Connect the two biplanes by strips of paper six inches in length pasted on the lower planes or main deck of the little aeroplane. The forward planes should be fixed at a slightly elevated angle by running struts from the connecting strips to the upper plane. The accompanying picture will show how simple this all is. The biplanes as a rule require no weighing. To launch them, hold them high in the air and merely let go. They fly best with their smaller planes forward. By varying the angle of the front plane, you can soon bring it to an even keel. A vertical rudder placed three inches behind the main plane will increase the model’s directional stability. An amazingly clever little glider may be made of a piece of reed or cane, say five inches in length, and a sheet of writing paper. With a pair of scissors cut two planes, one three by one inch and the second two by half an inch. You will also need a vertical rudder one inch square. Round off the corners slightly and glue the planes at either end of the stick and exactly on a level. Now fasten the rudder at right angles to the planes beneath the larger plane. If it dips, the front plane is too far back, while if it rises too quickly and settles back, the front plane must be brought back. The paper gliders form an excellent kindergarten preparation to the study of aviation, leading up to the construction of large model gliders. You will thus gain a skill in adjusting the planes and fixing the centers of gravity and of pressure, which will prove valuable later on. The possibilities of glider building come as a surprise to the laymen in such matters. THE SLING-SHOT GLIDER. A fascinating field of experiment is opened by combining the sling-shot principle with the ordinary glider. The speed with which one can launch a glider from the hand is, of course, limited. Now use a small strand of rubber to launch the planes, and the increased speed will not only lengthen the flight surprisingly but make possible a really remarkable spectacular flight. A small glider may be made to return to the starting point or even loop the loop two or three times before touching the ground. By a simple adjustment of the planes, these curves may be varied indefinitely. [Illustration: Designs for Sling-Shot Gliders.] When you have adjusted your glider to fly well, try the same arrangement of planes on a piece of reed, say eight inches in length, and bend the end over in the form of a hook. By heating the cane over a flame, you can make it turn without breaking and hold its position. Now loop a single rubber band over your thumb and forefinger, and passing the hook over the rubber, pull back exactly as you would use a sling shot. As you release the glider, pull your other hand quickly out of range. By using a heavier paper, one which will hold its shape, and turning the forward edges up slightly, the glider may be made to travel upward in a variety of graceful curves.