Whatever the professional distinction may be between the two branches of the aviation service, the broad difference in the public mind between the Royal Flying Corps and the Royal Naval Air Service is that the former fly over land and the latter over sea. And whatever the relative advantages, and the reverse, of these opposite conditions may be, a certain amount of sympathy inevitably goes out to the naval airman in the supposedly more difficult element from which he starts and on which he has to make his "landing" on return. The mystery and the menace of the sea, which has always made sailors a race apart, is so real and apprehensible a thing, even to the landsman, that instinctively the sea is felt to be a source of greater peril to the airman than the land. Be this as it may, it has fallen to the lot of the Royal Flying Corps in this war to face an "element"--if one may call it such--as mysterious as the ocean, and not a whit less menacing. This is the desert--a thing which casts a spell upon those who have to dare it as potent and as fearful as any with which the sea holds the mariner in thrall. Mutable to the eye as the face of the waters, sudden and fickle in mood as the sea itself, there lurks in the desert an even grimmer menace than that which gives the sailor his wary, vigilant eye. The cruelty of the sea is nothing to the cruelty of the desert. Ask the airman who has made trial of both, and he will tell you that better a hundred times the risk of falling into the clutches of the uncertain sea than the chance of finding himself at the mercy of the pitiless desert. Here is a case in point--a little excerpt from the doings of the Royal Flying Corps, which it would be hard to match even in the records of that adventurous service. Pilot and observer set off in an aeroplane upon a single-handed reconnaissance towards the enemy's lines in Sinai. A long flight was made over the desert, and the machine was a long way from its base when that terrible bugbear known as "engine-trouble" developed. All attempts to right it in the air proved abortive, and a forced descent was made. The aeroplane alighted on the desert waste, and the two occupants worked feverishly to adjust the faulty mechanism. Their dismay can be imagined when they found repair impossible, and realized that between themselves and the Canal lay a stretch of some twenty miles of desert, over which no means of progress was possible to them save their own legs. It says much for the loyalty to the duty of these two airmen that they carefully dismantled the gun which was mounted on the machine before setting fire to the latter, and that they actually set off on their long tramp across the burning desert carrying the gun between them.