this subject may be classified
under seven heads--

(1) That the Phoenicians erected them for fire temples.

(2) That the Christians built them for bell towers.

(3) That the Magians used them for astronomical purposes.

(4) That they were for Christian anchorites to shut themselves up in.

(5) That they were penitentiaries.

(6) That the Druids used them to proclaim their festivals.

(7) That the Christians used them to keep their church plate and
treasures.

[Illustration: URN AND ITS CONTENTS FOUND IN A CROMLECH IN THE PHOENIX
PARK, DUBLIN.]

Contradictory as these statements appear, they may easily be ranged into
two separate theories of pagan or Christian origin. Dr. Petrie has been
the great supporter of the latter opinion, now almost generally
received. He founds his opinion: (1) On the assumption that the Irish
did not know the use of lime mortar before the time of St. Patrick. For
this assumption, however, he gives no evidence. (2) On the presence of
certain Christian emblems on some of these towers, notably at Donaghmore
and Antrim. But the presence of Christian emblems, like the cross on the
Ogham stones, may merely indicate that Christians wished to consecrate
them to Christian use. (3) On the assumption that they were used as
keeps or monastic castles, in which church plate was concealed, or
wherein the clergy could shelter themselves from the fury of Danes, or
other invaders. But it is obvious that towers would have been built in a
different fashion had such been the object of those who erected them.
The late Mr. D'Alton has been the most moderate and judicious advocate
of their pagan origin. He rests his theory (1) on certain statements in
our annals, which, if true, must at once decide the dispute. The Annals
of Ulster mention the destruction of fifty-seven of them in consequence
of a severe earthquake, A.D. 448. He adduces the testimony of Giraldus
Cambrensis, who confirms the account of the origin of Lough Neagh by an
inundation, A.D. 65, and adds: "It is no improbable testimony to this
event, that the fishermen beheld the religious towers (_turres
ecclesiasticas_), which, according to the custom of the country, are
narrow, lofty, and round, immersed under the waters; and they frequently
show them to strangers passing over them, and wondering at their
purposes" (_reique causas admirantibus_). This is all the better
evidence of their then acknowledged antiquity, because the subject of
the wri