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useful book is another result of the author's intelligent interest in the mechanical education of boys. He has contributed various volumes to this object, dealing with the subject in different ways, but all aiming at a practical familiarity with mechanical operations, and successfully to combine working and thinking. The "Boy Engineers" begins with the construction of a plain and simple workshop which a couple of boys extemporize, and then it follows them through a course of self-culture in mechanics. They first get up a grindstone for their purposes and learn to sharpen tools. Then they make a lathe and go on with the preparation of various workshop appliances. A wooden clock was next constructed, and then they proceeded to make an organ. Carpentry and the problem of house-construction were next attacked, and after that they devoted themselves to all sorts of mechanical contrivances and operations such as might constitute a fitting preparation for the thorough study of engineering. The book is well adapted to interest enterprising boys, and is full of information that will be useful to many grown men.

the dozen lectures comprising this volume Mr. Philbrick has made a very excellent statement of the main conditions to be observed in sanitary construction, and presented the chief considerations which show the need and importance of such work. In his introductory lecture he points out the great progress that has been made toward a higher standard of cleanliness, and the need of a continuance in the same direction to meet the conditions of modern life. The first of bis two lectures upon ventilation he devotes to a very full statement of the conditions which affect the purity of the air, the vitiation of it produced by respiration, lights and fires, the proper amounts of watery vapor for different temperatures, the influence of the materials of walls in allowing an air circulation, and the position of the rooms with regard to exposure to the external air, the results of the most trustworthy experiments being given on these points. In the second lecture on this subject the various ways of moving air are considered; and in this connection the different methods of heating are treated, their several advantages as determined by experience being indicated. In speaking of gaslight he points out what has been frequently pointed out before, but has been very little heeded, that, by the simple device of placing a duct above a chandelier, air vitiation by gas can be entirely obviated. This construction also secures excellent ventilation. The chapters upon drainage and sewage include a consideration of the different systems of sewage disposal, the proper construction of sewers, the means of ventilating them, and brief descriptions of closets, traps, and the various appliances connected with the water-carriage system, which the author regards as the only practicable system for cities. The subject throughout is considered with reference to American climatic conditions.

author assumes that, by reason of its isolation from the land and from other water systems, a far more complete and independent equilibrium of organic life and activity is found in a single body of water than in any equal body of land. Hence each form of life must be studied with reference to its relation to other forms and to its whole environment, of which its food relations are one of the most important features. A number of definite general correspondences between structure and food are indicated by the study of certain structural conditions about the mouth, throat, and gills of fish, of which it is hoped a full enough knowledge may be reached to enable the character of the food of an unknown species to be determined by a mere inspection of the fish itself. The present paper is a contribution to the study in these relations of the Acanthopteri.