In our high-tech world it’s easy to forget the simpler things. Take a bicycle, for instance. No engine, no computerized braking system, no fancy fuel injection: all you need is air in the tires and off you go. Simple, that is, until you take a closer look at bicycles with multiple speeds. How do all […]
All you need for this trick is a twenty-five-cent piece and a small postage stamp. Put the stamp on the desk and hold the quarter horizontally about half an inch above the stamp. Now blow hard down onto the quarter.Now blow hard down onto the quarter.
Like all mirrors, two-way mirrors have a reflective coating. However, while the reflecting coating on regular mirrors is dense and returns all the light that strikes its surface, the reflective coating on two-way mirrors is more sparse.
The large ones we see when a bird stretches its wings are “flight feathers,” but they also have fluffy ones called “down feathers.”