In

The intruder was strapped beneath a miniature balloon. one hand he bore a small Union Jack; in the other a tube, at the end of which sprouted a propeller.

"Excuse my not removing my hat," he said, catching sight of her at once. "The fact is, it's not a hat at all. It's a helmet."

"It speaks," she murmured. ("Oh, Willow!")

"It" also brushed a few fragments of the scenery from its shoulders..

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I Do not, pray, think this hump is natural. Fact is, it's a little invention of mine for providing suitable breathing air. What you are looking at is not my head, either. I am not at all bad looking, from about the distance you are standing. It's an ether diver's helmet. The balloon is also detachable. I don't want it really. It is a concession to an old-fashioned prejudice. As a matter of fact, most of the lift is done by my 70,000 League Ergaer Boots. I mention these facts in case you should think I'm a freak, or a volcanic eruption. Pray came a little nearer. Heavens ! Be still, my heart!" The last was aside. All airmaids are charming. Meanwhile, the airmaid played a meditative air upon her pipe.

And what do you call this place?' "What should I call it," she replied, "but the airth? "American accent, "" he remarked. He, also, played meditatively, but 'twas with the tube he bore in his hand conveying current to the propeller that guided his every movement.

No," said he, absently.

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" 'Cos why?

None the less," he added, a lot of importance is attached to gas. Ha! ha!"

Have you a pain? enquired the airmaid.

"I merely laughed," replied the airman. "It's this confounded helmet. It exaggerates things. I'm not accustomed to speaking out of a safety valve in the back of my neck. There I go again! Now, do you know its exceedingly rare for me to make two jokes running. Must be the effect of the rarity of the atmosphere." "That's what I

You are so original," said the airmaid.

like about you.

Do you know, I have never seen anybody

quite like you before."

"How splendid of you to say so," he replied. "I should look better still without this helmet. It isn't really like me at all.

So matters hung for a while.

And is the the place you come from very dreadful? And are you a very naughty-airman?

So, so," replied he, with modest skill. The fact is, you know, I was one of the first men to try and fly off the world. Consequently, I have gone up considerably in public estimation, and am one of the first men on it. My character is moderately good-only moderately." "Fain," said the airmaid, Fain would I visit this strange home of thine, and learn more of it and thee. Fain," and

"Then why not fly with me?" said the airman. This was subsequently, so there was no attempt at rhyme. "Touch me not," exclaimed the airmaid, totally mistaking a If you squeeze me I shall die!" "Too true," said the airman, regretfully. "I'm afraid you would. I'm much denser than you, but I'm not so dense as all that. Alas! And, in any case, what would my wife say? I must descend. FareToo late! My oxygen is giving out. well, child of my dreams, a long farewell! I hope to see you again. Though whether I shall strike the same place again,

In the drafting of Government contracts and specifications in the case of articles whose form and limitations are known with precision, no clause is of greater importance than any other, and the terms in use being customary, have but, one technical meaning. But in the case of specifications relating to things, the combination of the details of which are still in a nebulous state and of which the limitations are not known to any degree of accuracy, it is a matter of difficulty for manufacturers to appreciate the degrees of importance of the different requirements.

Take, for instance, the supply of a battery of guns of a standard type. It is known to authorities exactly what a gun of the type specified can do, therefore all the items of the 'specifications are equally possible and are insisted upon to an equal degree. On the other hand, in the ordering of the product of a new science, as but little is known of the possibilities, the attributes marked as necessary in the specification are subject to alterations in the final trials and often to elimination. In the course of years this indefiniteness will disappear, but the manufacturer's present trouble will not be the less because the future holds promise of improvement in the clarity of the language of official papers.

The conditions and specifications relating to the military aeroplane competition were published by the War Office in December last. Such comment as was made on them by those who have knowledge of the difficulties in the way of the officials whose duty it was to arrange the specifications was highly favourable, and some surprise was expressed that these difficulties were overcome so well.

To such people as have had no experience of the phraseology employed by the War Office or of the particular definition of certain words used, many of the clauses appeared ambiguous to a degree. To a great extent this ambiguity will disappear as the manufacturers become more accustomed to the form of Government contracts. But it would be well if at the present stage of affairs the War Office could find it possible to issue an explanatory statement of the meaning of the separate clauses of the conditions.

Certain conditions laid down are definite and unalterableconditions which can be fulfilled by the manufacturers if they take the necessary trouble. Of such is the first clause.

"The machine must be delivered in a packing case suitable for transport by rail, and not exceeding 32 ft. by 9 ft. by 9 ft. The case must be fitted with eyebolts, to facilitate handling."

Questions of transport have dictated the details of this condition. The aeroplane in time of war will be sent by rail to the headquarters of the particular force to which it is to be attached. It is essential that it be securely packed in a case that no damage may come to it by reason of rough handling, and also that it may be in most compact form, so that it will Occupy the least possible space. Munitions of war and supplies of all kinds occupy so large a space in the modern army that all means possible are taken to reduce the bulk of each item as much as may be.

At the rail-head the aeroplane, still in its case, will be transferred to a trolley towed behind a motor wagon, or to a Renard road-train; and until it is put to actual use it will remain in a packed condition. The conditions relating to packing cases are with a view to rail transport chiefly, but the circumstances governing both rail and road are very similar. Those who are conversant with the problems of transport will realise how liberal the authorities have been in the questions of dimensions.

Clause 8, that the machine must "be capable of change from flying trim to road transport trim, and travel either on its own wheels or on a trolley on the road; width not to exceed 10 ft.," and the desirable attribute," " (f) that the time and number of men required for the change from flying trim to road trim, or packed for transport by rail and vice versa, should be small, and these will be considered in judging the machine. The time for changing from road trim and packed condition to flying trim to include up to the moment of leaving the ground in flight, allowance being made for difficulty in starting engine,' must be considered together and are of great importance, for, one would think, obvious reasons. Mobility and speed of action are of such great importance in modern warfare that the question of time has a large bearing on the usefulness of any object used in the carrying on of a campaign. The value of an aeroplane to a general officer commanding will vary according to the speed with which

it can be brought into action. It is therefore necessary that the time taken to assemble an aeroplane shall be as little as possible. The same necessity, of course, applies to the rapidity of packing the same machine. It is equally necessary that these two operations should not require the employment of a large number of highly-trained men.

No period of time is laid down in which it is required that the assembling and dissembling of machines shall be completed. An aeroplane may be put into flying trim from a packed state in record time, and yet be manifestly unsafe to fly. Officer-pilots killed in action may be mourned and missed, but their deaths will be accepted as a necessary feature of war; whereas the death of pilots through the collapse of machines badly though rapidly assembled will cause sufficient annoyance to make the manufacturer's life a burden and a disgrace.

The time absorbed in erecting aeroplanes will be judged according to the efficiency of the said machines after erection. The assembly of one aeroplane may take half an hour and another may take two hours, and yet the latter may be looked on with more favour. It is entirely a question of efficiency. Clause (11) "All parts of aeroplane must be strictly interchangeable, like parts with one another and with spares from stock, is essentially one of delicate ambiguity to the civilian and almost equally so to the prescient ones of Whitehall. Despite rumours to the contrary, it is not intended that an engine cylinder should be used in emergency as a rudder or a shock absorber; but it is intended, as has been previously said in this paper, that it should be possible to change a propeller, an engine, or a wing, and so on, for similar parts which shall be strictly the same in dimensions. Further, it appears as though the authorities desired manufacturers to use, for instance, as few different gauges of wire as possible, wirestrainers, in so far as they are able, of a similar size, and so on. The reduction in number of differing types of the same parts is aimed at, so that consequently it will not be necessary to carry so large a stock of spare parts as would otherwise be required. The War Office, from the depth of their knowledge, would no doubt prefer machines with wings so designed that either wing will fit either side, as in the case of the Antoinette. The clauses dealing with the actual flying capabilities of the machines engaged in the trials will settle their own difficulties. The makers of machines fulfilling all these requirements will find no difficulty in dealing with the previously discussed clauses. The weight carrying and duration clauses are neither unreasonable nor exacting, and both are essential points of the trials; but it is probable that the War Office will find it necessary to modify the speed of rising and the gliding angle. These two are the least essential of all the flying attributes required. The modification, however, will be slight.

The landing and getting-off clauses are all of great importance, but the results shown under these clauses during the trials will be examined in the calm light of reason. It is useless to insist on the impossible, and it is the duty of the manufacturers to demonstrate which requirements are impossible of attainment, if any.

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Another essential is Clause 13, that engines must be capable of being started up by the pilot alone"; but I presume no manufacturer will find that difficult of attainment. The use of a starting handle is apparently intended.

The remaining clauses are all obviously intended to be carried out to the letter, and are at the same time quite within the bounds of reason.

There is a proverb which speaks of the naming of dogs and its future effects on the canine reputation which in practice is only too true. The War Office has suffered heavily at the hands of its critics, often without cause, and the reputation of its officials for commonsense is of the weakest kind. But sweet reason dwells as amicably within the portals of the War Office as within the most civilised of business offices. To anticipate the worst in a competition is a poor way of beginning preparations.

It is certain that manufacturers will receive the most courteous treatment during the course of the trials, and it is also certain that any representations they make as a body will be given the deepest consideration by the departments of the War Office in whose hands these matters are placed.

[It should be particularly noted that Mr. Whittaker's article was already in type when the official notification from the War Office was received.-ED., THE AEROPLANE.]

The Formation of the Air Battalion.

It is not inappropriate to republish the Army Order relating to the formation of an Air Battalion in the British Army originally issued as a Special Army Order on February 28th, 1911. The text is as follows:

A.O. 61/1911. Organisation

Royal Engineers, Air Battalion-Peace

(1) Object.-With a view to meeting Army requirements consequent on recent developments in aerial science, it has been decided to organise an Air Battalion, to which will be entrusted the duty of creating a body of expert airmen, organised in such a way as to facilitate the formation of units ready to take the field with troops, and capable of expansion by any reserve formations which may be formed in the future.

In addition, the training and instruction of men in handling kites, balloons, aeroplanes, and other forms of air craft will also devolve upon this battalion.

(2) Organisation.-The establishment of this battalion, which will be organised into (i) headquarters, and (ii) two companies. The personnel of the headquarters will, in addition to the usual administrative duties, be available to form the nucleus from which the two companies can obtain additional officers, warrant officers, non-commissioned officers and required.

men as

Each company will be organised as a separate and self

contained unit.

(3) Personnel-how obtained.-The officers will be selected from applicants from any regular arm or branch of the Service on the active list.

(4) Qualifications of applicants. An applicant must be recommended by his commanding officer and be certified as medically fit for the work.

It is not considered necessary to lay down definite rules, except as regards the minimum length of service, but the following qualifications will be taken into consideration when selecting officers :-(a) Special recommendation by commanding officer; (b) possession of aviator's certificate; (c) previous experience of aeronautics; (d) rank not above that of captain; (e) medical fitness for air work; (f) good eyesight; (g) good map-reader and field sketcher; (h) unmarried; (i) not less than two years' service; (j) under 30 years of age; (k) good sailor; (1) knowledge of foreign languages; (m) taste for mechanics; (n) light weight (under 11 st. 7 lb.).

An application for appointment to the Air Battalion will be submitted to the War Office through the usual military channels.

(5) Conditions of service.-A selected candidate will, on joining the Air Battalion, go through a six months' probationary course (including two months' kiting and ballooning), and, if during this period he shows no aptitude for the work, he will rejoin his unit. An officer who satisfactorily completes the probationary period will be appointed to the Air Battalion for a period of four years (inclusive of the period of probation) and will be seconded.

Although the appointment to the Air Battalion will normally be for the above-mentioned period of four years, an officer may at any time be permitted to resign his appointment with the battalion.

(6) Pay and allowances.-An officer, other than an officer of the Royal Engineers, who is selected for the Air Battalion, will draw pay under Article 187 of the Pay Warrant, from the date of his first appointment to the battalion.

(7) Warrant officers, non-commissioned officers and men.The warrant officers, non-commisioned officers and men will be selected from the Corps of Royal Engineers.

(8) The existing Balloon School will be superseded by the Air Battalion, and the new organisation will be regarded as taking effect from April 1st, 1911.

It is an excellent example of the distance between intention and execution. The excellent promise shown in the Army Order has vanished almost as completely into thin air as do the freshly-made New Year's resolutions of unregenerate man. Those responsible for the framing of the Order apparently showed their opinion of it by ordaining that the new organisation should take effect from April 1st, 1911.

Clause 3, for one, has been ignored, a letter having been issued to General Officers Commanding asking for Royal Engineer officers to serve in the Air Battalion, a complete contravention of the terms of the Army Order.

The next clause also puts difficulties in the way of the appointment of useful officers. A good regimental officer finds it a matter of difficulty to persuade his commanding officer to recommend him for attachment to another branch of the Service.

The conditions of service (Clause 5) are similar to those laid down in the French and Italian Armies, and with the exception of the two months' kiting and ballooning, are excellent.

The Army Order, if carried out, would have provided the Army with a nucleus air corps of sufficient size to make expansion fairly easy. The damage done by issuing an order and then treating it with contempt spreads further than the section to which it refers. A surer system for the destruction of confidence in the good faith of the supreme authorities could not be devised.-W. E. DE B. W.

An Aeroplane in Action.

It is reported from Tripoli that on February 1st Lieut. Rossi, a volunteer military aviator, accompanied by Captain Montu as observer, flew from Tobruk over the enemy's camp. A number of bombs were dropped, apparently with good effect. The enemy replied with rifle fire, four bullets striking the machine, one of them slightly wounding Captain Montu. The aeroplane used was a Farman biplane, but as no information is given of the height maintained or of the weather conditions prevailing at the time, little can be learnt from this flight. The effect of rifle fire on aeroplanes in action has not yet been determined, and any information on the subject is of importCaptain Montu is member of the Chamber of Deputies, and went to Tripoli to organise a corps of volunteer aviators.-W. E. DE B. W.

ance.

a

Mr. Gilmour starting from Hendon on the MartinHandasyde Monoplane on his way to Brooklands.

The Aeronautical Society held an interesting, and at times amusing, discussion on Soaring Fight at the Royal United Services Institute on Tuesday of last week, Sir J. Wolff Barry being in the chair.

Mr. A. E. Berriman, opening the discussion, said that soaring "is that mode of flight in which a bird remains indefinitely aloft without flapping its wings. Gliding is also a mode of flight, but differs from soaring in that the path of motion is, on the whole, downwards, whereas in soaring there is no permanent loss of altitude. Flapping flight differs from soaring flight in that the bird exerts visible energy. From these facts may be deduced-what is otherwise a matter of elementary perception-that flight of any description involves the expenditure of power, and that in soaring flight this energy must come from the air. The primary question for discussion was, therefore, what form does this energy take?

In a

"All forms of flight demand relative motion between the object supported and the air. But the body thus supported offers resistance to such relative motion; consequently it will be blown away in the same direction as the wind unless an opposing force of propulsion enables it to hold its own. paper kite, this force is a pull on the string. In an aeroplane, it is the thrust of the engine-driven propellers. In a glider, it is the component of gravity in the line of motion. In a soaring bird it is the horizontal component of the wind pressure on the bird's wing which has a forward direction (i.e., against the wind) by virtue of the resultant being inclined forward of the vertical. It is impossible to obtain a forwardly inclined resultant from any kind of wing section in a truly horizontal and uniform wind, hence soaring flight is impossible under such conditions.

"If the wind is not horizontal, but has an adequate upward trend, sufficient propulsive component will be established to permit soaring flight to be continued indefinitely. The least upward velocity component that will satisfy this condition of soaring flight is numerically the same as the rate of vertical descent when gliding in calm. If the wind blows parallel to the side of a hill having the same slope as the gliding path of the bird, the wind must have at least the same velocity as the bird's natural flight in order to maintain soaring. Obstructions such as cliffs, houses, and ships, cause horizontal winds to trend upwards to an extent that is frequently adequate to maintain soaring.

"Mr. Lanchester says: The region of greatest up current is evidently immediately in advance of the upper edge of the cliff, and the useful region may roughly be defined as a circle whose centre is slightly above the level of the plateau, and whose diameter is about equal to the height of the cliff. . . . Further, in some cases the up current may arise from the motion of a body through the air in lieu of the air moving past the body. In this way ships, especially sailing vessels, may conceivably become the cause of an aerial disturbance that the soaring bird can turn to its advantage.' And further, 'The only estimate extant of the flight angle of a bird that can be considered reliable is that of Bretonniere, who, from observations made on a number of storks, concluded that the gliding angle of this bird is 10 degrees, or 1 in 5.7.'

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It is a question for discussion whether the evidence of a falling feather would be proof of the non-existence of an upcurrent in this order of magnitude. Dr. Hankin observed cases in which soaring flight is maintained in an atmosphere through which a feather detached from a bird's breast slowly fell to earth. Because we exist in the proximity of the boundary surface (the earth) to a fluid region (the atmosphere), where relative motion of any magnitude is only possible in a direction parallel to the surface, our common impression of winds is that they are all horizontal. Air that is lighter than its environment tends to rise by upward acceleration, causing thereby the colder air to flow in horizontally towards the hotter regions. Up currents are, therefore, the primary cause of the horizontal winds that we are so apt to regard as the only natural mode of air in motion. The cool air sweeps in horizontally toward the hot centre, but does not blow across it. An invisible core of rising air deflects its course, so that the bulk of the horizontal wind flows upwards from afar, and by gradual curvature at length acquires a vertical motion at a considerable height above the ground.

sure by which it is propelled will be equivalent to a head of one foot; this, by the principle of Torricelli, corresponds to a velocity of 8 ft. per second, which is more than sufficient to sustain a gliding bird without loss of altitude.

"All observers stationed in apparent calm who have watched soaring flight agree :

"1. That the birds do not begin to soar until after the sun has risen awhile.

"2. That all birds make a flapping ascent to an altitude of a hundred feet or so.

"It has been stated (1) that soaring in a calm is impossible, (2) that soaring in a uniform horizontal wind is impossible, (3) that soaring in a uniform wind blowing obliquely upwards is possible, (4) that soaring in an up current is possible.

It remains to state that soaring in a horizontal pulsating wind is possible. Lord Rayleigh in Nature,' 1893: The conditions for soaring flight: (1) The course is not horizontal; or (2) the wind is not horizontal; or (3) the wind is not uniform.' In order to maintain soaring in a horizontal wind, the velocity may fluctuate with time or place. That is to say, if the speed is the same simultaneously throughout the zone, then the velocity must change during the next instant of time, but if the velocity is different simultaneously in adjacent regions, then the speed at a given point may remain constant. "Langley says: In a high wind the air moves as a tumultuous mass, the velocity being at one moment perhaps 40 m.p.h., then diminishing to an almost instantaneous calm.'

Meteorology has shown that wind velocities commonly increase with altitude, wherefore the soarability of the air is presumably greater at greater heights. Obvious examples of fluctuation of wind velocity with place occur in the vicinity of obstacles capable of creating a region of dead water on their lee side. Sea waves may do this with a surface wind, and the low gliding flight of some sea-going birds is explicable by this theory.'

66

66

Ergaer."

Dr. Hankin, who followed, is well-known to the members of the Aeronautical Society as the propounder of the theory of Ergaer, which is a name he has coined for some undiscovered property of air which enables a bird to soar without an upward current, and he hazards the guess that this Ergaer operates by exploding under the bird's wing in certain conditions of the atmosphere.

Dr. Hankin said that in his published accounts he had written what he saw whether it appeared possible or not. He also said that his critics alleged that his arguments in favour of "Ergaer were insufficient, and pointed out that research was carried on to discover facts, that a theory was only a preliminary classification of facts, and he thought too much respect was paid to authorities, and not enough to the facts themselves. He had seen vultures avoiding known currents, and in a certain ravine where an up-current was known to exist the birds only soared in the sun and flapped when it clouded over (a neighbour in the audience suggested to me sotto voce that probably when the sun was hot the birds took it easy and only soared, but when it clouded over they flapped to keep warm à la cabmen).

Dr. Hankin wanted to know whether soaring was due to potential energy (Ergaer) or the kinetic energy in the wind. In the same ravine after rain the air was unsoarable, and wing beats were easily heard owing to the sound travelling far, thus showing the homogeneity of the air and absence of disturbance. This was an argument in favour of the kinetic theory. On the other hand, he had seen a cheel soaring and rising in a descending current, as shown by clouds descending on the lee side of a steep hill, although practically no wind was blowing at all. (Here my neighbour interjected the remark that probably the cheel had a better gliding angle than the clouds, and was so able to go up while the clouds were coming down.) Also he had seen hill crows circling and rising without flapping when no wind was blowing, and an adjutant bird doing 30 or 40 miles per hour without flapping, and passing close to a piece of thistledown floating immovable. He admitted the existence of heat eddies, but they could not account for some phenomena of soaring. He also described various forms of instability in soaring birds, which he attributed to patches of air which were short of Ergaer.

Mr. Weiss's Experiences.

Mr. José Weiss, who probably knows more about soaring flight than all the rest of the room put together, said that he had often observed up-currents on the lee side of hills, these