I have just reread Beau Geste, a stirring 1920s yarn by P.C. Wren. It tells of three affluent young men who, for the noblest of reasons, forsake their comfortable English life to subject themselves to the harsh conditions of the Foreign Legion.
Our heroes, of course, are faultless to a man, and their adversaries, most of all the hated and sadistic Adjudant Lejaune, are evil through and through - as indeed, so Wren would have it, are all the native inhabitants of Africa.
But it is good clean fun, and the hardships are endured with all three upper lips steadfastly, semper et ubique, stiff: "Life at Zinderneuf was not really life so much as the avoidance of death - death from sunstroke, heat-stroke, monotony, madness or Adjudant Lejaune. Everybody was more or less abnormal from frayed nerves, resultant upon the terrific heat and the monotony, hardship and confinement to a little mud oven of a fort." And there was wind: "Across all, the harmattan blew hard, that terrible wind that carries the Saharan dust a hundred miles to sea, not so much as a sand-storm but as a mist or fog or dust as fine as flour, filling the eyes, the lungs, the pores of the skin, the nose and throat; getting into the locks of rifles, the works of watches, defiling water, food and everything else; rendering life a burden and a curse." The harmattan is an unpleasant continental manifestation of the otherwise benign north-easterly trade winds that are such a boon to sailors.
It is a very hot, dry, dusty wind that originates in the northern regions of the Sahara and flows south-west across the desert from November until March. It takes its character from the terrain over which it passes: the temperature of the air rises as it flows across the hot desert, it gathers up dust and sand and its humidity drops to 10 per cent.
When the harmattan is blowing, vegetation withers, woodwork shrinks and the eyes and lips dry up and smart. The unimaginable quantity of dust accumulated is ultimately carried out over the sea in the vicinity of the Gulf of Guinea and the Cape Verde Islands.
However, because of its extreme dryness, remittent fevers disappear as if by magic, and it is said to be impossible to communicate infections while it blows. It is sometimes called "the Doctor" along the coast of the Gulf of Guinea, since it comes as a welcome relief from the damp heat which characterises the previous and succeeding seasons.