If the man in the street is asked his opinion of the future of aviation, he will almost invariably reply, “ Everyone will have an aeroplane on his roof and go straight up like this.” Whereupon he will go through the traditional motion of the spiral staircase joke.

The expert pilot or technician of to-day, overhearing this remark, smiles in a superior way. In his mind are two contrasting pictures : That of a city over which whirligigs are springing up from adjacent roof tops; and that of the vast empty spaces of even the busiest airport as he knows it.

The suggestion has been put forward by Dr. A. P. Thurston that the characteristics of a wing can be considerably improved by adding self-starting rotors at or near the wing tips. It is claimed that by placing these on each wing near the leading edge improvements analogous to those of a slotted wing tip can be obtained together with slow landing characteristics. Previous experiments (1) have shown that rotors can give about the same degree of lateral stability as tip slots. The primary object of these experiments was to test the second assertion, and the criterion by which this should be judged was that the gliding angle should be as steep as possible for a given rate of descent.

In the year 1884 the annual meeting of the Aeronautical Society was held in the rooms of the Society of Arts on the 2nd July. In those days the Society held one meeting only each year, and there were usually three or four papers read. On this occasion, the chairman was Mr. James Glaisher, F.R.S., and in his opening address he referred to the little progress which had been made during the past year, but drew consolation from the fact that there were still many earnest workers actively employed who were working more persistently and more perseveringly than ever. He also stressed the importance of experiment, stating that although the experimenter might not succeed, he could not make any experiment without increasing our knowledge in the way we desire it to be increased.

In the stressing of aeroplane wing spars account must be taken of end load, particularly when this end load is compressive. When the end load is continuous over each bay the strength of the spars may be calculated by what is known as the Berry method. It may happen, however, that owing to drag loads the end load may vary in the different portions of a bay, and in such circumstances it is customary to average out the various end loads and to regard this average load as acting over the whole bay. This practice is based on an investigation by Miss Cave-Browne-Cave in which the stability of a strut was considered, having regard to different compressive loads acting over each of the two portions into which the strut was divided. Miss Cave, who dealt only with compressive loads whose lines of action were parallel, found that the failing load for the whole strut was very approximately equal to the arithmetic mean of the two compressive loads which in combination produced instability failure.