Appendix 83 



so that no more air should be allowed to escape than is 

 absolutely necessary. No fixed rule is known, but for 

 Ford cars a pressure of 35 or even 30 pounds was found 

 safe and always gave good results. Tires are not damaged 

 by running "soft" in sand, but they should be immediately 

 pumped up when hard ground is reached, or they will suffer 

 rim cuts, stone bruises, or blow-outs. The tire gauge is a 

 necessity for judging the safe reduction of air pressure. 



One great trouble in soft sand is that the wheels lose 

 traction and spin, digging down and down into the sand. 

 This is frequently brought about by attempting to start too 

 suddenly. On the other hand, going too slowly when 

 moving induces the wheels to spin. After a wheel has 

 "dug in" it has to be "dug out" with a shovel, jacked up, 

 and the hole surfaced with brush, canvas, or stones to give 

 a bearing. Very effective use can be made of two strips of 

 heavy canvas, say 30 feet long and 18 inches wide, for 

 such difficulties. The strips must be thrust under the rear 

 wheel, then laid lengthwise ahead in the ruts, and it is 

 necessary to lift the front wheels and set them on the 

 canvas to hold it down while the rear wheels pull. Other- 

 wise the canvas is chewed up and "spit" out in the rear 

 by the spinning wheels. Canvas solved the trouble of the 

 worst sand for the Survey party without much recourse to 

 brush or shovelling. Progress is slow, but nearly any 

 bad place may be crossed in this manner. The use of canvas 

 for occasional trips on well-travelled roads is seldom neces- 

 sary. Most travellers, instead of using canvas, fill the ruts 

 with broken twigs, brush, stones, or anything else available 

 when they get stuck, but unfortunately the brush is usually 

 thinnest where the sand is thickest. There are various 

 devices on the market for pulling out automobiles which 

 get stuck, and one of these may be a valuable part of the 

 equipment 



.... A surplus of water over probable needs of men 

 and automobiles should be provided. Oil and gasoline more 

 than enough for probable needs should be taken, and it 

 should be remembered that desert roads may require twice 

 as much per mile as pavement. 



