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aeroplane and enclosing both the engine and the passengers, for the simple open frame- 

 work of former days, and a considerable improvement in stability. In consequence, 

 the aeroplane in which the propeller revolved in the rear of the planes has been largely 

 replaced by the type known as the " tractor," in which the engine, mounted in the bow 

 of the body, drives by direct transmission a propeller rotating in front of the planes. 

 Generally speaking, the above features apply both to monoplanes and to biplanes, the 

 former type consisting of a single plane or pair of outstretched wings, whereas in the 

 latter two lifting planes are superposed and interconnected by struts. The relative 

 advantages of these two main types are chiefly constructional; the girder shape of the 

 framework rendering the structure stronger in the biplane, and leading to its general 

 employment where heavy weights have to be carried. In the case of a monoplane, the 

 wings are stayed by means of steel wires or cables attached to the landing chassis and to 

 an overhead staymast, an arrangement which, while reducing head resistance, presents 

 obvious engineering difficulties of a constructional nature. The controlling surfaces 

 are usually situated in the tail, fixed to the after end of the body; they consist of an 

 ordinary vertical rudder for steering in a horizontal plane, and of a horizontal rudder or 

 " elevator " for steering upwards and downwards and for maintaining longitudinal 

 balance. Lateral stability is usually controlled either by the process originated by the 

 brothers Wright and known as " warping " the planes, i.e. twisting their rear outer 

 extremities to produce an increase in lift on the lowered side and to reduce the lift on 

 the raised side, or by the equivalent means of operating balancing flaps attached to the 

 rear edge of the planes or mounted in between them. 



Two further distinctive features mark the recent development of aviation: the vastly 

 increased reliability of the aeroplane motor and the evolution of the hydro-aeroplane, 

 by which is denoted a craft able to rise from and alight upon the sur- 

 face of the water. Two distinct types of aeroplane motors have been cre- 

 ated, the rotary air-cooled engine and the water-cooled stationary type, of which the 

 former, generally speaking, is most effective for comparatively low powers, while the 

 latter is usually employed for the heavy passenger-carrying class of aeroplanes. The 

 power developed ranges from 25 h.p. in a small school machine to 140 h.p. in a racing 

 aeroplane, or one designed for extended flights. These motors, with the exception of the 

 rotary type, show little difference from the average motor-car engine, save only in a con- 

 siderable reduction in the weight, which ranges from 2 to 6 Ibs. per horse-power. 



The hydro-aeroplane owed its first development to the American, Glertn Curtiss, who 

 equipped his aeroplanes with floats as early as 1910. Two main types have already been 

 evolved, though with countless modifications. In the first the only feature 

 Hydro- that distinguishes the marine type from that destined for use on land, is the 



substitution of one or more floats for the o'rdinary landing chassis, though 

 this is sometimes retained in the shape of disappearing wheels. The second class, 

 variously termed " flying-boat " and " air-boat," consists essentially of a long boat- 

 shaped hull, wherein the passengers' seats are contained, and on which the planes are 

 built up in the form of a superstructure. This latter type of craft seems destined to a 

 greater sphere of utility than the former, by reason of its being better able to withstand 

 the battering of waves and the shock of alighting on rough water. General technical 

 opinion foresees a greater future for the marine aeroplane than for the terrestrial type, 

 owing to the fact that it can be used in the colonies and in undeveloped countries where 

 suitable alighting grounds are scarce; while, on the other hand, it would solve the 

 difficulty and danger of alighting in a heavy high-speed aeroplane. 



In the, sport of aviation, as evidenced in the record of performances during the last 



two years, progress has been startlingly rapid. The year 1911 was marked by the 



organisation of a series of long-distance cross-country races, among the 



The . . most noteworthy being those from Paris to Madrid, won by J. Vedrines; 



ablation. from Paris to Rome, won by A. Beaumont; the so-called European circuit, 



which extended over 1000 miles through France, Belgium, Holland and 



England with Paris as the starting and finishing point; and the 1000 miles circuit of 



