Circus Science: Sideshow Semantics

Traditionally, sideshows consist of a “10-in-1 bill,” in which you could see ten different acts perform for the price of one admission. What has always struck me as fascinating is the amount of science behind many of the classic sideshow acts. Both fire eating and lying on a bed of nails, for example, are based in science. In my last article, I talked about the science involved in pulling a tablecloth out from under dishes. Well bust out your lab coat and goggles one more time, because it’s time to look at your favorite sideshow acts, one scientific principle at a time…


The bed of nails is one of my favorite acts because of how difficult and dangerous it looks compared to how simple and safe it actually is. The bed of nails consists of a performer laying down on the spikes of a few hundred nails. The trick relies on the properties of pressure. Pressure (P) is the ratio of force (F) to the area (A) over which the force is distributed, and is represented by the equation P = F/A. The force in this case, is the weight of the performer. The area is the area of all of the nail spikes. This trick works not because of the area of a singular nail spike, but because of the large quantity of the spikes.

Think about it this way: if you laid down on one singe nail, it would probably go straight through your back. You would have a very large force, your weight, distributed over an area that was less than one square centimeter (I apologize to all of you fans of the inch out there, but the metric system is used in science), resulting in a very large pressure. However, when you increase the total area over which the force is distributed by a factor of over 100, the resulting pressure is very small. Your weight is now distributed among all of the nail spikes. Now don’t get me wrong, just because there are lots of nails doesn’t mean that it’s like lying in your bed. It’s still uncomfortable, but bearable enough and too small of a pressure to pierce the skin.


Fire is weird; you can touch it, but you can’t really hold it. What is fire anyway? Good question! Fire is actually a continuous chemical reaction, which means that a new substance is produced due to the rearranging of a substance’s molecules. Specifically, fire is a chemical reaction known as oxidation, in which one substance gains oxygen molecules (this is the same type of reaction that causes metal to rust and turns fruit brown when left out, the only difference is the rapid rate at which the reaction occurs when there is fire).

Fire needs three things in order to work: fuel, heat, and oxygen. If any of these three components are not present, the fire won’t burn, which is exactly how fire eating works. The end of the torch is wrapped in cotton, which is then dipped in lighter fluid. Fuel: Check! The heat is needed to ignite the lighter fluid and start the chemical reaction. A lighter is used to start the fire. Heat: Check! The oxygen needed for the oxidation is in the air. Oxygen: Check!

The performer takes the torch and puts the fire into their mouth so that they don’t touch their lips or gums to the cotton (that would result in a nasty burn). The performer then closes their mouth tightly, cutting off a majority of the incoming air and oxygen. With very little oxygen left, the fire goes out. The fire is not “eaten” as much as it is just extinguished, but “fire eating” certainly sounds much more dangerous than “fire extinguishing with the mouth,” don’t you think?

Now remember, just because you know how these tricks work and they’re based in science does not mean that they are 100% safe. For this reason, please DO NOT try either one of these tricks at home. On that note, until next time, SCIENCE!

Matthew “Phineas” Lish, 17, is an award-winning clown and juggler, and has been trained by members of the Big Apple Circus Clown Care Units, as well as Ringling Bros. and Barnum & Bailey Clown College graduates. Notable performances include off-Broadway, the Ronald McDonald House, the Century Club with Dick Cavett, and guest ringmaster at the Big Apple Circus. He currently holds the world record for juggling clubs while bouncing on a pogo stick.

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