flapped in an upward and downward direction. An account of his helicoptère or screw model appeared in the Aeronaut for January 1872, but before giving a description of it, it may be well to state very briefly what is known regarding the history of the screw as applied to the air. The first suggestion on this subject was given by A. J. P. Paucton in 1768. This author, in his treatise on the Theorie de la vis d'Archimède, describes a machine provided with two screws which he calls a "ptérophores." In 1796 Sir George " a and b, fig. 36, are two corks, into each of which are inserted tour wing feathers from any bird, so as to be slightly inclined like round shaft is fixed in the cork a, which ends in a sharp point. At the sails of a windmill, but in opposite directions in each set. A the upper part of the cork b is fixed a whalebone bow, having a small pivot hole in its centre to receive the point of the shaft. The bow is then to be strung equally on each side to the upper portion of the shaft, and the little machine is completed. Wind up the string by turning the flyers different ways, so that the spring of the bow may unwind them with their anterior edges ascending; then place the cork with the bow attached to it upon a table, and with a finger on the upper cork press strong enough to prevent the string from unwinding, and, taking it away suddenly, the instrument will rise to the ceiling." Cayley's screws were peculiar, inasmuch as they were superimposed and rotated in opposite directions. He estimated that if the area of the screws was increased to 200 sq. ft., and moved by a man, they would elevate him. His interesting experiment is described at length, and the apparatus figured in Nicolson's Journal, 1809, p. 172. Sarti in 1823, followed Cayley at moderate intervals, constructing Other experimenters, such as J. Degen in 1816 and Ottoris flying models on the vertical screw principle. In 1842 W. H. Phillips succeeded, it is stated, in elevating a steam model by the aid of revolving fans, which according to his account flew 1859 H. Bright took out a patent for a machine to be sustained across two fields after having attained a great altitude; and in by vertical screws. In 1863 the subject of aviation by vertical screws received a fresh impulse from the experiments of Gustave de Ponton d'Amécourt, G. de la Landelle, and A. Nadar, who with graduated weights a distance of from 10 to 12 ft. These exhibited models driven by clock-work springs, which ascended models were so fragile that they usually broke in coming in contact unsatisfactory, from the fact that it only lasted a few seconds. with the ground in their descent. Their flight, moreover, was FIG. 36.-Cayley's Flying Model. Cayley gave a practical illustration of the efficacy of the screw as applied to the air by constructing a small machine, consisting of two screws made of quill feathers, a representation of which we annex (fig. 36). Sir George writes as under: "As it may be an amusement to some of your readers to see a machine rise in the air by mechanical means, I will conclude my present communication by describing an instrument of this kind, which any one can construct at the expense of ten minutes' labour. "The Aero-bi-plane, or First Steps to Flight," Ninth Annual Report of the Aeronautical Society of Great Britain, 1874. "Resistance to Falling Planes on a Path of Translation," Ninth Annual Report of the Aeronautical Society of Great Britain, 1874. The Aeronaut for January 1872 and February 1875. FIG. 37.-De la Landelle's Flying-machine. m, n, o, p; g, r, s, t, Screws arranged on vertical axes to act vertically upwards. The vertical axes are surmounted by two parachutes, and the body of the machine is furnished with an engine, propeller, rudders and an extensive aeroplane. Stimulated by the success of his spring models, Ponton d'Amécourt had a small steam model constructed. This model, which was shown at the exhibition of the Aeronautical Society of Great Britain at the Crystal Palace in 1868, consisted of two superposed screws propelled by an engine, the steam for which was generated (for lightness) in an aluminium boiler. This steam model proved a failure, inasmuch as it only lifted a third of its own weight. Fig. 37 embodies de la Landelle's ideas. All the models referred to (Cayley's excepted') were provided | the ground for a distance of from 120 to 130 ft. It flies this with rigid screws. In 1872 Pénaud discarded the rigid screws distance in from 10 to 11 seconds, its mean speed being something in favour of elastic ones, as Pettigrew had done some years before. like 12 ft. per second. From experiments made with this model, Pénaud also substituted india-rubber under torsion for the Pénaud calculates that one horse-power would elevate and whalebone and clock springs of the smaller models, and the steam support 85 lb. of the larger ones. His hélicoptère or screw-model is remarkable for its lightness, simplicity and power. The accompanying sketch will serve to illustrate its construction (fig. 38). It con a D. S. Brown also wrote (1874) in support of elastic aerobiplanes. His experiments proved that two elastic aeroplanes united by a central shaft or shafts, and separated by a wide f b FIG. 38.-Hélicoptère or Screw-Model, by Pénaud. sists of two superposed elastic screws (a a, b b), the upper of which (aa) is fixed in a vertical frame (c), which is pivoted in the central part (d) of the under screw. From the centre of the under screw an axle provided with a hook (e), which performs the part of a crank, projects in an upward direction. Between the hook or crank (e) and the centre of the upper screw (a a), the indiarubber in a state of torsion () extends. By fixing the lower screw and turning the upper one a sufficient number of times the requisite degree of torsion and power is obtained. The apparatus when liberated flies into the air sometimes to a height of 50 ft., and gyrates in large circles for a period varying from 15 to 30 seconds. Pénaud next directed his attention to the construction of a model, to be propelled by a screw and sustained by an elastic aeroplane extending horizontally. Sir George Cayley proposed such a machine in 1810, and W. S. Henson constructed and patented a similar machine in 1842. Several inventors succeeded in making models fly by the aid of aeroplanes and screws, as, e.g. J. Stringfellow in 1847,2 and F. du Temple in 1857. These models flew in a haphazard sort of a way, it being found exceedingly difficult to confer on them the necessary degree of stability fore and aft and laterally. Pénaud succeeded in overcoming the difficulty in question by the invention of what he designated an automatic rudder. This consisted of a small elastic aeroplane placed aft or behind the principal aeroplane which is also elastic. The two elastic aeroplanes extended horizontally and made a slight upward angle with the horizon, the angle made by the smaller aeroplane (the rudder) being slightly in excess of that made by the larger. The motive power was india-rubber in the condition of torsion; the propeller, a screw. The reader will understand the arrangement by a reference to the accompanying drawing (fig. 39). Models on the aeroplane screw type may be propelled by two screws, one fore and one aft, rotating in opposite directions; and in the event of only one screw being employed it may be placed in front of or behind the aeroplane. When such a model is wound up and let go it descends about 2 ft., after which, having acquired initial velocity, it rises and flies in a forward direction at a height of from 8 to 1o ft. from 1 Cayley's screws, as explained, were made of feathers, and consequently elastic. As, however, no allusion is made in his writings to the superior advantages possessed by elastic over rigid screws, it is to be presumed that feathers were employed simply for convenience and lightness. Pettigrew, there is reason to believe, was the first to advocate the employment of elastic screws for aerial purposes. Stringfellow constructed a second model, which is described and figured further on (fig. 44). FIG. 39.-Aeroplane Model with Automatic Rudder. a a, Elastic aeroplane. bb, Automatic rudder. d. e torsion, attached to hook or crank at f. By holding the aeroplane (a a) and turning the screw (cc) the necessary power is obtained by torsion. (Pénaud.) rudder and screw. India-rubber, in a state of interval, always produce increased stability. The production of flight by the vertical flapping of wings is in some respects the most difficult, but this also has been attempted and achieved. Pénaud and A. H. de Villeneuve each constructed winged models. Marey was not so fortunate. He endeavoured to construct an artificial insect on the plan advocated by Borelli, Strauss-Dürckheim and Chabrier, but signally failed, his insect never having been able to lift more than a third of its own weight. De Villeneuve and Pénaud constructed their winged models on different types, the former selecting the bat, the latter the bird. 6' De Villeneuve made the wings of his artificial bat conical in shape and comparatively rigid. He controlled the movements of the wings, and made them strike downwards and forwards in imitation of natural wings. His model possessed great power of rising. It elevated itself from the ground with ease, and flew in a horizontal direction for a distance of 24 ft., and at a velocity of 20 m. an hour. Pénaud's model differed from de Villeneuve's in being provided with elastic wings, the posterior margins of which in addition to being elastic were free to move round the anterior margins as round axes (see fig. 24). India-rubber | F. H. Wenham, thinking to improve upon Henson, invented springs were made to extend between the inner posterior parts of the wings and the frame, corresponding to the backbone of the bird. A vertical movement having been communicated by means of india-rubber in a state of torsion to the roots of the wings, the wings themselves, in virtue of their elasticity, and because of the resistance experienced from the air, twisted and untwisted and formed reciprocating screws, precisely analogous to those originally described and figured by Pettigrew in 1867. Pénaud's arrangement is shown in fig. 40. If the left wing of Pénaud's model (a b, c d of fig. 40) be compared with the wing of the bat (fig. 18), or with Pettigrew's artificial wing (fig. 32), the identity of principle and application is at once apparent. In Pénaud's artificial bird the equilibrium is secured by the addition of a tail. The model cannot raise itself from the ground, but on being liberated from the hand it descends 2 ft. or so, when, having acquired initial velocity, it flies horizontally for a distance of 50 or more feet, and rises as it flies from 7 to 9ft. The following are the measurements of the model in question:-length of wing from tip to tip, 32 in.; weight of wing, tail, frame, india-rubber, &c., 73 grammes (about 24 ounces). (J. B. P.) Flying Machines.-Henson's flying machine, designed in 1843, was the earliest attempt at aviation on a great scale. Henson was one of the first to combine aerial screws with exten sive supporting structures occupying a nearly horizontal position. The accompanying illustration explains the combination (fig. 41). in 1866 what he designated his aeroplanes. These were thin, light, long, narrow structures, arranged above each other in tiers like so many shelves. They were tied together at a slight upward angle, and combined strength and lightness. The idea was to obtain great sustaining area in comparatively small space with comparative ease of control. It was hoped that when the aeroplanes were wedged forward in the air by vertical screws, or by the body to be flown, each aeroplane would rest or float upon a stratum of undisturbed air, and that practically the aeroplanes would give the same support as if spread out horizontally. The accompanying figures illustrate Wenham's views (figs. 42 and 43). Stringfellow, who was originally associated with Henson, and built a successful flying model in 1847, made a second model FIG. 41.-Henson's Aerostat. FIG. 43.-A similar system, planned by Wenham. a, a, Main spar 16 ft. long; spar. aeroplanes, consisting of six webs of thin holland 15 in. broad. The aeroplanes are kept in parallel plane by vertical divisions of holland 2 ft. wide. Thin tie-band of steel with London, in 1868. It was remarkably compact, elegant and "The chief feature of the invention was the very great expanse of its sustaining planes, which were larger in proportion to the weight it had to carry than those of many birds. The machine advanced,e, with its front edge a little raised, the effect of which was to present its under surface to the air over which it passed, the resistance of which, acting upon it like a strong wind on the sails of a windmill, prevented the descent of the machine and its burden. The sustaining of the whole, therefore, depended upon the speed at which it travelled through the air, and the angle at which its under surface impinged on the air in its front.... The machine, fully prepared for flight, was started from the top of an inclined plane, in descending which it attained a velocity necessary to sustain it in its further progress. That velocity would be gradually destroyed by the resistance of the air to the forward flight; it was, therefore, the office of the steamengine and the vanes it actuated simply to repair the loss of velocity; it was made, therefore, only of the power and weight necessary for that small effect." The editor of Newton's Journal of Arts and Sciences speaks of it thus:-" The apparatus consists of a car contairing the goods, passengers, engines, fuel, &c., to which a rectangular frame, made of wood or bamboo cane, and covered with canvas or oiled silk, is attached. This frame extends on either side of the car in a similar manner to the outstretched wings of a bird; but with this difference, that the frame is immovable. Behind the wings are two vertical fan wheels, furnished with oblique vanes, which are intended to propel the apparatus through the air. The rainbow-like circular wheels are the propellers, answering to the wheels of a steam-boat, and acting upon the air after the manner of a windmill. These wheels receive motions from bands and pulleys from a steam or other engine contained in the car. To an axis at the stern of the car a triangular frame is attached, resembling the tail of a bird, which is also covered with canvas or oiled silk. This may be expanded or contracted at pleasure, and is moved up and down for the purpose of causing the machine to ascend or descend. Beneath the tail is a rudder for directing the course of the machine to the right or to the left; and to facilitate the steering a sail is stretched between two masts which rise from the car. The amount of canvas or oiled silk necessary for buoying up the machine is stated to be equal to one square foot for each half pound of weight." FIG. 44.-Stringfellow's Flying Machine. very good idea of the arrangement-a, b, c representing the superimposed aeroplanes, d the tail, e, f the screw propellers. The superimposed aeroplanes (a, b, c) in this machine contained a sustaining area of 28 sq. ft., in addition to the tail (d). Its engine represented a third of a horse power, and the weight of the whole (engine, boiler, water, fuel, superimposed aeroplanes and "On Aerial Locomotion," Aeronautical Society's Report for 186 |