markable. No such brilliant gathering of scientific, literary, and professional gentlemen has ever before assembled on a festive occasion in this metropolis. As his lecture-rooms, in the various cities he has visited, have been crowded by the most intelligent and cultivated people, so the dining-hall at Delmonico's was filled with two hundred guests, many from abroad, and representing the colleges and scientific institutions of the country, together with a large body of the most eminent gentlemen of our city. The spirit of the occasion was one of harmonious enthusiasm for the distinguished professor in whose honor it was made, and of lively interest in the subjects and ideas he represents. The speaking was excellent, and, although graver and more didactic than is customary at such times, was yet by no means unexciting, and met with the most cordial responses. Of course Delmonico, prince of caterers, lost no reputation in the elegant and sumptuous repast which he furnished, but the social and intellectual treat was the great feature of the evening. Prof. Tyndall made a happy address, in which he explained the motive of his coming to this country, the laborious character of the work which his lectures involved, and the reasons which compelled him to decline the numerous urgent invitations that have poured in upon him from all directions, to lecture in the cities of the interior and the West. We have no space now to refer to the several admirable speeches that were made, upon subjects variously connected with the interests of science. They were too valuable to be left in the incomplete shape in which the reporters gave them to the newspapers, and they will be shortly published as an appendix to the little volume of his lectures which Prof. Tyndall has carefully prepared, and which will be given to the public in a few days.
The Earth a Great Magnet. A Lecture delivered before the Yale Scientific Club. By Alfred Marshall Mayer, Ph.D., Professor of Physics in the Stevens Technological Institute. Chatfield & Co., New Haven.
The author of this lecture is well known to the scientific world, both in this country and Europe, as an original investigator in the field of physics. He has made numerous researches in various physical branches, the results of which have been published in the scientific journals, domestic and foreign. He is now prosecuting various inquiries at the Stevens Institute of Technology, in Hoboken, where they have the finest collection of physical apparatus that can be found in any institution in this country, if not in the world. Having won his spurs as an original experimenter, and established his place among those who extend and create scientific knowledge, he now turns his attention to the work of diffusing it among the people. It is common to say that original investigators are not good expositors; and this is often true, but it is also true that they are frequently the very best of teachers. We have recently had a conspicuous example of this in Prof. Tyndall, and we now have another in Prof. Mayer. The lecture before us is a model, in its logical form, its copious and beautiful experiments, and its lively and graphic language. As an exposition of the elements of terrestrial magnetism in a compressed and readable form, it is perfect. Trübner, of London, has caught it up and issued it; and the London and Edinburgh Philosophical Magazine, the first scientific authority, has reviewed it in so just and discriminating a way that we cannot do better than to quote a portion of its statement: This is the report of a lecture delivered before the Yale Scientific Club on February 14, 1872, in which the lecturer proposed to present to his audience 'one prominent truth in simple and striking experiments'. The truth which is kept steadily before the mind throughout the lecture is, that the earth is a great magnet; and this truth is developed step by step by experiments of the most conclusive kind, each having been rendered distinctly
