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Frank H. Wenham
http://www.hq.nasa.gov

Frank H. Wenham , a Council Member of the Aeronautical Society of Great Britain, is generally credited with designing and operating the first wind tunnel in 1871. Wenham had tried a whirling arm, but his unhappy experiences impelled him to urge the Council to raise funds to build a wind tunnel. In Wenham's words, it "had a trunk 12 feet long and 18 inches square, to direct the current horizontally, and in parallel course." A fan-blower upstream of the model, driven by a steam engine, propelled air down the tube to the model.

Francis Wenham late in life
Royal Aeronautical Society
http://www.armchair.com

Wenham mounted various shapes in the tunnel, measuring the lift and drag forces created by the air rushing by. For such a simple experiment, the results were of great significance to aeronautics. Wenham and his colleagues were astounded to find that, at low angles of incidence, the lift-to-drag ratios of test surfaces could be surprisingly high-roughly 5 at a 15 degree angle of attack. Newton's aerodynamic theories were much less optimistic. With such high lift-to-drag ratios, wings could support substantial loads, making powered flight seem much more attainable than previously thought possible. These researches also revealed the effect of what is now called aspect ratio: long, narrow wings, like those on modern gliders, provided much more lift than stubby wings with the same areas. The wind tunnel idea was already paying off handsomely.

With the arrival of the wind tunnel, aerodynamicists finally began to understand the factors that controlled lift and drag, but they were still nagged by the question of model scale. Can the experimental results obtained with a one-tenth scalemodel be applied to the real, full-sized aircraft? Almost all wind tunnel tests were and still are performed with scale models because wind tunnels capable of handling full-sized aircraft are simply too expensive.

centennialofflight.gov
http://www.centennialofflight.gov

In 1858, the Englishman Francis Wenham, who in 1871 would design the first wind tunnel, carried out tests with a multiplane glider, which, although it did not fly, demonstrated that a cambered wing derived most of its lift from the front portion of the wing. Therefore, a high aspect-ratio wing had superior lifting qualities. In 1866, he presented a paper advocating these views at the newly formed Royal Aeronautical Society of Great Britain, which was established to bring together students of mechanical flight to discuss experiments and new theories and to publish technical journals.

microscopyu.com
http://www.microscopyu.com

During the mid-nineteenth century, Francis Herbert Wenham of London designed the first truly successful stereo microscope. Wenham incorporated a novel approach by utilizing an achromatic prism to split the light beam at the rear of a single objective. A few years later, John Ware Stephenson produced a similar instrument (see Figure 1). The Wenham binocular, as the microscope design became known, suffered from artifacts brought about by the single lens and did not actually produce a true stereoscopic effect.

Progress in Flying Machines
Octave Chanute, Aeroplanes : Part IV, September 1892.
http://invention.psychology.msstate.edu

In 1866 Mr. F. H. Wenham patented the meritorious proposal of superposing planes or surfaces above each other, so as to increase the supporting area without increasing the leverage. These were to be "kept in parallel planes by means of cords, or rods, or webs of woven fabric.... The long edges of the surface," made of silk or other light material, to be placed "foremost in the direction of motion." This system of surfaces being arranged above a "suitable structure for containing the motive power." If manual power was employed, the body of the operator was to be placed in a horizontal direction, and "the arms or legs to work a slide or treadle from which the connecting cords convey a reciprocating motion to oars or propellers, which are hinged above the back of the person working them."

In a very able paper, which has become classical, read at the first meeting of the Aeronautical Society of Great Britain, in 1866 Mr. Wenham gave an account of his observations, concluding with a very valuable discussion of the problem of flight, and with the following description of his experiments:

Having remarked how thin a stratum of air is displaced beneath the wings of a bird in rapid flight, it follows that in order to obtain the necessary length of plane for supporting heavy weights, the surfaces may be superposed or placed in parallel rows, with an interval between them. A dozen pelicans may fly, one above the other, without mutual impediment, as if framed together; and it is thus shown how two hundred weight may be supported in a transverse distance of only 10 ft.

In order to test this idea, six bands of stiff paper 3 ft. long and 3 in. wide were stretched at a slight upward angle in a light rectangular frame, with an interval of 3 in. between them, the arrangement resembling an open Venetian blind. When this was held against a breeze, the lifting power was very great; and even by running with it in a calm it required much force to keep it down. The success of this model led to the construction of one of a sufficient size to carry the weight of a man. Fig. 46 represents the arrangement, being an end elevation; a a is a thin plank tapered at the outer ends, and attached at the base to a triangle, b, made of similar plank for the insertion of the body. The boards a a were trussed with thin bands of iron c c, and at the ends were vertical rods d d. Between these were stretched five bands of holland 15 in. broad and 16 ft. long. the total length of the web being 80 ft. (100 sq. ft. Of surface). This was taken out after dark into a wet piece of meadowland one November evening, during a strong breeze, wherein it became quite unmanageable. The wind acting upon the already tightly stretched webs, their united pull caused the central boards to bend considerably, with a twisting, vibratory motion. During a lull, the head and shoulders were inserted in the triangle, with the chest resting on the base board. A sudden gust caught up the experimenter, who was carried some distance from the ground, and the affair, falling over sideways, broke up the right-hand set of webs.

fig.46, Wenham's designs of of 1866

In order to meet these conditions, the following arrangement was afterward tried: a a, fig. 47, is the main spar, 16 ft. long, 1/2 in. thick at the base, and tapered, both in breadth and thickness, to the end; to this spar was fastened the panels b b, having a base board for the support of the body. Under this, and fastened to the end of the main spar, is a thin steel tie band, e e, with struts starting from the spar. This served as the foundation of the superposed aeroplanes, and, though very light, was found to be exceedingly strong; for when the ends of the spar were placed upon supports, the middle bore the weight of the body without any strain or deflection; and further, by a separation at the base-board, the spars could be folded back with a hinge to half their length. Above this were arranged the aeroplanes, consisting of six webs of thin holland 15 in. broad (giving 120 sq. ft. of supporting surface); these were kept in parallel planes by vertical divisions 2 ft. wide of the same fabric, so that when distended by a current of air, each two feet of web pulled in opposition to its neighbor; and finally, at the ends (which were sewn over laths), a pull due to only 2 ft. had to be counteracted, instead of the strain arising from the entire length, as in the former experiment. The end pull was sustained by vertical rods, sliding through loops on the transverse ones at the ends of the webs, the whole of which could fall flat on the spar till raised and distended by a breeze. The top was stretched by a lath, f, and the system kept vertical by stay-cords taken from a bowsprit carried out in front. All the front edges of the aeroplanes were stiffened by bands of crinoline steel. This series was for the supporting arrangement, being equivalent to a length of wing of 96 ft. Exterior to this two propellers were to be attached, turning on spindles just above the back. They are kept drawn up by a light spring, and pulled down by cords or chains running over pulleys in the panels b b, and fastened to the end of a swiveling cross-yoke sliding on the base-board. By working this cross piece with the feet, motion will be communicated to the propellers, and by giving a longer stroke with one foot than the other, a greater extent of motion will be given to the corresponding propeller, thus enabling the machine to turn, just as oars are worked in a rowing boat. The propellers act on the same principle as the winds of a bird or bat; their ends being made of fabric stretched by elastic ribs, a simple waving motion up and down will give a strong forward impulse. In order to start, the legs are lowered beneath the base-board, and the experimenter must run against the wind.

fig.47, Wenham's designs of of 1866

Another arrangement has since been constructed having laths sewn in both edges of the webs which are kept permanently distended by cross stretchers. All these planes are hinged to a vertical central board, so as to fold back when the bottom ties are released, but the system is much heavier than the former one, and no experiments of any consequence have yet been tried with it.

It may be remarked that although a principle is here defined, yet considerable difficulty is experienced in carrying the theory into practice. When the wind approaches to 15 or 20 miles per hour, the lifting power of these arrangements is all that is requisite, and, by additional planes, can be increased to any extent; but the capricious nature of the ground- currents is a perpetual source of trouble.

If Mr. Wenham tried any further experiments with his apparatus, he has not, to the writer's knowledge, published an account of the results. They would be nearly certain to be unsatisfactory for want of stable equilibrium. The Wenham aeroplane was even more unstable than that of the bird and the latter is constantly in need of adjustment to counteract the "ground currents" and the variations in speed and in the angle of incidence. Moreover, the horizontal position selected by Mr. Wenham was most unfavorable because unnatural to man, in directing the movements of an apparatus; so that as often as he might rise upon the wind, just so often he was sure to lose his balance and to come down with more or less violence. The two propellers described by him would of course have proved quite ineffective in sustaining the weight, because man's muscular power is quite insufficient to have worked them with a speed adequate to that purpose, but they might have served to direct the course, had the equilibrium of the apparatus been stable.

Indeed, the writer believes that the first care of the aviator who seeks to solve the problem of flight, must be to seek for some form of apparatus which shall be, if possible, more stable in equilibrium than the bird. The latter is instinct with life; he meets an emergency instantly. Man's apparatus will be inanimate, and should possess automatic stability. Safety is the first requisite--safety in starting, in sailing, and in alighting, and the latter operation must be feasible almost everywhere without special preparation or appliances before the problem can be said to be fairly solved. It will probably prove the most difficult detail to accomplish, but it does not seem impossible when we see the feat performed by the birds so many times every day.

Mr. Wenham's proposal to superpose planes to each other in order to obtain large supporting surfaces without increasing the leverage, and consequent weight of frame, will probably be found hereafter to be of great value. The French experimenter Thibaut found that when two equal surfaces were placed one behind the other, in the direction of fluid motion, the resistance more nearly equaled that of the two separate surfaces than might be supposed. Thus for two square planes, placed at a distance apart equal to their parallel sides so as to cover each other exactly, M. Thibaut found the resistance equal to 1.7 times that of one single surface. When the hinder plane projected by 0.4 of its surface beyond the front plane, the resistance was 1.95 times that of the single surface. This diminished to 1.84 times, when it became 0.9. Beyond this it reached nearly twice the resistance.21 Professor Langley found in his experiments with superposed planes, 15 X 4 in., soaring at horizontal speed, that "when the double pairs of planes are placed 4 in. apart or more, they do not interfere with each other, and the sustaining power is, therefore, sensibly double that of the single pair of planes; but when placed 2 in. apart, there is a very perceptible diminution of sustaining power shown in the higher velocity required for support and in the greater rapidity of fall."22

We may hence conclude that there will result a material, indeed a great advantage in superposing planes, provided they are so spaced as not materially to interfere with each other, and provided also that they are arranged so as to afford a good equilibrium.

also see...

On Aerial Locomotion and the Laws by which Heavy Bodies impelled through Air are Sustained
F. H. Wenham
http://invention.psychology.msstate.edu

which in part discusses his flying machines i some detail..

The annexed diagram, Fig. 1, would be about the proportions needed for a man of medium weight. The wings, a a, must extend out sixty feet from end to end, and measure four feet across the broadest part. The man, b, should be in a horizontal position, encased in a strong framework, to which the wings are hinged at c c. The wings must be stiffened by elastic ribs, extending back from the pinions. These must be trussed by a thin band of steel, e e, Fig. 2, for the purpose of diminishing the weight and thickness of the spar. At the front, where the pinions are hinged, there are two levers attached, and drawn together by a spiral spring, d, Fig. 2, the tension of which is sufficient to balance the weight of the body and machine, and cause the wings to be easily vibrated by the movement of the feet acting on treadles. This spring serves the purpose of the pectoral muscles in birds. But with all such arrangements the apparatus must fail - length of wing is indispensable! and a spar thirty feet long must be strong, heavy, and cumbrous; to propel this alone through the air, at a high speed, would require more power than any man could command.

Wenham's designs of of 1866

These considerations bear no relation to artificial wings; so in designing a flying-machine, any deviations are admissible, provided the theoretical conditions involved in flight are borne in mind.

Having remarked how thin a stratum of air is displaced beneath the wings of a bird in rapid flight, it follows that in order to obtain the necessary length of plane of supporting heavy weights, the surfaces may be superposed, or placed in parallel rows, with an interval between them. A dozen pelicans may fly one above the other without mutual impediment, as if framed together; and it is thus shown how two hundred weight may be supported in a transverse distance of only ten feet.

In order to test this idea, six bands of stiff paper, three feet long and three inches wide, were stretched at a slight upward angle, in a light rectangular frame, with an interval of three inches between them, the arrangement resembling an open Venetian blind. When this was held against a breeze, the lifting power was very great, and even by running with it in a calm it required much force to keep it down. The success of this model led to the construction of one of a sufficient size to carry the weight of a man. Fig. 3 represents the arrangement. a a is a thin plank, tapered at the outer ends, and attached at the base to a triangle, b, made of similar plank, for the insertion of the body. The boards, a a, were trussed with thin bands of iron, c c, and at the ends were vertical rods, d d. Between these were stretched five bands of holland, fifteen inches broad and sixteen feet long, the total length of the web being eighty feet. This was taken out after dark into a wet piece of meadow land, one November evening, during a strong breeze, wherein it became quite unmanageable. The wind acting upon the already tightly stretched webs, their united pull caused the central boards to bend considerably, with a twisting, vibratory motion. During a lull, the head and shoulders were inserted in the triangle, with the chest resting on the base board. A sudden gust caught up the experimenter, who was carried some distance from the ground, and the affair falling over sideways, broke up the right-hand set of webs. In all new machines we gain experience by repeated failures, which frequently form the stepping-stones to ultimate success. The rude contrivance just described (which was but the work of a few hours) had taught, first, that the webs, or aeroplanes, must not be distended in a frame, as this must of necessity be strong and heavy, to withstand their combined tension; second, that the planes must be made so as either to furl or fold up, for the sake of portability.

In order to meet these conditions, the following arrangement was afterwards tried: - a a, Figs. 4 and 5, is the main spar, sixteen feet long, half an inch thick at the base, and tapered, both in breadth and thickness, to the end; to this spar was fastened the panels b b, having a base-board for the support of the body. Under this, and fastened to the end of the main spar, is a thin steel tie-band, e e, with struts starting from the spar. This served as the foundation of the superposed aeroplanes, and, though very light, was found to be exceedingly strong; for when the ends of the spar were placed upon supports, the middle bore the weight of the body without any strain or deflection; and further, by a separation at the base-board, the spar's could be folded back, with a hinge, to half their length. Above this were arranged the aeroplanes, consisting of six webs of thin holland, fifteen inches broad; these were kept in parallel planes, by vertical divisions, two feet wide, of the same fabric, so that when distended by a current of air, each two feet of web pulled in opposition to its neighbour; and finally at the ends (which were each sewn over laths), a pull due to only two feet had to be counteracted, instead of the strain arising from the entire length, as in the former experiment. The end-pull was sustained by vertical rods, sliding through loops on the transverse ones at the ends of the webs, the whole of which could fall flat on the spar, till raised and distended by a breeze. The top was stretched by a lath, f, and the system kept vertical by staycords, taken from a bowsprit carried out in front, shown in Fig. 6. All the front edges of the aeroplanes were stiffened by bands of crinoline steel. This series was for the supporting arrangement, being equivalent to a length of wing of ninety-six feet. Exterior to this, two propellers were to be attached, turning on spindles just above the back. They are kept drawn up by a light spring, and pulled down by cords or chains, running over pulleys in the panels b b, and fastened to the end of a swivelling cross-yoke, sliding on the base-board. By working this cross-piece with the feet, motion will be communicated to the propellers, and by giving a longer stroke with one foot than the other, a greater extent of motion will be given to the corresponding propeller, thus enabling the machine to turn, just as oars are worked in a rowing boat. The propellers act on the same principle as the wing of a bird or bat: their ends being made of fabric, stretched by elastic ribs, a simple waving motion up and down will give a strong forward impulse. In order to start, the legs are lowered beneath the base-board, and the experimenter must run against the wind.

An experiment recently made with this apparatus developed a cause of failure. The angle required for producing the requisite supporting power was found to be so small, that the crinoline steel would not keep the front edges in tension. Some of them were borne downwards and more on one side than the other, by the operation of the wind, and this also produced a strong fluttering motion in the webs, destroying the integrity of their plane surfaces, and fatal to their proper action.

Another arrangement has since been constructed, having laths sewn in both edges of the webs, which are kept permanently distended by cross-stretchers. All these planes are hinged to a vertical central board, so as to fold back when the bottom ties are released, but the system is much heavier than the former one, and no experiments of any consequence have as yet been tried with it.

It may be remarked that although a principle is here defined, yet considerable difficulty is experienced in carrying the theory into practice. When the wind approaches to fifteen or twenty miles per hour, the lifting power of these arrangements is all that is requisite, and, by additional planes, can be increased to any extent; but the capricious nature of the ground-currents is a perpetual source of trouble.

Great weight does not appear to be of much consequence, if carried in the body; but the aeroplanes and their attachments seem as if they were required to be very light, otherwise, they are awkward to carry, and impede the movements in running and making a start. In a dead calm, it is almost impracticable to get sufficient horizontal speed, by mere running alone, to raise the weight of the body. Once off the ground, the speed must be an increasing one, if continued by suitable propellers. The small amount of experience as yet gained, appears to indicate that if the aeroplanes could be raised in detail, like a superposed series of kites, they would first carry the weight of the machine itself, and next relieve that of the body.

Until the last few months no substantial attempt has been made to construct a flying-machine, in accordance with the principle involved in this paper, which was written seven years ago. The author trusts that he has contributed something towards the elucidation of a new theory, and shown that the flight of a bird in its performance does not require that enormous amount of force usually supposed, and that in fact birds do not exert more power in flying than quadrupeds in running, but considerably less; for the wing movements of a large bird, travelling at a far higher speed in air, are very much slower; and, where weight is concerned, great velocity of action in the locomotive organs is associated with great force.

It is to be hoped that further experiments will confirm the correctness of these observations, and with a sound working theory upon which to base his operations, man may yet command the air with the same facility that birds now do.

Flying Machines: Construction and Operation
W.J. Jackman and Thos. H. Russell
http://www.bookrags.com

Chapter I. Evolution of Two Surface Flying Machine : Renard's "Dirigible Parachute"
By Octave Chanute.

I am asked to set forth the development of the "two-surface" type of flying machine which is now used with modifications by Wright Brothers, Farman, Delagrange, Herring and others.

This type originated with Mr. F. H. Wenham, who patented it in England in 1866 (No. 1571), taking out provisional papers only. In the abridgment of British patent Aeronautical Specifications (1893) it is described as follows:

Two or more aeroplanes are arranged one above the other, and support a framework or car containing the motive power. The aeroplanes are made of silk or canvas stretched on a frame by wooden rods or steel ribs. When manual power is employed the body is placed horizontally, and oars or propellers are actuated by the arms or legs. A start may be obtained by lowering the legs and running down hill or the machine may be started from a moving carriage. One or more screw propellers may be applied for propelling when steam power is employed.

...and as it applies to Francis Wenham... [Ed]

Second Wenham Aeroplane

His second aeroplane was sixteen feet from tip to tip. A trussed spar at the bottom carried six superposed bands of thin holland fabric fifteen inches wide, connected with vertical webs of holland two feet apart, thus virtually giving a length of wing of ninety-six feet and one hundred and twenty square feet of supporting surface. The man was placed horizontally on a base board beneath the spar. This apparatus when tried in the wind was found to be unmanageable by reason of the fluttering motions of the fabric, which was insufficiently stiffened with crinoline steel, but Mr. Wenham pointed out that this in no way invalidated the principle of the apparatus, which was to obtain large supporting surfaces without increasing unduly the leverage and consequent weight of spar required, by simply superposing the surfaces. This principle is entirely sound and it is surprising that it is, to this day, not realized by those aviators who are hankering for monoplanes.

A History of Aeronautics
by E. Charles Vivian

Part V., Wenham
http://www.bookrags.com

Mention has already been made of the founding of the Aeronautical Society of Great Britain, which, since 1918 has been the Royal Aeronautical Society. 1866 witnessed the first meeting of the Society under the Presidency of the Duke of Argyll, when in June, at the Society of Arts, Francis Herbert Wenham read his now classic paper Aerial Locomotion. Certain quotations from this will show how clearly Wenham had thought out the problems connected with flight.

'The first subject for consideration is the proportion of surface to weight, and their combined effect in descending perpendicularly through the atmosphere. The datum is here based upon the consideration of safety, for it may sometimes be needful for a living being to drop passively, without muscular effort. One square foot of sustaining surface for every pound of the total weight will be sufficient for security.

'According to Smeaton's table of atmospheric resistances, to produce a force of one pound on a square foot, the wind must move against the plane (or which is the same thing, the plane against the wind), at the rate of twenty-two feet per second, or 1,320 feet per minute, equal to fifteen miles per hour. The resistance of the air will now balance the weight on the descending surface, and, consequently, it cannot exceed that speed. Now, twenty-two feet per second is the velocity acquired at the end of a fall of eight feet--a height from which a well-knit man or animal may leap down without much risk of injury. Therefore, if a man with parachute weigh together 143 lbs., spreading the same number of square feet of surface contained in a circle fourteen and a half feet in diameter, he will descend at perhaps an unpleasant velocity, but with safety to life and limb.

'It is a remarkable fact how this proportion of wing-surface to weight extends throughout a great variety of the flying portion of the animal kingdom, even down to hornets, bees, and other insects. In some instances, however, as in the gallinaceous tribe, including pheasants, this area is somewhat exceeded, but they are known to be very poor fliers. Residing as they do chiefly on the ground, their wings are only required for short distances, or for raising them or easing their descent from their roosting-places in forest trees, the shortness of their wings preventing them from taking extended flights. The wing-surface of the common swallow is rather more than in the ratio of two square feet per pound, but having also great length of pinion, it is both swift and enduring in its flight. When on a rapid course this bird is in the habit of furling its wings into a narrow compass. The greater extent of surface is probably needful for the continual variations of speed and instant stoppages for obtaining its insect food.

'On the other hand, there are some birds, particularly of the duck tribe, whose wing-surface but little exceeds half a square foot, or seventy-two inches per pound, yet they may be classed among the strongest and swiftest of fliers. A weight of one pound, suspended from an area of this extent, would acquire a velocity due to a fall of sixteen feet--a height sufficient for the destruction or injury of most animals. But when the plane is urged forward horizontally, in a manner analogous to the wings of a bird during flight, the sustaining power is greatly influenced by the form and arrangement of the surface.

'In the case of perpendicular descent, as a parachute, the sustaining effect will be much the same, whatever the figure of the outline of the superficies may be, and a circle perhaps affords the best resistance of any. Take, for example, a circle of twenty square feet (as possessed by the pelican) loaded with as many pounds. This, as just stated, will limit the rate of perpendicular descent to 1,320 feet per minute. But instead of a circle sixty-one inches in diameter, if the area is bounded by a parallelogram ten feet long by two feet broad, and whilst at perfect freedom to descend perpendicularly, let a force be applied exactly in a horizontal direction, so as to carry it edgeways, with the long side foremost, at a forward speed of thirty miles per hour--just double that of its passive descent: the rate of fall under these conditions will be decreased most remarkably, probably to less than one-fifteenth part, or eighty-eight feet per minute, or one mile per hour.'

And again: 'It has before been shown how utterly inadequate the mere perpendicular impulse of a plane is found to be in supporting a weight, when there is no horizontal motion at the time. There is no material weight of air to be acted upon, and it yields to the slightest force, however great the velocity of impulse may be. On the other hand, suppose that a large bird, in full flight, can make forty miles per hour, or 3,520 feet per minute, and performs one stroke per second. Now, during every fractional portion of that stroke, the wing is acting upon and obtaining an impulse from a fresh and undisturbed body of air; and if the vibration of the wing is limited to an arc of two feet, this by no means represents the small force of action that would be obtained when in a stationary position, for the impulse is secured upon a stratum of fifty-eight feet in length of air at each stroke. So that the conditions of weight of air for obtaining support equally well apply to weight of air and its reaction in producing forward impulse.

'So necessary is the acquirement of this horizontal speed, even in commencing flight, that most heavy birds, when possible, rise against the wind, and even run at the top of their speed to make their wings available, as in the example of the eagle, mentioned at the commencement of this paper. It is stated that the Arabs, on horseback, can approach near enough to spear these birds, when on the plain, before they are able to rise; their habit is to perch on an eminence, where possible.

'The tail of a bird is not necessary for flight. A pigeon can fly perfectly with this appendage cut short off; it probably performs an important function in steering, for it is to be remarked, that most birds that have either to pursue or evade pursuit are amply provided with this organ.

'The foregoing reasoning is based upon facts, which tend to show that the flight of the largest and heaviest of all birds is really performed with but a small amount of force, and that man is endowed with sufficient muscular power to enable him also to take individual and extended flights, and that success is probably only involved in a question of suitable mechanical adaptations. But if the wings are to be modelled in imitation of natural examples, but very little consideration will serve to demonstrate its utter impracticability when applied in these forms.'

Thus Wenham, one of the best theorists of his age. The Society with which this paper connects his name has done work, between that time and the present, of which the importance cannot be overestimated, and has been of the greatest value in the development of aeronautics, both in theory and experiment. The objects of the Society are to give a stronger impulse to the scientific study of aerial navigation, to promote the intercourse of those interested in the subject at home and abroad, and to give advice and instruction to those who study the principles upon which aeronautical science is based. From the date of its foundation the Society has given special study to dynamic flight, putting this before ballooning. Its library, its bureau of advice and information, and its meetings, all assist in forwarding the study of aeronautics, and its twenty-three early Annual Reports are of considerable value, containing as they do a large amount of useful information on aeronautical subjects, and forming practically the basis of aeronautical science.