From the Library

[Biggles]

Even before dawn the next day the temperature was already at a ferociously high level and the glowing red bail of the sun gave us the impression of some dreadful scourge. We made ourselves face-masks out of linen which we wore under the front of our tropical helmets, hanging down to our chests, with big round holes cut out only for the eyes. Short trousers and sleeveless shirts also proved an agony in the midday heat. Long trousers and long sleeves would have kept off the heat better.   
Seeing the Bedouin going about muffled up to their noses like skiers in a snowstorm, we realised that warm clothing, especially wool, gives protection against heat as well as against cold. That's why in the heat one should put clothes on rather than take them off, but we were not yet wise to these desert tricks.
India The Shimmering Dream  Max Reisch p48

[Biggles]

It is an error to think of the pillion rider solely as a passenger. Much depends on him and on his state of alertness. Just like the man in front, he has to be constantly aware of the state of the ground. He must know by the sound of the engine how hard the machine is working in the sand, and whether it is going to make it or is liable to get stuck. The main thing when riding through sand is to keep up the momentum. The watchword is "Don't stop!"
Whenever Herbert noticed that the engine was straining at its last gasp, he would nip off behind and get pushing. He did it so neatly that I often didn't notice that he was no longer on the motorcycle. This resulted in half comic, half tragic situations. When the surface eventually grew better and I chanced to turn round for a quick word with Herbert, he would have disappeared! This meant that the good chap had been left standing far behind in the desert, sometimes many kilometres back, all alone and callously abandoned by his friend. As far as road conditions allowed, I would ride back, but Herbert had many a long walk through the desert. Then he would begin to revolt and say, "Why don't you let me have a go up in front for once? Then you can see how you like pushing and being left behind and having to traipse along on foot..."
India The Shimmering Dream  Max Reisch p51