time without having safely landed. In the early days French machines were fitted with wheels for landing, while the Wright machines saved both weight and wind resistance by using skids only. They had, however, to be launched off a special trolley which was not available away from home; the inconvenience of this was soon learnt, and wheels were substituted. Nevertheless, it was the Wright brothers who brought home to the rest of the world the value of skids for spanning unevennesses in the ground; and Farman combined skids and rubberspringed wheels in a way which has remained practically unchanged. The Wrights, on their return to America, obviously profited by their European experience, for the latest Wright aeroplane has wheels on the skids very much after the European style. The wheels run and keep the skids clear of the ground when the ground is level, and diminish the friction at starting; but the skids are present to bridge over any groove or ditch, as well as to take any bump severe enough to try the wheel-springs to their limit. One of the duties of the landing-frame is to take side pressures in the event of a flyer alighting across the wind. In some measure the indiarubber device and the triangular guide on the Farman type allows for this, but the contingency is more elaborately provided for in the castor-mounting of his wheels arranged by Blériot. The latter, however, suffers on bad ground by having no skid. One difficulty due to the heavy strains on the landingchassis. is its weight, amounting to well over 100 lb. in a Farman, for example. The members of the chassis are in compression when it is in use, which generally means weight unless some hydraulic system can be introduced by which the energy of the blow can be taken up by allowing a piston to do work while travelling through some considerable distance, as, for example, by forcing air or a fluid through a fine hole. Vickers, Pelterie, Breguet and the R.A.F. have been engaged on this for some time. Such an arrangement is better than a pneumatic cushion which is resilient, because any bouncing tends to increase the trouble with the inertia of the wings, and imposes alternating stresses upon their guys. For safety over water the first step was merely to conceal an air-bag in the fuselage, as Blériot did to cross the Channel. Where there was no fuselage, cigar-shaped air-bags were attached by our navy flyers near the skids to keep the aeroplane unsubmerged when alighting. Voisin in France and Curtiss in America improved on this by borrowing the idea of a float with a flat bottom and down-turned stern from Thornycroft's wonderful hydroplane boats. With this Curtiss' waterplane was the first to quit the sea under its own power. Fabre and Voisin were successful on the same lines; and the study spread to England, where Sueter, assisted by Schwann as flyer at Barrow, Wakefield and Gnosspelius at Windermere, Short at Sheppey and de Havilland on the large water at Fleet, all adapted Thornycroft floats to aeroplanes and so left the water. Farman did the same at Bue and carried all before him at Monaco. Yet all these aeroplanes, if their weights were disposed to the best advantage for gusty air before the floats were fitted, are less good as aircraft with 160 lb. added to their lowest point. The science provides no means of measuring relative stability in gusts, so that we cannot as yet compare results. We can welcome the appearance of any variants which widen our scope, such as the alternative design initiated after the early trials by the R.A.F. for making a hydroplane boat to fly by a raised engine and propeller instead of causing an aeroplane to float. The evolutions of the Donnet l'Evêque, which independently carries out this scheme, will be watched with interest. We cannot quit this subject without tendering our thanks to those whose daring has advanced the study of methods of flight, or our homage to those who in its pursuit have sacrificed their lives for their country as surely as if they had fallen in battle. MERVYN O'GORMAN. Art. 12.-THE TRIPOLITAN WAR FROM THE TURKISH SIDE. 1. Across the Sahara: From Tripoli to Bornu. By Hanns Vischer, M.A. London: Arnold, 1910. 2. A travers la Tripolitaine. La Tripolitaine d'Hier et de Demain. By H.-M. de Mathuisieulx. Paris: Hachette, 1901, 1912. 3. La Conquista di Tripoli. By Enrico Milan Fratelli Treves, 1912. Corradini. 4. Trade and Economic State of the Vilayet of Tripoli during the past forty years. 1902. [Cd 787-14.] 5. Trade of the Benghazy District for the years 1905-06, and 1906-08. [Cd 3283-91, and 4146-38.] DESPITE its proximity to Europe, Tripolitania seems to be an almost unknown country. There is no map of it at all comparable either in fullness or in accuracy with the maps we have of every other province of Northern Africa; and the three Consular reports cited at the head of this article represent, so far as I can discover, the sum total of official information obtainable in England. Hardly less meagre is unofficial literature on the subject. Every fresh contribution to it deserves therefore a grateful welcome, especially at the present hour, when upon the fate of that province depend issues extending far beyond its boundaries. Among the most valuable of these contributions is Mr Hanns Vischer's simple and straightforward record of his adventurous journey from Tripoli to Bornu in the latter half of the year 1906. The author, in the form of a modest and intensely interesting personal narrative, gives us a great deal of information concerning the regions which he traversed—the plain that spreads along the littoral on the north, the mountains that border it on the south, and the great desert that stretches beyond; and he accompanies his picture of the land with a minute account of the tribes which dwell in the oases or wander over the wilderness of sand and scrub. The work labours under one unavoidable limitation; it covers only the territory that lay on the traveller's route. For supplementary information about other parts of the country the reader may turn to M. H.-M. de Mathuisieulx's two volumes, embodying the fruits of four different journeys of exploration into the interior of that jealously guarded land, carried out from 1901 to 1907. These works furnish us with an adequate impression of the stage. The third book on our list deals with the first act of the drama. It is a collection of letters by an Italian war correspondent beginning with the blockade of Tripoli on September 30 and ending with the occupation of Ain Zara on December 4. All the operations that took place within that period are described vividly but, of course, from the Italian point of view. I reached the seat of war just after the Turkish retreat from Ain Zara, and found the Turkish headquarters where they still are, at Azizia-about twentyfour miles to the south. But though the centre is so far, the Turkish advanced posts, which radiate from Azizia in two main lines, stretch to within three or four miles of the Italian fortified positions at Girgaresh, Bu Meliana, and Ain Zara. The Italians since December 4 have made only one attempt to penetrate further south; and their experience deserves description not only on account of its uniqueness, but also because it illustrates in a most instructive manner the conditions which have hitherto frustrated Italy's efforts to conquer the province which she annexed nine months ago. In the small hours of Dec. 19, 1911, an Italian column composed of two battalions of the 11th Bersaglieri, one battalion of the 2nd Grenadiers, two pieces of mountain artillery and one squadron of calvary-altogether over 2000 men-marched out of the Ain Zara trenches under the command of Colonal Fara and pushed up the Sidra Way. The Italians had been informed by two Arab sheikhs of Bughamtsa that the Turkish position on that side was very weak, and that Ben Gashir, the main camp on the right wing, did not contain more than 250 Arab auxiliaries and a handful of Turkish regulars; further, that the natives of the district were prepared to welcome the invaders with open arms. Encouraged by these reports, the Italians left their trenches and marched south. Meanwhile the Turco-Arab forces at Ben Gashir had detected the flight of the two sheikhs, and, suspecting treason, took their precautions accordingly. It is true that their strength on the spot was not much greater than it had been represented-about fifty Turkish regulars and 500 Arab volunteers all told. But this little army was made to go a very long way. A body of Arabs was posted across the Sidra Way near a well called Bir Tobras, about nine miles to the south of Ain Zara and a little to the north of Bughamtsa. Another detachment was sent to Fenduk es Shereef, a spot on the Wadi Mejneen about four miles south of Ben Gashir. A third to Fenduk el Aoon, also on the Wadi Mejneen, about four miles to the north of Ben Gashir and seven to the south of Ain Zara. In this manner both routes were watched, and the TurcoArab patrols which stole close up to Ain Zara saw the enemy's movement and gave the alarm. The Italians, utterly unaware of the preparations made for their reception, blundered up the Sidra Way and, thanks partly to the darkness, partly to their own curiously defective topography, took nine hours to cover as many miles. It was not till 11 a.m. that their cavalry reached Bir Tobras; there they suddenly found themselves greeted with a furious fusillade from the Arabs posted on that spot. The column came to a standstill, and answered the Arab fire with its artillery. The report of the guns acted, as it always does, as a signal for all the other Turco-Arab forces in the neighbourhood to rush to the scene; and the battle began. The Italians entrenched themselves among the sandhills. The Turks and Arabs assaulted them from three different points -west, south and east. The total number of these forces barely amounted to five hundred. But what they lacked in number they made up in recklessness, dashing up to within twenty-five metres of the enemy's front. The latter, on finding advance impossible, endeavoured to retreat under cover of their mountain guns, which they planted on a knoll close to Bir Tobras. Such was the position when night fell. During the night the Italians began to fall back, while a Turkish lieutenant, who commanded the Arab contingent to the east, tried to cut off their retreat by a turning movement. In this, however, he failed, partly because the force under him was too undisciplined to carry out the movement, and partly because the reinforcements which the commandant of the right wing had requested from his colleague on the left did not arrive in time. Meanwhile, the Italians also had intimated their |