Dec. 14, 1857.] GALTON ON THE EXPLORATION OF ARID COUNTRIES. 63 
rations, and we must make our selection between a division of the 
day’s rations into one, two, or three meals. In the steady equable 
travel which I have in view, I entertain no doubt that the best 
economy of strength and food, both in man and beast, is to be ob- 
tained by assigning them two journeys and two meals a day — a 
morning and an afternoon journey, and a noon and an evening 
meal. This, then, will be the arrangement I shall lay most stress 
upon. 
Size of the “ Sections .” — The number of men that turn back would 
naturally bear in each case a constant ratio to the numbers that go 
on. If, for example, the exploring party consist of 10 men, and the 
detachment that last left them consisted of 10 men also, this same 
proportion would hold from first to last throughout the journey ; that 
is to say, whenever a detachment broke off, the number of men that 
returned in it would exactly equal the number of those who con- 
tinued to advance. Theoretically speaking, any proportion whatever 
might be adopted, but it so happens that the one I have taken as 
an example, half going back and half going on, is the one that is 
likely to be the most generally useful ; for it is very simple and easy 
to be remembered, very generally applicable, and one of the most 
economical as regards work done and numbers employed. In this 
paper I shall give most space to its description, and simply indicate 
other cases which might be serviceable by drawing attention to the 
General Table, No. 4. To this I must again refer. At present, 
recurring to our Unary system, if the exploring party consists of a 
number of men equal to e, the following Table (3) shows what must 
be the constitution and size of its supporting party, according to the 
number of “ sections ” intended to be employed in it : — 
Table 3. — Binaky System. 
At end 
of last 
Stage. 
At end 
of last 
but one. 
f Of last 
jbut two. 
Of last 
but 
three. 
Of last 
but 
four. 
&C. 
Total number of Advance party 
e 
2 e 
4 e 
8 e 
16 e 
See. 
Exploring party 
Supporting party : — 
e 
e 
e 
e 
e 
Latest detachment 
e 
e 
e 
e 
Last but one 
2 e 
2 e 
2 e 
Last but two 
. # 
. , 
4 e 
4 e 
Last but three 
&c 
&c. 
8 e 
Length of Stages and Loads carried . — The Table (4) (see page 64), 
so far as it extends, shows every case in which there can be an 
exact adjustment of loads, meals, and subdivisions of the party. It 
