The object of this report is the description of a method which seems to be practicable for determining the path of an airplane, especially in taking off and landing. This report tells how, by means of a camera, preferably a kinetograph, which simultaneously photographs a stop watch the distance of an airplane from the camera and its height above the ground can be determined.

Now that the two-stroke-cycle engine has begun to make its appearance in automobiles, it is important to know what services we have a right to expect of it in aeronautics, what conditions must be met by engines of this type for use on airplanes and what has been accomplished.

"We propose to show how to calculate the cooling capacity of all radiators through which the air flows in separate streamlets, whether enclosed in actual tubes or not and whatever cross-sectional shape the tubes may have. The first part will give the fundamental principles for calculating velocity of air in the tubes and the heat exchange by radiation, conduction and convection, and show, by examples, the agreement of the calculation with experiments. In the second part, the effect of the dimensions and conditions of operation on the heat exchange will be systematically investigated" (p. 1).

The Behm acoustic sounder for aircraft enables the barometric determination for the altitude by night or fog and therefore promises to prove of great importance in safeguarding air traffic.

"Through the utilization of the "Magnus effect" on the Flettner rotor ship, the attention of the public has been directed to the underlying physical principle. It has been found that the Prandtl boundary-layer theory furnishes a satisfactory explanation of the observed phenomena. The present article deals with the prevention of this separation or detachment of the flow by drawing the boundary layer into the inside of a body through a slot or slots in its surface" (p. 1).