YOU NEED :
- Two pencils of the same length but of different colours
Let’s start with the assumption that one of the two pencils used for this trick is red and the other blue. Hold the red pencil vertically and place the blue pencil horizontally on top to make a T, as in the illustration. To onlookers the red pencil will seem be considerably longer than the blue one. Make the T again, this time with the blue pencil in a vertical position and the red one on top. Now the blue pencil will seem longer than the red one.
HOW DOES IT WORK?
This simple demonstration is till today largely unexplained. It is felt that the vertical pencil seems longer than the one placed horizontally, because the position is reinforced by the vertical position of the arm and body while the trick is being more...