Prof. Henry's investigations, constituting an advance of scientific knowledge in this branch of acoustics, that Prof. Tyndall has omitted or "suppressed" in his work? If any thing has been accomplished in this country toward the scientific solution of such acoustical problems in relation to fog-signaling—if any new light has been cast upon the phenomena that explains anomalies and reconciles contradictions, which was not acknowledged by Prof. Tyndall in his book—we submit that it was the obvious duty of the writer in the Nation to point out what it was. He should have indicated the gap in Prof. Tyndall's summary of the present state of knowledge, or he should have shown us what principles or results, there stated, are due to American research. He says: "It is no part of our present purpose to institute a critical inquiry into the conflicting views of Prof. Henry and of Prof. Tyndall with regard to the hypotheses respectively espoused by each for the explanation of the phenomena of sound, in its passage through wide tracts of air." Yet the whole question turns on the scientific "views" contributed by Prof. Henry which it is alleged that Tyndall has ignored. He speaks of the views "respectively espoused" by the parties; but the question is on the views originated. Prof. Henry is understood to adopt the theory propounded by Prof. Stokes at the British Association in 1857, according to which sound-waves are tilted through the air under the influence of wind. That theory is certainly not "suppressed" from the new edition of "Sound." In his rejoinder to Prof. Tyndall's letter, the Nation's critic reaffirms his assertion, saying, "The question between us is not one of science, but of historical fact" But his complaint in the first article was certainly of the non-recognition of "American science." Obviously Prof. Tyndall had to decide what is science and what is not, which looks to us very much like a scientific question. In his "summary of existing knowledge," it was not his* business merely to chronicle experiments. He had to deal only with such systematic inquiries into causes as yield results properly entitled to take their place in the body of scientific knowledge. We do not say that Prof. Henry's researches have failed to extend the domain of positive scientific knowledge, but only that the writer in the Nation was bound to establish this, before accusing Prof. Tyndall of delinquency in not recognizing it.
But it is the closing passage of the Nation's article which has excited the greatest surprise, betraying, as it obviously does, a vicious state of feeling on the part of the writer. He there represents Prof. Tyndall as having claimed to demolish the authority of Prof. Henry, and as swaggering over the "ruin" he had accomplished. In half a dozen hues, Tyndall is accused of "superciliousness," "self-complacency," "vanity," "conceit," "arrogance," and "self-laudation;" and this upon an utterly false and absurd interpretation of some incidental remarks in his preface. The following is the passage that called forth this storm of offensive epithets:
"The clew to all the difficulties and anomalies of this question is to be found in the aërial echoes, the significance of which has been overlooked by General Duane, and misinterpreted by Prof. Henry. And here a word might be said with regard to the injurious influence still exercised by authority in science. The affirmations of the highest authorities, that from clear air no sensible echo ever comes, were so distinct, that my mind for a time refused to entertain the idea. On the day our observations at the South Foreland began, I heard the echoes. They perplexed me. I heard them again and again, and listened to the explanations offered by some ingenious persons at the Foreland. They were an 'ocean-echo;' this is the very phraseology now used by Prof. Henry. They were echoes 'from the crests and slopes of the waves;' these are the words of the hypothesis which he now espouses. Through a portion of the month of May,
