[_Face p. 80_
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In the future, the types of roadless vehicles are likely to be great as
the surface of the ground differs in various countries; also fuels of
all kinds are likely to be burnt, such as petrol, oil and coal, and in
tropical countries, where these fuels are scarce or expensive, producer
gas is almost certain to become the main motive power.
The most remarkable achievement as yet carried out by roadless vehicles
is undoubtedly the crossing of the Sahara from Touggourt to Timbuctoo,
during the winter of 1922–1923, by Citroën motorcars fitted with half
tracks invented by Monsieur Kegresse. The distance travelled was three
thousand six hundred kilometres, and the time taken was twenty days,
that is on an average one hundred and twelve miles a day. All machines
returned safely, and the total journey there and back was over seven
thousand kilometres.
The nature of the country crossed was by no means uniform, for it was
sandy, rocky, mountainous and, in the neighbourhood of the river Niger,
covered with tropical vegetation. To build a railway from Touggourt to
Timbuctoo would cost, at the lowest reckoning, a thousand millions of
francs—possibly much more; this alone accentuates the importance of the
achievement and its interest to us, for the Empire contains thousands of
square miles of roadless country.
I fully realize that, though the roadless vehicle can replace the
motor-car, it cannot replace the railway, if the railway is an efficient
one. This is, however, not the problem. The problem is, first to bridge
the gap between the producer and the railway, and secondly to create in
undeveloped countries sufficient wealth to enable more railways to be
built. Co-operation with existing railways, this is what must be aimed
at.
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