CIENTISTS of European reputation, like Mr. C. G. Lamb, M. A., University Lecturer in Electrical Engineering at Cambridge, consider it to be of great importance, in connection with any serious attempt to solve the problem of aërial locomotion, that investigation should first of all be made by experiments as to whether the lines of design should proceed on those seen in nature or on entirely different lines.

Therefore, some highly interesting experiments have just been undertaken by some members of the Aeronautical Society of Great Britain, including Mr. E. P. Frost, Mr. F. W. H. Hutchinson, and Mr. C. R. D'Esterre, with an experimental flying-machine model whose action is scientifically based upon the movements of birds' wings. The experimenters have collected a vast mass of data on the subject, including the studies of Mr. Hargrave of New South Wales, and those of M. Marey, whose work Le Vol des Oiseaux is a standard authority.

The wing of a bird may be said to

In regard to the problem of propulsion in water, the exigencies of mechanical construction have rendered it impossible to follow the method found in nature, since in that case the flexibility of the moving body is an essential. But in the case of birds and insects, this confinement to an imitation of their methods of progression does not arise.

have two portions. First, we have the section extending to the outer side of the wrist-joint. The principal feathers of this part usually number about ten, and are known as "primary feathers." Then there is the inner side of the wrist-joint, known as the "body" of the wing. If the primary feathers are examined, it will be seen that each differs from its

fellow in a graduated series, and the curves are more pronounced midway between the wrist and the shoulder-joint. Mr. Frost, after years of observation of the structure of natural wings of all kinds, and of their movement in flight, concluded more than twenty years ago, that, in the ordinary flight of a bird, the wing is merely beaten up and down, so that a lift and a drive are obtained. The wing is so shaped that the down stroke encounters much greater resistance than the up stroke, apart from the question of energy; and Mr. Frost contended that the primary feathers are so arranged that on being struck downward in the air their ends travel forward and upward. For example, in flight, the wing-tips of the rook can be seen to be curled upward. Marey obtained confirmation of this by fixing a piece of white paper to the tip of the first primary of a black crow, which was then caused to fly in front of a dark screen, when the lens was exposed during five beats of the wing. Major B. Baden-Powell, the well-known aëronaut and inventor of military kites, also

conducted some curious experiments with small birds, by liberating them in paper tubes the internal surfaces of which were coated with lamp black.

It was found that the wing as a whole is essentially an elastic structure; and during flapping flight the primary feathers automatically exert a clawing, swimming action. It was obvious to observers, too, that a bird's wing, both as a gliding and as a propelling surface, is a beautifully efficient instrument.

To test these views, Messrs. Frost, Hutchinson, and D'Esterre arranged the apparatus shown in Fig. 1.

A pair of dried natural wings about three square feet in area, were arranged with a small electric motor and a reduction gear so that they flapped up and down, the whole concern being suspended by a spring balance from the balanced arm. With 24 volts, a maximum lifting power of five pounds was developed (350-400 flaps per minute). The effect was most curious. The huge "bird" flapped itself round and round, although it sagged heavily between the down

strokes. But it should be borne in mind that its speed was only four or five miles. an hour, and the apparatus was crude. Moreover, the bird itself weighed twenty-one pounds; so it is little wonder that it drooped on the up strokes. The ratio. of horse-power to lift was 1 horse-power to 50 pounds. This agrees with the figures given by various authorities as that obtaining among larger birds. In what was called the "hovering lift," 1 horsepower gave a lift of 10 pounds.

The results were considered so encouraging that a much larger model was built (Fig. 2) and mounted on a special carriage. The new model has a total wing area twenty times the size of its predecessor's-that is, about 60 square feet. The entire machine measures 20 feet

across.

The transmission is by a coned friction-clutch and chains in two stages to the connecting rod. The crank-throw is adjustable for altering the size of the angle of the flap. "Pectoral cords" of elastic are attached to the brackets below the wings. These are for storing up energy on the up stroke. A gasoline cycle engine of about 3 horse-power is the mo

tor.

The wings flap 100 times a minute; and when the machine has been suspended from a tree-bough, the whole apparatus apart from the carriage, weighing 232 pounds, is lifted up bodily into the air and carried forward. It exactly resembles a giant bird trying to fly. At the down stroke, it seems that if the rope were then cut the powerful sweep of the wings would lift and carry away the entire machine. With 100 flaps per minute, the wings evoked a resistance of about 100 pounds each, and each stroke raised the machine about 2 feet. Experiments showed that a feathered wing made up of a number of units exerts greater resistance than a simple wing such as that of an insect or a bat, or the mechanical wings hitherto made for wing-flapping machines.

It was clearly seen that the primary feathers act as a series of stepped aëroplanes; and altogether a mass of data was secured which is about to be embodied by the investigators in a far more ambitious machine than has yet been built. It is proposed to form a small syndicate of men with scientific tastes, to complete the work and produce a regular man-lifting machine.

HE Rowland system of telegraphy was invented by the late Prof. Henry A. Rowland, of Johns Hopkins University, one of the world's greatest men of attainments in science. In this system, the alternating current was first successfully applied to the uses of telegraphy.

In their endeavors to improve upon the existing methods of communication and increase the capacity of wires, experimenters have developed apparatus of two kinds the Multiplex, which aimed to send many messages simultaneously over one wire; and the Rapid, which increases the speed of the, single transmitter. Of the first kind, however, a Morse apparatus sending two messages each way was until recently the only one in practical use. The rapid systems have been dropped, one after another, because their use involved the preparation of a perforated tape, which, being shot rapidly through a transmitter, caused the reproduction of

a perforated or printed tape at the other end of the line. The operations connected with transmission by this method offered too many loopholes for error and were too cumbersome to be practical.

Professor Rowland, in devising his new system of telegraphy, aimed to accomplish two great results. First, realizing that the vast network of telegraph wires spread over the world was working far below its possible capacity, he wished to increase this capacity by multiplexing. Second, he wished to invent a machine that would automatically and directly record, in page form, printed characters. In both these fields, little practical advance had been made. As was remarked above, two messages each way was the limit of the multiplexing systems; and, although machines had been built to record in printed characters, they were found impracticable in America after

trial.

Professor Rowland solved both these problems with astonishing success. His apparatus at its full capacity sends four