From Grand Illusions.
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Balance a ruler using two fingers. It doesn’t matter whereabouts you place your fingers, so long as they can balance the ruler without it falling to the ground. Then move your two fingers slowly together. If your fingers are equidistant from the mid point of the ruler, your fingers will move together towards the middle of the ruler at a constant speed. However if your fingers are not equidistant from the middle of the ruler, the finger that is further from the centre will move first, as it has less weight pressing down on it, until the two fingers are equidistant from the middle, and then they will move together.
A joke item from the late 1970s – either a centipede that shows centimetres on one side, and a foot ruler showing a foot on the other side. Although a joke item, it does still work as a ruler.
A giraffe tape measure…
A tape measure called a ‘diameter tape’. Initially it looks like a normal tape measure, with inches shown on one side. But the numbers on the other side seem very strange, although they are still marked in inches. Tim demonstrates with a wine bottle that using the ‘normal’ side of the tape, you can measure the diameter of the bottle. Use the other side and you can read off the diameter of the bottle. Tim thinks that plumbers might make use of this to find out the diameter of a pipe that is fixed in place in such a way that you do not have access to the end.
A pencil with a ruler printed on the side, so you can see how much of the pencil is left, since every time you sharpen it, it gets a bit shorter.
A ‘rolling ruler’ which allows you to draw parallel lines, with a given distance between the lines.
A novelty ruler with centimetres on one side, and rulers of the United Kingdom on the other side. It goes all the way back to Roman Britain, so technically it was not called the United Kingdom then of course.
Japanese lenticular rulers, with all kinds of alternating images.
The Lucky Rule – marked in inches, and seems perfectly normal until you look more closely and discover there is no ’13’ marked. The ruler goes from 12 to 14, missing out the unlucky 13!
Finally, from the UK company Bear Bear & Bear Ltd (sadly no longer in existence) a tape measure with an unusual feature – it is stretchy! So when you measure your waist for example, the more you stretch the tape, the smaller your waist appears to be!
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Finally, on a philosophical note, here is an interesting thought…
"We have to find a way of making the important measurable, instead of making the measurable important."
Apparently this was said by former US Secretary of Defense Robert McNamara.
