Dec. 14, 1857.] GALTON ON THE EXPLORATION OF ARID COUNTRIES. 71 
A well-acclimated horse can barely be driven for four days without 
water in an arid country, two days out and two days home ; he 
certainly would succumb before the close of the fifth day : and here 
we see that, by carrying no extraordinary weight, and by using no 
impracticable size of caravans, a distance of up to nine days’ journey 
out and then back again, or 18 days in all, can be accomplished 
without any stint whatever as regards their commissariat. 
It is not easy to specify the average distances that may be accom- 
plished by horses working for their lives, upon short rations, but 
I think that the gain in using my plan may be moderately stated 
thus 
A horse that carries no water may, at the risk of 
his life, accomplish 4 days’ journey ; viz. . . . . 2 out and 2 home. 
A horse that carries day rations may, without 
stint, accomplish 6 days’ journey ; viz. 3 out and 3 home. 
A horse that carries 5| day rations may, at the risk 
of his life, accomplish 10 days’ journey ; viz. .. 5 out and 5 home. 
A horse, backed by a supporting party, and that 
carries 5J day rations, may, without stint, easily 
accomplish 18 days’ journey; viz 9 out and 9 home. 
A horse, backed by a supporting party, and that 
carries 5| day rations, may, at the risk of his life, 
accomplish 22 days’ journey; viz 11 out and 11 home. 
It will make the disposition of the entire party perfectly intelli- 
gible if, in any case that may be fixed upon, a schedule of their 
intended proceedings be drawn out on a large sheet of paper, ac- 
cording to the form of Table 11. In it I have taken for an example 
those of a party aided by two sections organised after the binary 
system, each individual carrying 3J day rations, and two meals 
being issued per day. The exploring party is represented by E, 
and I will suppose it to consist of three men ; and, therefore, the two 
sections which are represented by A and B will consist respectively 
of six and of three men. The small figures, 6, 3, 3, refer to the 
number of meals consumed or cached by the parties to whose names 
they are attached and at the places where they are entered by the 
addition of these numbers together we obtain the results printed 
at the foot of the several columns. For distinctness sake I have 
been obliged to withhold all reference to the meals carried by the 
relief parties, whose proceedings are indicated by small letters, a 
and b, and who form an expedition entirely self-sustaining and 
independent of the main one. 
* It is not in the least necessary that a cache should be made at every place 
where a meal has to be consumed. It would be quite sufficient if a double or a 
treble one, as the case might be, were formed at each encampment from which a 
section turns back. 
