Environmental Engineering Reference
In-Depth Information
only about 30 kg of force could wheel a 1-t load, 150 kg
might be needed on a loose gravel surface, and more
than 200 kg on sandy or muddy roads. In addition,
smaller and inadequately fed animals were often quite
unimpressive performers.
Ancient societies reserved most of their horses for fast
action: war chariots and cavalry, races—Homer's Iliad
gives the earliest description—and mounted messengers
(Clutton-Brock 1992; Hyland 2003). Horses use a re-
markable energy-saving mechanism. The muscular work
of galloping is halved because they store and return elas-
tic energy strain in muscle-tendon units (about 1 kJ/
stride for a 500-kg animal) (Wilson et al. 2001). The
horse-drawn transport of goods became more common
only during the last centuries of the Roman Empire,
particularly using the cursus publicus. This public trans-
portation system, set up by Augustus primarily to relay
important official dispatches, was also used to a much
lesser degree to haul imperial freight and military supplies
(Hyland 1990; Kolb 2001). Both draft and pack horses
were widely used during the Middle Ages, but they
remained fairly small; the stallions of medieval knights
were typically just 140-145 cm at the shoulders. More
powerful breeds were introduced only during the eigh-
teenth century.
War horses represented a major energy drain on many
preindustrial societies. They consumed feed and required
much human labor for their breeding, care, and trading).
This was particularly so in dynastic China, where the ne-
cessity to import and maintain horses in the large num-
bers needed for recurrent military campaigns against the
encroaching nomads represented a major strain on
the state's resources (Creel 1965). But superior animals
and skillful horsemanship decided many battles even dur-
ing the nineteenth century. Perhaps most notably, on
June 18, 1815, at Waterloo the heavier English horses
and the charge of the Household Brigade led the British
to victory (Vesey-Fitzgerald 1946). Cavalry remained an
important military component during WW I, and both
the Red Army and the Wehrmacht relied on horses dur-
ing WW II (Edgerton 2007).
A pair of early twentieth-century European draft horses
could pull a 3-4-t rubber-tired cart on hard-top roads,
but their smaller Chinese counterparts could pull no
more than about 800 kg/head with wooden- or iron-
rimmed carts on good dirt roads. Forbes (1965) esti-
mated that the tractive effort was no more than 680
kgm/s for a typical preindustrial European horse cart,
and the Theodosian code (438
C
.
E
.) prescribed 490 kg
as the maximum load for goods wagons pulled by oxen.
The low speeds of walking animals restricted the daily
range of freight carts and wagons to just 15-20 km for
oxen and no more than 30 km for horses. People with
wheelbarrows could do just 10-15 km, but where the
loads had to be carried, they had the advantage of being
able to walk on very narrow paths. Similarly, mules and
donkeys with panniers were preferred to pack horses be-
cause of their better mobility on narrow paths, their
higher resilience (harder hooves, lower water require-
ments), and their endurance. Typical loads were about
30% of an animal's weight (50-120 kg) on the level and
25% in the hills, and speeds did not exceed 5 km/h.
Preindustrial land transport was unfit for the large-
scale movement of goods, a reality perfectly illustrated
by Diocletian's edictum de pretiis rerum venalium (301
C
.
E
.): it cost more to move grain 120 km on roads than
to ship it across the Mediterranean. And even after the
Egyptian grain arrived at Ostia, only 20 km from Rome,
it was reloaded by saccarii to naves caudicarii (barges)
that were drawn by oxen upstream to the capital rather
