arranged that battery volts and booster volts shall equal
the volts on the mains. Under this excitation there is no
tendency for the battery to charge or discharge. But any
additional excitation leads to strong currents one way or the
other. Excitation C1 rises with the load on the line,
and gives an E.M.F. helping the battery to discharge most
when the load is greatest. C2 is dependent on the bus-bar
voltage, and is greatest when the generator load is small: it
opposes C1 and therefore excites the booster to charge the
battery. The exact generator load at which the booster
shall reverse its E.M.F. from a charging to a discharging
value is adjusted by the resistance R2 in series with C2.
A similar resistance R6 allows the excitation of C3 to be
adjusted. Very remarkable regulation can be obtained by
reversible boosters of this type. In traction and lighting
stations it is quite possible to keep the variation of bus-bar
pressure within 2% of the normal value, although the load
may momentarily vary from a few amperes up to 200 or 300.
J. B. Entz has introduced an auxiliary device which enables
him to use a much more simple booster. The Entz booster
has no series coil and only one shunt coil, the direction
and value of excitation due to this being controlled by
a carbon regulator, it having two arms, the resistance
of each of which can be varied by pressure due to the
magnet- izing action of a solenoid. The main current
from the generator passes through the solenoid and causes
one or other of the two carbon arms to have the less
FIG. 23.
resistance. This change in resistance determines the direction
of the exciter field current, and therefore the direction of the
boost. A photograph of the switchboard at Greenock where this
booster is in use shows the voltmeter needle as if it had been
held rigid, although the exposure lasted 90 minutes. On the
same photograph the ammeter needle does not appear, its incessant
and large movements preventing any picture from being formed.
Alkaline Accumulators.--Owing to the high electro-chemical
equivalent of lead, a great saving in weight would be secured
by using almost any other metal. Unfortunately no other metal
and its compounds can resist the acid. Hence inventors have
been incited to try alkaline liquids as electrolytes. Many
attempts have been made to construct accumulators in this way,
though with only moderate success. The Lalande-Chaperon,
Desmazures, Waddell-Ent2 and Edison are the chief cells. T.
A. Edison's cell has been most developed, and is intended for
traction work. He made the plates of very thin sheets of
nickel-plated steel, in each of which 24 rectangular holes
were stamped, leaving a mere framework of the metal. Shallow
rectangular pockets of perforated nickel-steel were fitted
in the holes and then burred over the framework by high
pressures. The pockets contained the active material. On the
positive plate this consisted of nickel peroxide mixed with
flake graphite, and on the negative plate of finely divided
iron mixed with graphite. Both kinds of active material
were prepared in a special way. The graphite gives greater
conductivity. The liquid was a 20% solution of caustic
potash. During discharge the iron was oxidized, and the
nickel reduced to a lower state of oxidation. This change was
reversed during charge. Fig. 24 shows the general features.
Fig. 24.--Edison Accumulator.
The chief results obtained by European experts showed
that the E.M.F. was 1.33 volt, with a transient higher
value following charge. A cell weighing 17.8 lb. had a
resistance of 0.0013 ohm, and an output at 60 amperes of 210
watt-hours, or at 120 amperes of 177 watt-hours. Another
and improved cell weighiog 12.7 lb. gave 14.6 watt-hours
per pound of cell at a 20-ampere rate, and 13.5 watt-hours
per pound at a 60 ampere rate. The cell could be charged
and discharged at almost any rate. A full charge could be
given in 1 hour, and it would stand a discharge rate of 200
amperes (Journ. Inst. Elec. Eng., 1904, pp. 1-36).
Subsequently Edison found some degree of falling-off in
capacity, due to an enlargement of the positive pockets
by pressure of gas. Most of the faults have been overcome
by altering the form of the pocket and replacing the
graphite by a metallic conductor in the form of flakes.
REFERENCES.---G. Plante, Recherches sur L'electricite
(Paris, 1879); Gladstone and Tribe, Chemistry of Secondary
Batteries (London, 1884); Reynier, L'Accumulateur voltaique
(Paris, 1888); Heim, Die Akkumulatoren (Berlin, 1889);
Hoppe, Die Akk. fur Elektricitat (Berlin, 1892); Schoop,
Handbuch fur Akk. (Stuttgart, 1898): Sir E. Frankland,
``Chemistry of Storage Batteries,'' Proc. Roy. Soc., 1883;
Reynier, Jour. Soc. Franc. de Phys., 1884; Heim, ``U.
d. Einfluss der Sauredichte auf die Kapazitat der Akk.,''
Elek. Zeits., 1889; Kohlrausch and Heim, ``Ergebnisse von
Versuchen an Akk. fur Stationsbetrieb,'' Elek. Zeits.,
1889; Darrieus, Bull. Soc. Intern. des Elect., 1892; F.
Dolezalek, The Theory of the Lead Accumulator (London, 1906);
Sir D. Salomons, Management of accumulators (London, 1906)
E. J. Wade, Secondary Batteries (London, 1901); L. Jumau,
Les Accumulateurs electriques (Paris, 1904). (W. HT.)
ACCURSIUS Ital. ACCORSO), FRANCISCUS (1182-1260), Italian
jurist, was born at Florence about 1182. A pupil of Azo, he
first practised law in his native city, and was afterwards
appointed professor at Bologna, where he had great success as a
teacher. He undertook the great work of arranging into one
body the almost innumerable comments and remarks upon the
Code, the Institutes and Digests, the confused dispersion
of which among the works of different writers caused much
obscurity and contradiction. This compilation, bearing
the title Glossa ordinaria or magistralis, but usually
known as the Great Gloss, though written in barbarous Latin,
has more method than that of any preceding writer on the
subject. The best edition of it is that of Denis Godefroi
(1549-1621), published at Lyons in 1589, in 6 vols.
folio. When Accursius was employed in this work, it is
said that, hearing of a similar one proposed and begun by
Odoiced, another lawyer of Bologna, he feigned indisposition,
interrupted his public lectures, and shut himself up,
till with the utmost expedition he had accomplished his
design. Accursius was greatly extolled by the lawyers of
his own and the immediately succeeding age, and he was even
called the idol of jurisconsults, but those of later times
formed a much lower estimate of his merits. There can be
no doubt that he disentangled the sense of many laws with
much skill, but it is equally undeniable that his ignorance
of history and antiquities often led him into absurdities,
and was the cause of many defects in his explanations and
commentaries. He died at Bologna in 1260. His eldest son
Franciscus (1225-1293), who also filled the chair of law
at Bologna, was invited to Oxford by King Edward I., and
in 1275 or 1276 read lectures on law in the university.
ACCUSATION (Lat. accusatio, accusare, to challenge to
a causa, a suit or trial at law), a legal term signifying
the charging of another with wrong-doing, criminal or
otherwise. An accusation which is made in a court of justice
during legal proceedings is privileged (see PRIVILEGE),
though, should the accused have been maliciously prosecuted,
he will have a right to bring an action for malicious
prosecution. An accusation made outside a court of justice
would, if the accusation were false, render the accuser
liable to an action for defamation of character, while, if the
accusation be committed to writing, the writer of it is liable
to indictment, whether the accusation be made only to the party
accused or to a third person, A threat or conspiracy to accuse
another of a crime or of misconduct which does not amount to
a crime for the purpose of extortion is in itself indictable.
ACCUSATIVE (Lat. accusativus, sc. casus, a translation
of the Gr. aitiatike ptosis, the case concerned
with cause and effect, from aiti'a, a cause), in
grammar, a case of the noun, denoting primarily the
object of verbal action or the destination of motion.
ACE (derived through the Lat. as, from the Tarentine
form of the Gr. eis) the number one at dice, or the
single point on a die or card; also a point in the score
of racquets, lawn-tennis, tennis and other court games.
ACELDAMA (according to Acts i. 19, ``the field of blood''),
the name given to the field purchased by Judas Iscariot
with the money he received for the betrayal of Jesus
Christ. A different version is given in Matthew xxvii.
8, where Judas is said to have cast down the money in the
Temple, and the priests who had paid it to have recovered the
pieces, with which they bought ``the potter's field, to bury
strangers in.'' The MS. evidence is greatly in favour of
a form Aceldamach. This would seem to mean ``the field of
thy blood,'' which is unsuitable. Since, however, we find
elsewhere one name appearing as both Sirach and Sira (ch
= aleph), Aceldamach may be another form of an original
Aceldama (aleph kamatz mem shvah daleth lamedh tzareh
qoph patach heth), the ``field of blood.'' A. Klostermann,
however, takes the ch to be part of the Aramaic root
demach, ``to sleep,'; the word would then mean ``field
of sleep'' or cemetery (Probleme im Aposteltexte, 1-8,
1883), an explanation which fits in well with the account
in Matthew xxvii. The traditional site (now Hak el-Dum),
S. of Jerusalem on the N.E. slope of the ``Hill of Evil
Counsel'' (Jebel Deir Abu Tor), was used as a burial place
for Christian pilgrims from the 6th century A.D. till as
late, apparently, as 1697, and especially in the time of the
Crusades. Near it there is a very ancient charnelhouse, partly
rock-cut, partly of masonry, said to be the work of Crusaders.
ACENAPHTHENE, C12H10, a hydrocarbon isolated from
the fraction of coal-tar boiling at 260 deg. -270 deg. by M. P.
E. Berthelot, who, in conjunction with Bardy, afterwards
synthesized it from a-ethyl naphthalene (Ann. Chem.
Phys., 1873, Yol. xxix.). It forms white needles (from
alcohol), melts at 95 deg. and boils at 278 deg. . Oxidation
gives naphthalic acid (1.8 naphthalene dicathoxylic acid).
Acenaphthalene, C12 H8, a hydrocarbon crystallizing
in yellow tables and obtained by passing the vapour of
acenaphthene over heated litharge. Sodium amalgam reduces it
to acenaphthone; chromic acid oxidizes it to naphthalic acid.
ACEPHALI (from a'-, privative, and kefale, head), a
term applied to several sects as having no head or leader;
and in particular to a strict monophysite sect that separated
itself, in the end of the 5th century, from the rule of
the patriarch of Alexandria (Peter Mongus), and remained
``without king or bishop'' till they were reconciled by Mark
I. (799-819).1 The term is also used to denote clerici
vagrantes, i.e. clergy without title or benefice, picking
up a living anyhow (cf. Hinschius i. p. 64). Certain persons
in England during the reign of King Henry I. were called
Acephali because they had no lands by virtue of which they
could acknowledge a superior lord. The name is also given to
certain legendary races described by ancient naturalists and
geographers as having no heads, their mouths and eyes being
in their breasts, generally identified with Pliny's Blemmyae.
ACEPHALOUS, headless, whether literally or metaphorically,
leaderless. The word is used literally in biology; and
metaphorically in prosody or grammar for a verse or sentence
with a beginning wanting. In zoology, the mollusca are
