Your Magic Finger

Your Magic Finger

You will need: Tin can with tight-fitting lid, water, pitcher, gimlet, and bowl.

You can use the knowledge gained in the previous experiment with the drinking straw to help mystify your friends. Tell them about your 'magic finger.' No matter how many holes you make in the bottom of a tin can you can still make it hold water-with the aid of your magic finger!

You will need a sharp gimlet to bore the necessary holes in the can. Start by making a hole in the lid of the can. Make three or four holes in the bottom, too-or better still, let your friend make the holes for you, so that he can see there is no trickery involved.

Hold the can over an empty bowl and pour water into it. Water will immediately begin to stream through the holes you have punched in the bottom. Perhaps your friend would like to try stopping this flow of water. There is not much chance of his success, unless he has seen the experiment before.

To perform the operation successfully yourself, you must fill the can with water, press the lid tightly and quickly into position, and place your finger over the hole in the lid. Immediately, you stop air from entering the top of the can and the outer air presses upward on the under-side of the can to prevent the water from running out.

You will be able to control the flow of the water from the can. Cover the hole in the lid with your finger and the flow will stop. Release your finger and the water will again pour from the bottom of the can.