organic lengths furnish those
approximate measures which satisfied men's needs in ruder ages, but they
furnished also the standard measures required in later times. One
instance occurs in our own history. To remedy the irregularities then
prevailing, Henry I. commanded that the ulna, or ancient ell, which
answers to the modern yard, should be made of the exact length of _his
own arm_.

Measures of weight again had a like derivation. Seeds seem commonly to
have supplied the unit. The original of the carat used for weighing in
India is _a small bean_. Our own systems, both troy and avoirdupois, are
derived primarily from wheat-corns. Our smallest weight, the grain, is
_a grain of wheat_. This is not a speculation; it is an historically
registered fact. Henry III. enacted that an ounce should be the weight
of 640 dry grains of wheat from the middle of the ear. And as all the
other weights are multiples or sub-multiples of this, it follows that
the grain of wheat is the basis of our scale. So natural is it to use
organic bodies as weights, before artificial weights have been
established, or where they are not to be had, that in some of the
remoter parts of Ireland the people are said to be in the habit, even
now, of putting a man into the scales to serve as a measure for heavy
commodities.

Similarly with time. Astronomical periodicity, and the periodicity of
animal and vegetable life, are simultaneously used in the first stages
of progress for estimating epochs. The simplest unit of time, the day,
nature supplies ready made. The next simplest period, the mooneth or
month, is also thrust upon men's notice by the conspicuous changes
constituting a lunation. For larger divisions than these, the phenomena
of the seasons, and the chief events from time to time occurring, have
been used by early and uncivilised races. Among the Egyptians the rising
of the Nile served as a mark. The New Zealanders were found to begin
their year from the reappearance of the Pleiades above the sea. One of
the uses ascribed to birds, by the Greeks, was to indicate the seasons
by their migrations. Barrow describes the aboriginal Hottentot as
denoting periods by the number of moons before or after the ripening of
one of his chief articles of food. He further states that the Kaffir
chronology is kept by the moon, and is registered by notches on
sticks--the death of a favourite chief, or the gaining of a victory,
serving for a new era. By which last f