LESSONS IN ELEMENTARY PRACTICAL PHYSICS - VOL. I - 1901 - PREFACE TO FIRST EDITION - THE work of which this is the first volume took its origin in the felt necessity for systematising the work in our physical laboratory. We first of all commenced by using short manuscript accounts of the various processes and instruments for the-use of our students. , This, although satisfactory as far as it went, was found insufficient, and had to be supplemented by references to boolrs not always accessible. Learning from various quarters the desirability of a simple yet systematic . treatise on physical instruments, me were at length induced to undertake the task ourselves. It was first proposed to publish the whole in one volume, but as th matter grew under our hands it was suggested to us by Professor Sir Henry Roscoe that it might be advantageously published in three volumes. This arrangement will, we imagine, be convenient for students who wish to cultivate some particular branch of physical inquiry. The present volume will, me hope, be followed in due course by one on Electricity and Magnetism and our work will be rendered complete by a third on IIeat, Light, and Son - n . d It has sometimes been a cause of remark that, while natural philosophy forms a very important branch of education, there should be so few physical laboratories compared with the number of chemical laboratories that exist. One obvious reason of this is that for teaching purposes chemical processes lend themselves to a system more readily than those of physics. In a chemical laboratory, for instance, each student may have his own set of apparatus and his own place. This, of course, could not take place in a physical laboratory. Further, it has generally been thought that the expense of a physical laboratory is so great as to be almost prohibitive, except for large institutions. In this respect, howeyer, we are of opinion that the physical will compare very favourably with the chemical laboratory. The first expenses of fitting up a complete chemical laboratory are very great whereas, for a pllysical laboratory, they are comparatively small-a few deal benches and firmlyconstructed slabs being all that is absolutely necessary. If, on the other hand, it be urged that physical instruments are very expensive, our reply is that this is a matter of first cost, an instrument carefully handled lasting many years, whereas in a chemical laboratory the working expenses due to breakages and the use of reagents are considerable. Nor is it necessary to commence a physical laboratory with a large number of expensive instruments, such as the dividing engine, the cathetometer, the magnetometer, etc., for excellent substitutes may be made for some of the most expensive instruments, and constructed at little cost by the aid of 6 local worker in metal and wood. It is hoped that this book may prove of use to three separate classes of students, embracing, in the first place, those who are attending an elementary course in a well-furnished laboratory secondly, those who have access to a laboratory containing only a few instruments and thirdly, those who are desirous of acquiring a knowledge of the processes of physics while they have not the opportunity of working in any laboratory. This last class will value the engravings me have given...