The organization of a meteorological service for an air route involves the solution of two distinct problems: distribution and grouping of meteorological stations and communications. Experience gained in the establishment of two lines, Paris-Warsaw and Constantinople-Bucharest enables us to establish certain principles, which may be of interest to note here.

At the request of the N.A.C.A. the "Universal Propeller" was operated and explained by the inventor, Mr. Spencer Heath, for the purpose of demonstrating the following features of design: 1) Elimination of continuously running gears, collars or bearings in the pitch control mechanism; 2) The use of engine power in place of manual labor in changing blade angle; 3) The absence of any structural limitation to the range of blade angles available and the possibility of limiting the blade travel between any two predetermined extreme positions; 4) Continuous indication on the instrument board of the blade position; 5) Automatic throttling of the engine while the propeller is passing through the position of neutral pitch.

This report is a description of a method of propelling airplanes by the reaction of jet propulsion. Air is compressed and mixed with fuel in a combustion chamber, where the mixture burns at constant pressure. The combustion products issue through a nozzle, and the reaction of that of the motor-driven air screw. The computations are outlined and the results given by tables and curves.

In the following report, we will first draw some conclusions of purely theoretical interest, from the general equations of motion. At the end, we will consider the motion of an airplane, with the engine dead and with the assumption that the angle of attack remains constant. Thus we arrive at a simple result, which can be rendered practically utilizable for determining the trajectory of an airplane descending at a constant steering angle.

The future of aerial photography is examined with special reference to corporate uses.

Different maps and scales are discussed with particular emphasis on their use in aviation. The author makes the observation that current navigation methods are slow and dangerous and should be replaced by scientific methods of navigation based on loxodromy and the use of the compass.

This report provides a list of landing locations for seaplanes on the Atlantic coast of the United States and the facilities and services located there.

We see with great satisfaction that Bagnulo's studies and experiments on his high-speed, heavy-fuel engines, promise to solve not only the general problem of economical power and hence of thermal efficiency, but also all other special problems, of weight and space, and, what is still more important, range of error.

Different systems of navigations beacons are discussed with an emphasis on radiotelegraphy and radiotelephony.

Report issued by the U.S. Bureau of Mines on the air quality in metal-mines after using wet drills. Dust samples are collected and compared to samples collected from similar metal-mines in South Africa and Australia. This report includes tables.

The favorable speed of an airship is chiefly determined by the condition of the consumption of the least amount of fuel per unit of traveled distance, although other conditions come into play. The resulting rules depend on the character of the wind and on the variability of the efficiency of the engine propeller units. This investigation resulted in the following rules. 1) Always keep the absolute course and steer at such an angle with reference to it as to neutralize the side wind. 2) In a strong contrary wind, take a speed one and one half times the velocity of the wind. 3) As a general rule, take the velocity of the wind and the velocity of the course component of the wind. Add them together if the wind has a contrary component, but subtract them from each other if the wind has a favorable component.

The problem of insuring the emerging commercial aeronautic industry is detailed. The author also motes that a complete solution cannot be obtained until the necessary statistics are compiled.

It is shown by the author's experiments that hydrogen which escapes to the atmosphere through openings in the system may burn spontaneously if it contains dust. Purely thermal reasoning can not account for the combustion. It seems to be rather an electrical ignition. In order to determine whether the cause of the spontaneous ignition was thermo-chemical, thermo-mechanical, or thermo-electrical, the experiments in this paper were performed.

Thus far, all attempts at the quantitative determination of drag, on the basis of the theory of viscous fluids, have met with but slight success. For this reason, whenever a more accurate knowledge of the drag is desirable, it must be determined by experiment. Here, a few experimental results are given on the drag of a cylinder exposed to a stream of air at right angles to its axis. It is shown that the drag depends on the absolute dimensions of the body and the velocity and viscosity of the fluid in a much more complex manner than has heretofore been supposed.

An airship model made by the Goodyear Rubber Company was filled with water and suspended from a beam. The deformations of the envelope were studied under the following conditions: 1) both ballonets empty; 2) forward ballonets filled with air; 3) rear ballonets filled with air; and 4) both ballonets filled with air. Photographs were taken to record the deflections under each of these conditions, and a study was made to determine the minimum head of water necessary to maintain the longitudinal axis of the envelope under these conditions. It was concluded that any pressure sufficient to keep the airship full may be used. It appears that a pressure of one inch of water would provide a suitable factor of safety, and therefore it is the pressure that is recommended.