vi PREFACE 



has been to make the volume a combined class-book and practi- 

 cal exercise book on the rudiments of physical and chemical 

 science. 



Many of the experiments follow the course of instruction in 

 elementary science contained in the physics and chemistry syllabus 

 prepared by a Committee of the Incorporated Association of Head 

 Masters. The results are indicated in each case, hence the 

 experiments may be regarded in a way as solved examples of the 

 general laws and phenomena of physical science, but the 

 examples can only be properly understood by actually following 

 the various stages which lead to their solution. In a few sec- 

 tions of the book it has been necessary to illustrate by numerical 

 examples the principles involved ; and to exercise the student in 

 solving simple problems of this kind numerous questions have 

 been added to the chapters. For a large number of these, and 

 more especially for those appended to Chapters III VII, we are 

 indebted to Mr. Walter J. Wood, B.A., who has collected many 

 from actual examination papers, and has supplied the answers. 



Throughout the preparation of the following pages we have 

 found the assistance and advice of Professor K. A. Gregory 

 invaluable. Teachers who know Professor Gregory's Exercise 

 Book of Elementary Practical Physics will recognise in the earlier 

 chapters of the present volume several experiments described in 

 that book. The opportunity of expressing thanks for permission 

 to introduce these is gladly taken ; and we also desire to express 

 our obligations to the Publishers for permitting free use of 

 suitable illustrations from several of their elementary books in 

 the various branches of science with which this volume is 

 concerned. 



It is worth remark that although the book is, in a broad 

 sense, a joint production, one of us (A. T. S.) is more directly 

 responsible for Chapters I XIII, and the other (L. M. J.) for 

 Chapters XIV XXIII. 



A. T. SIMMONS. 

 L. M. JONES. 



LONDON, March, 1898. 



