THE readers of the Monthly will find elsewhere in our pages an article which appeared several weeks ago in the Nation, containing an attack upon Prof. Tyndall, which, from the character of its charges, and the bitterness of its tone, excited the surprise and regret of many. It was replied to by Prof. Tyndall, whose letter we also republish. It will be seen that the assault is directly met, and, in his rejoinder to Prof. Tyndall's letter, the writer in the Nation admits that he was in error, while his admission covers the main and most offensive imputations. But, as his further comments are calculated to continue a false impression, and as base charges always go faster and farther than their retractions, especially when considerable time elapses before they can be authoritatively contradicted, it is desirable that we should here briefly review the leading features of the case. The charge against Prof. Tyndall, as the reader will see, is generally, that, in the third and recently-published edition of his work on "Sound," he has not done justice to the contributions of American science toward the elucidation of the subject of fog-signals. More specifically it is that, when in this country, he got information upon the subject from a paper read by Prof. Henry, went home and entered upon the investigation himself, published in his book the results of his own inquiries, and, while acknowledging that he knew generally of what had been done in America, and that it was not without influence on his conduct, yet that he ignored or "suppressed" from his summary of existing knowledge upon the subject any recognition of what had been accomplished by the United States Lighthouse Board under the direction of Prof. Henry.
Now, let us see what Prof. Tyndall's position was as avowed by himself in a statement widely published in this country months before the attack in the Nation was made. The August number of The Popular Science Monthly contains, in full, the preface to the third edition of "Sound," in which the American relations of the matter are considered. A summary is there given of the experiments of Prof. Henry in regard to the penetration of fog by sound, and the performance of various instruments of American construction designed to be used as coast-signals; and the remark is added that "it is quite evident from the foregoing that, in regard to the question of fog-signaling, the Lighthouse Board of Washington have not been idle." Prof. Tyndall states, furthermore, that he had recommended American instruments for fog-signaling to the British authorities as superior to the English instruments, and that they had been adopted on his recommendation. Every fair-minded reader, upon perusal of that paper, will agree, we think, that Prof. Tyndall wrote truthfully when he said: "In presence of these facts it will hardly be assumed that I wish to withhold from the Lighthouse Board of Washington any credit which they may fairly claim." But, having thus testified to the character, extent, and importance of American work upon this subject. Prof. Tyndall proceeds to state what in his opinion the Lighthouse Board has failed to do. He says: "My desire is to be strictly just; and this desire compels me to express the opinion that their report fails to establish the inordinate claim made in its first paragraph. It