Minutes of Proceedings, 
31 
Acting Palseontologist to the Irish branch of the Geological Survey, 
and in 1868 Demonstrator in Palaeontology to the Eoyal College of 
Science for Ireland, which offices he continued to hold until his 
death. 
He was the author of numerous Papers on subjects in his depart- 
ment of I^atural History, the value of which was enhanced by 
their being illustrated so admirably by his skilful and accurate pencil. 
The number of labourers in the field of Irish antiquities is so 
limited as to make the loss of any student of the Irish language a 
matter of deep regret ; and in the case of Mr. Hennessy the loss is the 
more sensibly felt, because he was specially familiar with the early 
history and geography of Ireland. His knowledge was, unfortunately, 
not worked up permanently into a connected whole, such as would 
adequately represent his learning : Celtic scholars would have been 
grateful indeed for the heritage of an Irish Encyclopaedia of archae- 
ology and geography, such as perhaps he alone could have written. 
Eut though no monumental work remains, enough is left to show 
clearly the range and accuracy of his scholarship. 
In his publication of the " Annals of Loch Ce," and the 
Chronicon Scotorum," in the Master of the Polls' Series, he has 
given proofs of consummate ability and unsparing diligence, in the 
solution of many a knotty problem whose difficulty can only be 
appreciated by fellow-students : often, too, the printed work giving 
no adequate idea of the labour expended in attaining the desired 
solution. 
Perhaps his most admirable piece of work, as it certainly is the 
most interesting, was his translation of the famous Irish Tale in the 
"Leabhar Breac," the Yision of Mac Conglinny, published in Eraser's 
Magazine," September, 1873. It is not an exaggeration to say that this 
translation would of itself have placed him in the first rank of Irish 
scholars of the day : though wonderfully literal, it yet enables a reader 
to recognize the attractiveness of the original. As almost the only tale 
remaining to us from olden time of genuine Irish humour, it was 
well that it should receive admittance into the general current of 
literature through the excellent translation of so capable a scholar. 
Other works, which need not here be mentioned, exhibit equally 
clearly the deep interest he took in all questions of Ireland's history and 
