edges, without influence on his conduct in giving direction to his researches, it will naturally occur to ordinary minds that this knowledge should also have been "not without influence" on his pen when he was professing to give a summary of the existing state of science on this subject. And when to this statement of the case, as acknowledged by himself, we add that he was made acquainted with the nature and purport of Prof Henry's explorations on this question, not only "in a general way," but also in a very special way, it becomes still more inexplicable that, in defining "the blank" which he claims to have filled by his recent inquiry, he should have disregarded the labors and results of American science, and that, too, while profiting by the instruments and methods of that science in the very conduct of his investigations. The reader will understand the force of our remark that Prof. Tyndall was acquainted with the researches of Prof. Henry, not only "in a general way," but also in a special way, when we state that a paper by the latter—on the abnormal phenomena of sound in relation to fog-signaling—was read by its author in the hearing of Prof. Tyndall at a meeting of the Washington Philosophical Society, called for the purpose of doing honor to the British savant while he was sojourning in the national capital. And the force of our remark that he has ignored the results of American science in magnifying "the blank" which he describes, while profiting by the instruments and methods of that science in conducting his inquiry, will be understood when we say that the researches of Prof. Tyndall were prosecuted with the help of a steam-siren, gratuitously lent to him by the Lighthouse Board at Washington, constructed and patented by a citizen of Mew York, and introduced by Prof. Henry into the lighthouse system of the United States.
We are now prepared for the next stage of this review. It so happened that while Prof. Tyndall was conducting his researches on sound in relation to fog-signaling, an officer of the United States Corps of Engineers, Major Elliot, had been deputed by the Lighthouse Board at Washington to make a tour of inspection in Europe, with instructions to report upon matters relative to lighthouse apparatus and the management of lighthouse systems. Major Elliot reached London a few days before Prof. Tyndall began his experiments at Dover, and was courteously invited to be present, but for want of time was compelled to forego the privilege. The results of the English experiments were, however, subsequently communicated to Major Elliot by Sir Frederick Arrow, the Deputy Master of Trinity House (who, we are sorry to say, has since deceased), and were embodied in his report on the "European Lighthouse Systems," as recently published. The publication of Major Elliot's report was accompanied, in the annual report of the United States Lighthouse Board for the year 1874, with the following observations:
"Major Elliot gives a detailed account of a late series of experiments by the
