Henry Ernest Dudeney/Modern Puzzles/49 - Exploring the Desert

by : $49$

 * Exploring the Desert
 * Nine travellers, each possessing a motor-car, meet on the eastern edge of a desert.
 * They wish to explore the interior, always going due west.
 * Each car can travel $40$ miles on the contents of the engine tank,
 * which holds a gallon of petrol,
 * and each can carry $9$ extra gallon tins of petrol and no more.
 * Unopened tins can alone be transferred from car to car.


 * What is the greatest distance at which they can enter the desert without making any depots of petrol for the return journey?