Elephant No. 101: Thaumatrope

I've always been enchanted by optical toys and illusions, so today I thought I'd try to make a thaumatrope. 

Thaumatropes—a name derived from the Greek words thauma ("wonder") and tropos ("turn")—were popular toys in Victorian times. Each thaumatrope consists of a cardboard disc with pictures on both sides, threaded onto a pair of strings. When the strings are twirled, the two pictures appear to combine into a single image. This is due to a principle once known as persistence of vision, by which the retina was thought to retain images long enough for them to blend together. This has since been explained as a phenomenon rooted in the brain's perception of motion.

The thaumatrope is most commonly credited to John Ayrton Paris, who in 1824 used a thaumatrope to demonstrate "persistence of vision" to the Royal College of Physicians in London, England. His invention was based on the ideas of astronomer John Herschel and geologist William Henry Fitton, the latter of whom is also sometimes said to have invented the thaumatrope. Others give credit to Charles Babbage, inventor of the world's first mechanical computer.

The range of images on thaumatropes is vast, the most famous of which is a bird in a cage. Sayings, poems or riddles are also sometimes inscribe along the outside of the disc. There is an excellent collection of thaumatropes, many of which can be viewed in action, on the delightful and informative Richard Balzer Collection website.

For today's elephant, I decided to draw a "naked" elephant on one side, with a hat and clown suit on the other side. Hopefully, when the thaumatrope is spun, the two will blend. The faster the disc spins, the stronger the illusion of a single image.

Making a thaumatrope is quite simple. To start, you need two cards or discs of identical size and shape. I opted to cut a couple of discs measuring about 7.5 cm (3 inches) in diameter, since this is the traditional thaumatrope shape. I used a lightweight bristol board, but any light cardboard will do. Index cards are also recommended on some sites offering instructions on making thaumatropes.

Once you have the discs cut, you can either punch the holes in the sides right away, or start your first drawing. I didn't want to punch the holes quite yet, so I sketched an elephant in the middle of one disc with pencil. I lightly sketched the hat and clown outfit as well, so that I would have some idea of how it would look when I did the reverse side. Once I was happy with the elephant, I went over it with a permanent black marker and erased the pencil lines. I also put small black dots where I intended to punch holes.

To create the second drawing, you need to be able to see the first drawing. The easiest way to do this is either hold it up to a window and trace, or use a light table. I used a window, because I don't actually have a light table. Shocking, I know. In addition to drawing the hat and clown outfit, carefully leaving out any parts of the elephant, I added a few confetti dots in the background, and repeated the small punch-out dots.

Then I decided both sides needed a bit of colour, so I painted them with watercolour.

The thaumatrope was now ready to be assembled. The most important thing to remember here is that the discs must be upside-down to one another. I don't know why this is—and it's beyond me to either understand or explain it—but I do know that, if you don't make them opposite to one another, the thaumatrope will look really weird. In this case, the hat would float around in the space below the elephant's body as soon as I set it spinning.

To finish the thaumatrope, you need to make holes in the two discs, and attach loops of string, or elastic bands, on either side. I pierced the holes with a large needle, and used red embroidery floss for the string.

Double over the string and feed it through both discs. 

Feed the cut ends through the loop and tighten. 

Tie knots in the cut ends. This not only finishes it off nicely, but gives you a place to loop your fingers when spinning the thaumatrope. 

Now comes the magic part. To spin the thaumatrope, I twirled it between my fingers until the string was tightly twisted. As soon as I pulled the two pieces of string out to the sides, the thaumatrope began to spin, and the pictures blended together. This was hard to photograph with just me to both spin and record, but you get the idea. Interestingly, there are no single shots in the original clip in which both sides of the disc are visible, so your eyes and brain really are responsible for this entire illusion. 

This was technically quite easy, and only took extra time because I wanted to carefully draw and paint it to give it an old-fashioned feel.

I like the final result a lot, and may even make a few for friends someday.

Elephant Lore of the Day

Elephants have the largest brains of all mammals, and are highly intelligent. In addition to being able to work out problems, they often alter their behaviour in response to new challenges.

They are also excellent escape artists. In the 1970s, at Marine World Africa in the United States, an Asian elephant named Bandula figured out how to either break open or unlock several devices used to secure the shackles on her feet. The most complex of the devices was a brommel hook, which closes when its two sides slide together. Bandula fiddled with it constantly, finally learning how to slide the hook apart by aligning the sides. 

Once Bandula freed herself, she helped the other elephants to escape along with her. There was a certain element of cunning involved as well: before escaping, Bandula and her companions looked around to be sure that no one was watching before they ran away. 

Similarly, a female elephant described in Eugene Linden's book, The Octopus and the Orangutan: More Tales of Animal Intrigue, Intelligence and Ingenuity, worked out how to unscrew iron eye bolts measuring 2.5 cm (1 inch) in diameter. Using her trunk to create leverage, she managed to completely untwist the bolt and free herself. 

To Support Elephant Welfare
World Wildlife Fund
World Society for the Protection of Animals
Elephant sanctuaries (this Wikipedia list allows you to click through to information on a number of sanctuaries around the world)
Performing Animal Welfare Society
Zoocheck
Bring the Elephant Home
African Wildlife Foundation