Page:Popular Science Monthly Volume 47.djvu/141

Rh kinetics of a particle, and the remainder is given to the study of the kinetics of a rigid body and a brief discussion of the fundamental principles of the kinetics of a system. In the discussion of the motion of a particle (impact, rectilinear motion) such fundamental ideas as momentum, impulse, kinetic energy, force, work, potential energy, and power are gradually introduced and illustrated in an elementary way. Then the general equations of motion of a particle are discussed; and the principle of kinetic energy, that of angular momentum, and the principle of d'Alembert are explained and applied—first, to the motion of a free particle, then to constrained motion. In treating of the motion of a rigid body, after the discussion of the fundamental principles and of the theory of moments and ellipsoids of inertia, the action of impulses and the motion under continuous forces are taken up separately. The last chapter, on the motion of a system, is brief, but includes the theory of Lagrange's generalized co-ordinates and of Hamilton's principle.

A suggestive and useful little book prepared by William C. Connell, and published by G. P. Putnam's Sons, is The Currency and the Banking Laws of the Dominion of Canada, considered with Reference to Currency Reform in the United States. It contains the substance of an address delivered at the American Bankers' Convention held at New Orleans in 1891, in which financial straits that have since occurred were predicted; followed by the Banking Act of Canada, given entire. This act is presented as completely filling all the requirements of the community in which it exists and flourishes, and worthy of consideration in reconstructing our own financial system.

The Dynamics of Life (Blakiston & Son, Philadelphia) presents the substance of an address delivered before the Medical Society of Manchester, England, in October, 1894, by W. R. Gowers, M. D. In it are explained, without the author assuming any claims for novelty in conception, the operations of Latent Chemical Energy, the Dynamics of Muscle, the Dynamics of Nerve, and the Dynamics of Disease. Summing up the results of his inquiry, the author observes that, search as earnestly and thoroughly as we may, that which we call life eludes our search and resists our efforts. "We may, indeed, trace the relations to vitality of matter and of the energy it bears—their entrance into the domain of life, their exit, their effects." But we see them only as shadows in the mist.

In the Fifth Annual Report of the Missouri Botanical Garden, for 1893, mention is made of the destructive effects of drought and extreme alternations of winter temperature on the lawns and the evergreens. The Norway spruce has particularly suffered, and it will be only a few years before all the older trees will have disappeared. The old red cedars and the arbor vitæs are also succumbing, and are being gradually removed. A similar experience is recorded at the Harvard Botanic Garden. The year's additions to the herbarium number 19,417 sheets. In addition to the "Shaw Premiums" already awarded annually, a gold medal has been instituted for the introduction of a plant of decided merit for cultivation not previously an article of North American commerce. The Garden and the School of Botany, endowed by Mr. Shaw in Washington University, are working harmoniously together. The volume, including the report, containg the usual anniversary publications and scientific papers on the Venation of Salix, by Dr. N. M. Glatfelter; the Tannoids, by J. C. Beny; the Sugar Maples, by Dr. Trelease; Gayophytum and Boisduvalla, by Dr. Trelease; Pomological Notes for 1892 and 1893, by J. C. Whitten; The Emergence of Pronuba from Yucca Capsules, by J. C. Whitten; Plants collected in Southeastern Missouri, by B. F. Bush; Notes and Observations, by Dr. Trelease; and more than forty plates.

The first of the two volumes of Lord Rayleigh's work on The Theory of Sound, first issued in 1877, has come to a second edition (Macmillan, $4). The work is a mathematical presentation of the subject, aiming to include the more important of the advances made in modern times by mathematicians and physicists. The present volume includes chapters on the vibrations of systems in general, followed by a more detailed consideration of special systems, such as stretched strings, bars, membranes, and plates. In the second edition are two new chapters, dealing respectively with curved plates or shells and with electrical vibrations. Minor changes and new sections are inserted