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Introduction to Experimental Physics, Theoretical and Practical, 

 including directions for constructing Physical Apparatus and for 

 making experiments. By Adolph F. Weinhold, Professor in 

 the Royal Technical School at Chemnitz. Translated and edited, 

 with the Author's sanction, by Benjamin Loewt, F.R.A.S. With 

 a Preface by G. C. Foster, F.R.S. 



This is an elementary treatise on Experimental Physics which 

 differs materially from those ordinarily used in our Schools 

 and Universities. The object of the writer has been to pre- 

 sent the general facts of elementary physics as plainly as pos- 

 sible, always in a concrete form, to keep abstractions as much as 

 possible in the background, and to give instructions with such 

 detail and minuteness as will enable the reader who is provided 

 with simple tools and materials and endowed with a proper amount 

 of patience, to make all the apparatus and perform all the experi- 

 ments described in the book. These instructions are without 

 doubt the most valuable part of the book, and constitute the fea- 

 ture by which it is distinguished from other elementary works on 

 physics. 



The subjects treated of are General Properties of Matter, General 

 Mechanics and Mechanics of Solid Bodies, Mechanics of Liquid 

 and Gaseous Bodies, Acoustics, Optics, Electricity, Magnetism, and 

 Heat. To judge by the number of pages assigned to each of these 

 subjects, they are considered of very unequal importance. While 

 Heat is disposed of in 78 pages, as many as 316 are allotted to the 

 Mechanics of solid and fluid bodies. The disproportion, however, 

 is not so great as it seems, since of the latter many pages are 

 occupied with a description of tools and methods of operating, 

 which are as much employed upon apparatus for Heat as for 

 Mechanics. 



The study of Mechanics is introduced by an experimental investi- 

 gation of the laws of falling bodies by Atwood's machine. This 

 plan is one of which we cordially approve. An intelligent com- 

 prehension of the meaning of the term force is one of the most 

 difficult to instil into the mind of a student. Usually an abstract 

 definition of force is given in the beginning of the text-books 

 which the student learns by heart ; and not until he has worked 

 his way through all manner of propositions involving the relations 

 of forces does he learn the connexion between force and weight, 

 how the weight of a body is a concrete expression of the attractive 

 action of the earth upon it, and how forces are to be measured by 

 the motional effects which they produce in bodies. It is a misfor- 

 tune, however, that greater stress is not laid on the distinction 

 between weight and mass, and also between force and acceleration. 

 The term mass is introduced suddenly (p. 52) without any indica- 

 tion of the meaning it is intended to bear, and is frequently used 

 as synonymous with weight. 



The avoidance of abstractions and formulae is sometimes carried 

 to an excess. For instance, in the case of falling bodies, the ex- 



