The Metric System [pp. 174-185]

8'he Metric System.
ment in places of security. At Rome they
were kept in the Temple of Jupiter; among
the Jews they were in the custody of the
family of Aaron.
The excavations at Pompeii have revealed
many household articles in use among the
Romans during the first century of our era.
It is well known that this city was buried
under the ashes of Vesuvius in the year 79
of our era. Fine specimens of steel-yards,
called statera, or trzufina camipana, have been
found, bearing inscriptions showing that they
had been provzed at Rome in the year 77,
two years before the destruction of the city.
These excavations have likewise revealed a
pair of scales, with equal arms (called libra),
having scale-pans and the appliances for
delicate weighing, including a graduated arm,
with a movable rider for indicating fractional
weights.
From an early period the English standard
of length was, as it is now, the yard. There
is no reason to doubt the commonly received
account which derives the yard from the
length of the arm of King Henry i., about
the year I I 5. For the purpose of securing
some degree of uniformity among the ordinary measures of the kingdom, certain standards were preserved in the Exchequer, with
which all rods were required to be compared
before they were stamped as legal measures.
The most ancient of these in actual existence
dates from the reign of Henry vii., about
1485, but it has long been disused.
That which, till the year i824, was considered as the legal standard, was a brass
rod, placed in the Exchequer in the time of
Queen Elizabeth, about I570. To this rod
belonged a brass bar, on one edge of which
was a hollow bed or matrix fitted to receive
the square rod of the standard yard; and
into this bed were fitted the yard measures
brought to be examined and stamped with
the standard marks. All rods so stamped
became standard measures. It is evident
that measures determined in this coarse manner could have no strict claim to be considered as accurate copies of the original standard. Moreover, from Mr. Baily's report, it
would seem that the standard itself was in
capable of affording any definite or correct
measure. Mr. Baily, who had an opportunity of examining this curious instrument,
thus describes it (Memoirs Roy. Ast. Soc.,
Vol. ix.): "A common kitchen poker, filed
at the ends in the rudest manner, by the
most bungling workman, would make as good
a standard. It has been broken asunder, and
the two pieces been dovetailed together, but
so badly that the joint is nearly as loose as
that of a pair of tongs "; and yet, as late as the
year i820, "to the disgrace of this country,
copies of this measure have been circulated
all over Europe and America, with a parchment document accompanying them, certifying that they are true copies of the English
standard."
Such being the condition of the English
legal standard, it was obviously impossible
that it could be applied to any purpose
where great accuracy and minuteness were
demanded. In fact, it was utterly inapplicable to any scientific purpose whatever.
In the year I742 some Fellows of the Royal
Society of ILondon and Members of the
Academy of Sciences of Paris, proposed to
have accurate standards of the measures of
both nations made and carefully examined,
in order that means might be provided for
comparing the results of scientific experiments in England and France. The committee having the matter in charge found,
besides the legal standard in the Exchequer,
some others which were considered of good
if not of equal authority. At Guildhall they
found two standards of length. Another,
preserved in the Tower of London, is a solid
brass rod forty-one inches long, on one side
of which was the measure of a yard, divided
into inches. Another, belonging to the
Clockmakers' Company, having the stamp
of the Exchequer for I67I, was a brass rod
on which the length of the yard was expressed by the difference between two upright pins. The committee selected the
standard in the Tower as being the best defined; and Mr. George Graham (the celebrated clockmaker) was directed to lay off
from it, with great care, the length of the
yard on two brass rods, which were sent to the
1885.]
175