To those who have not given attention to the structure of a bird's wing the following rough description may be of interest. The wing of a bird may be regarded as having two portions: (1) that part to the outer side of the wrist joint. The main feathers of this portion are usually about ten in number, and are known as the primary feathers. (2) That part of the inner side of the wrist joint which may be called the body of the wing. The main feathers of this portion vary according to the length of wing.

(a) A salient characteristic of a bird's wing as a whole is the comparatively rigid and heavy anterior edge and the light yielding elastic posterior margin.

On the occasion of the launching of the first balloon in Italy, a very interesting discussion was raised with regard to raising surfaces in the atmosphere and propelling them downwards — as to whether we experienced the same resistance. Professor Hergesell, of Strasburg, very kindly arranged for some experiments to be carried out. The apparatus was rigged up, and we tried spheres and discs of varying diameters; but with the spheres we were very much bothered, and I may say our chief trouble was with the vertical currents in the tower of the Cathedral. However, the experiments are still going on, and so far we have found that the spheres rise vertically quicker than they descend. It is rather difficult to understand this.

During the past year considerable advance has been made on the question of Aeronautics relating to flying arrangements heavier than air (exclusive of balloons). I have always maintained that the power required for bird life has been much over-estimated. Take, for example, the flight of the pelican, which I have often witnessed. A dead bird weighed 21 lbs., with an extent of wings of 10 feet from end to end, speed 70 strokes per minute, each stroke averaging about one foot. It is evident that during a period of gliding flight with motionless wings these sustain the whole weight of the bird. The exertion or force will be during the oscilating or downstroke of the wing against this pressure.

At the meeting of the Royal Meteorological Society on February 15 last, an exhaustive paper was read by Messrs. Hermann Elias and J. H. Field on the scientific ascent of the balloon “ Brandeburg “ from Berlin on September 1, 1904. By reason of the excellent arrangements made for carrying out the observations, the ascent may well serve as an object-lesson in such work. It goes far to emphasise the usefulness of ascents with manned balloons for scientific observation, and reminds explorers of the air that though ballons-sondes are invaluable for carrying out observations with self-recording instruments at heights inaccessible to human beings and kites have their special value in affording opportunities of continued research in isolated conditions, still there is an undoubted gain when intelligence can regulate the use of instruments and apply them to the circumstances of the moment.

Having only quite lately got back from the World's Fair Exposition at St. Louis, I feel that some short account of what has been going on there will not be out of place. Our Society was well represented there. Colonel Capper and Mr. Walter Eeid both took a prominent part in the meetings of the Aëronautic Conference, and also on the jury in the Kite Competition. It seems very unfortunate that we have not more interesting results to record. The Administration offered numerous large prizes in hopes of attracting inventors and being able to show some startling novelties. But these were not forthcoming. It is with much regret that I feel bound now to refer to this method of offering prizes.

Is the navigable balloon worth improving? That is a question which is frequently asked by the general public. Now there are many of us who, with reason, feel convinced that the ultimate future solution of the problem of aërial navigation will be found to be in the body heavier than air—the aëroplane— and some will doubtless say that it is waste of time to endeavour to improve what appears only capable of improvement within only finite limits, that all our united efforts should be directed to the system which, when certain first principles are successfully applied, will not display those boundary lines to further progress which seem so apparent in the case of navigable balloons.

This machine was taken in hand in 1899 with the assistance of Mr. P. Y. Alexander. A staff of competent draughtsmen were employed in getting out fully detailed working drawings of different powers. The propellers are 30 feet in diameter revolving in opposite directions mounted on, separate shafts, one inside the other, by this means the necessary reactions for rotation is obtained. The steam engines are below; the engines in this particular design are of somewhat novel type; the bed plate cylinders are connected to one of the shafts, the outer one, and the crank shafts to the inner one, so that we have the engine bed cylinders, etc., revolving in one direction, and the crank shaft in the opposite direction.

At the present time kites are used to obtain information about the temperature and humidity of the air above us, and efforts are being made to construct a flying machine capable of carrying one or more persons.

At first sight it might appear as though there were no relation between these two matters, but they are, in reality, very closely connected. The kite is held by a string or wire, and the wind passing over the kite supports it and at the same time causes it to exert an upward pull upon the wire. To fly a kite in the ordinary way the first requisite is sufficient wind, but if the lower end of the string to which the kite is attached can be moved forward with sufficient rapidity, by fastening it, for example, to a fast steamer or motor car, the kite can be flown when there is no wind.

The 30-foot diameter air propeller was mounted on a horizontal shaft. The propeller was of the double kind built up of solid drawn steel tubes tied and strutted together. The propeller was designed to give a thrust or lifting power of 600 lbs., and having a factor of safety of 3½, it weighed 120 without the canvas, the idea of the double form or superimposed structure was for reasons of strength.

It is on the same principle as a lattice or “ warren ” girder supported at one end and loaded at the other, the members of one blade being in compression and the other in tension.

This propeller was tested, and it gave way with 600 lbs. on the extreme top or 1,200 in propeller, a deflection curve was taken which showed that even with 600 at the top it was well within the limits of elasticity.

The title of my paper should really have been “ Stability in Ordinary Conditions of Wind near the Ground,” to indicate that the stability about which I want to talk here to-night is not the equilibrium of a machine in calm air, or in an unfluctuating breeze (if there is such a thing), but the ability which a machine must have to remain stable under ordinary conditions of wind most days in the year. Although my ideas on feathering fans are brought in as one way of meeting the conditions which have certainly up to the present not been provided against in any experiment, I by no means hold by them if any better way could be devised for this vital purpose. Now the ordinary conditions of a breeze near the ground have been ably described by Sir Hiram Maxim and Professor Langley.