Home › Appendix › Example I: Experiments

Example I: Experiments

Experiments to shew the Power of Repulsion.

Dip a ball in oil and put it in water; a ditch will be formed all round it. Pour water on oiled paper, and it will run off. Sprinkle water on a dusty floor, it rolls over it in globules. Sprinkle it upon a floor that has been swept, and this will not be the case, as it then comes in contact with the wood, and is diffused over it.

We may observe, that rain water stands in globules on the leaves of cabbages. If we blow up soapbubbles, and 'et them fall on the carpet, they will not for some time burst. .

Let them fall on the table, or any smooth surface, and they will burst instantly.

If we pour as much water into a cup as it will possibly old, we shall see the water above the level of the sides, if the edge be dry, but otherwise we shall not.

Lay a very fine needle, or a piece of tinfoil, on the surface of water, and it will fioat, until it become wet, when it sinks.

Lay a piece of gold on mercury, and it will float on the surface; but if depressed below the surface, it will sink to the bottom, like the needle on water.

Experiments respecting the Centre of Gravity.

The centre of gravity is that part of a body, round which ail its parts are so equally balanced, that, if it be supported, the whole body will be so too.

Take a book, and find, by trial, under what part the finger must be placed to keep the book from falling; that point is the centre of gravity.

Take a rod, or stick, and find that place about the middle of it, under which the finger being placed, it will be balanced ; that is the centre of gravity. The moment the centre or centre of gravity ceases to be supported, the whole body falls.

Move a piece of board to the edge of a table, and gradually farther and farther off it; the instant the centre of gravity gets beyond the edge of the table, the board falls.

Run the point of a knife much slanting into the same board, it may then be brought much farther over the edge of the table than it could before, as the knife, leaning the way of the table, brings the centre of gravity that way.

Take a bottle, with a cork in it; stick in the middle of the cork a needle, with the point upwards; then take another cork, and with a knife make a slit in one of its ends, in which place a shilling so far as to make it fast; then take two forks, or penknives, and stick one on each side the cork, slanting a little downwards; then place the edge of the shilling on the point of the needle, and it will rest secure. It may be made to revolve, with great rapidity, on the point of the needle, without falling off.