OUTLINES OF THE EVOLUTION OF WEIGHTS AND MEASUEES AND THE METRIC SYSTEM OUTLINES OF THE EVOLUTION OF WEIGHTS AND MEASURES AND THE METRIC SYSTEM BY WILLIAM HALLOCK Ph.D. PROFESSOR OF PHYSIOS IN COLUMBIA UNIVERSITY IN THE CITY OF NEW YORK AND HERBERT T. WADE EDITOR FOR PHYSICS AND APPLIED SCIENCE, ' THK NEW INTERNATIONAL ENCYCLOPAEDIA THE MACMILLAN COMPANY LONDON : MACMILLAN AND CO. LTD. 1906 ac 2b SEP 8 <i ;\ OFT 9239G3 GLASGOW I PRINTED AT THE UNIVERSITY BY ROBERT MACLEHOSE AND CO. LTD. PREFACE. In the following pages it has been the aim of the authors to present in simple and non-technical language, so far as possible, a comprehensive view of the evolution of the science of metrology as it is now understood. Inasmuch as the introduction of the Metric System into the United States and Great Britain is a topic of more or less general interest at the present time, it has seemed that a work designed both for the student of science and for the general reader, in which this system is discussed in its relation to other systems of weights and measures past and present, would fill a certain need. While there are many works on metrology that treat at considerable length the historic and scientific sides of the subject, as well as the economic and archaeological questions involved, and a large number of books and pamphlets dealing with the teaching of the Metric System, besides those supplying tables and formulas for converting from one system to the other, yet there is apparently a distinct lack of works, which in small compass discuss the subject comprehensively from its many points of view. Indeed, the student of metrology is apt to be embarrassed by an extensive literature rather than by any deficiency in the amount of collected material, though much of the latter, to be sure, is included in various Eeports and Proceedings of learned societies and official documents rather than in single works. A large amount of this literature devoted to metrology represents a minute specialization and critical analysis often discussing either a certain epoch, or a single system or group of weights and measures, where the treatment is from the standpoint of either archaeology, economics, or physical or mathe- matical science, and but rarely combining the three points of vi PREFACE view. In addition, much of this literature is of an argumentative nature, and debate and discussion rather than definite conclusions compelling universal acceptance seem to be characteristic of metrological writing. It has been the intention of the authors to consider briefly and systematically the general history of weights and measures, the scientific methods by which units and standards have been determined, the concrete standards by which the units are represented, and the present aspect of modern systems of weights ' and measures, together with the difficulties and advantages involved in any proposed changes. Experience derived while giving instruction in physics to students in applied science has suggested the general plan of treatment, and it has seemed desirable to present from an American standpoint the most essential facts in as logical relation as is possible in a science that is often marked by conditions quite illogical. From the copious notes and bibliographical references, which it is hoped will be appreciated by advanced students and those specially interested in the subject, it will be seen that at the outset any claims to striking originality must be dismissed, and the obligations of the authors to the various authorities mentioned in the notes are ungrudgingly acknowledged. The authors hope that their work will serve two useful ends : first, as an introduction to metrological science designed especially for the student entering on the study of physics to whom a of units and standards is most and knowledge necessary ; second, as preparatory to an intelligent understanding of the discussions involved in the proposed adoption of the Metric System by English-speaking peoples, especially by those to whom Metric and Anti-Metric arguments are being addressed with such frequency and persistence. It has been the intention of the authors to avoid as far as possible all controversy for several reasons the first and most of which is that this side ; important of the question has been and is being abundantly covered elsewhere, so that it has seemed preferable in this work to include a mere statement of facts rather than to repeat or even add to the arguments. Such has been their intention, but they are also compelled to admit that they are supporters of the Metric propaganda, and they must ask indulgence for any PREFACE vii departures from the plan determined on. However that may be, they have endeavored to give a fair and concise history of the Metric System so that its logical development and character- istics will be apparent, and this, together with the experience of European nations as briefly described, will supply sufficient data on which may be formed an intelligent opinion as to the desirability of adopting in America and Great Britain at an early date the International System of weights and measures. In view of the fact that such a work has involved the use of a vast number of authorities, it is manifestly impossible to specify in detail other than in the notes the great indebtedness on the part of the authors to the labors of many famous metrologists. Naturally they have consulted freely the classic work of Mechain and Base du General Morin's Delambre, sysUme Mttrique ; Notice sur le Le historique systtme Mdtrique ; Bigourdan's syst&me Guillaume's La Convention du Metre and his excellent MStrique ; ; little treatise on UniUs et Etalons, as well as Benoit's Eeport on Standards of Length to the International Physical Congress of 1903. In addition they have used the various publications of the International Bureau of Weights and Measures. For ancient weights and measures many sources have been consulted, while for English standards and metrology the works of Chisholm and Chaney have been found most helpful, but they have been supplemented by various papers of Parliamentary commissions and the Proceedings of scientific societies. In the United States the Keports and other papers of the Coast and Geodetic Survey, the recently established National Bureau of Standards, and the Committees on Coinage, Weights and Measures, of the House of Eepresentatives have formed a nucleus that has been supple- mented by extensive reference to other scientific literature. In conclusion the authors would gratefully acknowledge their obligations to M. Ch. Ed. Guillaume, Assistant Director of the International Bureau of Weights and Measures, and Professor S. W. Stratton, Director of the U.S. Bureau of Standards, who most kindly consented to look over the proofs and have rendered assistance in many substantial ways. CONTENTS. CHAPTER I. PAGE Beginnings and Development of the Science of Metrology, 1 Underlying Principles of Metrology. Development of the Science among Primitive Peoples. Metrology of the Babylonians. Hebrew Metrology. Weights and Measures among the Egyptians. Greek Weights and Measures. The Roman System and its Spread. Mediaeval Conditions. Development of Anglo-Saxon Metrology. Early French Weights and Measures. European Conditions Generally. CHAPTER II. Origin and Development of the Metric System, - - 41 Reasons for the Change and Preliminary Efforts. Scientific and Other Steps in its Development. The Derivation of the Meter and Kilogram. Adoption of the System. Method of bringing about the Change. Systeme Usuelle. Spread of the Metric System and Compulsory Legislation of 1837. The Metric Treaty and the Formation of the International Bureau of Weights and Measures. Work and Organization of the Bureau. CHAPTER III. Extension of the Metric System throughout Europe and elsewhere, - 80 Confusion Existing and Reasons for the Change. Dates and Methods of Making the Change—Germany. Austria. Hungary. Belgium. Egypt. Greece. Italy. Japan. Netherlands. Portugal. Russia. Spain. Sweden and Norway. Switzerland. Turkey. Great Britain. Mexico. South and Central America. Table showing Dates when Metric System was adopted. x CONTENTS CHAPTER IV. PAGE Weights and Measures in the United States, - 109 Connection of Weights and Measures with Systems of Currency. Development of the Decimal Principle. Early National Legisla- tion. Various Plans Proposed. John Quincy Adams' Report on Weights and Measures. The Development of a National System and Progress towards Uniformity. Early Standards and Definitions. Spread of the Metric System. Summary of Metric Legislation. CHAPTER V. The Metric System of To-Day—Its Essential Character- istics and Fundamental Principles, - - - - 135 General Characteristics. Linear Measures. Superficial Measures. Cubical Measures. Measures of Capacity. Measures of Mass. CHAPTER VI. The Metric System for Commerce, - - - - - 150 The Advantages of a Universal System. The Metric System for International Trade. Its Applicability to the Ordinary Transaction of Commerce. The Advantages of a Homogeneous and Decimal System. CHAPTER VII. The Metric System in Manufacturing and Engineering, 172 Simplicity of Metric System. Ease with which Change could be made. Question of Gauges. Linear Measurements in Mechanical Engineering. The Question of Screw Threads. Introducing the Metric System into a Machine Shop. CHAPTER VIII. The Metric System in Medicine and Pharmacy, - - 191 General Nature of its Use and its Advantages. Adoption by U.S. Army and Navy Medical Departments. CONTENTS xi CHAPTER IX. PAGE International Electrical Units, - - - 199 The Absolute System. Derivation of Electrical Units from the Metric System. The C.G.S. System of the British Association. Definitions of Electrical Units at Chicago, 1893. Specifications for the Practical Application of these Definitions. New Magnetic Units. Shortcomings of Present Units. CHAPTER X. Standards and Comparison, - - - - - - 218 Nature and History of Standards. Methods of Comparison. Present Day Standards. Definition of the Meter in terms of the Wave Length of Light. APPENDIX. Tables of Equivalents and Useful Constants, - - 267 U.S.