when we say that; it is by an Ohio lawyer—formerly a judge of Cincinnati. It has been held as one of the redeeming features of the English bar, that the author of the able and admirable essay on "The Correlation of Forces" belongs to it; and it is certainly to the credit of the legal profession in this country that a member of it has cultivated physical philosophy to such excellent purpose as is evinced by the article we now publish.
The Unity of Natural Phenomena. A Popular Introduction to the Study of the Forces of Nature. From the French of M. Emile Saigey. With an Introduction and Notes by Thomas Freeman Moses, A.M., M.D. Boston: Estes & Lauréat. Price $1.50. 253 pages.
Although this neat and attractive little volume claims to be a popular introduction to the study of the forces of Nature, we think it should rather be regarded as a book for those who have been previously introduced to the subject. It is rather devoted to an exposition of the author's speculative views than to a simplified and elementary statement for those who are beginning to study. The author holds to a universal ether, and maintains besides that matter is constituted from it, and consists of it, and he aims to build up the universe of ethereal atoms and motion. The work is written from the modern point of view of the correlation of forces, and contains much interesting information upon this subject, but the author is less concerned merely to interpret the phenomena of interaction among the forces than to get below them to what he regards as the causes of their unity. "The atom and motion, behold the universe!" is a somewhat Frenchy and fantastic cosmology. To readers of a speculative turn of mind the book will prove interesting.
Sanitary Engineering: a Guide to the Construction of Works of Sewerage and House-Drainage. By Baldwin Latham, C.E. 352 pages. Price $12. New York: E. & F. N. Spon.
This work is in all respects a contrast to that of M. Saigey. Instead of transcendental ether, it treats of descendental sewerage, and, instead of remote imaginative speculations, it is occupied with the most immediate and practical of the interests of daily life. Of the importance of the subject treated, the preservation of life and health by the thorough construction of sanitary works, there can be no question, and the author claims that it is the first book exclusively devoted to subjects relating to sanitary engineering. He has gathered his material from official reports, periodical papers, and various works which touch the subject incidentally, and, adding to them the results of his own practice, has produced a most valuable treatise. As science unravels the complicated conditions of life, it becomes more and more apparent that health can only be maintained by the destruction or thorough removal of those deleterious products which are engendered in dwellings. The necessity of drainage is well understood, and the art has been long practised in all civilized countries; but, like all other arts, its intelligent and efficient practice depends upon scientific principles, and therefore progresses with a growing knowledge of the subject. The questions involved in the proper sewerage of a district are numerous. Its geological character and physical features have to be considered; the meteorological element of rainfall is important; the constitution of the soil and subsoil must be taken into account; the sources and extent of artificial water-supply are of moment; and the area of the district to be sewered, and its present and prospective population, cannot be overlooked. Much information of this kind requires also to be called into requisition in the construction of separate country-residences. The physical circumstances being given, there then arise numerous questions in regard to drainage, construction, household contrivances, the materials employed, and the cost, efficiency, and permanency of works. Mr. Latham's volume treats this whole series of topics in a systematic and exhaustive way. It is profusely illustrated with wood-cuts and maps, and contains numerous tables which are indispensable for the guidance of constructors. It is not reprinted, but is supplied by the New-York branch of the London house, who hold it at an exorbitant price.