Obtain a large cardboard box, as well made as possible. Cut out a portion about 5 inches square at one end and paste over the opening a piece of tracing paper. At the opposite end of the box make a large pin hole, but see that the hole has a clear cut circumference without any frayed pieces of card adhering. Then go round the box and stick strips of paper over the lid and elsewhere, so that the little piece of apparatus is light tight.
You have a kind of pin hole camera. Place it on the table and, directly in front of the hole, put a lighted candle. Arrange it so that the distance between hole and screen is as nearly the same as between hole and flame. Look at the screen and you will see an image of the flame. It is inverted, however. Note that if the image is not very distinct, it can be seen better by enveloping your head and the screen in a dark cloth.