_The Martyrology of Donegal_ was completed on the 19th of April, 1630, in the Franciscan convent of Donegal. The compilers were Brother Michael O’Clery, a lay brother of that convent, with three associates who with him are so well known by the name of “The Four Masters”. Colgan (_Acta Sanctorum Hiberniae_, tom. 1, p. 5 a.) thus speaks of it: “Martyrologium quod Dungallense vocamus, nostris diebus ex diversis tum Martyrologiis, tum annalibus patriis collectum est, partim operâ Authorum qui Annales communes, de quibus infra, compilarunt in Conventu Dungallensi; partim opera Patrum ejusdem Conventus qui sanctos, qui extra patriam vixerunt et de quibus hystorici exteri scripserunt, addiderant”. The Donegal copy of 1630 was a more complete transcript of a first copy, made by Michael O’Clery in the preceding year at Douay. Both copies are now extant in the Burgundian Library at Brussels, but circumstances have not permitted Dr. Todd to get the first copy also transcribed. Both copies are autographs of Michael O’Clery. The first to discover the mine of Irish MSS. in Brussels was Mr. L. Waldron, M.P., who, in 1844, at the request of Professor O’Curry, examined the library there. By the influence of Lord Clarendon, then lord-lieutenant of Ireland, with the government, Dr. Todd procured from the Belgian government, in 1848, the loan of several MSS. of the greatest importance, with the permission to have them transcribed. One of these was the autograph MS. of the _Martyrology of Donegal_, prepared for the press by the author, with the approbations of his ecclesiastical superiors. A copy of it was executed by the late Professor O’Curry with the skill and beauty of his unequalled penmanship; and this copy was collated with the original, whilst it was still in Dr. Todd’s possession. From O’Curry’s copy Dr. Reeves made another for his own use, and from this he made a third transcript for the printers, and the translator, Dr. O’Donovan. This translation was the last labour of Dr. O’Donovan’s life.