History of The Baal's Bridge Square.
Everything points to the fact that the Craft was flourishing in Ireland in the sixteenth century. It is impossible, however, to be dogmatic about the point, whether or not it possessed any esoteric ceremonies. With most of us that will be a matter of faith rather than evidence. Yet if we may trust the testimony of a certain old relic of antiquity, some measure of ethical symbolism was associated on occasion with the implements of masory, as is shown by what is usually known as the "Baal’s Bridge Square," carefully preserved by Union Lodge No. 13, Limerick, warranted November, 1732, and probably "time immemorial" like others of our ancient Lodges.
This ancient brass square "was discovered in excavating the foundations of Baal’s Bridge, in the City of Limerick, in November, 1830. It was dug out of the eastern corner of the foundation of the northern land pier on the King’s Island or English Town side of the river Shannon, where the abutment of the new bridge now  stands." The position in which the square was found indicates that one of our Masonic customs, still in vogue, was practiced in Ireland over 400 years ago. The sketch hereunder of the square is an exact facsimile (full size) reproduced from a rubbing, a matter of some difficulty owing to the metal being much corroded, made for us by Brother James Le Gear, the courteous Secretary of Triune Masonic Lodge, No. 333, Limerick.
In the Freemasons' Quarterly Review, 1842, p. 288, Bro. Furnell, under the date of 27th. August, 1842, printed a short note on this relic of antiquity, accompanying which is a facsimile sketch. He says that Bro. Pain, in 1830, had been contractor for re-building Baals Bridge in Limerick, and on taking down the old structure, he discovered under the foundation stone at the English town side, this old brass square, much eaten away. In the facsimile sketch, Bro, Furnell puts the date as 1517, which is a mistake, as the square bears the date 1507. A heart appears in each angle.
In the book by H. F. Berry, Assistant Keeper of the Irish Records, “The Marencourt Cup and Ancient Square.” dated 1905, Bro. Berry records that “Ball's (or Baals) Bridge is a beautiful structure, of a single arch, built in 1831, to replace an ancient bridge of the same name, which consisted of four arches, with a range of houses on its west side. The date of the erection of this ancient structure has not been ascertained, but possibly the old square, dated 1507, may have been placed, under the foundation stone in that year. In any case, Bro. Furnell informs us that the old bridge is mentioned in records of 1558.
It would be easy to give earlier instances of this implement being invested with a moral meaning, but this is the first definite Irish example. It is suggestive of much.*
* See article by Bro. Twiss in A.Q.C. xviii. 18; and The Freemasons' Quarterly Magazine and Review, 1850, p. 320.
History of the Grand Lodge of Free and Accepted Masons of Ireland, John Heron Lepper and Philip Crossle. Dublin: Lodge of Research, CC., 1925. pp. 29-30.