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Excerpt from A Manual of Physical Measurements The close attention to every detail and the exercise of deliberate judgment which are required in every experiment if a worthy result is to be obtained, tend to produce a habit of accuracy which is of inestimable value. This training is obtained only when every effort is made to get the very best result that the time allowed for the experiment and the apparatus employed will permit. Before observations on any experiment are begun, the theory of the experiment should be mastered as well as the functions of the various parts of the apparatus which is to be used. Without such study, necessary observations may be omitted or taken in the wrong way, and apparatus whose value depends upon its accuracy may be injured permanently because of a lack of knowl edge about its delicate parts. Furthermore it is important to determine the degree of accuracy of every result which is obtained. Errors - For various reasons it is impossible to obtain the absolute value of an unknown quantity. Any measurement is affected, to a greater or less extent, by errors which may be classified under the two heads: constant and accidental. As examples of constant errors may be mentioned the following. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.