Olmsted, s Introduction to A^'atural Philosophy. 355 



accustomed to teach. A peculiarity which distinguishes the Trea- 

 tise of Bridge from almost every similar work, is the great variety of 

 problems with which the work is enriched. This feature Professor O. 

 has borrowed very fully, having retained (though with considerable 

 modification) the greater part of the Questions for Practice, contmn- 

 tained in the original work, and having added many more. Upon 

 this subject he makes the following remarks. " A great variety of 

 problems are annexed to each chapter, the utility of which must be 

 obvious to every experienced instructor. Indeed, problems hold so 

 important a place in the estimation of the writer, that he has intro- 

 duced them into various parts of the work, wherever the subject ap- 

 peared to be susceptible of deriving aid from them. Problems put 

 the student upon his own resources; they compel him to think for 

 himself; they lead him to a just understanding of the principles dem- 

 onstrated ; and they teach him how to reduce his knowledge to prac- 

 tice. These truths are so obvious, that it is difficult to account for 

 the singular fact that treatises on Natural Philosophy, usually contain 

 few or no problems, although they occupy so large a space in most of 

 the branches of pure mathematics." 



In the subsequent parts of the work. Hydrostatics and Pneumatics, 

 Acoustics, Magnetism, Electricity and Optics, have severally their 

 proportionate share of attention. To seize upon a few principles of 

 very extensive application ; to make the learner well acquainted with 

 these ; and to follow them out in many of their practical bearings ; 

 are objects which the writer has evidently had constantly in view. 



Accordingly, along with these fundamental principles, the truth of 

 which is established by the best evidence of which they are respec- 

 tively susceptible, the learner is supplied with as great an amount of 

 practical information as could be. brought within so narrow limits. 

 For example, in the course of the work, the student will be made 

 familiarly acquainted with the principles of the Steam Engine, the Mi- 

 croscope and the Telescope. 



The work is neatly printed, and contains nearly three hundred 

 diagrams in wood, which serve a very valuable purpose, especially in 

 cases where the student has not the advantage of extensive experi- 

 mental illustrations ; and even where he has such aid from appara- 

 tus, the diagrams prepare him to take the benefit of them much 

 more fully than he would otherwise do. 



The Analysis which is prefixed to each volume, furnishing a clue 

 to all the principal matters contained in every paragraph of the text, 



