The Sound of the Past

This is just a neat little side note about a cool process used to recover a very old voice recording. The recording was done by Edison in 1875 on a 5 X 15 inch piece of tinfoil, but due to the nature of tinfoil playing it back damages the recording. So you might be wondering how you can recover a recording on something you can’t play back. Researchers at California’s Berkeley Lab recovered it by making a virtual copy and playing that back. To make the digital copy they used a 3D scanner that scanned all the grooves of the tin foil a produced a 3D model on a computer and then simulated the needle running through the grooves to replay the sound that was locked away for 134 years. You can head over to their website to hear the recording at

The Annoying Red Planet

In “the annoying red planet”, Mars was a central plot point (as indicated by the name of the episode). I’m sure by now that you have heard of the curiosity rover lading on the surface of Mars, but do you know the insane entry process that the rover took? The scientist at NASA called it the seven minutes of terror, and for good reason. I’ve included a video of a CG version of the entry, but you have to click the image at the start of the post. Let’s start near the edge of Mars’ atmosphere where the rover is hurtling through space towards Mars, as the capsule enters the atmosphere the heat shield starts to heat up due to the friction of the atmosphere rushing passed. The capsule then deploys a supersonic parachute, but because the atmosphere is so thin and the rover so heavy, about 1 tonne, the parachute won’t slow the descent enough. This is when we start to move into something that appears to be out of science fiction, the capsule releases what NASA calls a sky crane. This is basically a platform with four jets, that slows the descent even more, but to not destroy the rover as it lands, when it is 10 meters above the surface the sky crane starts to hover and lowers the rover to the surface with tethers. Once it reaches the surface, the crane flies off and crashes somewhere on the surface of Mars. This landing was ultimately successful and if you are interested, you should take a look at some of the pictures that the rover has taken from the surface of mars.


This is by far the most complicated animation device we have yet looked at. Continuing with the trend of first explaining the etymology of the name, the praxinoscope means “action viewer” in greek. It was invented in France by Charles-Emile Reynaud in 1877 nearly 50 years after the zoetrope. The general design is similar to the Zoetrope, it has an outside drum with the animation frames drawn on the inside. The difference is that instead of slits, the praxinoscope has a series of mirrors in the middle in the shape of a box with a plus sign. It worked the same ways as all the previous animation devices we’ve looked at, the mirrors reflect image and the configuration of the mirrors prevents the blurring of the image. Two years later Reynaud created a projecting  praxinoscope by having the outer barrel transparent and shining a light through that reflected off the mirror and on to a projection screen. This was our last in the series of animation devices, maybe one day we will take a look at Edison’s kinetoscope. Click on the picture below to see a praxinoscope in action, in is quite impressive.


We are going to have a look at an improved version of the phenakistoscope despite it being invented earlier. The zoetrope is a cylinder with the animation drawn on the inside and like the phenakistoscope has slits between the animation frames. You would spin the cylinder and the frames would animate, the faster the smoother as we know from the persistence of vision post. Like most of these animation inventions, there have been many versions before they were adopted into the public consciousness. The very first version was created in China around 180 AD and used a hot air to spin the disk and create the animation. Over 1600 years later it was rediscovered by a mathematician in 1833 but this isn’t the end of the story, it was finally patented and named in the 1860’s when by William Lincoln. The name Zoetrope comes from the greek word zoe meaning alive and trope meaning turn. The combination of these words loosely means wheel of life, a fitting name because the wheel brings the still pictures to life. We only have one more animation device in our series, one with another ridiculous greek name.


Now we are going to look at an animation device that has the longest name in our series of simple animation devices. With a name bordering on the ridiculous, the phenakistoscope etymological origin is the greek word phenakizien that means to deceive. So what exactly is this deception scope? It is a disk with animation frames drawn around the outside and in between each of these frames are slits that point towards the center. To see the animation you need to point the disk towards a mirror and spin the disk. When you look through the slits, you can see an animation because the slits interrupt the image enough to prevent it from blurring. The man credited with the invention was Joseph Plateau who invented (and named) the phenakistoscope in 1841, but there was an explosion of similar inventions around the time. Tomorrow, we will look at another version of the phenakistoscope.


The kineograph or as most of us know it as, the flip book. As children we have probably used them or even made them ourselves amazed by the movie that we’ve made. The flipbook was patented in 1868 by John Linnett. The flipbook is an incredibly simple design, it is several pages bound together, each page has a drawing that changes a little from page to page. When we flip through the pages, the drawings seem to merge together and create motion. If you want to make one yourself an easy way is to set your camera to burst/continuous shutter mode. If your camera is fast enough it should capture frames in a quick enough secession that it will make a good flipbook, otherwise take a movie and grab frames using vlc movie player. Now print the pages with multiple pictures with the desired size. The simply cut out the pictures and and bind them, now you have a simple movie.  


We are going to start with one of the simplest demonstrations of persistence of vision one that you can even make yourself. The thaumatrope is a circular card that has a design on each side and two strings. When you wind the disk around the strings and then pull them, the image on each side of the disk will rapidly alternate and appear to be one.  The first recorded thaumatrope was used to demonstrate persistence of vision in 1824. Even further back, there is evidence that cavemen had this primitive form of animation using disks of bone. If you want to make one yourself, cut out a disk and then draw a frame on each side. You have to make sure that when you flip the disk that both the images are facing the same direction, to do this you have to flip it on the same axis that you have punched the holes on. Now string rubberbands through the holes and spin it, you now have instant animation! Tomorrow we will look at a more complex form of animation that you can also make yourself.