The accompanying photographs and sketches will probably be almost self-explanatory so far as the Bristol machines entered for the War Office Competition are concerned.

As was announced last week, four Bristols are entered, two monoplanes, which will be flown by Messrs. Busteed and Valentine; and two tractor biplanes, to be flown by Messrs. Gordon England and Pixton. Both the former have 80-h.p. Gnôme engines. Of the latter one has a 100-h. p. Gnôme driving its tractor direct, and the other a 70-h.p. Mercédés-Daimler driving a geared-down tractor through a chain.

The writer was able, by the courtesy of the British and Colonial Aeroplane Company, Ltd., to inspect three of these machines on Salisbury Plain on Wednesday of last week, but the last-mentioned had not then arrived from the works. On the whole, the general impression given by the new monoplanes designed, one understands, by M. Coanda, is favourable. They look fast, and they certainly fly fast, judging from Mr. Busteed's machine, in which the motor was not fully tuned up.

It appears that each new type of engine has to be specially learnt, for the 70-h.p. Gnôme, which seemed to be a failure at first, is now running pretty satisfactorily everywhere, and it is probable that the 80 h.p.'s will also behave properly when the various mechanics have got used to their tricks. Meantime all is not quite peace with them, so one had not quite a fair

opportunity of seeing how fast Mr. Busteed's machine really was, nor how it could lift.

Mr. Valentine's machine is practically the same, except that it has the new Gnôme carburetter instead of the old simple jet and choke-tube, and as this is placed about 4 in. to 6 in. from the observer's rudder-bar inside the body, it might be awkward in case of a blow-back through a broken valve-spring setting light to the carburetter.

Of course, the machine is beautifully made, and is full of interesting details. The methods of jointing up the various struts and skids in the chassis are not only ingenious, but strong and neat. The cross tubes and wheel axles in the chassis are neatly streamlined with pieces of light wood clipped on to their lee sides. The quick-release catch for the cables is also worthy of attention. It is similar in principle to that used on the Coventry Ordnance machine, the little cross-piece which prevents the pin from coming out of the tube being turned into a vertical position when the spring is pulled up, so that it can pass down inside the tube.

The wings are cut away close to the spars, back and front, near the fuselage, to give pilot and observer a better view, much in the way recently described in the Deperdussin machines. The four simple chassis struts are made very deep fore and aft, and narrow thwartwise, so as to approximate to a good streamline, tapering almost to a knife-edge aft. They

are hollowed in section, the two halves being sewed together with cord, as in the Maurice Farman and Caudron struts.

As far as the back of the pilot's seat the body is cased with aluminium sheet, but aft of that it tapers into a square fuselage covered with fabric, on the end of which is a flat tail-plane followed by a long capable-looking elevator flap, which is not "balanced" in any way, but merely hinged. The rudder is perched on top of the tail, and is balanced" by having a fair amount of its surface in front of the stout steel rudder post. In front of the rudder is a vertical fin, exactly like the dorsal fin of a shark. There are various good reasons for having it there, such as a desire to give more vertical area aft of the centre of gravity, the intention to increase directional stability and to decrease the fierceness of the balanced rudder, but, peculiarly enough, it seems necessary to the look of the machine, for it adds to the wicked " appearance given to the forward part by the grey-painted rounded cowl over the

engine and the stubby upper masts, only it would have looked still better and might have given better streamlines if the oval section of the forward part had been carried right aft. However, the machine is a good specimen of sound English work, and one hopes it will distinguish itself in the trials. Incidentally, it is worthy of note that all the Bristol twoseated monoplanes at present in the sheds at Lark Hill have now been fitted with semi-circular fixed tails, with large flat elevator flaps, instead of the balanced elevators without fixed planes, formerly fitted, which gave rise to so much controversy on the question of longitudinal stability. Some of them also have the body considerably lengthened, and the pilots seem, on the whole, to prefer these to the older type.

The Biplanes.

The Gordon-England biplane was described and illustrated in detail in THE AEROPLANE not very long ago, and in a gene

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Aerohydroplanes and Hydroaeroplanes.

It is noticeable that the Daily Mail, which coined the word water-plane" to describe a hydroaeroplane, has adopted "aerohydroplane" for the Donnet-Lévêque type of waterflier. Strangely enough, the word really does describe what it is intended to describe, though "waterplane" and "airman" most distinctly do not. The difference is this: the hydro-aeroplane is an aeroplane intended for flying off and on to water, whereas the aero-hydroplane is a hydroplane intended to be used in the air. Most hydro-aeroplanes are simply aeroplanes with floats, and are pulled off the water by the planes when they have reached their lowest flying speed. The aerohydroplane is a hydroplane with wings which forces itself out of the water when it reaches a certain speed and skims along the surface, as a hydroplane boat does, till it reaches its flying speed, when the wings take charge and lift it off the water, not out of it.

Diagrammatic sketch of the Gordon-England biplane, as altered for 100-h.p. engine.

The difference in efficiency is shown most markedly in starting with the wind behind; for a hydro-aeroplane will take a long time to get into the air owing to the drag of the floats in the water preventing it from reaching its flying speed, whereas an aero-hydroplane will be forced onto the surface by a following wind, and may actually get into the air more quickly than if starting head to wind.

Of course, the hydro-aeroplane may have a comprehensive boat body which does not hydroplane at all, and an aerohydroplane may have comparatively small floats-one or more of them-which hydroplane exceeding well, so it is impossible to tell whether a machine belongs to one type or the other till one has seen it in operation, but though representatives of either type may be similar in appearance, they differ exceedingly in operation. It is, however, fairly obvious that the true aero-hydroplane must in the end displace the other type for regular use off water.

Limited,

FILTON HOUSE, BRISTOL.