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Rh blundering stupidity in regard to the first law of motion. But the curious thing about it is that the writer in "Science" is inclined to attribute the scientific incapacity of this metaphysical author to Spencer himself, or, rather, to make it a result of familiarity with Spencer's works. He says: "Meanwhile, let the case serve as a warning to those who imagine that our American public is to receive useful instruction in elementary physical science from the now popular works of the great teacher of the evolution philosophy. Here is a very good student, indeed—diligent, logical, and ingenious. What philosopher could hope for a better? He has carefully studied Mr. Spencer's works, and this is what he has got out of them." A gem of judicial criticism, truly, of which "Science" may well be proud!

possesses much geological interest. The formations, from the Lower Silurian to the Carboniferous, are well exposed in their order from east to west, and abound in limestones and sandstones suitable for varied economical purposes, lime, cement, and coal, while the northern part of the State is deeply covered with glacial drift. Springs and streams abound. The soil in the central and northern parts is deep, and contains the elements of a prolonged fertility. As late as 1880 timber was spoken of in Professor Collett' s report as still in excess. It is of hard wood, and suitable for fine work. Coal is found in fields covering an area of 7,000 square miles, which are entered in all directions by railroads. The non-caking "block-coal" is found within an area of 600 square miles, and is a valuable metallurgical agent. The coal-mines employ a capital of $2,500,000, and the same sum represents the value of the product of 1882. The building stones are of various and excellent qualities. The oolitic limestone of Lawrence, Monroe, Owen, Crawford, Harrison, and Washington Counties is easily worked, develops in hardening a strength of from 10,000 to 12,000 pounds to the square inch, takes on an agreeable color, is of imprecedented purity, and gives a promise of durability. Pure glass sand is found in four counties, gravel is "common as air," lime and cement are "so abundant as to escape attention"; brick-clay is "as common as water"; kaolin and fire-clay occur in workable beds, natural gas is mentioned, and some salt is produced. Fine fossils abound in all the formations. Professor Collett has added much to the value of his reports by calling in the aid of persons already familiar with the geology of the State and their own counties, and of scientific experts. In these volumes and the preceding report for 1880 we have, besides the special surveys of ten counties, descriptions of fossils by Dr. J. C. McConnell, of Washington, D. C, Professor James Hall, and Dr. C. A. White; a paper on palæozoic botany, by Professor Lesquereux; a flora of the elevated region of the State; and a microscopic study of potable waters, by the Rev. Dr. Curtis. Special attention is given to archæological features.

its general method this book follows the "mode of teaching under which the whole of natural philosophy is regarded as substantially a single science, in which scattered facts are collected and coordinated by reference to the principles of dynamics and the great experimental law of the conservation of energy." The treatise confines itself strictly to the field denoted by its title, applications of principles and matters of solely historic interest being rigidly excluded. After some preliminary considerations of measurements, including the measurement of force and of energy, there is a chapter devoted to kinematics, in which waves and simple harmonic motions are treated at considerable length. The essential or general properties of matter are next stated, and then the characteristics of each of the three states of matter. The opening of the chapter on heat well illustrates the character of the book, and is as follows:

Heat is a form of energy. It would, perhaps, indeed be more correct to say that we designate under the one name heat two totally distinct forms of