viii SCIENCE PROGRESS. 



Technical College, the portions of the subject which are suitable for an 

 elementary course to first year students being printed in larger type 

 than the more advanced portions. 



In addition large collections of numerical and graphical exercises, 

 (with answers appended), are given at various stages in the development 

 of the subject. These will prove very useful both to teachers and 

 students. 



One of the most interesting features of the book is the description 

 and illustration of several pieces of laboratory apparatus, which have 

 been designed by Prof. Perry for students' use in performing quanti- 

 tative experiments in Applied Mechanics. 



In fact the professor takes up strongly the position of a reformer 

 of the "academic" methods of instruction in Applied Mechanics which 

 he conceives to be in vogue in too many places, and insists on the 

 absolute necessity for students making quantitative experiments in a 

 Mechanical Laboratory as an essential part of any proper course of 

 instruction in Mechanics. He refers with just pride to more than 

 twenty complete sets of his apparatus which have already been made 

 for various institutions, and no doubt the publication of this book will 

 induce many other colleges and technical classes to follow more or less 

 closely his system of instruction. 



Prof. Perry acknowledges the pioneer work of Prof. Ball at the 

 Royal College of Science, Dublin, in initiating quantitative experimental 

 work in illustration of the principles of Mechanics. But instead of 

 building up each piece of apparatus out of a small number of elements, 

 which served for many different experiments, Prof. Perry's plan has 

 been to use a distinct piece of apparatus for each experiment (with the 

 obvious advantage of having the apparatus always ready for use), and 

 instead of the lecturer performing the experiment the "student measures 

 things for himself; illustrates mechanical principles ; finds the limits 

 to which the notions of the books as to friction and properties of 

 materials are correct ; learns the use of squared paper, and the accuracy 

 of graphical methods of calculation ; and, above all, really learns to 

 think for himself". 



Another excellent feature of the work before us is the freshness of 

 the information and the originality of method obvious on nearly every 

 page. Whilst many teachers will consider the style too polemical for 

 a text-book, and will look on some of the attacks on what are here 

 called "academic" methods, and "academic'' persons as uncalled for 

 and quite unnecessary in a "treatise for the use of students," no one 

 interested in the training of mechanical engineers can afford to neglect 

 the results of Prof. Perry's experience as embodied in this treatise. 



In regard to the " get up " of the book the illustrations with some 

 few exceptions are very satisfactory, but the paper is too thin, or rather 

 is not sufficiently opaque, and this makes the small type very trying to 

 the eyes ; the printing also of the mathematical portions leaves much 

 to be desired. 



