Many have noticed the animated diagrams in recent postings. “How do you do that?” they ask. It’s all in the photo format.
Almost all (but not entirely all) photos taken with pocket cameras, tablets and cell phones are in the JPG (jay-peg) format that have the extension .JPG. They are compressed files, created by the camera software before you even see it. The compression makes the files much smaller by discarding some of the color information gathered by the sensor, but they still meet almost anyone’s photographic standards.
But another common format is GIF, pronounced like the peanut butter brand, with the extension .GIF. This format supports fewer colors, but the file size is then smaller than even a JPG, and, importantly, they can be stacked. That is, each photo can consist of many layers that display in sequence at a set interval. The one in the Paternoster posting of 6/29, for example, has 40 layers. The 40 only cover one quarter rotation of the gray wheel and what you are seeing is that one quarter turn repeated over and over. The diagram of the ball mill in the posting of 7/3 on Scattering the Ashes is cruder with only six layers. The mechanism of the display is built into the GIF format and is independent of where it is viewed.
An animated GIF file has to be created with a photo editing program, but it is not difficult, and is not limited to diagrams. The ones I use are copied from the Internet already made up. The first example I noticed many years ago was an apparently static passport-type photo of a pretty girl. After several seconds, however, her clothing suddenly disappeared and she winked. Sure got my attention. E-cards are full of them, showing things like falling leaves, flowers blossoming, and moving clouds. Internet advertisements also use them to attract attention. Emoji, those little smiley faces added to email, are tiny GIF files often with layers to add animation. My favorite rolls its eyes using 9 layers. That one is provided by my Yahoo email account, but a Google search will bring up many free files of them anyone can use by a copy-and-paste. (Many are too small to appreciate the animation. After pasting, right-click on it to see a surrounding box and drag outward on one of the corners to enlarge it.)