f them were on an extensive
scale, consisting of a fortress and barracks surrounded by a stone
parapet. These were evidently intended as a shelter for the Imperial
armies when on the march.

[Illustration: A Peruvian postman]

The communication throughout the country was by means of runners, each
of whom carried the message entrusted to him with great swiftness for
five miles, and then handed it over to another. These runners were
specially trained to their work and wore a particular dress; their
stations were small buildings erected five miles apart along all the
roads. The messages might be verbal, or conveyed by means of the
'quipus.' A quipu was a cord two feet long, composed of differently
coloured threads twisted together, from which were hung a number of
smaller threads, also differently coloured and tied in knots. Indeed,
the word 'quipu' means 'a knot.' By means of the colours and the various
knots the Peruvians expressed ideas--it was their method of writing--but
the quipus were chiefly used for arithmetical purposes. In every
district officers were stationed who were called 'keepers of the
quipus'; their duty was to supply the Government with information as to
the revenues, births, deaths, and marriages, number of population, and
so on. These records--in skeins of many-coloured thread--were inspected
at headquarters and carefully preserved, the whole collection
constituting what might be call the national archives. In like manner
the wise men recorded the history of the empire, and chronicled the
great deeds of the reigning Inca or his ancestors. The Peruvians had
some acquaintance with geography and astronomy, and showed a decided
talent for theatrical exhibitions, but it was in agriculture that they
really excelled. The mountains were regularly hewn into stone-faced
terraces, varying in width from hundreds of acres at the base to a few
feet near the snows. Water was conveyed in stone-built aqueducts for
hundreds of miles, from some snow-fed lake in the mountains, fertilising
all the dry and sandy places through which it passed. In some of the
arid valleys they dug great pits twenty feet deep and more than an acre
in extent, and, after carefully preparing the soil, planted grain or
vegetables. Their method of ploughing was primitive indeed. Six or eight
men were attached by ropes to a strong stake, to which was fastened a
horizontal piece of wood upon which the ploughman might set his foot to
force the sha