iving
their promotion to it. In the same way cardinal deacons can pass after
ten years to the order of priests, while retaining after their passage
the rank in the Sacred College given them by the date of their
promotion.

With the exception of the classes resulting from the order to which
they belong, there are no distinctions between the rights of the
various cardinals. As to the ordination obligatory upon them, it is
that indicated in their title; cardinal bishops must naturally be
bishops; for cardinal priests it is enough to have received the
priesthood, though many of them are actually bishops; similarly, it is
enough for cardinal deacons to have received the diaconate, though
most of them are priests; cases have occurred, however, even in quite
recent times, of cardinals who have only received the diaconate, e.g.
Cardinal Mertel.

There is one cardinal chosen by the pope from among the Sacred College
to whom is entrusted the administration of the common property; this
is the cardinal camerlengo or chamberlain (_camerarius_). His office
is an important one, for during the vacancy of the Holy See it is he
who exercises all external authority, especially that connected with
the Conclave.

Number and distribution.

The number of the cardinals reaches a total of 70: six cardinal
bishops, fifty cardinal priests and fourteen cardinal deacons. This
number was definitively fixed by Sixtus V. (constit. _Postquam_, 5th
December 1586); but the Sacred College never reaches its full number,
and there are always ten or so "vacant hats," as the saying goes. Though
the rule laid down by Sixtus V. has not been modified since, before him
the number of cardinals was far from being constant. For a long time it
varied in the neighbourhood of twenty; in 1331 John XXII. said that
there were twenty cardinals; in 1378 they were reckoned at 23. Their
number increased during the Great Schism because there were several
rival obediences. The councils of Constance and Basel reduced the number
of cardinals to 24; but it did not rest at that for long, and in the
16th century was more than doubled. In 1517 Leo X., in order to
introduce strong supporters of himself into the Sacred College, created
31 cardinals at the same time. The highest number was reached under Pius
IV., when the cardinals numbered as many as 76.

The composition of the Sacred College is subject to no definite law; but
the nece