CLOSE
Original image
Getty Images

Who Cracked the Liberty Bell?

Original image
Getty Images

Chalk the Philly landmark’s famous blemish up to faulty building materials from across the pond. In 1751, the Pennsylvania Provincial Assembly shelled out 100 pounds to London’s Whitechapel Bell Foundry for a bell to hang in the State House (known post-Revolution as Independence Hall). The Whitechapel Bell Foundry—famous for casting Big Ben a century later and listed in the Guinness Book of World Records as Great Britain’s oldest manufacturing company—dropped the ball on the bell, casting it with too-brittle metals.

When the bell arrived in Philadelphia in 1752, it cracked on its first test strike. Two local craftsmen, John Pass and John Stow, twice cast a new bell using metal from the cracked English bell. They also added more copper, to make the bell less brittle, and silver, to sweeten its tone. The recast behemoth weighed in at 2,000 pounds: 70 percent copper, 25 percent tin, and a scattering of lead, zinc, gold, silver, and arsenic. 

Once Americans gained independence in 1776, the landmark fell by the wayside until the 1830s, when abolitionists adopted the bell (dubbing it “The Liberty Bell” in William Lloyd Garrison’s anti-slavery publication, The Liberator) as a symbol for their movement.

There’s no one widely accepted story for how the recast bell got its now-famous crack. One account asserts that the bell fractured during Revolutionary War hero Marquis de Lafayette’s visit to the City of Brotherly Love in 1824. Another insists that it cracked while tolling a fire warning later that year. Craftsmen tried to prevent further damage by boring out hairline cracks on the bell, keeping them from expanding dangerously.

Two legends about the Liberty Bell’s infamous fracture remain the most popular: one contends that the bell cracked during the 1835 funeral of Chief Justice John Marshall, though it may not be historically true—Philly newspaper stories about the funeral don’t mention the bell ringing.

The cause that stuck (at least according to official city reports) was that the Liberty Bell was irreparably damaged in 1846, when Philadelphia mayor John Swift ordered the bell rung to commemorate George Washington’s birthday. The bell had been repaired earlier that year when a thin crack started throwing off the sound of the bell, but after it cracked again, it hasn’t been rung since.

The Philadelphia Public Ledger chronicled the bell’s final peal in a February 26, 1846 story:

"The old Independence Bell rang its last clear note on Monday last in honor of the birthday of Washington and now hangs in the great city steeple irreparably cracked and dumb. It had been cracked before but was set in order of that day by having the edges of the fracture filed so as not to vibrate against each other ... It gave out clear notes and loud, and appeared to be in excellent condition until noon, when it received a sort of compound fracture in a zig-zag direction through one of its sides which put it completely out of tune and left it a mere wreck of what it was."

 

 

Original image
iStock
arrow
Big Questions
Where Is the Hottest Place on Earth?
Original image
iStock

The summer of 2017 will go down as an endurance test of sorts for the people of Phoenix, Arizona. The National Weather Service issued an extreme heat warning, and planes were grounded as a result of temperatures exceeding 120 degrees. (Heat affects air density, which in turn affects a plane’s lift.)

Despite those dire measures, Phoenix is not the hottest place on Earth. And it’s not even close.

That dubious honor was bestowed on the Lut Desert in Iran in 2005, when land temperatures were recorded at a staggering 159.3 degrees Fahrenheit. The remote area was off the grid—literally—for many years until satellites began to measure temperatures in areas that were either not well trafficked on foot or not measured with the proper instruments. Lut also measured record temperatures in 2004, 2006, 2007, and 2009.

Before satellites registered Lut as a contender, one of the hottest areas on Earth was thought to be El Azizia, Libya, where a 1922 measurement of 136 degrees stood as a record for decades. (Winds blowing from the nearby Sahara Desert contributed to the oppressive heat.)

While the World Meteorological Organization (WMO) acknowledged this reading as the hottest on record for years, they later declared that instrumentation problems and other concerns led to new doubts about the accuracy.

Naturally, declaring the hottest place on Earth might be about more than just a single isolated reading. If it’s consistency we’re after, then the appropriately-named Death Valley in California, where temperatures are consistently 90 degrees or above for roughly half the year and at least 100 degrees for 140 days annually, has to be a contender. A blistering temperature of 134 degrees was recorded there in 1913.

Both Death Valley and Libya were measured using air temperature readings, while Lut was taken from a land reading, making all three pretty valid contenders. These are not urban areas, and paving the hottest place on Earth with sidewalks would be a very, very bad idea. Temperatures as low as 95 degrees can cause blacktop and pavement to reach skin-scorching temperatures of 141 degrees.

There are always additional factors to consider beyond a temperature number, however. In 2015, Bandar Mahshahr in Iran recorded temperatures of 115 degrees but a heat index—what it feels like outside when accounting for significant humidity—of an astounding 163 degrees. That thought might be one of the few things able to cool Phoenix residents off.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

Original image
iStock
arrow
Big Questions
How Does Autopilot Work on an Airplane?
Original image
iStock

How does autopilot work on an airplane?

Joe Shelton:

David Micklewhyte’s answer is a good one. There are essentially a few types of features that different autopilots have. Some autopilots only have some of these features, while the more powerful autopilots do it all.

  • Heading Hold: There’s a small indicator that the pilot can set on the desired heading and the airplane will fly that heading. This feature doesn’t take the need for wind correction to desired routing into account; that’s left to the pilot.
  • Heading and Navigation: In addition to holding a heading, this version will take an electronic navigation input (e.g. GPS or VOR) and will follow (fly) that navigation reference. It’s sort of like an automated car in that it follows the navigator’s input and the pilot monitors.
  • Altitude Hold: Again, in addition to the above, a desired altitude can be set and the aircraft will fly at that altitude. Some autopilots have the capability for the pilot to select a desired altitude and a climb or descent rate and the aircraft will automatically climb or descend to that altitude and then hold the altitude.
  • Instrument Approaches: Autopilots with this capability will fly preprogrammed instrument approaches to the point where the pilot either takes control and lands or has the autopilot execute a missed approach.

The autopilot is a powerful computer that takes input from either the pilot or a navigation device and essentially does what it is told to do. GPS navigators, for example, can have a full flight plan entered from departure to destination, and the autopilot will follow the navigator’s guidance.

These are the majority of the controls on the autopilot installed in my airplane:

HDG Knob = Heading knob (Used to set the desired heading)

AP = Autopilot (Pressing this turns the autopilot on)

FD = Flight Director (A form of navigational display that the pilot uses)

HDG = Heading (Tells the autopilot to fly the heading set by the Heading Knob)

NAV = Tells the autopilot to follow the input from the selected navigator

APR = Tells the autopilot to fly the chosen approach

ALT = Tells the autopilot to manage the altitude, controlled by the following:

VS = Vertical Speed (Tells the autopilot to climb or descend at the chosen rate)

Nose UP / Nose DN = Sets the climb/descent rate in feet per minute

FLC = Flight Level Change (An easy manual way to set the autopilot)

ALT Knob = Used to enter the desired altitude

This post originally appeared on Quora. Click here to view.

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios