astrobiology reporting describes organisms that survive without sunlight for photosynthesis by using chemical reactions involving sulfur and iron compounds. That makes the site a natural laboratory for asking how life can persist when familiar surface energy sources are absent.

Scientists are careful not to turn that analogy into evidence of extraterrestrial life. Blood Falls does not prove that organisms exist beneath Martian ice or inside the icy moons of the outer Solar System. It shows something narrower and valuable: on Earth, a cold, salty, lightless system can remain liquid and biologically active under conditions once assumed to be inhospitable.

The origin story of the brine has developed as evidence improved. NASA’s Earth Observatory summarized a long-standing interpretation in which ancient seawater or a saltwater lake occupied Taylor Valley before advancing ice trapped and concentrated it. Later studies mapped where brine exists within the glacier and how it can move. Details of the system’s age, geometry, and geochemical history are scientific questions, not reasons to present a single dramatic reconstruction as settled fact.

The visible stain is only the outlet

Blood Falls earns attention because of its color, but the stranger feature is invisible: liquid threading through a glacier that has little surface melt. The surface apron can grow with new discharge and partly degrade during warmer periods, so its appearance changes. What a visitor or satellite sees is a temporary expression of a much larger system.

Seen that way, the name is almost misleading. The remarkable thing is not a glacier “bleeding.” It is the combination of salt, pressure, fractures, phase changes, iron chemistry, and microbial metabolism operating beneath an Antarctic ice mass. The red stain is a window into that hidden machinery—vivid enough to draw the eye, but only the final step of the story.

Sources

• Badgeley et al., “An englacial hydrologic system of brine within a cold glacier,” Journal of Glaciology (2017)
• NASA Earth Observatory, “Blood Falls, Antarctica’s Dry Valleys”
• NASA Astrobiology, “Life at Blood Falls”