Page:The Sources of Standard English.djvu/464

Rh ''they have their name as plane sections of a cone. This method is calcu&shy;lated'' to produce a material simplification in these curves, and to make the ''proof of their properties more easily understood and remembered. It is also'' a powerful instrument in the solution of a large class of problems relating to these curves.

The theory of friction is as truly apart of Rational Mechanics as the ''theory of gravitation. This book is taken up with a special investigation'' of the laws of friction; and some of the principles contained in it are ''believed to be here enunciated for the first time. The work consists of eight'' ''Chapters as follows: — I. Definitions and Principles. II. Equilibrium'' ''with Friction. III. Extreme Positions of Equilibrium. IV. Movement'' ''of a Particle or System of Particles. V. Motion of a Solid Body. VI. Necessary'' ''and Possible Equilibrium. VII. Determination of the Actual'' ''Value of the Acting Force of Friction. VIII. Miscellaneous Problems —'' ''1. Problem of the Top. 2. Friction Wheels and Locomotives. 3. Questions'' ''for Exercise. “The work is one of great research, and will'' add much to the already great reputation of its author.” —.

This little book is intended to meet a difficulty which is probably felt more ''or less by all engaged in teaching Algebra to beginners. It is, that while'' ''new ideas are being acquired, old ones are forgotten. In the belief that'' constant practice is the only remedy for this, the present series of miscel&shy;laneous ''exercises has been prepared. Their peculiarity consists in this,'' that though miscellaneous they are yet progressive, and may be used by ''the pupil almost from the commencement of his studies. The book'' being intended chiefly for Schools and Junior Students, the higher parts of Algebra have not been included.