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.