Dec. 14, 1857.] GALTON ON THE EXPLORATION OF ARID COUNTRIES. 75 
2 water tins, and the other 1 water tin and 3 food tins, or exactly three 
complete meals in all. 
The expedition will consist as follows : — 
The explorer Ej carrying nothing, and his attendant E 2 
carrying 3 meals and the spare bag or 3 meals in all. 
Two natives 1$! and B 2 carrying 3 meals each .. .. or 6 meals in all. 
Four natives A x A 2 A 3 A 4 carrying 3 meals each .. or 12 meals in all. 
Let them start in the early morning and travel for half-a-day, 
say hours, without stopping; then let them encamp at Camp I., 
and take a meal out of the loads of the party A, the packages of B 
and of E being left untouched : there are 8 mouths to feed and 12 
meals, leaving an overplus of 4 meals. In the afternoon the party 
A is sent back to camp with 8 empty sets of tins, and each of the 
parties B and E take 2 meals and cache them separately, and then 
proceed on their journey for another 4^ hours. At night, at 
Camp II., B’s packs are opened, the 6 meals are taken out, and 4 of 
them are eaten by B and E, while the 2 remaining ones are given 
to E, who caches them. In the morning, B turns back and the 
party E pursues its journey (B opens its cache at Camp I. at midday, 
and, having eaten the 2 meals contained in it, stores the empty tins 
in the places left vacant in its bags by the two meals left behind 
with E, and starting in the afternoon, reaches the home party at 
night). The party E travels on for half-a-day to Camp III., and 
then its men eat two of their meals ; the third is intended to be kept 
as a reserve in case of any emergency. In the afternoon they fall 
back upon Camp II., dig up their cache, eat the food contained in it, 
and place the empty tins in the spare bag. In the morning they start 
for Camp I., reach it at noon, dig up the cache, eat their meals, and 
carry off the empty tins as before, and reach the home party at 
night. 
The next adventure, which I will not describe in detail, might be 
to leave the parties A, B, and E exactly as before, but to lade the 
explorer E t with three meals, and also to make a repeated journey 
of one long half-day’s stage. In doing this, 16 extra sets of tins 
would be found necessary, and a distance of 2 j- days’ journey from 
camp would be finally reached. 
The President directed the attention of the Fellows to the value of Mr. 
Galton’s labours in elaborating such a scheme for the guidance of travellers 
in dry and arid countries, and mentioned his calculations as being analogous 
to those by which a quartermaster-general enabled troops to make effective 
marches. 
Dr. Barth, f.r.g.s. — I think the plan proposed by Mr. Galton suitable to a 
country like Australia, where the danger of the caches being destroyed by bar- 
barous tribes is not very great ; but it is not applicable to such a country as 
Northern Africa, where a depot cannot be deposited without running the risk of 
VOL. II. H 
