citizens subjected to civil degradation (infamia) as the
result of following certain professions (e.g. acting),
of dishonourable acts in private life (e.g. bigamy) or of
conviction for certain crimes; (3) persons branded by the
censor. Those who were thus excluded from the tribes and
centuries had no vote, were incapable of filling Roman
magistracies and could not serve in the army. According to
Mommsen, the aerarii were originally the non-assidui
(non-holders of land), excluded from the tribes, the comitia
and the army. By a reform of the censor Appius Claudius
in 312 B.C. these non-assidui were admitted into the
tribes, and the aerarii as such disappeared. But in 304,
Fabius Rullianus limited them to the four city tribes, and
from that time the term meant a man degraded from a higher
(country) to a lower (city) tribe, but not deprived of the
right of voting or of serving in the army. The expressions
``tribu movere'' and ``aerarium facere,': regarded by Mommsen
as identical in meaning (``to degrade from a higher tribe
to a lower,'), are explained by A. H. J. Greenidge---the
first as relegation from a higher to a lower tribe or total
exclusion from the tribes, the second as exclusion from the
centuries. Other views of the original aerarii are that they
were--artisans and freedmen (Niebuhr); inhabitants of towns
united with Rome by a hospitium publicum, who had become
domiciled on Roman territory (Lange); only a class of degraded
citizens, including neither the cives sine suffragio nor
the artisans (Madvig); identical with the capite censi of
the Servian constitution (Belot, Greenidge). See A. H. J.
Greenidge, Infamia in Roman Law (1894), where Mommsen's theory
is criticized; E. Belot, Histoire des chevaliers romains,
i. p. 200 (Paris, 1866); L. Pardon, De Aerariis (Berlin,
1853); P. Willems, Le Droit public romain (1883); A. S.
Wilkins in Smith's Dict. of Greek and Roman Antiquities
(3rd ed., 189I); and the usual handbooks of antiquities.
AERARIUM (from Lat. aes, in its derived sense of ``money'')
the name (in full, aerarium stabulum, treasure-house) given
in ancient Rome to the public treasury, and in a secondary
sense to the public finances. The treasury contained the
moneys and accounts of the state, and also the standards of
the legions; the public laws engraved on brass, the decrees
of the senate and other papers and registers of importance.
These public treasures were deposited in the temple of
Saturn, on the eastern slope of the Capitoline hill, and,
during the republic, were in charge of the urban quaeators
(see QUAESTOR), under the superintendence and control of the
senate. This arrangement continued (except for the year 45
B.C., when no quaestors were chosen) until 28 B.C., when
Augustus transferred the aerarium to two praojecti aerarii,
chosen annually by the senate from ex-praetors; in 23 these
were replaced by two praetors (praetores aerarii or ad
aerarium), selected by lot during their term of office;
Claudius in A.D. 44 restored the quaestors, but nominated by
the emperor for three years, for whom Nero in 56 substituted
two ex-praetors, under the same conditions. In addition
to the common treasury, supported by the general taxes and
charged with the ordinary expenditure, there was a special
reserve fund, also in the temple of Saturn, the aerarium
sanctum (or sanctius), probably originally consisting of
the spoils of war, afterwards maintained chiefly by a 5% tax
on the value of all manumitted slaves, this source of revenue
being established by a lex Manlia in 357. This fund was not
to be touched except in cases of extreme necessity (Livy vii.
16, xxvii. 10). Under the emperors the senate continued to
have at least the nominal management of the aerarium, while
the emperor had a separate exchequer, called fiseus. But
after a time, as the power of the emperors increased and
their jurisdiction extended till the senate existed only in
form and name, this distinction virtually ceased. Besides
creating the fiscus, Augustus also established in A.D.
6 a military treasury (aerarium militare), containing all
moneys raised for and appropriated to the maintenance of the
army, including a pension fund for disabled soldiers. It.was
largely endowed by the emperor himself (see Monumentum
Ancyranum, iii. 35) and supported by the proceeds of the tax
on public sales and the succession duty. Its administration
was in the hands of three praefecti aerarii militaris, at
first appointed by lot, but afterwards by the emperor, from
senators of praetorian rank, for three years. The later
emperors had a separate aerarium privatum, containing
the moneys allotted for their own use, distinct from the
fiscus, which they administered in the interests of the empire.
The tribuni aerarii have been the subject of much
discussion. They are supposed by some to be identical with
the curatores tribuum, and to have been the officials
who, under the Servian organization, levied the war-tax
(tributum) in the tribes and the poil-tax on the aerarii
(q.v.). They also acted as paymasters of the equites and of
the soldiers on service in each tribe. By the lex Aurella
(70 B.C.) the list of judices was composed, in addition
to senators and equites, of tribuni aerarii. Whether these
were the successors of the above, or a new order closely
connected with the equites, or even the same as the latter, is
uncertain. According to Mommsen, they were persons who
possessed the equestrian census, but no public horse. They
were removed from the list of judices by Caesar, but replaced by
Augustus. According to Madvig, the original tribuni aerarii
were not officials at all, but private individuals of considerable
means, quite distinct from the curatores tribuuin, who
undertook certain financial work connected with their own
tribes. Then, as in the case of the equites, the term was
subsequently extended to include all those who possessed the
property qualification that would have entitled them to serve
as tribuni aerarii. See Tacitus, Annals, xiii. 29, with
Furneaux's notes; O. Hirschfeld, ``Das Aerarium militare in
der romischen Kaiserzeit,'' in Fleckeisen's Jahrbuch, vol.
xcvii. (1868); S. Herrlich, De Aerario et Fisco Romanorum
(Berlin, 1872); and the usual handbooks and dictionaries of
antiquities. On the tribuni aerarii see E. Belot, Hist.
des chevaliers romains, ii. p. 276; J. N. Madvig, Opuscula
Academica, ii. p. 242; J. B. Mispoulet, Les Institutions
politiques des Romains (1883), ii. p. 208; Mommsen,
Romisches Staatsrecht, iii. p. 189; A. S. Wilkins in Smith's
Dictionary of Greek and Roman Antiquities (3rd ed., 1890).
AERATED WATERS. Waters charged with a larger proportion of
carbon dioxide than they will dissolve at ordinary atmospheric
pressure occur in springs in various parts of the world (see
MINERAL WATERS). Such waters, which also generally hold in
solution a considerable percentage of saline constituents,
early acquired a reputation as medicinal agents, and when
carbon dioxide (``fixed air'') became familiar to chemists the
possibility was recognized, as by Joseph Priestley (Directions
for impregnating water with fixed air . . . to communicate
the peculiar Spirit and Virtues of Pyrmont water, 1772),
of imitating them artificially. Many of the ordinary aerated
waters of commerce, however, do not pretend to reproduce any
known natural water; they are merely beverages owing their
popularity to their effervescing properties and the flavour
imparted by a small quantity of some salt such as sodium
bicarbonate or a little fruit syrup. Their manufacture on a
considerable scale was begun at Geneva so far back as 1790 by
Nicholas Paul, and the excellence of the soda water prepared
in London by J. Schweppe, who had been a partner of Paul's, is
referred to by Tiberius Cavallo in his Essay on the Medicinal
Properties of Factitious Airs, published in 1798. Many forms
of apparatus are employed for charging the water with the
gas. A simple machine for domestic use, called a gasogene or
seltzogene, consists of two strong glass globes connected
one above the other by a wide glass tube which rises nearly
to the top of the upper and smaller globe. Surmounting the
small globe there is a spring valve, fitted to a narrow tube
that passes through the wide tube to the bottom of the large
globe. To use the machine, the lower vessel is filled with
water, and in the upper one, round the base of the wide tube,
is placed a mixture, commonly of sodium bicarbonate and tartaric
acid, which with water yields carbon dioxide. The valve head
is then fastened on, and by tilting the apparatus some water is
made to flow through the wide tube from the lower to the upper
vessel. The water in the lower globe takes up the gas thus
produced, and when required for use is withdrawn by the
valve, being forced up the narrow tube by the pressure of the
gas. In another arrangement the gas is supplied compressed in
little steel capsules, and is liberated into a bottle containing
the water which has to be aerated. On a large scale, use is
made of continuously acting machinery which is essentially of
the type devised by Joseph Bramah. The gas is prepared in a
separate generator by the action of sulphuric acid on sodium
bicarbonate or whiting, and after being washed is collected
in a gas-holder, whence it is forced with water under pressure
into a receiver or saturator in which an agitator is kept
moving. Some manufacturers buy their gas compressed in steel
cylinders. The water thus aerated or carbonated passes
from the receiver, in which the pressure may be 100-200 lb. on
the square inch, to bottling machines which fill and close
the bottles; if beverages like lemonade are being made the
requisite quantity of fruit syrup is also injected into the
bottles, though sometimes the fruit syrup mixture is aerated in
bulk. For soda water sodium bicarbonate should be added to
the water before aeration, in varying proportions up to about
15 grains per pint, but the simple carbonated water often
does duty instead. Potash water, lithia water and many others
are similarly prepared, the various salts being used in such
amounts as are dictated by the experience and taste of the
manufacturer. Aerated waters are sent out from the factories
either in siphons (q.v.) or in bottles; the latter may be
closed by corks, or by screw-stoppers or by internal stoppers
consisting of a valve, such as a glass ball, held up against an
indiarubber ring in the neck by the pressure of the gas. For use
in ``soda-fountains'' the waters are sent out in large cylinders.
See W. Kirkby, Evolution of artificial Mineral Waters (Manchester, 1902).
AERONAUTICS, the art of ``navigating'' the ``air.'' It is
divisible into two main branches--aerostation, dealing properly
with machines which like balloons are lighter than the air,
and aviation, dealing with the problem of artificial flight
by means of flying machines which, like birds, are heavier
than the air, and also with attempts to fly made by human
beings by the aid of artificial wings fitted to their limbs.
Historically, aviation is the older of the two, and in the
legends of gods or myths of men or animals which are supposed
to have travelled through the air, such as Pegasus, Medea's
dragons and Daedalus, as well as in Egyptian bas-reliefs,
wings appear as the means by which aerial locomotion is
effected. In later times there are many stories of men who have
attempted to fly in the same way. John Wilkins (1614-1672),
one of the founders of the Royal Society and bishop of Chester,
who in 1640 discussed the possibility of reaching the moon by
