Before publishing his classic paper on the _Permanent Patency of the Aortic Valves_, on which his reputation as a wonderful clinical observer in medicine rests, Corrigan had called attention to some mistakes in the classification of heart murmurs as made by Laennec in Paris. At this time Laennec was considered to be the best authority in Europe {203} on diseases within the thorax. As regards diseases of the lungs, he well deserved the reputation. To him the medical world owes all that it knows about diseases of the chest, as far as these can be detected by means of the ear. His young contemporary in Ireland, however, was able to show that in diseases of the heart some of the ideas acquired in long years of study of the lungs were leading Laennec into false conclusions as regards the significance of murmurs of the heart. Even genius does not succeed in doing more than one thing well, and especially in the matter of taking a second step into the unknown. While the distinguished Frenchman might have been thought just the one to complete the work he began so well on the heart, and while his experience with the lungs might have been expected to help him in the recognition of the significance of heart murmur, this did not prove to be the case. The privilege of solving the mystery of heart diseases was to be left for his Irish contemporaries, one of the most successful of whom in this matter was Corrigan. Anyone who wishes to see how little subsequent study has added to our knowledge of aortic disease should read Corrigan's original paper on this subject. He describes all the varying forms of affections of the aortic valve, with their various clinical manifestations. His paper is illustrated by a set of plates that would still be valuable for demonstrative purposes, and which serve to show how painstaking were his pathological studies. He illustrated experimentally his ideas of how the murmurs and thrills occur by means of an apparatus consisting of rubber tubes through which water might be allowed to flow under pressure, and varying calibre. Some of his conclusions, derived from experimental observations, will not stand the test of our modern knowledge, but they are very suggestive. Perhaps the best idea of the clinical {204} value of Corrigan's observations can be given by a quotation from his original paper, in which he discusses the interesting and difficult question of the relationship between aneurism of the aorta and inadequacy of the aortic valve. He said: