Why Do Fire Stations Still Use Sirens?

iStock
iStock

Growing up in southwestern Pennsylvania, I lived next to railroad tracks and a fire station. Coal-carrying trains, which rumbled through town at all hours of the day and night, could be tolerated. But occasionally I’d be startled awake by the deafening wail of a fire siren.

With the advent of modern technology and advanced emergency notification systems, are sirens still necessary? It isn't just me who wondered this, either; communities across the country have been raising the same question at their local meetings, with some addressing the issue as early as the 1990s. As it turns out, sirens technically aren’t necessary, and whether or not they’re used at all is a local decision, according to the National Volunteer Fire Council.

Although no law mandates their use, many departments have fought to keep them in place, despite complaints from annoyed residents. Chris Hash, of the Easton Volunteer Fire Department in Maryland, wrote in a blog post that sirens are needed because other communication devices, like pagers and cell phones, are not infallible.

“Batteries die, pagers and cell phones are not on the person, and text messaging and smartphone apps like Active 911 are often delayed, with some calls not coming through at all,” Hash wrote. “The National Fire Protection Association recommends that there are at least two reliable means to alert firefighters [of an emergency].”

Plus, there’s no missing or mistaking a fire siren. "When you're out working in the yard on a lawn mower, you can't hear your pager, but you can hear that siren,” George McBride, a member of the Hillcrest Volunteer Fire Department in Mechanicville, New York—where a debate arose over whether to replace a siren that had been disconnected—told the Times Union in 2014.

In addition to notifying firefighters of an emergency, the siren is also used to let local residents know they should remain alert. Some advocates of the fire siren argue that it lets drivers and pedestrians know they should stay off the roads, and residents with sprinklers are reminded to turn them off to conserve water.

One fire department in Mitchell, Ontario, hadn’t used its fire siren in nearly a decade, but after a firefighter nearly struck a pedestrian while driving to the fire hall, the town decided to start using it again earlier this year. Another department in Calistoga, California, considered purchasing a siren in the aftermath of a deadly wildfire, even though they had gotten rid of it years before in response to noise complaints.

More have joined suit. Duncan Scott, a sales manager at Federal Signal, told the Napa Valley Register in April that departments from all over California have placed orders for sirens after a number of wildfires swept through the state.

Other communities have struck a balance by keeping their sirens, but limiting their usage during hours when most people are sleeping. Of course, in some small towns, sirens still sound daily at noon or sundown—a holdover from a time when sirens were used to let residents know when it was time for lunch or for their children to come inside. Some communities keep this going for the sake of tradition.

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Why Are Elections Held on Tuesdays?

iStock/YinYang
iStock/YinYang

Ever wonder why Americans always vote in federal elections on Tuesdays? There are a few reasons—including a little something to do with the horse and buggy.

Between 1788 and 1845, states decided their own voting dates. In 2012, then-Historian of the Senate Don Ritchie told NPR that strategy resulted in chaos, a "crazy quilt of elections" held all across the country at different times to pick the electors—the white, male property owners who would cast their votes for president on the first Wednesday of December. In 1792, a law was passed mandating that state elections be held within a 34-day period before that day, so most elections took place in November. (Society was mostly agrarian; in November, the harvest was finished but winter hadn’t yet hit, making it the perfect time to vote.)

The glacial pace of presidential elections wasn't a huge issue in the late 18th and early 19th centuries—communication was slow, so results took weeks to announce anyway—but with the advent of the railroad and telegraph, Congress decided it was time to standardize a date. Monday was out, because it would require people to travel to the polls by buggy on the Sunday Sabbath. Wednesday was also not an option, because it was market day, and farmers wouldn’t be able to make it to the polls. So it was decided that Tuesday would be the day that Americans would vote in elections, and in 1845, Congress passed a law that presidential elections would be held on the Tuesday after the first Monday in November.

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

This article originally ran in 2012.

Does Sound Travel Faster or Slower in Space?

iStock/BlackJack3D
iStock/BlackJack3D

Viktor T. Toth:

It is often said that sound doesn’t travel in space. And it is true … in empty space. Sound is pressure waves, that is, propagating changes in pressure. In the absence of pressure, there can be no pressure waves, so there is no sound.

But space is is not completely empty and not completely devoid of pressure. Hence, it carries sound. But not in a manner that would match our everyday experience.

For instance, if you were to put a speaker in interstellar space, its membrane may be moving back and forth, but it would be exceedingly rare for it to hit even a single atom or molecule. Hence, it would fail to transfer any noticeable sound energy to the thin interstellar medium. Even the somewhat denser interplanetary medium is too rarefied for sound to transfer efficiently from human scale objects; this is why astronauts cannot yell to each other during spacewalks. And just as it is impossible to transfer normal sound energy to this medium, it will also not transmit it efficiently, since its atoms and molecules are too far apart, and they just don’t bounce into each other that often. Any “normal” sound is attenuated to nothingness.

However, if you were to make your speaker a million times bigger, and let its membrane move a million times more slowly, it would be able to transfer sound energy more efficiently even to that thin medium. And that energy would propagate in the form of (tiny) changes in the (already very tiny) pressure of the interstellar medium, i.e., it would be sound.

So yes, sound can travel in the intergalactic, interstellar, interplanetary medium, and very, very low frequency sound (many octaves below anything you could possibly hear) plays an important role in the formation of structures (galaxies, solar systems). In fact, this is the mechanism through which a contracting cloud of gas can shed its excess kinetic energy and turn into something compact, such as a star.

How fast do such sounds travel, you ask? Why, there is no set speed. The general rule is that for a so-called perfect fluid (a medium that is characterized by its density and pressure, but has no viscosity or stresses) the square of the speed of sound is the ratio of the medium’s pressure to its energy density. The speed of sound, therefore, can be anything between 0 (for a pressureless medium, which does not carry sound) to the speed of light divided by the square root of three (for a very hot, so-called ultrarelativistic gas).

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

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