An ingenious motor anchorage of metal construction has been hit upon by the builders of model aeroplanes in France. We are all familiar with the difficulty of raising the hook, holding the rubber bands, high enough above the main frame, or fusilage, to be perfectly free. Instead of attaching a wooden block, the French boys bend a piece of tin, or some such metal, very simply into a support for the hook. You will need a sheet of metal heavy enough to withstand the full force of the motor when wound up. The tin used in cans, as a rule, is not heavy enough. For each support you will need a rectangle of tin or metal measuring three by one and one-half inches. Parallel to the longer base, draw a line one-quarter of an inch above. From the center, erect a long rectangle one-quarter of an inch wide, extending to the opposite side. Now connect the ends of the line above the base with the points at which the upright rectangle intersects the top line, round off the edges neatly and cut away this triangle. Four holes should be cut or punched in the tin, as indicated in the drawing. Now bend the tin on the two upright lines until the two sides are parallel. This support is fitted to the end of a motor base and secured by driving nails through the three holes at the base covering the wood. The end of the hook which holds the rubber strands of the motor should be passed through the opening at the end, bent over and fastened into position with a drop or two of solder. Such a support adds practically nothing to the weight of the frame, and obviously anchors the motor rigidly. [Illustration: Model built by Rutledge Barry, winner of spectacular flight contest.] [Illustration: A model by Percy Pierce, winner of the indoor long-distance record.] The efficiency of a rubber-strand motor may be considerably increased by careful adjustment. If the strands first be wound rather loosely, as a rope is formed, and strung between the propeller hook and the motor anchorage, you will find that about thirty per cent. more rubber may be added without increasing the length and that a five to ten per cent. increase in the number of effective turns may be gained as well. By increasing the amount of rubber, you will, of course, add accordingly to the power of the motor. It is safe to say that the efficiency of your motor is increased upwards of twenty-five per cent. by this adjustment. The credit of this ingenious arrangement is due to Mr. W. Howell, Jr. It will be well to experiment with a short-strand motor, using a single strand of rubber for the test. Let us assume that your motor is twelve inches in length, thus making a double strand twenty-four inches long. First knot this, string it between the two hooks and turn it, counting the revolutions until the first row of double knots begins to appear. Note the number of turns.