The question is often asked whether the rear edge of the front plane should be straight or brought back and tipped at either end. A study of the various models of the standard manufacturers shows that there is considerable difference of opinion among the experts. The builders of model aeroplanes in America still retain the straight line, while in England the tips are brought well back in a great many of the designs. The theory of this form is, obviously, that this tip tends to damp out any lateral motion, and makes for stability. In the most successful American models the rear line of the plane is kept straight without apparent loss of stability. Turning now to the large machines, we find a similar contrast. In none of the Bleriot models is the rear line broken. The Wright, Curtis and Antoinette machines, even in their latest form, still retain the straight line. The Etrich monoplane has had good results with rear wing tips. The model has been accepted by the Austrian Minister of War who has ordered a fleet of twenty of these craft for the army. The rear tip was first suggested by Lilienthal. The friends of this form claim that it more nearly approaches the form of a bird’s wing than any of the other planes now in use. The depth of the main plane is nine and three-quarter feet and at the tips twelve feet. The entire tip is so adjusted that it may be flexed at will from the pilot’s seat. It will be seen that this arrangement makes it possible to imitate the flight of a bird very closely. In adopting this idea in model aeroplanes it will be well to attach the extension by a hinge so that it may be turned up or down at will. Since it is placed well out from the main axis of the machine its leverage is naturally great. In the large machines as well as in the models there seems to be a general tendency to increase the aspect ratio of the main planes. The Bleriot XI still retains its broad deep plane, but in several of the models the depth of the model has been greatly reduced. In the new Voisin monoplane the main wing has a width of thirty-seven feet and a depth of but five feet, thus giving it an aspect ratio of nearly one to eight. The machine flies with great ease, its resistance is very low and it answers well to its stabilizing devices. The Cody biplane again has supporting planes measuring fifty-two feet by only seven feet six inches.