; a small mule, 90
lbs.; a horse lbs.; an ox lbs.; a camel lbs. to 200 lbs.;
elephant lbs. In level countries--where there is grain, and where
the road is known and a regularity in the day's work can be ensured--the
weights that may be carried are fully double those of the above list.
Captain Burton's donkeys, in East Africa, carried immense weights. Dogs
will draw a "travail" (which see) of 60 lbs. for a distance of 15 miles a
day, upon hard level country.
Theory of Loads and Distances.--How should we load men or animals of
transport, and how should we urge them, in order to obtain the largest
amount of effective labour? If they carry a mere feather-weight, they may
make long days' journeys; but their value, as animals of transport, is
almost nothing. Again, on the other hand, if we load them with an
excessive weight, they will soon come to a standstill; and in this case,
as in the first, their value as beasts of transport is almost nil. What
then, is that moderate load by which we shall obtain the largest amount
of "useful effect"? this is a problem which many of the ablest engineers
and philosophers have endeavoured to solve; and the formulae--partly
based on theory and partly on experiment--which were used by Euler, are
generally accepted as a fair approximation. They are very simple, and
peculiarly interesting on account of their wide applicability.
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