PROFESSOR TYNDALL.
THIS distinguished scientific philosopher, it is expected, will soon arrive in this country to give several courses of lectures in the chief Atlantic cities. Many of our people have read and admired his books, and become deeply interested in his themes, and those who can will no doubt gladly avail themselves of this opportunity to witness his beautiful experiments, and listen to his eloquent expositions. Dealing as he does with the various branches of physical science, and the familiar agencies and operations of Nature in their latest philosophical interpretations, his lectures will be of a high order of interest, and arrest the attention of our most thoughtful and intelligent citizens.
The indebtedness of the people of the United States to European thinkers for works of genius and learning in all departments of literature and science is acknowledged, but we owe to Europe another debt for lending us now and then the living use of her great men. "We are thus enabled to know not only what manner of books they write, but what manner of men they are, and to be brought immediately under the vital magnetic influence of their personalities. It was a great gain to American science when Prof. Agassiz left his foreign home and took up his abode in this country. His works would, of course, have produced an important influence, but that would have been as nothing to what he has been able to accomplish by his actual presence with us. Not only in his extensive original investigations by which our knowledge of Nature has been enlarged, and not only by the stimulus which he has given to multitudes of young men in the study of natural history, has he been of great service, but also by his public lectures, in all parts of the country, which have helped to increase the popular appreciation of these subjects.
A generation has now passed away since Dr. Lardner lectured in the principal towns in the United States to large and interested audiences, and the impulse he gave to the public mind in creating an interest upon these topics will produce its salutary effects for years to come. His general field of science was the same as that of Prof. Tyndall, but physics has made a long stride in the last thirty years. New departments of transcendent interest have been wholly created within this period. Dr. Lardner died the same year that Kirchhoff and Bunsen startled the world by the announcement of Spectrum Analysis. This was not only a new and splendid revelation which has thrown a flood of light upon many obscurities of Nature that science had never before dreamed of penetrating, but it was a new and powerful instrument of research of permanent value in the work of future discovery. Moreover, since the time of Lardner, new views of the energies of Nature of a most fundamental character have been arrived at. The doctrine of the correlation and conservation of force—"the highest law in physical science," says Dr. Faraday, "which our faculties permit us to perceive"—has been announced, elucidated, and established within the last generation. Dr. Lardner was too early for this subject; he belonged to the preceding epoch. As Dr. Whewell wrote the history of the science of heat without referring to the discoveries of Rumford in the last century—discoveries which involved a complete revolution in our views of
