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Rh Spanish at Oxford in 1902 and Gilmour professor of Spanish language and literature from 1909 to 1916, when he was trans- ferred to London as Cervantes professor of Spanish language and literature to the university of London. This post he resigned in 1920. He became a fellow of the British Academy and corre- sponding member of the Royal Spanish Academy and other Spanish societies, and a Knight Commander of the Order of Alphonso XII. Amongst his publications are a Life of Cervantes (1892); an Introduction to the editio princeps of Don Quixote (1898-9); a History of Spanish Literature (1898); Cervantes in England (1905); Cervantes and, Shakespeare (1916) and many other books and papers.

FLAMETHROWERS (Germ. Flammenwerfer). The World War revived the old weapon of "liquid fire." No doubt, the use of incendiary projectiles and devices had never altogether vanished from modern warfare, but these have usually been employed for destruction of material rather than for effect on personnel, and we have to go back to the sieges of mediaeval times to find examples of the use of heat, as such, to repulse an enemy. The townspeople of a mediaeval city, having only massacre to expect if their walls were stormed, observed no limitations in their choice of weapons, and not only used incendiaries proper to de- stroy the besiegers' hoarding- work and catapults but also boiling oil against the bodies of the men. From time to time in modern his- tory proposals have been made for flame-throwing devices, and one such was actually experimented with in Prussia about 1700. But until modern methods of storing a gas propellant under pressure came into being, anything in the nature of an effective flamethrower was impossible.

In reality therefore the flamethrower dates from experiments made in Germany a few years before the World War, when, no doubt in consequence of the trench warfare of Port Arthur, Richard Fiedler produced in 1906 a service model which was under experiment when the war broke out. Like other weapons of siegecraft this was brought into the field as soon as the nature of the fighting changed from open-field warfare to trench war- fare. Already in the winter of 1914-5 they appeared sporadically on the western front, and they obtained their first striking success in the Bois d'Avocourt (Verdun) on Feb. 26 1915. It should be noted that the use of such weapons was not prohibited by the Hague Convention, save in so far as it might be called a weapon " calculated to cause unnecessary suffering " a phrase which is susceptible of many interpretations. In this it differed from the gas warfare initiated at Ypres in April 1915, although by the accident of circumstances gas and flamethrowers have come to be associated in the popular mind.

When the German Flammenwerfer appeared it was considered essential both in France and in England to design weapons of this class at once; in England the question of their employment was reserved, but it was felt that the soldiers who were exposed to flame attack should, for reasons of moral, be made aware that similar devices were available on their own side. In France the military authorities proceeded without hesitation to the creation not only of the apparatus but of the units to work them. This difference in the way in which flamethrowers were regarded in the two chief Allied countries persisted to the end of the war. The French used them as constantly as the Germans, whereas in the British Army their employment on service was limited to a very few occasions in the battle of the Somme, and to the Zeebrugge attack of St. George's Day 1918. By the American Expedi- tionary Force they were not used at all, though the question of their employment was taken into consideration. In 1919 they figured largely in the local street-fighting by which the German Republic made good its authority.

The flamethrower essentially consists, in all designs, of (a) a container filled with some mixture of heavy and light oils; (6) a strong- walled vessel filled with air, nitrogen, CO 2, etc., under high pressure; and (c) a discharge tube with nozzle and in most cases an ignition device. Between (a) and (6) is a reducing valve, and between (6) and the nozzle a firing valve or trigger. When air or gas under high pressure is admitted into (a) from (6) it expels through (c) a powerful jet of oil, which when ignited (either at the nozzle or subsequently) becomes " liquid fire."

Flamethrowers are essentially short-range weapons, whose characteristic effect is to make an area untenable by living beings, by actual burning and also by heating the surrounding air to an intolerable temperature. This effect imposes, as a condition of their use, maximum range, not only because range as such is a desirable military quality but because the operators themselves must not be put out of action by their own weapon. Range, however, is difficult to obtain with a liquid jet. Even in vacua such a jet with an initial velocity of 50 metres per second would not theoretically range to 300 yd., and, owing to the resistance of the air, the maximum range ever known to have been attained in practice was 134 yd. actual throw (with an experimental British type of heavy flamethrower). Beyond the actual range of the jet there is of course an area (which varies according to the conditions of the shoot) made momentarily untenable owing to the heating of the air, and this area extends laterally as well as forward. But the fact of limited range remains a constant drawback. It is especially pronounced with the light portable types, few of which outrange the hand-grenade.

Amongst the design factors influencing initial velocity and therefore range, two are of principal importance, the pressure of the gas propellant in the oil container and the loss of energy in the discharger pipe and nozzle. The first would seem, at first sight, to be limited only by the weight and strength of the containers those of the gas "bottle" in the first instance and those of the oil container secondarily. But in practice the size of the nozzle orifice sets an upper limit to working pressure; if it is too small in proportion to the pressure the liquid, instead of being propelled in a consistent jet, is atomized and loses its forward energy very soon. But the larger the orifice the greater the quantity of liquid discharged per unit time. Hence, to obtain a long throw of any useful duration the flamethrower must be large, heavy and cumbrous. Conversely, when minimal weight is important, either range or duration must be sacrificed. Up to the limit thus fixed, of course, maximal pressure is aimed at in design, and it is found that, with modern materials and workmanship, gas bottles capable of standing the unreduced or storage pressure and oil containers able to endure the reduced or working pressure can be constructed within practicable weights.

The second important factor is loss of head, which varies with the length and smoothness of the internal surface of the discharge system, and is affected still more by the occurrence of abrupt bends and contractions in the piping or nozzle. A discharge system as straight, as short, and as large in bore as possible is therefore aimed at. But here again practical limits exist. In all heavy and medium and in most "knapsack" flamethrowers the position of the container has no relation to the axis of the jet. It is not, like a gun, pointed in the direction of the target, but is built in under cover or stood up on the ground or carried on a man's back, and aim is taken by pointing the nozzle only. Hence the most that can be done is to smooth out the angles of bend as much as possible and to diminish the length of piping to the strict minimum. Large bore is always desirable but not always attainable, since increased volume of oil per unit time means either increased dimensions for the oil container or diminished duration of action without reloading.

The dimensions of the nozzle itself, in this connexion, are important as affecting the form of the jet. Progressively, in its passage through the air, the solid vein of liquid breaks up into globules and loses its forward energy; the higher the initial velocity the longer this break-up is delayed, and velocity is, as we have seen, a function of working pressure and orifice dimensions. Moreover, the larger the vein itself the less surface it presents to disintegration by the air for a given volume; and the same reasoning excludes all cross-sections of the nozzle other than circular.

The oils employed varied, in the World War, according to available supplies, but were always in principle mixtures of heavy oil and light oil (petrol or benzol), the former for the sake of maintaining forward energy in the air (giving " sectional density " in ballistic language), the latter for ease of ignition. In winter the proportion of light oil was increased up to one-third in the French service.

The propellant gases used were also varied. Compressed air, being most readily available, was probably the most frequently employed. The Germans even tried compressed oxygen, a most dangerous expedient when nozzle-ignition is employed, as the mixture in the interior of the container is liable to detonate if a back flame from the jet reaches it. 1 This risk attaches also in a lesser degree to compressed air, and inert gases are always preferable. COa has the disadvantage that it forms a deposit in the piping and so increases loss of head, and in the end nitrogen either the pure product of chemical factories or a " deoxygenated air " produced in the field by a mobile plant was generally accepted.

So far only the expulsion of the oil jet has been considered. Broadly, there are two forms of ignition. In the one the ground occupied by the enemy is sprayed with the unignited oil, and then fired by throwing on to it incendiary bombs or grenades. This is mechanically the simplest way, and it gives the most thorough effect, since all parts of the ground, even the floors of trenches, are set on fire. But the throwing of grenades on to the correct spot is a difficult

1 A very serious accident occurred on one occasion in England from this cause, an oxygen bottle having been accidentally substituted for an air bottle.