Trastevere; and such is the famous _calix marmoreus_, which formerly
stood near the church of SS. Apostoli, mentioned in the Bull of John
III. (A. D. 570), by which the boundary line of that parish was
determined. This historical monument, a prominent landmark in the
topography of mediaeval Rome, was removed to the Baths of Diocletian at
the beginning of last year.

In many of our churches visitors may have noticed one or more round
black stones, weighing from ten to a hundred pounds, which, according
to tradition, were tied to the necks of martyrs when they were thrown
into wells, lakes, or rivers. To the student these stones tell a
different tale. They prove that the classic institution of the
_ponderaria_ (sets of weights and measures) migrated from temples to
churches, after the closing of the former, A. D. 393.

[Illustration: Kantharos in the Court of St. Caecilia.]

As the _amphora_ was the standard measure of capacity for wine, the
_metreta_ for oil, the _modius_ for grain, so the _libra_ was the
standard measure of weight.[26] To insure honesty in trade they were
examined periodically by order of the aediles; those found _iniquae_
(short) were broken, and their owners sentenced to banishment in
remote islands. In A. D. 167, Junius Rusticus, prefect of the city,
ordered a general inspection to be made in Rome and in the provinces;
weights and measures found to be legal were marked or stamped with the
legend "[Verified] by the authority of Q. Junius Rusticus, prefect of
the city." These weights of Rusticus are discovered in hundreds in
Roman excavations.[27]

The original standards were kept in the Temple of Jupiter on the
Capitol, and used only on extraordinary occasions. Official duplicates
were deposited in other temples, like those of Castor and Pollux, Mars
Ultor, Ops, and others, and kept at the disposal of the public, whence
their name of _pondera publica_. Barracks and market-places were also
furnished with them. The most important discovery connected with this
branch of Roman administration was made at Tivoli in 1883, when three
_mensae ponderariae_, almost perfect, were found in the portico or
peribolos of the Temple of Hercules, adjoining the cathedral of S.
Lorenzo. This wing of the portico is divided into compartments by
means of projecting pilasters, and each recess is occupied by a marble
table resting on "trapezophoroi" richly ornamented with symbols of
Hercules and Bacchus, like the club and