Fig. 2.
To make the experiment a success it is as well to remember the conditions. The bubble rises because the air it contains is lighter than that which surrounds it; it floats when the air is of the same temperature, it falls when the air within is colder than the air without. The air in the bubble comes hot from the lungs, and the greater the difference in heat between that air and the air you breathe the higher will the bubble go. In short, to have bubbles in perfection you should blow them in an ice room! As it is not every one that can obtain the use of a meat storage safe for bubble blowing, let us make our first experiment in a cool room. Begin with working up a good stiff lather; and the better the soap the better the suds for our purposes. Use your tube as you would your pipe, and blow downwards into the basin steadily and strongly. Take a good breath of air to begin with, and hold it for a second or two. Keep the point of the tube downwards until you have fixed on the disc in the way shown in the sketch. No gum or stickiness is required: all you have to do is to let the dry disc drop lightly on the wall of the balloon; the moisture will keep it in its place provided the knot of the cotton is small enough. If you pass the cotton through with a needle and have the same sort of single knot as if sewing, the disc will answer all your requirements.
Fig. 3.
As soon as the disc is firmly fixed, turn the tube gently upwards, and away will go the bubble, aëronaut and all. It will not cross the Atlantic, but it will at least reach the ceiling; and if on a cold day you try it out of doors, you may get it to travel unchecked for several hundred yards.
VI.—Marionettes,
or Fantoccini, are very entertaining when dexterously worked, as they may be by a little practice. Say you have a table with drapery arranged round it to form a little platform, and drapery also at the back. Let the latter be dark in colour, so that the string, thread, or silk, with which you work the dolls, may be less distinguishable if they are so at all.
Fig. 1.