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Full text of "Outlines of the evolution of weights and measures and the metric system"

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 



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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 
knowledge of units and standards is most necessary ; and 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 important of which is that this side 
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 Delambre, Base du sysUme Mttrique ; General Morin's 
Notice historique sur le systtme Mdtrique ; Bigourdan's Le syst&me 
MStrique ; Guillaume's La Convention du Metre ; and his excellent 
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. 



PAGE 



x CONTENTS 

CHAPTER IV. 

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. Legal Equivalents. British Legal Equivalents. Table for 
Conversion of Units of Length. Table for Conversion of Units 
of Mass. Equivalents, Millimeters and Fractions of an Inch. 
Comparison of Prices : Length — Inches and Centimeters, Feet and 
Meters, Yards and Meters, Miles and Kilometers. Areas — Acres 
and Hectares. Capacity — Liquid Quarts and Liters, Gallons and 
Liters. Mass — Avoirdupois Pounds to Kilograms, Comparison of 
Tons and Pounds. Capacity — Various Equivalents. Mass — Various 
Equivalents. Apothecaries' Weight — Table of Equivalents. Den- 
sity, Melting Point and Boiling Point Tables. Thermometer Scales 
— Table of Equivalents. Miscellaneous Constants and Equivalents. 

Index, - - 295 



CHAPTEE I. 

ORIGIN AND DEVELOPMENT OF THE SCIENCE OF 
METROLOGY. 

Few questions concern the human race more directly and 
universally than the subject of weights and measures. In fact, 
so intimate is this connection that the common weights and 
measures of a people bear much the same relation to it as does 
the language of ordinary speech, being assumed and applied in 
their daily occupations without active thought, and resisting 
changes and reforms, even when brought about by the most 
strenuous efforts and with convincing proof of their desirability 
or necessity. For the origin of weights and measures it is 
necessary to go back to the earliest days of the human race and 
deal with the elementary mental processes of primitive man. The 
idea of measuring must have been closely akin to that of 
number, which, of course, implied the perception that certain 
objects could be grouped together either actually or at least 
ideally. The next step would be the comparison of the various 
objects of such a group, and this would involve a simple ratio 
in terms of one of the members of the group. When the 
comparison was extended to other groups, there was need of a 
standard, and, when various classes of objects were compared, 
a standard had to be selected which would answer in common. 
Such standards would readily suggest themselves. If it took a 
certain number of days and nights to make a journey, the distance 
travelled in one day, that is from one sunrise or sunset to 
the next, would straightway be considered as a natural measure 
of journeys of considerable duration, while, for shorter distances, 

A 



2 EVOLUTION OF WEIGHTS AND MEASURES 

the pace as a regularly recurring interval would be adopted 
for measuring the total distance, and the single pace would 
be taken as a unit. 

For measuring still smaller distances the primitive man would 
take, say the length of his foot or the breadth of his hand, as it 
would be most convenient for him to employ as units in his 
measurements the objects usually at hand, and it was but 
natural that the dimensions of the body would furnish such 
units. Thus for linear measures there would be employed the 
breadth of the first joint of the forefinger, the breadth of the 
hand, the span of the extended fingers of one hand, the length of 
the foot, the length of the forearm, the step or single pace, the 
double pace, and the distance between the tips of the fingers 
when the arms were outstretched. All of these distances figured 
in the early systems of linear measures of the ancients, and, in 
fact, great diversity of measures was a characteristic of early 
civilization, due to the fact that originally only the convenience 
of the individual had to be consulted. With the growth of 
society the tendency was toward uniformity, and this tendency, 
with but occasional retrogressions, has been maintained. When 
several persons were concerned in the comparison of the size of 
an object or some other kind of measurement, it was necessary 
to consult the convenience of the group rather than that of the 
individual, while with the development of trade there was 
also added the idea of equity. 

Along with the general tendency of progress from diversity 
to uniformity of measures in the evolution of society, must also 
be considered the securing of uniformity of single measures. 
Thus, if a pace or length of a forearm was a convenient unit for 
a number of individuals, it would soon become necessary to 
specify the class of individuals, or, better still, the single indi- 
vidual whose pace or forearm was to be the standard; was it to 
be that of a man six feet in height or one considerably shorter ? 
Such a discussion could not but lead to the actual measuring 
of the pace or forearm which would by common consent serve as 
the measure, and then by laying off the distance on some surface 
a standard or concrete reproduction of the unit would be con- 
structed which would answer for the family or small group* 
Just as it was necessary for the family to come to some 



THE SCIENCE OF METROLOGY 3 

understanding as to what measures would be standard for their 
household, so it was soon realized that the interests of all 
would best be subserved if a single system should be employed 
throughout the tribe, either by a gradual adoption of a common 
mean, or by having some standard imposed by authority emana- 
ting from the ruler or headmen of the tribe. This latter practice 
was the more prevalent, and, remarkable to say, has persisted 
to modern times. So late as the time of Henry I. the length of 
the English yard, according to tradition, was fixed by the length 
of the sovereign's arm, while even in the United States in nearly 
all cases the national standards of weights and measures have 
been determined by executive order rather than by legislative 
action. 

While the foregoing observations would also hold true in the 
case of weights, yet in connection with the latter there are 
certain additional matters to be considered. When the primitive 
man had advanced in civilization to a point where he looked 
beyond his immediate needs, he would doubtless own a certain 
number of slaves and domestic cattle, and his life being spent in 
an habitation or home more or less permanent, it would be 
natural for him to accumulate stores of grain and other 
substances both for his future wants and to barter for other 
commodities. Now, it seems that the earliest unit of wealth 
and basis of exchange was the ox or cow, and this soon found 
an equivalent in a certain amount of gold, a substance which, 
on account of its practically universal distribution and its 
uniform scarcity, could readily be given a fixed value in terms 
of cows or oxen. 1 This would involve some rude form of 
measurement, such as a goose-quill for the measurement of gold 
dust by capacity, or a linear measurement if the gold was in the 
form of wire or strips, and eventually the use of a primitive 
balance with the natural seeds of plants for weights. These 
seeds indisputably were the first weights, as can be proved by 
studying the habits of primitive peoples past and present, where 
such use of seeds has been and is practically universal, and this 
custom, furthermore, has survived in the grains of the Anglo- 
Saxon weights and the carat (from the Arab carob or bean) of 
the dealers in precious stones. But this early weighing was 

1 Ridgeway, Origin of Metallic Money and Weights (Cambridge, Eng., 1892). 



4 EVOLUTION OF WEIGHTS AND MEASURES 

confined to gold for purposes of trade, and to other metals, such 
as silver and copper, when they were subsequently used for 
a similar purpose; and this is amply demonstrated by early 
Egyptian records where mention is made of weighing only gold, 
silver, and copper, and lapis lazuli, until the time of the seven- 
teenth dynasty. As it was not until the seventh century B.C. 
that coined money was used, this weighing of metals was 
universal, and the use of the balance was required in practically 
all transactions, as when " Abraham weighed to Ephron the 
silver which he had named in the audience of the sons of 
Heth, four hundred shekels of silver, current money with the 
merchant " (Gen. xxiii. 16). 

It followed naturally from such universal weighing that 
certain units should be formed, made up of a certain number of 
seeds and reproduced by stone or metal standards. Though we 
may agree with Eidgeway that the , earliest weighings were 
empirical, and were carried on by seeds and natural standards 
" before ever the sages of Thebes or Chaldaea had dreamed of 
applying to metrology the results of their first gropings in 
Geometry or Astronomy," 1 yet we must admit that some sort of 
a mathematical system of units of weight was bound to come 
where weighing was so widespread. Then with the development 
of civilization, especially as regards science and commerce, it was 
but natural that these weights should be defined either by royal 
decree or by common consent, and be based upon a standard 
which, according to some metrologists, was scientifically deter- 
mined, or in the opinion of others was merely an arbitrary 
weight or weights. At all events it must be borne in mind in 
considering questions of metrology from the earliest times down 
to within the last two centuries that accuracy in weights and 
measures was neither demanded nor possible, and that attempts 
of archaeologists accurately to weigh the weights or measure the 
linear scales from old ruins, and to use small differences in 
forming their theories, are in most cases quite unwarranted. 
There is, however, indisputably a certain amount of corre- 
spondence among the weights and measures of antiquity due to 
commercial intercourse which took place both by sea and by 
caravan, and which was much greater than we would be apt to 

1 Ridgeway, p. 232. 



THE SCIENCE OF METROLOGY 5 

suspect, and this should of course receive due weight in all 
discussions of the metrology of the ancients. 

For the measure of capacity it— is— tf uito obviou s tha - t the 
earliest units were natural objects such as eggs or gourds, and that a 
basket or jar would be constructed by a certain tribe which would 
be of a convenient capacity for the purposes for which it was 
used, such as carrying grain or water. Such natural or arbitrary 
units would straightway find application and would doubtless fill 
all needs, as capacity measurements would be of the simplest 
nature possible. In—kcct, with certain primitive - peoples, as is 
now the case among some Asiatic tribes, units of measure of 
capacity were quite unknown, and it is the general tendency for 
units of capacity to come after units of weight. If we are to 
follow the theories of some metrologists we must assume that the 
ancients derived their units of capacity from a cube one of whose 
sides was the linear unit, and that the unit of weight was this, 
or a proportionate cube, which was filled with pure water. In 
fact, such a process would give a unit of area by taking a square 
whose side was a linear unit, and a cubical measure formed by a 
unit cube whose edge was a linear unitj Whether or not the 
ancients followed such a process of reasoning it is impossible to 
say, but on both sides of the question there are many arguments 
which will briefly be referred to a few pages further on. 

While the development of weights and measures is a gradual 
evolution, yet it is a complex matter to which so many influences 
have contributed that it is difficult to trace any clear course or 
logical development. Ethnic conditions, the whims and caprices 
of rulers, imposition and fraud, conquest, and methods and habits 
of thought and life, all in turn have had their effect. Never- 
theless the growth of scientific knowledge and its application, the 
influence of the market-place, as well as that of a broader 
commerce and laws and customs, in every nation have tended to 
bring together into something more or less resembling a system 
all matters connected with weighing and measuring built up on 
such units as the tribe or nation had selected for their inter- 
change of commodities and ideas. 

For the units or bases of such systems it is possible to select 
two different classes of quantities, arbitrary and natural, and to 
use them in their development. By an arbitrary quantity is 



6 EVOLUTION OF WEIGHTS AND MEASURES 

meant one that is selected without reference to its occurrence in 
any natural object or condition, but merely a certain distance, 
mass, etc., which will furnish a convenient basis both in its 
original state and by its multiples and submultiples, for the 
measurements to which it will be applied. In actual practice 
the result has been, in spite of many attempts to construct 
systems based on natural units, that the fundamental units are 
arbitrary, and where interrelated are based upon actual standards 
of length rather than distances found in nature. As examples of 
natural units might be cited the measures derived from the 
human body already mentioned, which readily connect themselves 
one with another by certain relations. Thus : 

The Digit, ----- equals 1 part 



Palm or handbreadth, 


„ 4 , 


Span, ----- 


„ 12 , 


Foot, - 


n 16 , 


Cubit, 


„ 24 , 


Step or single pace, - - - 


„ 40 , 


Double pace, - - - - 


„ 80 , 


Fathom, or distance between ex- 




tended arms, - - - 


n 96 , 



This ratio we find observed in early systems of measurement, and 
it must be borne in mind in considering them. 

As typical of early natural measures as found in the Orient, 
the following passage from the writings of Hiuen Tsiang (Yuan 
Chwang), 603-668 A.D., a Chinese traveller and author, of Ho-ran, 
written in a.d. 629 in regard to the measures of India, may be 
cited : 1 

" In point of measurements, there is first of all the yojana 
(yu-shen-na) ; this from the time of the holy kings of old has 
been regarded as a day's march for an army. The old accounts 
say it is equal to 40 li ; according to the common reckoning in 
India it is 30 li, but in the sacred book (of Buddha) the yojana 
is only 16 li. In the subdivision of distances a yojana is equal 
to eight kros'as (keu-lu-she) : a kros'a is divided into 500 bows 
(dhanus) : a bow is divided into four cubits (hastas) : a cubit is 
divided into 24 fingers (angulis): a finger is divided into 7 barley- 

1 Beal, Buddhist Records of the Western World (London, 1884), vol. i. p. 70. 



THE SCIENCE OF METROLOGY 7 

corns (yavas) : and so on to a louse (yuka), a nit (liksha), a dust 
grain, a cow's hair, a sheep's hair, a hare's down, a copper water, 1 
and so on for seven divisions, till we come to a small grain of 
dust : this is divided sevenfold till we come to an excessively 
small grain of dust (ami) : this cannot be divided further without 
arriving at nothingness, and so it is called the infinitely small 
(paramanu)." 

Leaving out of consideration the source or antiquity of these 
particular measures, they may be considered as exemplifying the 
use of natural circumstances or objects as units and their connec- 
tion into a system. However, as is mentioned in the case of the 
yojana, and the same may be found in numerous other instances 
in early measures not only in the Orient but throughout the 
civilized world, the ancient systems may have contained units 
varying in value and in their relation to other units. It may be 
said in passing that it is fair to assume that these particular 
measures were much older than would at first glance appear from 
the date of the work quoted, as India and the adjoining countries 
boasted a civilization that was nothing if not conservative, and 
traced its traditions to a remote past. 

Another example of a natural unit, according to some of the 
older authorities on metrology, including Paucton, 2 though the 
theory is now regarded as entirely erroneous, was the base of the 
Great Pyramid, which was constructed equal to the five hundredth 
part of a " degree," and was divided into 600 Ptolemaic feet or 
400 Ptolemaic cubits. Likewise in the determination of the meter 
an attempt was made to measure the ten-millionth part of a 
quadrant of a great circle of the earth, but it was subsequently 
found that the meter thus obtained did not represent this fraction 
with sufficient accuracy, and it was concluded to retain such a meter 
as an arbitrary standard and as the basis of the metric system 
rather than attempt to secure a new natural unit which might 
require subsequent changing with future scientific developments. 

Even after the metric system had been developed, Sir John 
Herschel, the British astronomer, proposed as a standard the 

1 Possibly the size of the small hole in the tamri or copper cup for the admis- 
sion of water. 

2 Paucton, M&rologie, ou Traits des Mesures, Poids et Monnoies (Paris, 1780), 
chap. i. p. 109 et seq. 



8 EVOLUTION OF WEIGHTS AND MEASURES 

length of the polar axis of the earth, as , nn A nftnn P art °f 
this quantity would give the present British inch very closely. 1 

Another class of natural units that were employed as the basis 
of systems of weights and measures consisted of the dimensions or 
weight of grains of barley or corn, a number of such grains being 
placed in a row to form such a unit as the English inch, or col- 
lected to a certain number to form by their weight an English 
pound. 

Whether the units be natural or arbitrary there must be some 
that are fundamental, and on them can be based and developed 
others as civilization, commerce, and science need additional units 
to express the magnitudes with which they are forced to deal. 
For example, in the eighteenth century it was not possible to 
make any measurements of electricity, nor indeed were such 
demanded, yet one hundred years later a complete system of 
electrical measurements was developed based on measures and 
units previously used. 2 

For fundamental units it is possible and most convenient to 
start with the unit of length and develop from it units of weight 
and capacity by taking a volume equal to that of a cube, each 
side of which is equal to the selected unit of length, and then 
filling it with water, as was done with the modern metric system, 
and is a feature claimed for the weights and measures of the 
ancient Babylonians. Similarly, units of area could be developed 
by taking a square whose side is the linear unit, and with the 
addition of a unit of time, units of velocity, acceleration, etc., 
could readily be derived. By the time that these and other 
required units were obtained, they naturally would become asso- 
ciated into a system of more or less logical relation and arrange- 
ment. In such a system there necessarily would be a number of 
different units for different classes of quantities, and these would 
be multiples and sub-multiples of each other. Such arrangements 
and systems would reflect the methods of thought of the people 
by whom they were developed. Accordingly in ancient Egypt 
and also in China we find a decimal system employed as in their 
system of numerical notation, while among the Babylonians, 
Chaldaeans, Assyrians, and the Egyptians of certain later dynasties 

1 See chapter vi., p. 164. 

2 See chapter ix. — Electrical Units. 



THE SCIENCE OF METROLOGY 9- 

the basis of division was sexagesimal, as is retained in our modern 
notation of time. The Eomans used the duodecimal system, 
where the foot, sextarius (measure of capacity), libra (pound), etc.,. 
were divided into twelve equal parts. With the Hindus there 
was the binary subdivision which was also followed by the Ger- 
manic and Teutonic peoples, and also by the Arabs, despite their 
decimal system of notation. These examples show how national 
or racial conditions affect the development of a system of weights 
and measures, and of course as the political, commercial, or intel- 
lectual influence of a nation extended it was but natural that 
with it would go its weights and measures, which, if not sup- 
planting those of other countries, at least in many cases would 
have a corrupting and disintegrating influence. 

In any attempt at a brief historical survey of the origin and 
history of weights and measures there are many matters to be taken 
into consideration which prevent a complete and comprehensive 
sketch of the subject. For over two centuries there has been much 
attention devoted to ancient metrology, and many and contra- 
dictory theories have been advanced. They are for the most 
part founded on data or hypotheses by no means satisfactory ; 
though in nearly all instances plausible cases which often show 
the greatest study and ingenuity have been made out by workers 
whose sincerity and industry cannot be questioned. In certain 
of these systems and theories the ancients are credited with a 
knowledge of mathematics, both theoretical and applied, which 
some scholars do not think at all warranted, while other systems 
have been built up on limited data, often text allusions in ancient 
literature and inscriptions, which though harmonious to a greater 
or less extent do not absolutely convince one that the harmony is 
not quite as much the result of chance as of design. 

Assuming that the parts of the body were employed by many 
ancient races as the basis of measures of length, it is desirable to 
ascertain how these were united into a system and how such a 
system spread. It is usual to credit the origin of systems of 
weights and measures to Babylon or Egypt, the systems of both 
countries showing a common source, and there being various 
remains, literary and archaeological, on which have been based 
explanations of the origin of all ancient measures. Thus the 
great pyramid of Ghizeh, dating from about 4000 B.C., by some has 



10 EVOLUTION OF WEIGHTS AND MEASURES 

been thought to have an important bearing on metrology, and has 
figured in many discussions and theories, since by its dimensions 
and inscriptions it supplies data which are susceptible of various 
interpretations. Thus Paucton and Jomard, 1 two distinguished 
metrologists of the eighteenth century, assumed that the side of the 
pyramid represented a fraction of a degree of the earth just as 
the French scientists based the meter on a fraction of the earth's 
quadrant ; while later Prof. Piazzi Smyth 2 and Lieut. C. A. L. 
Totten 3 derived the Anglo-Saxon weights and measures directly 
from its dimensions. These theories, as well as the idea that the 
great pyramids played an important part in ancient astronomy, 
have been amply controverted, and according to the opinion of 
Lieut.-Gen. Sir Chas. Warren 4 in the light of the most recent 
investigations, " The Pyramid is simply a record of the measures, 
linear, capacity, and weight, which were in use in former days." 
There is nothing astronomical about it except its orientation and 
the direction of its great gallery to a point in the northern sky. 

There were, however, other great structures in Egypt and 
Babylonia in which stone and brick 5 of regular dimensions were 
used, and even in the earliest times of which we have record it 
seems conclusive that there must have existed fairly complete 
systems of weights and measures. 

According to the Jewish tradition given in Josephus, we are 
informed in the quaint language of Dr. Arbuthnot, " that Cain 
was the first monied man, that he taught his band luxury and 
rapine, and broke the public tranquillity by introducing the use of 
weights and measures." 6 What happened in the land of Nod, 

1 Paucton, Metrologie, ou Traits des Mesures, Poids et Monnoies (Paris, 1780); 
■Jomard, Memoire sur le Systeme Me'trique des Anciens Egyptiens (Paris, 1817). 

2 C. Piazzi Smyth, Life and Work at the great Pyramid (Edinburgh, 1867) ; Our 
Inheritance in the great Pyramid (London, 1864). These works and Professor 
Smyth's theories are discussed by Dr. F. A. P. Barnard in Proceedings Am. 
Metrological Society (New York), vol. iv., 1884, pp. 197-219. 

3 Charles A. L. Totten, An Important Question in Metrology (New York, 1884). 

4 Warren, "The Ancient Standards of Measure in the East," p. 222, Palestine 
Exploration Fund Quarterly, 1899. 

5 In Babylonia square bricks were used which measure 13 inches on each edge, 
•or \ of the double cubit as given by the Gudea Scale (see p. 14). 

6 Arbuthnot, p. 1, Tables of Ancient Coins (London, 1754). 



THE SCIENCE OF METROLOGY 11 

whither Cain had wandered with his band and where he founded 
his city (Genesis iv. 16 and 17), soon must have become universal, 
for we find the dimensions of the ark as Noah was told to construct 
it given in cubits (Genesis vi. 15). 

Apart from such traditions and scriptural legends we know 
from brick tablets and other remains that weights and measures 
in some form or other flourished in Babylonia and Egypt, and 
that the systems of the two countries doubtless had a common 
origin. Although it cannot be definitely proved it is likely that 
this origin was Babylonian, and much that has been written on 
ancient metrology is based on this view. Hommel, in speaking of 
the Babylonian metrology, 1 states that from it " admittedly all 
the ancient metrological systems (that of ancient Egypt included) 
were derived." This is also the opinion of Dr. Brandis. 2 Assum- 
ing such to be the case, we are brought at once face to face with 
a great diversity of opinion on the point as to whether a well- 
developed and scientific system of weights and measures existed 
in Babylonia, from which were derived the weights and measures 
of the adjoining nations, and which, through trade and commerce, 
spread over the then civilized earth, or whether various systems 
of weights and measures came into existence separately in 
different countries and gradually, with the development of civi- 
lization and under similar conditions, spread abroad and became 
more or less assimilated. The first is the point of view of 
Boeckh 3 and the members of a distinguished school of Conti- 
nental archaeologists and metrologists, and from available 
monumental and literary remains with endless patience and 
ingenuity they have evolved theories so scientifically constructed 
that they excite admiration if they do not convince. On the 
other hand there are a number of students of archaeology who 
dispute the scientific basis on which such systems are constructed, 
and deny that requisite knowledge and mental ability for such 
scientific reasoning and construction was possessed by these early 

^ee article "Babylonia," Hastings' Dictionary of the Bible (New York, 1903), 
vol. i. p. 218. 

2 See J. Brandis, Das Mum- Maass- und Gewichlswesen in Vorderasien bis auf 
Alexander den Grossen (Berlin, 1866). 

3 Boeckh, Metrologische Untersuchungen iiber Gewichte, Miinzfmse und Masse des 
Alterthums (Berlin, 1838). 



12 EVOLUTION OF WEIGHTS AND MEASURES 

peoples. They claim that weights and measures from some 
early body measures and natural standards developed according 
to the needs of the people and depended on widely understood 
ratios and rules of exchange rather than on any scientific 
basis. 

In considering the first point of view it is necessary to assume 
that considerable mathematical and astronomical knowledge was 
possessed by the ancient Babylonians and was used by them in 
standardizing their weights and measures. In other words, from 
ancient and arbitrary measures, doubtless of the body, they 
developed such a system as was early required by the demands 
of their scientific work in astronomy and their active building 
operations. As measuring is essential to all scientific work, it is 
not to be doubted that its importance was thus early recognized, 
and in conjunction with their system of numerical notation a 
permanent system was arranged. This was also brought into 
direct relation with their astronomical' work, which was by no 
means inconsiderable for these early times. In the course of 
their observations it was ascertained that at the equinox the 
apparent diameter of the sun on the horizon was ^-J-^ of the half 
circle. Furthermore, by using a water clock, where water was 
allowed to flow through a small orifice from one jar into another, it 
was found that the amount received in the twelve hours between 
sunrise and sunset was 360 times as much as when the sun was 
traversing a distance equal to its own diameter or two minutes of 
time. 1 This afforded an accurate method of measuring time, and 
formed the foundation of the sexagesimal system which was the 
underlying principle of all Babylonian metrology and harmonized 
perfectly with their system of numeration. This idea naturally 
involved the division of the circle into 360 degrees, or rather 720 
parts, which has continued to the present day, and the important 
geometrical fact that the radius is equal the chord of one-sixth 
the circumference was also well known at this time. 2 

1 L. Ideler, " Ueber die Sternkunde der Chaldaeer," Abhandl. der k. A had. 
Wissenschaft in Berlin, 1814-1815, p. 214. Referring to Cleomedes Cyclom. 
(On the Circular Theory of the Heavenly Bodies), 1. 11. p. 75 ed. Balfor ; 
Proclus Hypotyp. p. 41 (ed. Basil. 1540-4) ; Pappus, especially in his Com- 
mentary on the Fifth Book of the Almagest of Ptolemy. 

2 Hommel, article "Babylonia," Hastings' Dictionary of the Bible (New York, 
1903), vol. i. p. 219. 



THE SCIENCE OF METROLOGY 13 

By some authorities it was believed that the water jar referred 
to above was also used as a measure of capacity, and that it was 
divided on a duodecimal basis corresponding to the hour division. 
It was then assumed that from a cube equal to such a volume 
the unit of length was derived by taking the length of one of its 
edges, which was the Babylonian foot, and bore a natural relation 
to the cubit. This unit of volume when filled with water gave 
the Babylonian talent, from which other units of the same name 
were derived. This theory, however, which was supported for 
many years, has been abandoned, and it is believed that the unit 
of weight was derived from the unit of length, just as is done in 
the modern metric system. 

The relation of numbers and linear distances in Babylonian 
measures is best derived from a study of the Senkereh Tablet, 
which dates back to about 2500 B.C., and was discovered in 1850 
in a small Arab village on the site of the ancient city of Larsam 
or Larsa. It is now in the British Museum, and affords con- 
siderable information as to the Babylonian measures and the 
methods of computation. It is a clay tablet, on one side of 
which are the fractions and multiples of the ell or cubit, and on 
the other are the squares and cubes of the cubit from 1 to 40. 1 
This tablet has received the attention of a number of scholars, 
including the late Professor Eawlinson, and the sexagesimal 
character of the measures has been clearly demonstrated. In 
connection with the scale of Gudea, to be described a few lines 
below, it has been examined by the Rev. W. Shaw-Caldecott, who 
concludes that " The breadth of the hand-palm conventionalized 
was the fundamental of all length measures," and " That there 
were three ell (cubit) lengths in simultaneous use, each probably 
in a different kind of trade like our own Troy and avoirdupois 
weights." 2 

1 Hommel, article " Babylonia," Hastings' Dictionary of the Bible (New York, 
1903), vol. i. p. 218. 

2 Shaw-Caldecott, "Linear Measures of Babylonia about 2500," p. 263, Journal 
Royal Asiatic Society, 1903, London. In this article the characters on the 
tablet are reproduced. See also R. Lepsius, " Der Baby lonisch- Assy rischen 
Langenmasse nach der Tafel von Senkereh," in the Abhandlungen der 
Kbniglichen Akadernie der Wissenschaften %u Berlin, 1877. With this article 
is printed a photographic reproduction of the tablet, together with a recon- 
struction. 



14 EVOLUTION OF WEIGHTS AND MEASURES 

Accordingly from the tablet Mr. Shaw-Caldecott derives the 
following units and proportions : 

Line - - = y^ of a palm. 

Sossus - - - =-gL 

Twentieth of a palm - = -^ „ 

Twelfth of a palm - = t? » 

Third of a palm, or digit = ^ „ 

Palm. 

Small ell (cubit) - =3 palms. 

Medium ell (cubit) - = 4 palms. 

Large ell (cubit) - =5 palms. 

Small reed - = 4 small ells (cubits). 

Medium reed - = 6 medium ells (cubits). 

Large reed - = 6 large ells (cubits). 

While the Senkereh Tablet establishes the ratios between the 
various units yet it does not afford any' information as to their 
absolute value, and for this recourse is had to a tablet forming 
part of a statue discovered in 1881 at Telloh in southern 
Babylonia, not far from Senkereh, by M. E. de Sarzec, and 
now in the Louvre. 1 It dates from about the same period as 
the Senkereh Tablet, and represents King Gudea in a position 
of prayer, and holding on his knees a slab of stone on which 
is engraved the ground plan of a palace, a graving tool, and a 
double line, the latter being cut near the outer edge and being 
crossed by a number of indentations or cuts. This unmistakably 
is a scale, and, furthermore, it is the oldest scale that has been 
discovered up to the present time. By assuming that it is 
the same size as the scale of linear measures then in use, and 
by applying the proportions obtained from the Senkereh Tablet, 
it is possible to obtain the lengths of the various units in terms 
of modern equivalents, preserving the decimal and duodecimal 
division characteristic of the Babylonian arithmetical system. 
Thus we have the handbreadth or palm equal to 99-99*6 mm. 
(3*9-4 , l inches), and the cubit composed of five handbreadths 

1 E. de Sarzec, De'couvertes en Chaldee, 1884-1889, PI. 15. See also Shaw- 
Caldecott, loc. cit. See also Toy, " The Book of the Prophet Ezekiel " (Part 12, 
Sacred Books of the Old Testament, "Polychrome Bible") (New York, 1889),. 
Notes, pp. 179-180 for illustrations and description. 



THE SCIENCE OF METROLOGY 15 

equal to 495 mm. (19*483 inches), and also in early and wide- 
spread use a double cubit twice this length or 990 mm. (38*976 
inches). This latter unit is of interest on account of its close 
approximation to the modern meter of 1000 mm., and also on 
account of the fact, first discovered by Lehmann, that it is almost 
exactly the length of the second's pendulum for the latitude of 
Babylon (31 degrees north, at which point the theoretical length 
of a second's pendulum would be 992*35 mm.). Consequently 
he argues that the theory of the pendulum must have been 
known to the early Babylonians, who doubtless derived it from 
the plumb-line, which must have been employed in their 
building operations. 1 This fact, however, cannot be regarded 
as more than a mere coincidence, and while it is most 
interesting it is not considered possible that such an important 
physical principle should have been known at so early a day 
and then allowed to lapse from human knowledge until the 
time of Galileo. 

Multiplying the great cubit by 6 the " reed " was obtained, 
and by taking 12 great cubits the gar. To form the ush or 
stadion 60 gar were required, and 30 ush made a parasang or 
kasbu, which was equivalent to about 21 kilometers. These 
longer linear measures are again connected with the measure 
of time, as 360 great cubits represented the distance an average 
walker could accomplish in four minutes, while the great kasbu 
of 21,600 cubits was the distance traversed during a night watch 
of four hours or J of a day, and the small kasbu would be one 
half of this distance. 

Measures of area constructed by squaring the linear measures 
are also claimed for the Babylonians, and here again the sexa- 
gesimal ratio was preserved ; thus 180 she made a gin, which was 
possibly equal to a square cubit. A " garden " (sar) was com- 
posed of 60 gin, and 1800 gardens formed a "field" (gan). But 
the Babylonians, in common with other Asiatic nations, also 
employed for measuring land the amount of seed required to 

1 Lehmann, p. 89, " Ueber das babylonische metrische System und dessen 
Verbreitung, " Verh. der Physikalischen Gesellschaft zu Berlin (Berlin, 1890), vol. 
viii. pp. 81-101 ; also in abstract, pp. 167-168, vol. lxi., Nature (London, 1889). 
In this connection a paper by the same author, " Alt-babylonisches Maass und 
Gewicht und deren Wanderung," Zeitschriflfur Ethnologie (Berlin, 1889), pp. 245- 
328, may also be consulted with profit. 



16 EVOLUTION OF WEIGHTS AND MEASURES 

sow a field, and statements based on this idea are found in many 
old Assyrian documents. 1 

The Babylonian capacity measures started with a cube whose 
edge was a handbreadth in length (99-99*6 mm.), and which 
when filled with water gave the unit of weight, the great mina, 
which, occupying as it does almost the volume of a cubic deci- 
meter, would correspond quite closely with the modern kilogram. 
Such a capacity measure was known as the ka, and was nearly 
the equivalent of the modern liter. As multiples of the ka 
there was the gur, which was composed of either 360 or 300 
of the smaller units, there being not only two such gurs but 
a third divided into 180 parts and based on a double ka, from 
which the Hebrews probably obtained their kor, which they 
divided into 180 kab. Likewise in the subdivision of the 
Babylonian measures there was the gin or ^ of a ka, which 
in the Hebrew system was paralleled by the hin. 

The relation between the capacity and' weight we have already 
seen in the case of the great mina, which weighing, as it did, 
between 982*4 and 985*8 grams giy^s a noticeably close approxi- 
mation to the modern kilogram. \This great or heavy mina was 
composed of 60 shekels, each of 3(T0 she or grains of corn, thus 
combining in a system of weights two classes of natural units. 
The greater weight was the talent composed of 60 minas. \ Such 
a system would have been simplicity itself, were it notmr the 
fact that several systems of weights, just as of linear measures, 
are found employed at the same time. There was a light mina 
which weighed one half of the heavy mina, and in fact 
whole light and heavy systems standing to each other in the 
ratio of 1 : 2 are believed to have existed, of which representative 
weights have been found. Furthermore, as gold and silver, 
whose values were in the ratio of 40 : 3, were used as currency, 
other systems designed to accommodate both weight and value 
arose, and there was a mina of gold which was composed of 
50 units, each a shekel or g 1 ^ of the weight mina. Then there 
was a silver mina which weighed about ^ more than the Baby- 
lonian mina of weight, while there was a Phoenician mina which 
was also divided into 50 units, which made the whole equal to 
J$$ of the original weight mina. 

*C. H. W. Johns, Assyrian Deeds and Documents (London, 1902), vol. ii. 
pp. 219-220. 



THE SCIENCE OF METROLOGY 17 

The subject of Babylonian units of weight is one of consider- 
able complexity on account of the fact that weight and currency 
had so intimate a relation and that gold and silver were both 
standards. Furthermore, there was doubtless legislation stan- 
dardizing certain other weights so that discrepancies would be 
found on that score. 

Having considered such a carefully erected structure we must 
now discuss briefly the position of those that would demolish 
utterly any such scientific arrangement and basis for ancient 
weights and measures, and more particularly any connection 
between the two. We are called upon to proceed further along 
the lines indicated in the beginning of this chapter, and to 
observe that the use of weights and measures accompanied the 
gradual development of civilization, and that exactness in either 
the determination of units of measure or in the preservation of 
standards was no more characteristic of the twentieth or thirtieth 
century B.C. than it was of the second or third. Although the early 
Babylonians may have known how to divide time on a sexa- 
gesimal basis and to observe eclipses, yet so simple a mathematical 
process as obtaining area by multiplying length and breadth 
together seems to have been unknown according to a study of 
their literary remains, since for the measurements of land areas 
the unit was not a square, but a strip of uniform width. 1 
Furthermore, the extensive use of the amount of seed required 
superficial measures. The most strenuous objection has been 
made to any systematic relation and connection between weights 
and measures, and this feeling on the part of continental scholars 
is considered due to their intimate knowledge and use of the 
metric system, which acquired by them so readily would doubtless 
suggest the possibility of the employment of its fundamental 
features by the ancients. Why several thousand years should 
intervene before the mind of man would return to such devices, 
it is difficult if not impossible to explain, and like many other 
phenomena considered now so simple, it is most natural to 
assume that it was known to the ancients, yet at the same time 
it is impossible to prove it. Thus any such relations must be 
entirely hypothetical, and the only arguments to be advanced in 

1 C. H. W. Johns, Assyrian Deeds and Documents (London, 1902), vol. ii. 
pp. 219-220. 

B 



18 EVOLUTION OF WEIGHTS AND MEASURES 

their support must be founded on circumstances which are pro- 
bably mere coincidences, and doubtless most delusive. Professor 
Flinders Petrie, in speaking of this subject, says : 1 " All that 
can be said therefore to the many theories connecting weights 
and measures is that they are possible, but our knowledge at 
present does not admit of proving or disproving their exactitude.'* 
Though this was written some years ago, nevertheless it is fair 
to say that there has been no discovery or research that would 
warrant any different expression from one holding Mr. Flinders 
Petrie's views. According to another leading authority, the 
Kev. C. H. W. Johns, who has carefully examined many literary 
remains of the old Babylonians, there is not afforded by these 
documents any ground for believing in any connection between 
Babylonian measures of length and weight, while to him 
Lehmann's idea of the double cubit derived from the second's 
pendulum seems quite ridiculous. According to Bidgeway, 2 
considering the Hindus as an ancient people of culture, with 
whose literature we have some acquaintance, we find that 
" though they were clever mathematicians, yet they fixed their 
standards of weights by natural seeds in the good old primi- 
tive fashion, and did not make the slightest attempt to find 
a mathematical basis for their metrological work." 

In short, from this point of view the situation for the 
Babylonians, and indeed for any other nation whose claim 
for a similar priority should be advanced, may be summarized 
as follows : The Babylonians in common with other nations 
from body measures and seeds of grain or other plants developed 
such systems of measurements as sufficed for their wants; their 
standards were arbitrary and changing, but since they were 
the leading people of this part of the world as regards culture, 
their measures were impressed on their neighbors, and especially 
on the Phoenicians, by whom as the chief traders of this period 
of antiquity they were spread abroad. There is no reason to 
believe that the weights were preserved in any kind of purity, 
nor is there any reason to see why this should have occurred, 
and when we consider the variation in weights and measures 

a W. M. Flinders Petrie, article "Weights and Measures," Encyclopaedia 
firitannica, 9th ed. vol. xxiv. p. 482. 

2 Ridgeway, Origin of Metallic Coinage and Weights, Cambridge, 1892, p. 178. 



THE SCIENCE OF METROLOGY 19 

during more recent centuries with their scientific men and 
methods, their mints and their standards, not to mention 
government regulation, as exampled, say, in Great Britain, it 
is not natural to believe that those ancient units could have 
been fixed to any basis with scientific exactness. Such mere 
coincidences as that a cubic foot of water weighs 1000 ounces, 
and that a British imperial gallon of water at temperature of 
maximum density weighs ten pounds, if put back into the past 
would form a far better basis upon which to form decimal 
and other systems than many of the facts that have been 
employed by scientific metrologists. 1 

As an argument of this kind depends largely upon quoting 
authorities, and dealing in detail with apparent and actual 
inconsistencies, it is manifestly impossible to do justice to it in 
these few paragraphs ; but reference to Johns and Eidgeway 
in the volumes quoted will amply repay the student interested 
in this phase of archaeology and metrology, as by both authors 
the^i-ase is stated most ably and critically. 

{ The Jews, unlike their neighbors in Babylonia and Assyria, 
\iere not a people of scientific tastes, and their weights and 
measures were derived largely from the nations whose territory 
they adjoined, consequently it is not natural to expect much 
uniformity of weights and measures among them. Indeed, there 
are indications that there were at a single time among the 
Israelites as many as three different and distinct units of weight, 
Babylonian, Syrian, and Phoenician, and in each case there was 
both a heavy and a light system standing towards each other as 
two to one. Undeniably there were Egyptian influences on the 
Hebrew weights and measures, but far more is due to Babylon, 
as the civilization of that country was predominant in Canaan 
up to the fifteenth century B.C. according to records in the 
Tel-el-Amarna correspondence, and this predominance carried 
with it undoubtedly the Babylonian weights and measures. By 
the eighth century B.C., however, the Israelites had a legal system 
of weights and measures, put long before this they were 
accustomed to their use, "as when Abraham bought the field of 
Ephron he "weighed to Ephron the silver" (Gen. xxiii. 16). 

1 Flinders Petrie, article "Weights and Measures," Encyclopaedia Britannica, 
9th ed. vol. xxiv. p. 482. 



20 EVOLUTION OF WEIGHTS AND MEASURES 

In fact, the Israelites became so accustomed to the use of the 
balance and of measures that they began to employ false weights 
and wrong measures, with the result that not once but many 
times 1 their prophets and teachers are forced to emphasize honest 
dealing in matters of measurements and the weighings of daily 
life. The chief unit of length of the Hebrews was the cubit, ^ 
and with it were employed the usual body measures, such as 
finger breadths or digits, palms, spans, and fathoms and reeds. 
For these measures we have practically no data for determining 
their equivalents, and Professor A. E. S. Kennedy expresses the 
opinion " that reliable data for the exact evaluation of the 
Hebrew cubit do not exist." 2 In fact, values from 16 to 25*2 
inches have been proposed for this unit, and by many it is 
believed that there were two cubits, one the " cubit of man " 
of six handbreadths, and also " a cubit and an handbreadth " or 
seven handbreadths, which was used in the construction of the 
temple (Ezekiel xl. 5). This would correspond to similar cubits 
of the Egyptians, and there is reason for believing that the 
weights and measures of the two nations were intimately con- 
nected, if not quite similar at the time of the Exodus, but like 
many other points in metrology it is not possible to bring 
forward absolute proof. For the measurement of area the 
Hebrews employed generally the amount of seed required to 
sow the land, or the amount of ground that could be ploughed 
by a yoke of oxen, the latter unit being the zemed, which in the 
Old Testament is translated by acre. 3 This is thought to be an 
area equivalent to the Egyptian aroura, which was a square 100 
cubits on each side. 

The capacity measures of the Hebrews for both wet and dry 
commodities were arranged upon a systematic basis which has in 
not a few cases been obscured by imperfect translation in the 
, English Bible.TThe relation of the different measures is expressly 
stated in Ezekiel (xlv. 11 et seq.), where we learn that the ephah 
and bath were one and the same unit, the former being used for 

1 Leviticus xix. 35 et seq. Deuteronomy xx v. 13-16. Ezekiel xlv. 9-14. Amos 
viii. 5. Hosea xii. 7. Micah vi. 10. Proverbs xi. 1, xvi. 11, xx. 10. 

2 Kennedy, article "Weights and Measures," Hastings' Dictionary of the Bible 
(New York, 1903), vol. v. p. 907. 

3 1 Samuel xiv. 14 and Isaiah v. 10. 



vy 



THE SCIENCE OF METROLOGY 21 

dry measure and the latter for liquids. This unit was one-tenth 
of the homer, a dry measure, and its liquid equivalent was the 
kor. One-third of the ephah gave the seah, which was divided in 
half and formed a dry measure equivalent to the liquid hin. 
One-tenth of the ephah gave a dry measure known as the oner, 
while the next smaller unit, used for both dry and liquid 
measure, was the kab, which was T -|^ of the homer or kor. * The 
fourth of the kdb gave the log, the smallest liquid measure. I By 
taking the ephah-bath as equal to 36*92 liters, or 65 (British) 
imperial pints, a value derived from a study of Greek and 
Hebrew literature, the modern equivalents can be approximated, 
though this equivalent is variously stated from 3 6 '3 7 liters to 
40*5 liters. 

In considering the Hebrew units of weight we must bear in 
mind what has been stated about the Babylonian units and their 
fundamental proportions, where the talent was equal to 60 minas, 
each composed of 60 shekels, or in the case of the gold mina of 
50 shekels. There was the heavy and the light systems, stand- 
ing in the ratio of 2:1, and, as we have said above, systems 
based on Babylonian, Syrian, and Phoenician standards. Here 
of course it must be remembered that the units of weight were 
also units of currency, and to this fact is dudn no small degree 
much of the variation in the standards. The shekel was for the 
Hebrews the principal unit, and in the three different systems 
mentioned from literary evidence and actual weights the follow- 
ing values have been assigned : 

Babylonian unit, - - - 252 grains. 

Syrian unit, - - - -320,, 

Phoenician unit, - - 224 „ 

The Hebrews' weights without doubt were not preserved in 
anything like purity, and besides showing the effect of their 
Babylonian origin, in later times there are evidences of Persian, 
Greek, and Boman influences, so that our only means of iden- 
tifying them consists largely in the connections established by 
the later Hebrew and the Greek and Latin authors. The 
weights of the Bible have received considerable study, and the 
only warrant for dismissing the subject here so summarily is 
that each separate phase demands detailed treatment and a 



i 



22 EVOLUTION OF WEIGHTS AND MEASURES 

critical examination of authorities. Furthermore, the absence 
of positive conclusions which can be stated definitely relieves 
us of the necessity for fuller discussion in this brief historical 
skatch- 1 

In the study of Egyptian measures there is considerable data * 
for the metrologist, which is in the form of literary remains, such 
as papyri, monuments of one form or other from the Great Pyra- 
mid of Ghizeh to wall carvings, and actual wooden and stone 
scales. In the main there is little variation from the measures 
of Babylonia and many points of similarity both in the weights 
and measures and in the etymology of the words expressing them 
are seen, which indicate a common origin for the weights and 
measures of both nations, and aid in substantiating any theory 
based on the assumption that there was a definite parent systeml 
There is a correspondence between the royal or building ciiDit of 
seven palms and 28 digits which has been constructed from the 
measurements of temples and other . buildings in Egypt and 
the so-called sacred or building cubit of the Babylonians. Actual 
representatives of the former have been found in the nilometer 
cubit of Elephantis, and the wooden scale of Amenoemopht from 
the necropolis at Memphis, and other scales both wooden and 
stone. 2 A mean value obtained from actual scales and measure- 
ment gives for the modern equivalent of the cubit 525 mm. 
or 20-63 inches. 

With this royal cubit was also used a natural or common 
(short) cubit which was of the length of six palms, and cor- 
responded to the Greek cubit. The Egyptians employed the 
various subdivisions on the basis of the body measures, but they 
do not seem to have used either the foot or the fathom. All of 
these can be found expressed in their hieroglyphics, and are found 
in many of the ancient papyri. For long measure there was the 

1 For further information and detailed references the following authorities may 
be consulted : Kennedy, article " Weights and Measures," in Hastings' Dic- 
tionary of the Bible (New York, 1902), vol. v. p. 901 et seq. ; G. F. Hill, article 
" Weights and Measures," in Encyclopaedia Biblica (New York, 1903), vol. iv. 
p. 5292 et seq. These and allied articles contain full and detailed bibliography. 
See also C. R. Conder, "Hebrew Weights and Measures," Palestine Exploration 
Fund Quarterly Statement, 1902. 

2 For description and illustrations, see Lepsius, Ueber die alt-aegyptische Elle 
und ihre EintheUung (Berlin, 1865). 



THE SCIENCE OF METROLOGY 23 

khet, which was equal to 100 cubits, and was represented by a 
hieroglyphic of a coil of cord, as undoubtedly a line and reel were 
used for such measurements, just as Ezekiel (xl. 3) speaks of a 
"" flaxen line" and "measuring rod" being used in measuring the new 
temple, and Jeremiah (xxxi. 32) mentions the use of the " measur- 
ing line" in surveying land. For very long distances the Egyptians 
had a measure, the ater, equal to from 30 to 60 or more stades 
and known to the Greeks as a schoenus, but it is expressly stated 
by Strabo that it varied in different parts of the country. It is. 
of some importance, however, as it figures in geographical descrip- 
tions of Egypt, and has been actually found marked on the 
Memphis-Faium road. 1 The Egyptians had a series of square 
measures with a chief unit in the set equal to the Greek aroura 
and comprising a square, a khet, or 100 royal cubits on each side, 
the latter unit forming the basis of land measurement. For 
capacity the principal measure was the hekt, which was equal to 
-g 1 ^- of the cubit cubed, while for corn there was employed the 
khar ("sack") of 20 hekt until superseded by the sack of 16 hekt 
or the Greek medimnus, at or before the XVIII. dynasty. After U 
the Macedonian conquest the latter measure was halved to form 
the artdba, doubtless to conform with a measure introduced from 
Persia. Then there was the henu or ^ of the hekt, used both 
for solids and liquids, as well as numerous other measures. 
According to Griffiths, whom we have followed in this description 
of Egyptian weights and measures, 2 the Egyptian measures were 
not derived from a cubit or fraction of a cubit cubed, but it is 
probable that the cubic idea was introduced a considerable time 
after the measures had been quite definitely fixed by custom. 

In striking contrast to the many allusions to measures that are 
found in the early papyri there is a lack of information as regards 
weights. That weights existed and were used is known from a 
large number of weights that have been discovered, and from the 

blinders Petrie in Encyclopaedia Britannica, 9th ed. vol. xxiv., article 
"Weights and Measures," p. 483. Also id., Season in Egypt, pi. xxvi. (London, 
1888). 

2 F. L. Griffiths, "Notes on Egyptian Weights and Measures," Proceedings 
Society of Biblical Archaeology (London), vol. xiv. p. 403 et seq., 1892. In this 
paper will be found the various hieroglyphics and a full explanation of their use. 
See also a continuation of this paper by the same author in same Proceedings, 
vol. xv. p. 301, 1893. 



24 EVOLUTION OF WEIGHTS AND MEASURES 

fact that balances are shown in the decorations of the tombs of 
the V., XI., XII., and XVIII. dynasties. In fact, the earliest 
known weight is inscribed with the cartouche of Chufu (IV. 
dynasty), the builder of the Great Pyramid at Ghizeh, whose 
date was approximately 4000 B.C. 

The use of the balance in the earliest times was probably con- 
fined to exchange of gold and silver, and it doubtless was 
invented for this purpose. But one reference is found to weights 
before the XVII. dynasty, and only gold, silver, copper, and lapis 
lazuli were weighed even at that time, as no mention of weight is 
made in the so-called medical papyri, where it would be natural 
to find such an allusion were weights in current use. Their 
application increased slowly, and by the time of the Ptolemies, 
incense, honey, and drugs, as well as metals and precious stones, 
were weighed. About the time of the XVII. dynasty the 
deben or uten, a weight of 1400-1500 grains, and its tenth part, 
the kiti (also called Jcat) are found to, be the only recognized 
units of weight in the various documents, but there have been 
found a wide variety of actual weights, which it is quite impos- 
sible to identify either with any system or among themselves, 
and which serve to embarrass the investigator. 1 

Later the units of weight in widespread use were the talent, 
the mina, and the shekel, as in other ancient nations, but con- 
siderable diversity is shown, though in general plan much the 
same division was followed as for the weights of the Babylonians 
and Hebrews already described. By some authorities the basis 
of the Egyptian unit of weight is considered to be a cubic 
volume (the cubic foot or cubit) of water, but at all events there 
were also various foreign influences, such as Greek and Asiatic 
units of weight, which produced a certain amount of confusion, 
and prevented any universal and single system. Under Ptolemy 
Lagos (d. 283 B.C.), however, certain reforms of weights and 
measures were effected that resulted in perpetuating the old 
Egyptian system, and the talent weights thus defined were 
known subsequently as the Alexandrian talents. These were 

1 Flinders Petrie, article "Weights and Measures," Encyclopaedia Britannica, 
9th ed. vol. xxiv. p. 486. Griffiths, loc. cit. p. 435, and vol. xv. p. 307. A. E. 
Weigall, "Some Egyptian Weights in Professor Petrie's Collection," Proceedings 
Society Biblical Archaeology (London), vol. xxiii. p. 378, 1901. 



THE SCIENCE OF METROLOGY 25 

of two classes, each of which were divided into 60 minas of 
50 shekels or 100 didrachms each, but the greater Alexandrian 
talent of copper or brass weighed just twice as much as the 
smaller or lesser Alexandrian talent of silver. The former was 
divided into 125 pounds by the Eomans when they occupied 
Egypt, while the mina derived from the lesser talent was 
divided into 12 ounces (unciae), and weighing as it did 5460' 
grains, it became the predecessor of the series of European 
pounds of which the Troy pound is a type. From one of these 
ounces, if we may believe a Syrian authority, Anania de 
Schiraz, who wrote in the sixth century, by taking the T \± 
part the carats or diamond weight was originally formed. 1 

In Greece the fundamental unit of length was the foot, and 
while we find the cubit, yet it is the foot that plays the principal 
part. The same unit, namely, the Olympian foot, was found 
throughout Greece, though, of course, there was necessarily 
considerable divergence from any one value at different times 
and different places. A clue to the actual length, however, is 
found in the ruins of the Parthenon, where the main hall of 
the Temple of Athena is called, according to Plutarch, 2 Heka- 
tompedos (one hundred feet), and measurements show that it 
was 100 Attic feet in breadth by 225 in length, these numbers 
being derived from the ratio of the breadth to the length, and 
giving an Attic foot equal to '30828 meter or 12 '1375 inches. 
One hundred times the foot gave the plethron, which was 
squared and used as a measure of area. The Greek cubit, or 
1-J- times the foot, closely resembles the natural cubit rather 
than the sacred or building cubit of the Babylonians and Egyp- 
tians, and four of them made the orguia or fathom, that is the 
distance between the tips of the fingers when the arms were 
extended. This multiplied by 100 gave the stadion, originally 
the distance that a strong man could run without stopping for 
breath, and then fixed as the length of the Olympian stadion or 
athletic track, which was 600 feet in length. 3 This stadion was 

1 H. W. Chisholm, The Art of Weighing and Measuring (London, 1877), p. 42. 

2 Plutarch, Pericles, 13. 

3 Hultsch, Griechische und Rbmische Metrologie, 2nd ed. (Berlin, 1882), p. 33. 
This will be found a standard authority in classical measures, and will give 
text references to all authorities. On it are based most of the statements in 
the pages devoted to Greek and Roman metrology. 



26 EVOLUTION OF WEIGHTS AND MEASURES 

about one eighth of the Koman mile, and this ratio, as well as 8-^, 
is used by Strabo and Polybius. 

It was most natural that the measures of Greece should pass to 
Home, and we find between the two a close connection. The 
principle of subdivision was duodecimal, and we find the Greek 
foot introduced as a unit of length. It, as well as the as, or unit 
of weight, was divided into twelve unciae, whence our English 
words inch and ounce. Among the other measures of length 
employed by the Eomans was the palmipes, or foot and hand- 
breadth ; and the cubitus (cubit), or, as it was also known, the 
ulna, from which is derived the French word aulne and the 
English ell. The passus or unit of itinerary measure was 
equivalent to 5 Eoman feet, and when multiplied by 1000 gave 
the millia passuum, from which was derived the mile as subse- 
quently used in Britain and elsewhere. The passus was a double 
step or gradus, and was the distance covered from the time when 
one foot was taken from the ground until it was placed down 
again. For architects and surveyors there was a unit ten feet in 
length known as a pertica or decempeda, and the square of this 
distance gave the unit of area employed in surveying, twelve 
times which gave the actus or distance that a plow would 
encompass in a single course, while the actus multiplied by two 
would give the jugerum or Eoman acre (*6229 English acre). 

Perhaps the foot is the most important of the Eoman measures, 
as it not only extended throughout Europe as a fundamental 
unit, but in some form it has survived almost everywhere until 
supplanted by the meter. True, there were marked variations, 
and the standards employed were most arbitrary, but the supre- 
macy of the foot as the unit of length was maintained in Europe 
until the nineteenth century. The connection of the Eoman 
foot to that of Greece has already been shown, but attention 
should be called to the fact that it gradually become shorter, 
and in the time of Pliny it bore the relation to the Greek foot 
of 25 : 24. There was also a foot of Drusus which was used 
outside of Italy for measuring land, and became permanent in 
the countries along the Ehine and Lower Germany. This foot 
contained 13-|- Eoman inches or 13*1058 English inches, 332*6 mm., 
and doubtless came to Europe in some way from Asia Minor. 
It is worthy of note that, besides persisting in the Ehine 



THE SCIENCE OF METROLOGY 27 

countries, it was adopted by the Belgic tribes, and by them 
introduced into Britain, where it endured, as will subsequently 
be shown, until the fifteenth century. 1 

Greece originally had as its standard of weight the heavier 
Babylonian talent, or, speaking more exactly, this was in use 
in Aegina, and thence extended into the Spartan States and to 
Corinth, whose inhabitants being actively engaged in commerce 
did much to spread its use. This talent was considered equal 
to the weight of a cube of water whose edge was an Olympic 
cubit, or 1^- times a Greek or Olympic foot. By diminishing 
the Babylonian talent one-sixth, was obtained the Euboic talent 
which nourished in Greece and especially in Athens before the 
time of Solon. This latter ruler in order to release the people 
from the usurers established by decree (c. 592 B.C.) a smaller 
talent which amounted to § of the Babylonian talent, and 
weights were derived from it which alone were lawful in Athens. 
The close connection between money and weight then existing 
must be appreciated, and we find in ancient writings that the 
material of the talent when used as currency is mentioned, as a 
talent of silver (the standard) or a talent of gold. The Athenian 
talent was divided into 60 minas, each composed of 100 drachmas 
containing each 6 obols or 48 ehalkus. There was a half mina 
and a double drachma or didrachm, and also a gramma equal 
to one third of a drachma or 2 obols, one third of which was a 
lupine whose half in turn was a siliqua. The unit of liquid 
measure in the Athenian system was the metretes (3 9 '39 liters), 
which was subdivided into 12 chus or amphora, and so on on a 
duodecimal basis. The metretes was -^ of a Babylonian cubic 
foot. J The Attic unit of dry measure was the medimnos, which 
corresponded to 1 -J- metretes or in modern equivalents to 52*53 -j 
liters. It was divided into six hekteus or modius, each of which v ' 
was composed of two hemiekton or eight choinix. The choinix 
was made up of two xestes, and two kotule formed a xestes. 

The Roman unit of weight was the libra, or pound which 
corresponded in money to the as, and was divided on the 
duodecimal basis characteristic of the Romans. Thus the pound 
(327*45 grams) was composed of 12 unciae, each of 4 sicilii, each 
■of 2 drachmas, each of 33wri_pula, each of 2 obola, and each of 

J See p. 31. 




r~ 



28 EVOLUTION OF WEIGHTS AND MEASURES 

3 siliquae, these names surviving in modern apothecaries' 
measure. Its connection by water with the amphora and thus 
with the Greek measures will be given below, and may be 
further explained by stating that while the Attic talent of 
Solon was divided into 60 minas, the same weight of water 
contained in the amphora was divided into 80 pounds, thus- 
making 3 Attic minas equal to 4 Eoman pounds. Originally 
the Eoman pound was established on the basis of the Aeginetan 
weight, and was equal to T ^ of the Aeginetan half mina, 
this basis being used in the Eoman coinage. 

As a measure of liquid capacity the Eomans had the amphora, 
which was equal to a cubic footfand contained 80 librae (pounds) 
of water. This was divided into 8 congii, each composed of 
6 sextarii with further subdivisions. For dry measure one third 
of the amphora or modius served as the unit, and was made up 
of 16 sextarii. These measures harmonized with those of Greece, 
inasmuch as the amphora was two thirds of the JUtic metre tes, 
and the modius was one sixth of the medimnos.| In passing, 
mention might be made of the fact that a foot derived theo- 
retically from the amphora would not give a cube equal to 
the amphora, but differing by as much as a twentieth part 
and in some cases by as much as one twelfth, depending, of 
course, upon the cubical contents of surviving examples, of which 
there are several. 1 

The Eoman weights, measures, and coinage, by virtue of the 
conquests and influence of the empire, found their way all over 
Western Asia and Europe ; and with the decline of the imperial 
power formed the foundation for local systems, but with the lack 
of interest in science which soon began to characterize the age 
and the general decline of culture, weights and measures were no 
longer maintained in conformity with any system or with any 
due regard to primary standards. Consequently there was a 
distinct corruption of measures, and until the revival of experi- 
mental science in the middleages but little attention was- 
paid to the subject. Indeed, /all standards and systems were 
practically neglected, and by the sixteenth century there was 
virtually a return to the body measures throughout Europe. 

1 Flinders Petrie, article ' ' Weights and Measures," Encyclopaedia Britannica, 
9th ed. vol. xxiv. p. 486. 



THE SCIENCE OF METROLOGY 29 

__^- Bre yious to the beginnings of European scientific investiga - 
tion^ there was, however, important work done by the Arabs, and 
as measurement is an essential of all experimental science, it was 
natural that they should have devoted much attention to the 
subject, and included the discussion of measures in their writings. 
It i s quite certain that the measures of the Arabs owe their 
origin to the old Babylonian measures, especially as their 
philosophers were careful students of antiquity ; but it is evident 
that while the measures were maintained they lost sight of the 
underlying principles, and when it became necessary to define 
them or refer them to standards, entirely new methods were 
employed. In these an attempt was made to secure a natural 
basis, and such fundamental units as a degree of the earth, hairs 
of horses or mules, and grains of barley were used. Then, too, 
the contact between the Arabs and the Egyptians had its effect, 
and old and new measures were blended so that the absolute 
value of the weights and measures is quite impossible to 
determine, though by references to ancient authorities relative 
values can be obtained in many cases. 2 It was from the Arabs 
that the Yusdruman pound of Charlemagne, for so many years 
the standard of France, was obtained, and the idea of using 
barleycorns for the measure of length, as was done subsequently 
in England by statute. 

In this connection mention might be made of a unit of length, 
namely, the " black cubit," which figured in an important 
measurement of a degree of the earth's surface executed in 830 
A.D. by the astronomers of the Caliph Al-Mamun (713-833). 
This measurement, made on the plains of Mesopotamia, is 
generally spoken of in connection with similar measurements 
made by Eratosthenes (c. 276 — c. 196 B.C.), the Alexandrian, as 
they were the forerunners of later geodetic work, on which in 
part the modern metric system was founded, it being of course 
unnecessary to say that this and other ancient astronomers 
believed in the spheroidal form of the earth. The " black cubit," 

1 About the earliest systematic works in Metrology in England are A Discourse 
on the Roman Foot and Denarius and Origin and Antiquity of our English Weights 
and Measures (London, 1745), by John Greaves (1602-1652), and De Mensuris 
et Ponderibus Antiquis (Oxford, 1699), by Edward Bernard (1636-1696[7J). 

2 See Boeckh, Metrologische Untersuchungen (Berlin, 1838), pp. 246 et seq. 



30 EVOLUTION OF WEIGHTS AND MEASURES 

however scientific the use to which it was put, was not due to 
any particular metrological study, but, according to tradition, was 
the length of the arm of a favorite black slave of the Caliph, and 
has been said by Jomard to have been equal to 519*16 mm. 1 

The source from which the Anglo-Saxons derived their weights 
and measures is not particularly certain, yet they early en- 
deavoured to secure uniformity by enacting good laws, 2 and in 
this they were so successful that they were enabled to maintain 
these weights and measures in their integrity despite the Norman 
conquest. 3 In fact, they were specially recognized and preserved 
by a decree of William the Conqueror, which stated that " the 
measures and weights shall be true and stamped in all parts of 
the country, as had before been ordained by law." The stan- 
dards of the Saxon kings which had been preserved at Winchester 
were, however, removed to London, where they were deposited in 
the crypt chapel of Edward the Confessor in Westminster Abbey, 
which later became known as the Pyx Chapel, as here were also 
preserved the standard trial plates for gold and silver coin used 
at the trials of the pyx, or formal official assay of the coin of the 
realm. 4 With Winchester are associated the earliest Anglo- 
Saxon weights and measures, and their authority as standards 
is said to date back to King Edgar (reigned 958-975), who decreed 
that " the measures of Winchester shall be the standard." The 
unit of length was the yard or gird, which was identical with the 

1 See Boeckh, Metrologische Untersuchungen (Berlin, 1838), pp. 246, 250-3. 

2 Greaves, Origin and Antiquity of our English Weights and Measures (London, 
1745), p. 68. 

3 Bishop Fleetwood's Chronicon Preciosum (London, 1745), p. 27: "It was a 
good law of King Edgar that there should be the same money, the same weight, 
and the same measures, throughout the kingdom, but it was never well observed. 
What can be more vexatious and unprofitable both to men of reading and practice, 
than to find that when they go out of one country into another, they must learn 
a new language or cannot buy or sell anything. An acre is not an acre ; nor a 
bushel a bushel if you but travel ten miles. A pound is not a pound if you go 
from a goldsmith to a grocer, nor a gallon a gallon if you go from the alehouse to 
the tavern. What purpose does this variety serve, or what necessity is there, 
which the difference of price would not better answer and supply ? " 

4 See H. J. Chaney, Our Weights and Measures (London, 1897), pp. 120-121. 
An interesting account of the Pyx Chamber together with a description of the 
Jewel Tower, now the Office of the Standards, will be found in "The Story of a 
Tower," The Art Journal (London, 1900), pp. 200-203 and 244-247. 



THE SCIENCE OF METROLOGY 31 

ell, and as late as the reign of Eichard II. (1377-1399) the words 
virga or verge (yard) and ulna or aulne (ell) are found in the laws 
and official documents in Latin or Norman French, as the case 
may be, to denote the same unit of length. In addition to the 
purely Saxon measures there were those which had been brought 
by the Eoman, and which, though incommensurable with Saxon 
measures, had survived and become assimilated with the older 
measures. Among these were the mile, corresponding to the 
Eoman millia passuum, the inch and the foot, which soon became 
recognized as purely English measures and to have their own 
fixed values. Then, in addition, when the Belgic tribes migrated 
to Britain, they brought the Belgic foot of the Tungri, which 
was -J- longer than the Eoman foot, and was used until the 
fifteenth century. 1 The average length of this foot was 13 '22 
inches, and a yard formed by three such feet would be 39*66 
inches, which would correspond most closely with the meter of 
to-day, which is equivalent to 3 9 '3 7 inches. Such a yard existed 
and was known as the yard and the full hand, and eventually 
was suppressed by law in 1439. This was extremely unfortunate, 
as had this yard been retained it would have ensured a corre- 
spondence with the French metric system without the slightest 
difficulty. Furthermore, we are informed that the old English 
system was largely decimal, and had these features been pre- 
served a vast improvement would have been worked in the 
wretched system, or lack of system, with which the English- 
speaking people have been afflicted for centuries. 

In the Domesday Book (1086) we find the Saxon yard used a& 
a unit of measure, and land thus measured is referred to as terra 
virgata, and shortly afterwards, from the reign of Henry I. 
(reigned 1100-1135), the tradition is current that the legal yard 
was established from the length of that monarch's arm. \ In the 
reign of Eichard I. (reigned 1189-1199) there were laws ' enacted 
providing for standards of length constructed of iron and for 
measures of capacity whose brims should be of this material also, 
suitable standard measures to be kept by sheriffs and magistrates. 2 

1 Flinders Petrie, article "Weights and Measures," Encyclopaedia Briianuica, 
9th ed. vol. xxiv. p. 484. 

2 See Kelly, Metrology (London, 1816), p. 336. A brief and interesting account 
of early history of British Weights and Measures, with summary of legislation. 



V 



v 



32 EVOLUTION OF WEIGHTS AND MEASURES 

CThe most important early English legislation was contained in 
Magna Charta (1215), and laid stress on the principle of uni- 
formity by providing that there should be throughout the realm, 
one measure of wine, one of ale, and one of corn, viz., the quarter 
■of London : and that it should be of weights as of measures] 
This declaration of uniformity was considered so fundamental that 
it was subsequently repeated in numerous statutes in essentially 
its original form, and we find many acts passed as occasion 
demanded to carry out its manifest intention. This naturally 
involved the definition of the standards and measures, and from 
time to time statutes are found which supply us with more or 
less complete information about the measures of the period. 
Thus, while we know that the unit of monetary weight was a pound 
used from the times of the Saxon kings, yet we do not find it 
•defined until the time of Henry III. (51 Henry III., stat. I. 1266), 
when! the relation of the various weights and measures are given 
by the following law, forming a part of the well known statute of 
the Assize of Bread and Ale, where it' is stated, "that by the 
■consent of the whole realm of England, the measure of our Lord 
the king was made, viz., an English penny called a sterling, round 
and without any clipping, shall weigh thirty-two wheatcorns in 
the midst of the ear ; l and twenty pence do make an ounce, and 
twelve ounces a pound: and eight pounds do make a gallon of 
wine, and eight gallons of wine do make a bushel, which is tnV 
eighth part of a quarter." Thus we have defined the ancient 
Tower Pound, which, having the same weight as the old German 
medicinal or apothecaries pound, is believed to have been derived 
from the mina of Ptolemy or one-sixtieth part of the Lesser 
Alexandrian Talent of silver, as it was but 63 grains lighter than 
that weight. This was the earliest form of the British sterling 
pound, and the division into 20 shillings of 12 pence each was 
the same as is now practised, and in fact was the same as the 
•division of the livre esterlin of Charlemagne, which was slightly 
heavier (5666 Troy grains as compared with 5400, see p. 38). 
In addition, the English monetary weights were connected with 
those of Germany, based on the Cologne mark, by a mint weight 

1,4 This pennyweight was equal to 22^ Troy grains, which is found to be the 
average weight of existing coined silver pennies of the Saxon Norman Kings " 
(Chisholm, Weighing and Measuring, London, 1877). 



THE SCIENCE OF METROLOGY 33 

substantially equivalent to the latter and equal to two-thirds of 
the Tower pound. This was known as a mark, and was used for 
denoting both the weight and value of silver under the Norman 
kings. 1 While the Tower pound was defined in terms of grains 
of wheat, nevertheless it did not originally depend upon them, 
and their inclusion in the English system of weights was doubt- 
less due to French influences subsequent to the Norman Conquest, 
as the French had doubtless derived this idea from Oriental 
sources. With the Tower pound used for mint purposes, and for 
the derivation of measures of capacity, as well as for precious 
metals in general and drugs, there must be considered the com- 
mercial pound {libra mercatoria), which is of almost as great 
antiquity and of far more general use. It also is defined in a 
statute of Henry III. (54 Henry III.) and was the weight of 25 
shillings, or in other words equivalent to 15 ounces of the Tower 
pound. Commercial pounds were used also on the continent 
of Europe along with the Troy pound, and it is to one of 
these, namely the French commercial pound of 16 ounces, that 
we have to look for the source of the English avoirdupois 
pound which soon supplanted the commercial pound in that 
country. 

The early English Tower and commercial pounds were forced 
to give way before the French weights, the Troy pound and the 
avoirdupois pound, whose use the more intimate contact following 
the English victories in France at Poitiers and on other fields had 
doubtless spread through the English realm. As to the source of 
the Troy pound there is a difference of authorities, but it is usual 
to credit it to the city of Troyes in France, and in support of this 
view it is stated that associated with this city, a town of some 
commercial importance, were a livre cle Troyes and a marc cle Troyes, 
whose weights were comparable with the modern Troy pound. 
Going back still further, it is possible to derive the Troy pound 
from the Roman weight of 57592 grains, which was the 3-^5 of 
the large Alexandrian talent. This weight, after the fashion of 
the Romans, was divided into 12 ounces, and the original unit 
and its division may possibly have survived. At all events the 
Troy pound slowly made its way in England, and from as early 
as the first year of the reign of Henry IV., when it was employed 

1 H. W. Chisholm, The Art of Weighing and Measuring (London, 1877), p. 55. 

C 



34 EVOLUTION OF WEIGHTS AND MEASURES 

in an inventory of the Royal plate, it was increasingly used. In 
1495, in defining the bushel and the gallon, Henry VII. made use 
of the Troy pound, and in 1527 the Tower pound was formally 
abolished as the legal standard at the Mint by an Ordinance 
(18 Henry VIII.) enacting that " the Pounde Towre shall be no 
more used and occupied, but al maner of golde and sylver shall 
be wayed by the Pounde Troye, which maketh xii oz. Troye, 
which excedith the Pounde Towre in weight iii quarters of the 
oz." Likewise, as we have indicated, the avoirdupois pound was 
adopted as a commercial pound, and formed of 16 avoirdupois 
ounces, and composed of 7000 Troy grains, it is mentioned in 
a statute (Tractatus Ponderibus et Mensuris) of Edward I. 
(31 Edward I. 1303). From these origins the English Troy and 
avoirdupois pound have descended in substantial integrity to the 
present time, and such changes as have been made have been due 
to the restoration of standards, and have been of a minute and 
unavoidable character. 

Many standards of weight were constructed based on these 
fundamental definitions, and a number of them are still in exist- 
ence, having been used on numerous occasions for deriving other 
standards. In fact, one bell-shaped avoirdupois pound of the 
Exchequer of the reign of Queen Elizabeth was continuously used 
for this purpose from 1588 to 1825. This weight, which at the 
time of its construction in 1588 was supposed to be equal to 7002 
Troy grains, was found in 1873 to weigh 6999 grains of the 
imperial standard pound. 1 

In 1758 a standard Troy pound was constructed and standard- 
ized by Harris under authorization of an Act of Parliament, but 
it was not legalized until 1824 (5 Geo. IV. c. 74). It was then 
specified (§ 5) that in the event of the loss or destruction of this 
standard, that it should be reconstructed by considering that a 
cubic inch of distilled water at 62 degrees Fahrenheit, weighed in 
air with brass weights, and at 30 inches pressure of the mercurial 
barometer, should weigh 252*458 grains, of which the Troy pound 
contained 57 60. 2 This standard was destroyed together with 

1 H. W. Chisholm, The Art of Weighing and Measuring (London, 1877), pp. 62 
and 63. 

2 This definition bound the unit of weight to the unit of length, which was then 
considered fixed by its reference to the second's pendulum. 



THE SCIENCE OF METROLOGY 35 

the standard yard by the fire of October 16, 1834, when the 
Houses of Parliament were burnt. To construct new standards a 
Standards Commission was appointed in 1843, and for the unit of 
weight the avoirdupois pound was taken as the basis. The new 
standard was defined in terms of the lost Troy pound as given by 
various existing standards, and was duly legalized in 1855 (18 and 
19 Vict. c. 72). This standard pound will be more specifically 
described when we come to discuss the subject of Standards in a 
subsequent chapter. 1 

From the definition of the measures of capacity, given in the 
Statute of the Assize of Bread and Ale referred to above, the 
gallon and the bushel were obtained from the pound, using wine 
as the measuring medium. This class of measures was one that 
greatly concerned the government on account of the collection of 
the excise duties, and there are numerous statutes defining or 
regulating in one way or another the capacity and use of these 
measures. On the basis of the early legal definition, however, 
Henry VII. caused to be constructed a standard corn gallon and 
a standard corn bushel, the former having __a capacity of 27 4 -\ 
cubic inches and the latter 2 150 J cubic inches. 1 These- standards 
date from 1495, and are now in actual existence. The Win- 
chester corn gallon, as the measure is known, was employed 
until it was supplanted in 1824 by the imperial gallon, while its 
companion, the Winchester bushel, which was similarly outlawed 
in 1824 in favour of the imperial^ bushel in Great Britain, has 
survived in the United States. | In 1601 we find the British ale 
gallon with a capacity of 282 cubic inches duly recognized by 
Queen Elizabeth/Jand there is extant an Exchequer standard 
quart which bears this date and the royal initials and crown. 

In the reign of Queen Anne the standard wine gallon was 
defined by statute (5 Ann. cap. 27, 17) as " any cylinder 7 inches 
in diameter, and 6 inches deep, or any vessel containing 231 
cubical inches and no more shall be a lawful wine gallon." 
Such a standard of the Exchequer dated 1707 is still extant. On 
the reorganization of the weights and measures in 1824 the wine 
gallon was abolished, but it was never supplanted in the United 

1 Chas. Ed. Guillaume, Unite's et Etalons (Paris, 1893), p. 96. H. W . Chisholm, 
The Art of Weighing and Measuring (London, 1877), pp. 69-81. W. H. Miller, 
Philosophical Transactions (London, 1856), part iii. 



36 EVOLUTION OF WEIGHTS AND MEASURES 

States, and remains as the legal gallon. The British imperial 
gallon, legalized in 1824 (5 Geo. IV. c. 74) to the exclusion of the 
three former gallon measures, and which forms the basis of the 
present British measures of capacity, instead of being based on a 
given number of cubic inches, was taken as the volume of ten 
pounds of pure distilled water at 62 degrees Fahrenheit. This 
corresponds to 277*274 cubic inches. [JWith the gallon as the 
unit of capacity for liquid measures, it was determined to derive 
the imperial standard bushel or unit of capacity by taking a 
volume equal to eight imperial gallons, or a volume corresponding 
to 2218*192 cubic inches. ) 

Unlike the measures of weight and capacity, there have been 
few changes in those of length from the times of the Saxons, and 
the earliest surviving standards of length, those of Henry VII. 
(about 1490), and Elizabeth (about 1588), vary scarcely more 
than a hundredth of an inch from the present imperial yard. 1 
With the second of these standards there is also an ell rod of 
45 inches, and a bar with a bed or matrix for both the yard and 
the ell rods, but such an ell, which doubtless corresponded to the 
French measure of cloth, does not appear in any statute or in 
the records of the standards of this time. In fact, we find the 
Anglo-Saxon measures of length perpetuated on the same basis 
as is given in the statute of Edward II. (17 Edward II. 1324), 
where there is a restatement in statutory form of what has since 
become the well-known rule that three barley-corns, round and 
dry, make an inch, twelve inches a foot, three feet a yard (ulna), 
five and a half yards a perch, and forty perches in length and 
four in breadth an acre. 2 

Consequently the general discussion that has been devoted to 

1 See chapter x. on Standards, pp. 243-244. 

2 See H. W. Chisholm, Seventh Annual Report of the Warden of the Standards, 
1872-3 (London), pp. 25 and 34, English Parliamentary Papers, Reports from 
Commissioners, 1873, vol. xxxviii. Id., Weighing and Measuring (London, 
1877), pp. 51-53. George Graham, " Description of Standards and Use of Beam 
Compasses," Philosophical Transactions (London, 1742-3), vol. xlii. pp. 541-556. 
Francis Baily, Memoirs Royal Astronomical Society (London), vol. ix. 1836, 
pp. 35-184. William Harkness, "The Progress of Science as Exemplified in the 
Art of Weighing and Measuring," vol. x. Bulletin Philosophical Society of 
Washington, D.C., published as vol. xxx. Smithsonian Miscellaneous Collec- 
tions. The latter contains a good resume of British weights and measures as 
well as a useful bibliography. 



THE SCIENCE OF METROLOGY 37 

the British measures of length has been mainly towards securing 
standards of greater accuracy, or with the object of obtaining 
either a decimal division or the adoption of the metric system. 
With the exception of the act of 1824, which defined the yard in 
terms of the second's pendulum, and provided in case of its loss 
or destruction that it should be replaced on that basis, little 
has been done in the way of legislative enactment save to 
recognize and establish legally new standards of length. The 
determination and construction of such standards, however, has 
been of extreme importance, and has involved most careful and 
accurate scientific work, so that for this reason the various British 
standards and their development can best be treated in that 
portion of the present volume devoted to this subject. 1 

While there have been for well over a century many and 
earnest advocates of a decimal division of British weights 
and currency, yet the net results of their labors and agitation 
have been practically nothing other than to strengthen the 
cause of the metric partisans. In fact, decimalization never 
has progressed to the same point as in the United States, and 
it is probable that the old weights, measures, and methods 
will remain until supplanted by the metric system. 2 

Although the preservation of the French standards of measure 
in the royal palace is recorded from the time of Dagobert (650), 3 
yet it is usual to trace back such measures as might properly 
be considered as forming the national system to the time of 
Charlemagne (768-814), since during his reign there was a 
uniformity of weights and measures, and reproductions of the 
royal standards were widely distributed over the realm. 4 The 
unit of length in this system was the pied de Roi, or royal 
foot, representing, according to tradition, the length of the 

foot of the monarch, and which, following the duodecimal 

• 

x See chapter x. — Standards and Comparison. 

2 For progress of Metric System in Great Britain, see chapter iii. pp. 98 et seq. 
It is of course impossible in the present space to describe the various measures 
of Scotland, Ireland, and other local systems. These will be found quite fully 
described in Kelly, Metrology (London, 1816), and also in Chaney, Our Weights 
and Measures (London, 1897), the latter containing also a description of the 
various standards. 

3 Paucton, Metrologie ou TraiU des Mesures, Poids et Monnoies (Paris, 1780), p. 8. 

4 Ibid. p. 13. 



38 EVOLUTION OF WEIGHTS AND MEASURES 

division derived from the Komans, was divided into 12 inches 
(police) of 12 lines, which in turn were composed of 12 points. 
The French foot was longer than the English foot, being equal 
to 12*79 inches of the latter, and considerably longer than the 
ancient Eoman foot, which was 11*65 English inches in length. 
In the French system there was also the toise or fathom of six 
feet, and the earliest record of a standard of length dates back to 
the Toise du Grand Chatelet, constructed in 1668, and based (though 
five lignes shorter) on the ancient toise de magons of Paris, which 
was doubtless as old as the times of Charlemagne. 1 It is said 
by La Condamine 2 to represent one half the distance (12 feet) 
between the walls of the inner gate of the Louvre. Subsequently, 
copies of this were made, and the toise was used as the basis for 
standards of linear measures, such as the Toise de Perou? There 
was also the aune or ell, which, originally a double cubit, became 
adopted as a unit of linear measure for cloth, and survived until 
displaced by the meter. A standard Aune des Marchands, 
Merciers et Grossiers, 1554, divided into halves, quarters, thirds, 
sixths, etc., was preserved by that guild, and was the basis of 
this unit. The aune of Paris corresponded to 46^ Eng. inches, 
but it was never adopted in the latter country to any considerable 
extent or authorized by law, though a cloth aune or ell of 45 in. 
is found marked on the standard yard of Queen Elizabeth. 4 

For the origin of standards of weight in France we have to go 
back to the Arabs, as the basis of the ancient French system is re- 
puted to be an Arab yusdruma, which was sent by Caliph Al Mamun 
(786-833) to Charlemagne. This yusdruma, or later Arab pound, 
was the monetary pound or livre esterlin of Charlemagne, and 
amounted to 5666 J grains, or 367*128 grams. 5 It was divided into 
12 ounces, or 20 sols, of 12 deniers, of 2 oboles of 12 grains, or 
5760 grains in the aggregate, each grain weighing *063738 grams. 

1 La Hire, Mem. de VAcad. Roy. des Sciences, 1714, pp. 394-400 (Paris, 1717). 
2 La Condamine, Memoires de VAcad. Roy. des Sciences, 1772, 2nd part, 
pp. 482-501 (Paris, 1776). 

3 See chapter x. on Standards. 

4 See chapter on Standards, p. 243. Also ante, p. 31. 

5 The name "esterlin" was employed at one time in the French language to 
signify "true," being equivalent to the modern Fr. word "veritable." It has, 
however, disappeared from use, but has been retained in English, with the same 
signification, in the form of "sterling," as, for example, "pounds sterling." 



THE SCIENCE OF METROLOGY 39 

The livre esterlin of Charlemagne was one and a half times the 
weight of the marc of the monetary system which was established 
between 1076 and 1093 by Philip L, who used 8 of the 12 ounces 
of the former system for this purpose. This marc was doubled, 
and made to consist of 16 ounces, by King John the Good, in 
1350, and it was adjusted according to the weights of Charlemagne. 
The weights of King John were known as the " pile de Charle- 
magne," and were the French standards of weight until the 
adoption of the Metric System in 1789. 1 In this system the 
livre poid de marc, or pound, consisted of two marcs or half- 
pounds, 4 quarterons, 8 half -quarterons, 16 ounces, 32 half-ounces, 
128 gros (drachme) or grams, 384 scruples, or deniers, 9216 grains. 
There were also in France four other marcs duly and legally 
recognized, viz., that of Kochelle, which was called English, equal 
to 13 sols, 4 deniers, in terms of the livre esterlin; that of 
Limoges, equivalent to 13 sols, 3 oboles ; that of Tours, equal to 
12 sols, 11 deniers, 1 obole ; and that of Troyes and Paris, equi- 
valent to 14 sols, 2 deniers. 2 

We have referred specifically to early measures only in Great 
Britain and France, as throughout the rest of Europe there was 
such great diversity until well into the nineteenth century that 
little would be gained for our purpose by considering the dozens 
of kingdoms, principalities, free cities, etc., each with their 
separate systems. Local conditions and traditions everywhere 
governed, and riolTonly in different countries in the same region 
would there be different values for the same weights and 
measures, but also in different towns of the same state. 3 While 
the names feet, pounds, etc., were quite universally employed, yet 
they designated different quantities, and save for arbitrary 
standards, possibly in many cases not even duly legalized, there 
was no attempt at securing uniformity. A foot might be divided 



1 Guillaume, p. 94, Les Unites et Etalons (Paris, 

2 Quoted by Guillaume, p. 95, Les Unite's et Etalons, from Chronique de 1329 
■environ. 

3 "At the close of the last (eighteenth) century, in different parts of the 
world, the word pound was applied to 391 different units of weight and the 
word foot to 282 different units of length." T. C. Mendenhall, Measurements of 
Precision. Such a list with British and metric equivalents may be found in 
Barnard, The Metric System (Boston, 1879), pp. 348-360. The kilogram has 
.superseded over 370 of the different pounds. 



40 EVOLUTION OF WEIGHTS AND MEASURES 

duodecimally, as was done by the Eomans, or, on the other hand, 
it might be divided into nine, ten, eleven, or thirteen inches. 
Then again the actual distance represented by a foot varied 
from 9 to 18 inches, and equivalents are now known for many 
different European feet. 

As to the sources of these measures, we have to look to the 
Eomans and to the East, as the former nation in its conquests 
overran a great part of Europe, . and implanted its weights and 
measures with more or less permanence, while the effects of trade 
with the Orient and the intellectual influence of the Arabs 
doubtless served to introduce new measures or to corrupt old 
ones. Several mark weights soon became known as standards 
for coinage and precious metals, notably that at Cologne, while the 
Ehine foot enjoyed a pre-eminence in the neighboring countries. 1 
As practically no scientific work of a quantitative character was 
done for many centuries, the influence of science in systematizing 
and demanding exact standards of measure was not felt, so that 
only the needs of trade, often of a most restricted character, 
which could be satisfied by crude and imperfect systems, had 
to be provided for. The lineage of many of the old European 
weights and measures has been traced more or less satisfactorily 
back to ancient times, but the subject presents little scientific 
attraction, save to the historian or archaeologist and the student 
of metrology. 2 Lack of system prevailed, and apparently was 
quite satisfactory, but gradually the minds of scientists and 
statesmen became aroused to the importance of the subject and 
the need of fundamental changes, and a rational systematization 
was urged, which found its first substantial fruit in the develop- 
ment in France of the metric system. 

1 This Rhine foot defined in Prussia by law in 1816 was standardized by Bessel 
in 1835-1838, and survived in that kingdom until the adoption of the metric 
system. It is still (1906) the standard of length in Denmark. 

2 An interesting summary of ancient and modern measures, which, however, 
must be modified in many aspects, and considered in the light of modern 
researches and theories, is contained with a wealth of bibliographical material 
in Karsten, Allgemeine Encyklopddie der Physik, vol i. " Maass und Messen " 
(Leipsic, 1869). 



CHAPTER II. 

ORIGIN AND DEVELOPMENT OF THE METRIC SYSTEM. 1 

While the inconveniences and difficulties attending arbitrary 
systems of weights and measures were appreciated, nevertheless 
philosopher and peasant alike submitted, and it took many years 
for a feeling in favour of a rational and fixed system to develop. 
Such a system at its best, as we have seen, would involve an 
invariable unit derived from nature itself, which not only could 
be reproduced readily, but was capable of being measured with a 

1 In this chapter detailed references have been given to authorities for 
particular statements for the benefit of those who desire to pursue the subject 
further. The history of the Metric System has been well summed up in a 
treatise by M. Bigourdan (Le Systdme Me'trique, Paris, 1901), in which will be 
found usually the text of all French legislation and the salient features of 
discussion by lawmakers and scientists, as well as a complete bibliography. 
There is also an excellent historical sketch, "Notice historique sur le Systeme 
Metrique, sur ses developpements et sur sa propagation," contained in the 
Annales du Conservatoire (Imperial) des Arts et Metiers, by General A. Morin 
(Paris, 1870), vol. ix. pp. 573-640. This is a brief but excellent description of 
the origin and development of the system by a member of the Committee of 
Verification, director of the Conservatoire des Arts et Metiers, and a member 
of the first International Commission. "A Historical Sketch of the Foundation 
of the Metric System," by General Bassot, was published in the Annuaire pour 
Van 1901, of the Bureau of Longitude, Paris (translated into English by Miss 
F. E. Harpham of the Astronomical Department of Columbia University, and 
published in the School of Mines Quarterly, vol. xxiii. No. 1, November, 1901. 
First and foremost, however, is the classical work of Mechain and Delambre, 
Base da SystSme Me'trique, 3 vols. (Paris, 1806-1810), which is the primary 
source of information for the early work in establishing the Metric System. It 
is, of course, unnecessary to say that in the following pages these works have 
been most freely used, and can be recommended for those desiring additional 
information on the subject. 



42 EVOLUTION OF WEIGHTS AND MEASURES 

high degree of precision. Obviously such standards as barley- 
corns and human feet did not possess the slightest claim to 
invariability, and as soon as the subject began to be considered 
seriously and earnestly by scientific men, the choice for the 
fundamental unit of linear distance became narrowed to two 
classes of lengths, and around them most of the subsequent 
discussion centred. One was the length of a fraction of a great * 
circle of the earth, while the other was the length or a fraction 
of the length of a pendulum, vibrating in intervals of one second 
or some other chosen unit of time. For the first, proceeding on 
the assumption that the earth was a spheroid (or very nearly so), 
it was possible to measure the arc of a great circle even in the 
seventeenth century without any great difficulty. Such a measure- 
ment involved the determination with considerable accuracy of the 
geographical position, or in other words the latitude and longi- 
tude, of two points, and then a geodetic 'or trigonometrical ' 
survey which took into consideration the curvature of the earth's 
surface, measuring the actual distance between them in terms of 
a unit of length selected for that purpose and represented by a 
standard which was employed in the measurement of a base- 
line. The distance, as found by the triangulation, could then be 
compared with the difference in latitude between the two points, 
and thus the actual distance in degrees could be obtained in 
terms of the selected linear standard. The other invariable 
standard of length was that of a pendulum, which in a given 
place executed its vibrations always in the same time. By the / 
law of the pendulum, the time of vibration is inversely pro- 
portional to the square root of the acceleration due to gravity, and 
directly as the square root of the length. Consequently, being 
able to measure time, and, assuming that the acceleration of 
gravity at a given point is constant, it is possible to determine or 
reproduce accurately a given length by this instrumentality. 

After considering the invariability of the original standard, the 
next important matter to bear in mind is the symmetry and 
convenience in actual use of any system of measures which is 
based thereon. In the light of the development of the science of 
arithmetic and of the popular methods of reckoning, it can be 
safely said that the decimal system for money, weights, and 
measures, must stand as the most simple and useful. Therefore 



DEVELOPMENT OF THE METRIC SYSTEM 43 

in considering the genesis of the modern metric system, as a 
universal system founded on an invariable standard and sym- 
metrically and conveniently developed, it is necessary to go back 
to Gabriel Mouton, Vicar of St. Paul's Church, Lyons, who first 
proposed in 1670 a comprehensive decimal system having as a basis 
the length of an arc of one minute of a great circle of the earth. 
One minute of arc would give the length of a milliare or mille, 
which would be subdivided decimally into cenhtria, decuria, virga, 
virgula, decima, centesima, millesimal The virga and virgida would 
be the chief units of the system corresponding to the toise and the 
foot then in use. This geometric foot {virgula geometrica) was 
further defined by Mouton as corresponding to the length of a 
pendulum making 3,959*2 vibrations in a half hour at Lyons. 2 
This proposition contained essentially the germ of the modern 
metric system and Mouton's suggestion of the pendulum was soon 
repeated by Picard (1671), and by Huygens 3 (1673). The former 
said 4 " The length of a pendulum beating seconds of mean time 
would be called the astronomical radius (Rayon Astronomique), of 
which the one-third would be the universal foot : the double of 
the astronomical radius would be the universal toise, which would 

be at Paris as 881 to 864 If we should find by experience 

that the pendulums were of different lengths in different places, 
the supposition we had made touching a universal measure 
depending on the pendulum would not stand, but it would not 
alter the fact that in each place the measure would be perpetual 
and invariable." 

a See Bassot, "Historical Sketch of the Foundation of the Metric System," 
Annuaire pour Van 1901, publie par le Bureau des Longitudes, Paris. Translated 
in School of Mines Quarterly (New York), vol. iii. No. 1, Nov., 1901. 

2 Mouton, Observationes diametrorum Soils et Lunae . . . Huic adjecta est brevis 
dissertatio de. . . nova mensurarum geometricarum idea (Lyons, 1670), p. 427. In 
reference to Mouton's work an interesting paper by Professor J. H. Gore, "The 
Decimal System of Measures of the Seventeenth Century," in the American Journal 
of Science (Third Series, vol. xli. Jan., 1891, p. 22), should be consulted. 
Professor Gore quotes from Mouton's writings and describes his researches in order 
to show that the essential features of the Metric System were first announced by 
him. Furthermore he does not consider that due credit was given by the French 
scientists who founded the system and made use of Mouton's ideas. 

3 Horologium Oscillatorium, 4 prop. 25 (Paris, 1673). 

4 Mesure de la Terre, reprinted in Anciens Me'moires, vol. vii. p. 133. 



,.\ 



44 EVOLUTION OF WEIGHTS AND MEASURES 

Similar in character to the plan of Mouton, but considerably later 
(1720), was a proposition made by Cassini, in his celebrated work, 
Be la grandeur et de la figure de la Terre (pp. 158, 159), recom- 
mending the adoption of a unit known as the pied geomttrique. 
This was equal to ^FOTF P ar ^ °^ a mmu te of arc of a great circle, 
and 6 pieds formed a toise. J This foot had a length almost half 
that given by the x q o o^) o o o P ar ^ °^ tne ra( li us of the earth. 

Subsequently another plan involving the length of the second's 
pendulum as a unit, was brought forward and developed by Du Fay, 
and this, after his death, was elaborated and continued by La 
Condamine (1747), 1 who provided against the variation in length 
at various latitudes by taking as his unit the length of the 
second's pendulum at the equator (36 inches 7'15 lignes of the toise 
of Peru), which he together with Godin and Bouguer had quite 
accurately determined at Quito, while engaged in measuring an 
arc of meridian at the equator in 1735-1737. La Condamine also 
appreciated the advantages of the decimal division of measures of 
length, and saw the necessity for reforms in the measures of area, 
capacity, weight, etc., so that all might be brought into harmony 
with the linear measures, and thus be equally stable and invariable. 
He was farsighted enough to suggest, what has since been such a 
valuable feature of the metric system, namely the advantages of 
international joint effort in making the desired changes, and 
advocated consulting with the academies of foreign countries in 
this matter. 

Worthy of record also is the proposition made by M. Prieur 
Du Vernois, 2 who urged as the unit of length, that of the second's 
pendulum, in preference to that of a fraction of an arc of meridian, 
on the ground that the former could be reproduced more readily. 
He advocated taking the length of the pendulum at a single point, 
suggesting the Eoyal Observatory at Paris, and then making a 
standard of platinum, correct at a certain temperature such as 10°, 
which would be deposited in the Hotel de Ville. One-third of the 
length of this standard would be the French or natural foot, 
which would be divided into 10 inches, each inch in turn being 

1 Me"moires de VAcademie des Sciences, p. 489, 1747. 

2 See Prieur (Du Vernois), Me'moire sur la ne'cessite' et les moyens de rendre 
uniformes dans le royaume toutes les mesures d'entendue et de pesanteur, etc. (Paris, 
1790), pp. 9-11. 



DEVELOPMENT OF THE METRIC SYSTEM 45 

s/ 
divided into 10 lignes. Multiplying the foot by ten would give 

the national perch, while an area ten perches square would .be the 

national arpent. Units of volume would be measured by cubes of 

lignes, inches, and feet, and the unit of mass would be a national 

pound corresponding to the mass of a cube of distilled water at 

some determined temperature, ten inches square on each edge. 

Prieur also advocated a decimal system of money, in which the 

lime (franc) was divided into tenth and hundredth parts known 

as decimes and centimes. 

During the eighteenth century such schemes as have just been 
described were proposed by scientists for the improvement of the 
weights and measures, and although they were brought to the 
attention of the French Government they did not meet with 
such approval as to secure their adoption. Indeed there was no 
lack of plans proposed by the scientific men, and the government 
realized the necessity for uniformity throughout the realm, but 
the various schemes were discussed and discarded without any 
definitive action, and, just as in later times, the difficulties 
attending the introduction of a new system were anticipated 
and feared. In fact Necker, in a report made to Louis XVI. 
in 1778, speaks of the proposed reform of weights and measures 
with considerable diffidence. He writes, " I have occupied 
myself in examining the means which might be employed to 
render the weights and measures uniform throughout the king- 
dom, but I doubt yet whether the unity which would result 
would be proportionate to the difficulties of all kinds which this 
operation would entail on account of the changing of values 
which would necessarily be made in a multitude of contracts, of 
yearly payments, of feudal rights and other acts of all kinds. I 
have not yet renounced the project, and I have seen with 
satisfaction that the Assembly of Haute-Guyenne have taken it 
into consideration. It is in effect a kind of amelioration which 
can be undertaken partially, and the example of a happy success 
in one province would essentially influence opinion." 1 

With the changes wrought by the Kevolution it was possible 
to gain at the hands of the public consideration for radical ideas 
in science as well as in government and religion. The .schemes 

1 Necker, Compte rendu au Roi de 1778, Bigourdan, Le Syst&me Me'trique, 
<Paris, 1901), p. 11. 



46 EVOLUTION OF WEIGHTS AND MEASURES 

and discussions already mentioned paved the way for the favour- 
able reception of a plan for reform when it was urged in the 
National Assembly by a bold and able leader. Such was 
Talleyrand, then Bishop of Autun, who brought the matter to 
the attention of the National Assembly in April, 1790. He not 
only appreciated the necessity for a uniform system of weights 
and measures for France, but also the desirability of a system 
that would be truly international rather than merely the weights 
and measures of Paris. He proposed as a fundamental unit the 
length of a pendulum beating seconds at 45° latitude, and as a 
unit of weight that of a cube of water whose height should be 
one twelfth the length of the pendulum. New and most careful 
measurements were to be undertaken to determine the length of 
the pendulum, and for this purpose a joint commission of the 
Paris Academy of Sciences and the Eoyal Society of London was 
to be established. Talleyrand's proposal, after being considered 
by the Committee on Agriculture and Commerce and discussed 
in a report by the Marquis de Bonnay, was brought before the 
National Assembly, where, in the course of the general discussion 
upon it, the advantages of a decimal division were urged. The 
report was accepted and a decree was rendered on May 8, 1790, 
which was sanctioned by Louis XVI. on August 22 of the same 
year. Inasmuch as this decree describes with some detail the 
existing condition and the method of making the change, it is 
given below in full. It runs : 

" The National Assembly, desiring that all France shall forever 
enjoy all the advantages which will result from uniformity in 
weights and measures, and wishing that the relation of the old 
measures to the new should be clearly determined and easily 
understood, decreed that His Majesty shall be asked to give 
orders to the administrators of the different departments of the 
kingdom, to the end that they procure and cause to be remitted 
to each of the municipalities comprised in each department and 
that they send to Paris to be remitted to the Secretary of the 
Academy of Sciences a perfectly exact model of the different 
weights and elementary measures which are in usage. 

" It is decreed further that the King shall also beg His 
Majesty of Britain to request the English Parliament to concur 
with the National Assembly in the determination of a natural 



DEVELOPMENT OF THE METRIC SYSTEM 47 

unit of measures and weights ; and in consequence, under the 
auspices of the two nations, the Commissioners of the Academy 
of Sciences of Paris shall unite with an equal number of members 
chosen by the Eoyal Society of London, in a place which shall 
be respectively decided as most convenient, to determine at the 
latitude of 45°, or any other latitude which may be preferred, 
the length of the pendulum, and to deduce an invariable standard 
for all the measures and all the weights ; and that after this 
operation is made with all the necessary solemnity, His Majesty 
will be asked to charge the Academy of Sciences to fix with 
precision for each royal municipality the relation of the old 
weights and measures to the new standard, and to compose 
afterward for the use of the municipalities the usual books and 
elementary treatises which will indicate with clearness all these 
propositions. 

" It is decreed further that these elementary books shall be 
sent at the same time to all the municipalities to be distributed : 
at the same time there shall be sent to each of the municipalities 
a certain number of new weights and measures which they shall 
distribute gratuitously to those who would be caused great 
expense by this change ; and finally, six months only after the 
distribution, the old measures shall be abolished and replaced 
by the new. 

" The National Assembly decrees that the Academy, after con- 
sultation with the officers of the Mint, shall offer their opinion 
as to the suitability of fixing invariably the inscription of the 
coined metal to the end that the kinds shall never be altered 
except in their weight, and whether it would not be useful that 
the difference tolerated in the coins under the name of remedy 
be always beyond requirement, that is to say one piece may 
exceed the weight prescribed by law but must never be 
inferior. 

"Finally, the Academy shall indicate the scale of division 
which it believes most convenient for all weights, measures 
and coins." 

Under the terms of this decree the Academy took up its work 
in earnest, and on October 27, 1790, its committee consisting of 
Borda, Lagrange, Laplace, Tillet, and Condorcet, made a report in 
which they urged the adoption of the decimal division of the 



48 EVOLUTION OF WEIGHTS AND MEASURES 

moneys, weights, and measures. This report dealt with the 
comparative merits of the decimal and duodecimal system of 
calculation, and discussed many of the questions bearing on this 
subject which have been argued at such length before and since. 
Next in importance after settling on the principle of decimal 
division was the selection of a unit of length, and a committee 
consisting of Borda, Lagrange, Laplace, Monge, and Condorcet, 
presented a report to the Academy on March 19, 1791, in which 
they stated that, in their opinion, the units suitable for adoption 
as the basis of a uniform and rational system of weights and 
measures were three in number, as follows : the length of a 
second's pendulum, the quadrant of a great circle of the equator, 
and the quadrant of a great circle of meridian. Considering the 
relative advantages and drawbacks of each of these with great 
care and deliberation, the committee concluded that while the 
length of the second's pendulum was easily determined and 
susceptible of verification, it was dependent on the acceleration ' 
due to gravity, and that it was necessary to have the position 
specified exactly. The most desirable point would be at 45° 
latitude, a mean distance between the equator and the pole. At 
the latter points, owing to flattening of the earth at the poles, 
pendulums vibrating with the same period would have unequal 
lengths, that at the equator being shorter as the force of gravity 
there owing to the greater radius of the earth is less intense. 
But with the pendulum a new and unlike element, namely the 
second, is introduced, and this depends upon the arbitrary 
division of the day. The preference of the committee was for a 
terrestrial arc, inasmuch as it bore a nearer relation to the 
ordinary method of measuring distances, and their choice was in 
favor of an arc of a meridian rather than one of the equator. 
This decision was due to the fact that such an arc could be 
measured with greater facility, and also in several countries, 
while in addition no more assurance of the regularity of the 
equator than that of a meridian could be given. 

After an arc had been measured the length of a quadrant 
could then be computed, and one ten-millionth of its length could 
be taken as the base or fundamental unit of length. In other 
words the quadrant was to be measured in a single unit of length 
on a decimal basis, instead of in the former degrees, minutes, and 



DEVELOPMENT OF THE METRIC SYSTEM 49 

seconds. The plan proposed by the committee was to measure 
an arc of meridian between Dunkirk, on the northern coast of 
France, and Barcelona on the Mediterranean Sea, largely because 
these two places were each situated at the sea-level in the same 
medidian, because they afforded a suitable intervening distance of 
about 9° 30', the greatest in Europe available for a meridian 
measurement, because the country so traversed had in part been 
surveyed trigonometrically previously by Lacaille and Cassini in 
1739-1740, and furthermore because such an arc extended on 
both sides of latitude 45°. The committee outlined six distinct 
operations essential for the work. They were as follows : 

1. The determination of the difference in latitude between 
Dunkirk and Barcelona. 

2. The measurement of the old bases. 

3. The verification and measurement of the series of triangles 
used in a previous survey, and extending the same to Barcelona. 

4. The observation of the pendulum at 45° latitude. 

5. Verification of the weight in vacuum of a given volume of 
distilled water at the temperature of melting ice. 

6. Comparison of the old and new measures, and the con- 
struction of scales and tables of equalization. 

The National Academy straightway adopted the recommenda- 
tions of the committee, adopting the length of one fourth of a 
terrestrial meridian as the basis for the measures of length, and 
providing for the measurement of the arc from Dunkirk to 
Barcelona, and the appointment of supervisory committees by the 
Academy of Sciences. This latter body then addressed itself to 
the consideration of a suitable nomenclature, and fixed the length 
of the new unit provisionally at 36 inches 11*44 lignes, and 
assigning the name Metre to the one ten-millionth part of the 
quadrant of the earth's meridian. 1 The relations between the 
measures of length and capacity, capacity and weight, and weight 
and money were also considered. The provisional meter was 
derived from a calculation of the observations made by Lacaille 
when measuring a meridian in France in 1740. By this the 
value of one degree was given as 57,027 toises, which multiplied 
by 90 would give the length of the quadrant or distance from 
pole to equator, as 5,132,430 toises. Taking the ten-millionth 

1 Report of May 29, 1793. 
D 



50 EVOLUTION OF WEIGHTS AND MEASURES 





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52 EVOLUTION OF WEIGHTS AND MEASURES 

part of this value, and reducing it to the feet and lignes into 
which the toise was divided, the length of 3 feet 11*44 lignes 
was obtained. To show how little this provisional meter varied 
from the meter finally determined by the commission in 1799, it 
may be stated that the latter length in the same units is 3 feet 
11*296 lignes, or a difference of about *33 millimeters, an amount 
considered quite insignificant in every-day dealings. A standard 
of the provisional meter in brass was duly constructed by Lenoir 
in Paris, and is preserved in the Conservatoire des Arts et 
Metiers at Paris. 1 

The committee was unable to decide definitely on a system of 
nomenclature, and accordingly proposed two schemes : one, as 
they termed it, methodical, in which Latin prefixes were used for 
the various units ; the other simple monosyllabic names which 
they believed would be more readily adopted by the general 
population. The Convention, which in the meanwhile had 
replaced the National Assembly, adopted the recommendations 
of the committee, but preferred to use the methodical nomen- 
clature. This decree was dated August 1, 1793, and called atten- 
tion to the importance of the steps being taken to secure 
uniformity of weights and measures in France, and outlined 
the methods of practically establishing the new system through- 
out the country. The suppression of the Academy of Sciences 
occurred a few days (August 8, 1793) after passing this decree, 
and this event, together with various legislative enactments from 
time to time, had the effect of causing changes in the personnel 
of the scientific staff entrusted with the development of the 
system and some differences in the method of procedure. The 
place of the Academy was taken by a newly constituted National 
Institute of Sciences and Arts, which continued the scientific 
oversight, and in general the undertaking was pushed forward as 
rapidly as is possible with work of such character. 

As showing the extent to which the desire for changes and 
reforms was being manifested in France at this time, it may not 
be inappropriate to refer at this point to the innovations intro- 
duced in the calendar whereby the decimal system was here 
applied also. By a decree of November 24, 1793, time was to be 

^igourdan, Le Systeme Mttrique (Paris, 1901), chap. ix. pp. 90-93. Mechain 
and Delambre, Base du Systeme MUrique (Paris, 1806-1810), vol. iii. pp. 673-690. 



DEVELOPMENT OF THE METRIC SYSTEM 53 

reckoned from the establishment of the French Eepublic, Sep- 
tember 22, 1792, the day of the autumnal equinox. The year as 
formerly was to be divided into twelve months, but each of these 
was to be divided into three weeks, or decads, of ten days each. 
Each day was to be divided into ten hours, and each hour into 
one hundred minutes of one hundred seconds each. A picturesque 
feature was the grouping of the months according to the seasons 
with a different termination for the names of each season. Thus, 
beginning with the autumn equinox, Vende'miaire was the month 
of vintage, and was followed by Brumaire, the month of fogs, and 
Frimaire, the month of incipient cold. At the winter solstice 
came Mvose, the month of snow, and then Pluviose, the month of 
rain, and Ventose, the month of wind. The spring months were, 
Germinal, the month of buds ; Floreal, the month of blossoms ; 
and Prairial, the month of flowering fields. In the summer came 
Messidor, the month of harvests ; Thermidor, the month of heat ; 
and Fructidor, the month of fruits. 

This changed calendar was used until 1806, when the Gregorian 
calendar was resumed, but the division of the day into 100,000 
parts was abandoned in 1795. The lack of success of this method 
of dividing time can readily be explained, and by reasons which 
have but little bearing on the science of metrology. The doing 
away with the Christian Sabbath, the addition of a festival season, 
the changing of well-established modes of life by legislative enact- 
ment could hardly but be expected to fail of adoption. Further- 
more, the Gregorian calendar was at this time practically universal, 
and furnished no inconvenience either to scientific men or to the 
general public. It was a case of change merely for the sake of 
innovation, and as such was destined to fail. 

The time being ripe for further and more definite legislation 
on the subject of the new scheme of weights and measures, after 
Prieur (de la Cote d'Or) had made a full and comprehensive 
report describing the status of the work of establishment and 
recommending a new system of nomenclature, the Convention 
enacted the Law of 18 Germinal an III. (April 7, 1795), which 
defined precisely the different units, provided for standards, and 
the proper distribution of secondary standards, and the exact 
determination of the units of length and mass according to the 
original plan. Article 5 of this decree is worth quoting in full,. 



54 EVOLUTION OF WEIGHTS AND MEASURES 

as it gives precise definitions of the elementary units of the 
metric system. It reads : 

" Art. 5. — The new measures will be distinguished by the name 
of measures of the Eepublic : their nomenclature is definitely 
adopted as follows : 

" Meter, the measure of length equal to the ten-millionth part 
of a terrestrial meridian contained between the north pole and 
the equator. 

" Are, the measure of area for land equal to a square ten 
meters on each side. 

" Stere, the measure designed especially for fire- wood, and which 
shall be equal to a meter cube. 

"Liter, the measure of capacity both for liquids and dry 
materials, whose extent will be that of a cube of one-tenth of a 
meter. 

" Gramme, the absolute weight of a volume of pure water equal 
to a cube of one-hundredth part of a meter, and at the tempera- 
ture of melting ice. 

" Finally the unit of coinage shall take the name of franc to 
replace the livre used until to-day." 

Greek prefixes were provided to denote the multiples of the 
various units and the Latin prefixes for the subdivisions, while in 
the measures of weight and capacity, provision was made in addi- 
tion for double and half measures. 

Under the provision of this law, the scientific work was taken 
up with vigor, and the Government appointed a commission of 
twelve to complete the original determinations of length and 
mass. This body included Berthollet, Borda, Brisson, Coulomb, 
Delambre, Haiiy, Lagrange, Laplace, Mechain, Monge, Prony, and 
Vandermonde, all of whom had been interested actively in the 
work previously accomplished. This commission was then sub- 
divided, Delambre and Mechain taking charge of the astronomical 
and geodetic work, Borda, Haiiy, and Prony of the determination 
of the units of weight, Borda and Brisson of the construction and 
verification of the provisional meter, and Berthollet, Monge and 
Vandermonde of the construction of the definite meter. The 
length of a second's pendulum had already been determined by 
Cassini and Borda at Paris, and was found to be equal to 3 feet 
8*5593 lignes of the toise of Peru. 



DEVELOPMENT OF THE METRIC SYSTEM 55 

The measurement of the arc of meridian was the most impor- 
tant of the duties of the commission, and involved a vast amount 
of labor, both in observations in the field and in the reduction 
and calculation of these observations. The work was originally 
commenced in 1792 by M^chain and Delambre, and was carried 
on by them through various vicissitudes caused by changes in 
political conditions, with their consequent effect on the general 
and scientific plans for the various operations. 

Before describing their work, however, it may be of advantage to 
outline the underlying principles of a geodetic or trigonometrical 
survey such as is necessary to determine the length of an arc 
on the surface of the earth. Such a survey naturally involves 
the measurement of considerable distances, taking into considera- 
tion the curvature of the earth's surface, and requires a system 
or network of triangles connected one with another by means of 
common sides. The vertices are stations usually situated on 
some high altitude, or at any event so selected that each is 
visible with a telescope from several others. Always at one end, 
and often at or near both ends, there is what is known as a base- 
line, a horizontal distance on level ground actually measured 
with a linear standard to as high a degree of precision as is 
possible. This involves measuring a distance of from one to ten 
kilometers by means of rods, bars, or steel tapes, whose lengths 
have been determined with great accuracy at a standard tempera- 
ture, to which by correction the actual measurements may be 
reduced. Care must be taken to place the standards perfectly 
horizontal and end to end when they are being moved over the 
measured distance, or to make suitable corrections, and to 
observe the temperature. In this way the base line, or one side 
of the triangle, marked in the accompanying diagram by a 
heavy line, is accurately determined, and it is advantageous 
in an extended survey to have the base lines at or near sea-level. 

After the base line is determined, then the triangulation may 
be reduced and the distance calculated between the remote ends 
of the arc. If reference is made to plate vii. vol. i. of the 
work 1 of Delambre and Mechain here reproduced, it will be 
possible to illustrate the general method. The base shown 
between Salces and Vernet is near Perpignan, in the south of 

1 Le Base du Systeme Metrique, vol. i. 



56 EVOLUTION OF WEIGHTS AND MEASURES 

France, and at the end of the old arc previously measured. This 
distance is actually measured with the base line apparatus. 
Then by means of a divided circle, capable of measuring angles 
in both a horizontal and vertical plane, and transit or theodolite 
placed at the " terme boreal " (north end of the base line), the 
angle between the direction to Mt. d'Espira and to Mt. Forceral 
is measured, and then at the " terme austral " the corresponding 
similar angles are measured. Thereupon the instrument is taken 
to Mt. d'Espira and the angles around that point determined. 
This is the beginning of a long series of angle determinations at 
all the points of observation, as Mt. de Tauch, Pic de Bugarach, 
Mt. Alaric, Carcassonne, etc. All of the measurements are con- 
tinually checked by the fact that the sum of all the angles 
around a single point, as Mt. Alaric, must equal 360°, and that 
the sum of the three angles in any triangle must equal 180°. In 
any triangle, if one side and two angles, or two sides and one 
angle, are known, then it is a simple 1 matter to calculate the 
other parts. 

In this way it is not only possible to calculate the length of 
the sides of all the numerous triangles formed between Barcelona 
and Dunkirk, but also the projection of each upon the true north 
and south meridian. For example, as soon as the linear distance 
from Mt. Alaric to St. Pons is known, and the angle which the 
direction makes with the true meridian, then it is simple to 
calculate how far one is north of the other, or in other words, 
the section of the meridian corresponding to the distance of St. 
Pons due north of Mt. Alaric. Thus ultimately the distance of 
Dunkirk due north of Barcelona is calculated. The numerous 
triangles give continual checks upon the work, as do also other 
base lines distributed along the line of triangulation. 

The foregoing gives the merest outline of the work of triangu- 
lation, as there are numerous refinements and modifications 
involved in both observation and computation, which make the 
calculation one of no small magnitude. This, however, is but 
half of the work. There must be found, with an equal degree of 
precision, the geographical position, or, more particularly, the 
latitude, of the two extremities of the meridian by astronomical 
methods. In kind this is similar to the finding of the position 
of a vessel at sea, but more refined methods of observation are 



:v eO? 



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58 EVOLUTION OF WEIGHTS AND MEASURES 

necessary, and, at the present day, the nse of the zenith telescope 
is considered the most accurate of the several methods of deter- 
mining the latitude of a place. 



At the time of the measurement of the Dunkirk-Barcelona arc, 
however, the astronomers used the method of upper and lower 
transits of certain stars near the north pole of the heavens. 
Keferring to the accompanying figure, NDBES represents a 



DEVELOPMENT OF THE METRIC SYSTEM 59 

meridian of longitude through the place, D, the latitude of which 
is sought. That is, the plane of the paper is a plane through the 
axis of the earth NS and the place D. Evidently then the angle 
DCE is the latitude of the place D, and the angle DCN is called 
the colatitude. If the line DM indicates the direction in which 
& star appears, as seen from D at the instant when it passes the 
meridian, then the angle ZDM may be observed, and is called the 
zenith distance of the star. The lines DP, DP' and SCN are 
parallel, and indicate the direction to the celestial pole, that is, 
to the point where the axis NS pierces the heavens, then the 
angle ZDP is equal to DON the colatitude of the place. The 
angle MDP is the polar distance of the star. 

A series of determinations of the zenith distance of Polaris, the 
"north star," made on Jan. 17th, 1796, at Dunkirk, for the upper 
transit, gave 37° 11' 44"*36. Adding to this the pole distance of 
Polaris, l c 46' 39"*60, gives the colatitude 38° 57' 44"*36, and the 
latitude, or 90° minus the latitude, 51° 2' 15"*64. In the case of 
a lower transit, where the star crosses the meridian below the 
pole, the pole distance would be subtracted from the zenith 
distance. That is to say, Z'D'P' = Z'DM' - M'DP'. A similar 
determination at Barcelona, made on Dec. 17th, 1793, gave as 
the latitude of that place, 41° 22' 47"*83. This would give as 
the difference of latitude between Dunkirk and Barcelona, 
9° 39' 27"*81. 

A final determination of the difference of latitude between 
Dunkirk and Montjouy (Barcelona) 9°*67380, and the distance, 
measured in toises, was found to be 551 584*72. If the refine- 
ments of the polar flattening of the earth, etc., are neglected for 
the moment, then 551 58472 divided by 9*67380 would give 
57 018*7 as the number of toises in one degree of latitude. This 
number, 57018*7, multiplied by 90, gives 5 131 680. One ten- 
millionth part of this, or 0*5131680 of a toise, would then be the 
ideal meter. Naturally, in the actual calculation, all the cor- 
rections and refinements were applied. 

It must be remembered that in making these measurements 
much depends upon the accuracy of graduation of the circles, and 
that many measurements must be made and an average taken so 
as to obtain in each instance a mean value. The errors can be 
•distributed by the two considerations referred to above, that the 



60 EVOLUTION OF WEIGHTS AND MEASURES 

sum of all the angles around a point must be 360 degrees, and 
that the sum of the three interior angles of any triangle must 
equal 180 degrees. Furthermore, when the observations are 
reduced, allowance must be made for the difference in elevation of 
the stations and for the curvature of the earth, which, amounting 
to as much as 7 inches for each mile, becomes an important 
quantity in an extended survey. Triangulations analogous to 
those here indicated, carried out over the whole surface of a 
country, are the basis of all accurate map making, and, in. the 
United States, an arc of longitude has been measured which 
extends across the continent. 

The task of measuring the French meridian was divided by 
Delambre and Mechain, the former being assigned the northern 
portion between Dunkirk and Eodez, a distance of 380,000 toises, 
while to Mechain was given from Eodez to Barcelona, a distance 
of 170,000 toises. The reason for this unequal division was that 
the northern part of the meridian was situated in a much more 
accessible country, while Mechain's portion was in the moun- 
tainous region of Spain. In addition, the northern part had 
been measured twice previously, and the stations had been 
selected and recorded. On June 10, 1792, the King issued a 
proclamation, in which Delambre and Mechain were commended 
to the good offices of government officials and citizens generally, 
and various rights and privileges were secured to them. Both 
scientists straightway proceeded to their duties, but, owing to the 
turbulent conditions in the country, due to the Eevolution, they 
encountered from the beginning constant embarrassment and 
difficulties. In addition to being arrested and deprived of 
ordinary facilities to carry on their work, they met with little 
sympathy and co-operation on the part of officials and people, and 
experienced great difficulty in erecting and maintaining their 
signals, which were oftentimes believed to have been built for 
purposes of military communication. 

Mechain in Spain had a certain amount of assistance from the 
government of that country, but here, as in southern France, he 
was harassed and interfered with by political troubles. In fact, 
these two resolute engineers experienced almost incredible 
difficulties, being arrested by the various governing bodies that 
were at that time successively administering the affairs of France, 



DEVELOPMENT OF THE METRIC SYSTEM 61 

deprived of liberty and freedom, prevented from working by 
accident and disease, and, in short, accomplishing most creditable 
results under remarkably adverse circumstances. 

Finally, in November, 1798, Mechain and Delambre, having 
completed their work, arrived at Paris with a record of their 
observations, and an international commission invited by the 
Directory proceeded to examine and approve the geodetic and 
other scientific work accomplished in laying the foundation for 
the metric system. This commission consisted of delegates from 
the Batavian Eepublic, the Cis-Alpine Eepublic, Denmark, Spain, 
Switzerland, the Ligurian Eepublic, Sardinia (later from the pro- 
visional government of Piedmont), the Eoman Eepublic, and the 
Tuscan Eepublic, in addition to a French Committee composed of 
the physicists and mathematicians who had been chiefly concerned 
with the development of the system. The commission divided 
itself into three sections, each of which carried on a most 
thorough examination of the work already done, and made 
further calculations and verifications to establish its accuracy and 
reliability. 1 

The first section made a comparison of the bar used in measur- 
ing the length of the two bases at Melun and Perpignan, and 
found that it corresponded exactly with the toise of Peru. 
Examining the toise of Mairan, constructed from the length of 
the pendulum beating seconds at Paris, it was found to be "03413 
line shorter than the toise of Peru. The second section studied 
the measurement of the arc of meridian and the actual length of 
the meter, measuring the bases, examining the angles of each 
triangle, and finally computing separately their dimensions, em- 
ploying different tables of logarithms. The report which was 
prepared by Van Swinden, the delegate of the Batavian Eepublic, 
one of the committee to whom was assigned the actual calcula- 
tion, shows how carefully the work had been done, for, employing 
the base at Melun as a starting point in computing the triangles, 
it was found that the difference between the computed and 
measured lengths of the base at Perpignan was '160 toise (12'28 
inches = 31 '19 cm.). When it is remembered that the length of 
the Perpignan base was 6006'25 toises, and that of Melun 6075*9 

1 For a full account of this work reference should be made to Mechain and 
Delambre, Base du Systeme Metrique (Paris, 1806-1810), vol. iii. 



62 EVOLUTION OF WEIGHTS AND MEASURES 

toises, and that they were 550,000 toises apart, the accuracy of 
the measurement may be appreciated. 

The flattening of the earth was also computed, employing the 
present measurements in connection with those made in Peru, 
and it was found to be 3-J-4. 1 The most important result was 
the calculation of the length of the quadrant of the earth's 
meridian, 5,130,740 toises, which straightway gave 3 feet 11*296 *' 
lignes as the true length of the meter instead of 3 feet 11*442. 
lignes, the length of the provisional meter provided by the law of 
August 1, 1793. 

The third section, for which Tralles, the Swiss scientist, pre- 
pared the report, considered the determination of the unit of 
weight and the construction of the standard kilogram which had 
been prepared by Lefevre-Gineau, according to plans made by 
Lavoisier and Hauy, who performed the first experiments for 
this determination. 2 The preparation of this standard required 
much elaborate experimental work, and it was finally ascertained 
that the weight of a cubic decimeter of distilled water at its 
temperature of maximum density and weighed in vacuo, was 
* 18,827*15 grains, the mean of the sum of the weights of Charle- 
magne, which had been employed as the French standard for 
over 500 years. While it is not possible here actually to describe 
this determination of the unit of weight, nevertheless it is inter- 
esting to record that Lefevre-Gineau and his assistant Fabbroni 
* discovered that the maximum density of water was reached at 
4° Centigrade. 

From the sectional reports just mentioned, a general report 
was compiled by Van Swinden and presented to the Institute. 3 
The actual meter standards were then constructed by Lenoir and 
carefully compared with the toise standards. A platinum meter 
was adopted as the true meter, and was deposited in the Archives 
of State, whence it was subsequently known as the Meter of the 
Archives. Two other platinum standards 4 were constructed at the 

1 The accepted value to-day is x — , Clarke's Spheroid, 1866. 

r J 294-9784 r 

2 See Dumas, Lavoisier's Works, vol. v. 

3 See Mechain and Delambre, Base du Systeme Metrique, vol. iii. p. 592. 

4 See C. Wolf, "Recherches historiques sur les etalons de poids et mesures de 
l'Observatoire," Ann. de V Observatoire, Mem. xvii. p. 52, 1883 ; also Ann. de 
Chim. et Phys., 5 s. vol. xxv. p. 5, 1882. 



DEVELOPMENT OF THE METRIC SYSTEM 6a 

same time, and are now known as the Meters of the Conservatory 
and Observatory respectively. Iron standards were constructed 
also, and were distributed among the delegates. There was also 
constructed at the same time a platinum kilogram, and these 
standards (kilogram and meter) were formally presented by a 
delegation of the Institute to the Corps Legislatif on June 22, 
1799, and after being duly received were deposited in the 
Archives of the Eepublic. On December 10 of the same year 
by statute the provisional meter was abolished, and the new 
meter and kilogram definitely fixed and defined, and the stan- 
dards presented by the Institute to the Eepublic were adopted as 
the definite standards of weight and length. 

This act was known as the law of the 19 Frimaire, year VIIL, 
and is as follows. 1 " Article first. — The provisional determination 
of the length of the meter at 3 pieds, 11 '44 lignes, ordained by 
the laws of Aug. 1st, 1793, and the 18th Germinal, year III. 
(April 7, 1795), stands revoked and void. The said length, form- 
ing the ten-millionth part of the arc of the terrestrial meridian, 
comprised between the North Pole and the Equator, is definitely 
fixed, in its relation with the old measures, at 3 pieds, 11*296 
lignes. 

"Article second. — The meter and the kilogram in platinum, 
transmitted the four Messidor last, to the Corps Legislatif, by 
the National Institute of Sciences and Arts, are the definite 
standards of the measures of length and of weight throughout the 
Eepublic. Some exact copies of the same will be put in the 
hands of the Consular Commission, in order to serve as models 
for the construction of new measures and new weights. 2 

" Article third. — The other dispositions of the law of the 18 
Germinal, year III., concerning all that is relative to the Metric 
System, as well as to the nomenclature and the construction of 
the new weights and the new measures, will continue to be 
observed." 

Provision was made (Article IV.) for a commemorative medal, 
which, however, was never made officially, and not actually until 

^igourdan, Le Systeme Metrique, (Paris, 1901), pp. 176-177. 

2 This article was repealed in the law of July 11, 1903, by which the inter- 
national meter and kilogram were officially recognized, and the French copies 
(meter 8 and kilogram 35) were made the national standards. 



64 EVOLUTION OF WEIGHTS AND MEASURES 

1837, when the ideas of the Institute in regard to such a medal 
were carried out by MM. Gonon and Penin. 

With the scientific determination of the units and the con- 
struction of the standards accomplished, there remained but to 
effect the general adoption of the new weights and measures. 
Several conditions tended to delay this, and at times there was 
even pronounced opposition. Chief, perhaps, was the change in 
political conditions occurring in France, and it was but natural 
to expect on the part of an imperial government little interest in 
reforms effected during the republican regime. Furthermore, 
there was criticism of the system on account of the lack of 
uniformity and organization, as shown by contradictory legislation, 
and also on account of its nomenclature, much opposition being 
manifested to the use of Greek prefixes. The chief difficulty, 
however, was the lack of secondary standards, which were to 
have been constructed and distributed at the expense of the State. 
Accordingly, it was necessary to repeal such legislation, as the 
expense involved was much greater than the government could 
afford. Moreover, the temporary office or agency of weights and 
measures had been abolished too early to give the much-needed 
assistance in accustoming the people to the use of the new 
system. There was also embarrassment, due to the fact that, 
previous to March 15, 1790, there had been public scales where 
the people could weigh their merchandise. These institutions, 
which had been done away with by law, it became necessary to 
re-establish, and this was done for cities of over 5000 inhabitants 
by the Act of 27 Brumaire, year VII. (November 17, 1798), and 
subsequently for such other cities as was necessary. 

In the meantime, there were not only officials for weighing 
and measuring, but also private individuals who carried on a 
similar business, and were ready to employ the old as well as the 
new and legal measures. As a result, serious abuses and frauds 
prevailed, and the general appreciation of the merits of the new 
system was decidedly lukewarm. Nevertheless, it made progress, 
and was early adopted for all scientific works and papers 
published by the Institute to the exclusion of all other systems. 
The growth, however, was not as much among the citizens at 
large as among the government officials and scientific men. The 
reasons given were chiefly that both names and values were 



DEVELOPMENT OF THE METRIC SYSTEM 65 

changed, that foreign names and words were employed, that the 
names were too long, and that the old weights and measures were 
persistently used in bills and accounts. To answer these 
objections, but with the result of complicating matters further, a 
decree was issued 13 Brumaire, year IX. (November 4, 1800), 
which stated that the decimal system of weights and measures 
would definitely be put into execution for the entire republic 
beginning 1 Vend£miaire, year X., and, in order to facilitate its 
use, the names given to weights and measures in public documents, 
.as in customary usage, should be explained by French names as 
given in a list, which to a certain extent corresponded to the simple 
nomenclature tentatively submitted by the committee of the 
Academy of Sciences in 1793. There was to be no synonym for 
the meter, and every measure to which a public denomination 
was assigned must be a decimal multiple or subdivision of that 
unit. For the measurement of cloth the meter, with its tenth 
and hundredth divisions, was to be employed, while the term 
Mere was to be used still as a measure of firewood and as a 
solid measure, a tenth part of this measure being adopted for 
carpentry and known as a solive. The decree also provided that 
the new names should be inscribed on the weights already 
constructed, and that either one system or the other must be 
employed. 

While this action tended to weaken the integrity of the metric 
system, yet it preserved its fundamental feature of decimal 
division, but it was followed by a decree of Napoleon of February 
12, 1812, which had a most serious effect on the work already 
accomplished, and threatened its very existence. Despite the 
objections of Laplace and other scientists, a system of measures 
termed " usuelle " was established in which the metric system was 
•employed as the basis, but which made use of such multiples and 
fractions as would bring about measures that would harmonize 
with those long established by the usage of commerce and of the 
people generally. The space of ten years was fixed for a period 
during which actual experience might occasion further needs of 
further changes in weights and measures. The legal or metric 
system was to be taught in all the schools, including the primary 
schools, and was to be employed in all official transactions, 
markets, etc. To carry out the provisious of this decree an 

E 



66 EVOLUTION OF WEIGHTS AND MEASURES 

elaborate series of rules were published by Montalivet, Minister 
of the Interior, March 28, 1812. 

The " usuelle" measures were all denned in terms of the 
metric system, and there were included a large number corre- 
sponding to those in daily use. Thus the toise was the length of 
two meters, and was divided into six feet, each of which was 
denned as one-third of a meter. The foot, in turn, was divided 
into 12 inches, and each inch into 12 lignes. For the measure- 
ment of cloth and fabrics there was an aune, equal to 12 deci- 
meters, divided into halves, quarters, and sixteenths, and also 
into thirds, sixths, and twelfths. These divisions for toise and 
aune were to be marked along one face of the scale or measure, 
while the other must have the regular metric divisions on 
the decimal basis. Various weights and measures for retail 
business were provided and denned, in which the subdivision was 
by halves or some other non- decimal factor not always the same* 
Thus, for the measure of capacity, such as grain, there was the 
boisseau, defined as ^ of a hectoliter, with a double, half, and 
quarter boisseau. The liter also was divided into halves, quarters,, 
and eighths, and the shape and material of measures for various 
liquids was specified. The lime or pound was defined as equal 
to 500 grams or a half kilogram, and was divided into 16 ounces 
of 8 gros each. Provision was made for the verification and 
sealing of weights and measures by a government bureau, and 
also for the construction and distribution of secondary standards 
to the various departments. 

The use of measures other than the legal ones and those 
specified in the decree was forbidden as contrary to law. The 
legal system was still to be employed in all government works, 
officially and in commerce, and it was explained that the decree 
was designed only to affect retail business and the small trading 
of daily life. All formal notices must be expressed in legal 
measures rather than in those tolerated, and the legal system 
was to be taught in the public schools, including the primary 
schools, in its completeness. This law was in force until 
1837, and its results were most unsatisfactory, since it simply 
added to the confusion by increasing the number of weights, 
and measures. As, in any event, it was necessary to wait 
until the people at large gradually abandoned the old measures, 



DEVELOPMENT OF THE METRIC SYSTEM 67 

it served no useful purpose in the transition period to add 
new measures that essentially were neither new nor old. 
The prejudice of the people was slowly overcome, however, 
and the instruction given in the schools gradually had its 
effect. From government use and general commerce the use 
of the legal system extended slowly among retail dealers and 
small consumers. 

After an experience of a quarter of a century with the 
usuelle measures, it was thought that the time had arrived to use 
the metric system exclusively, and an attempt to that end was 
made in a bill presented in the House of Deputies, February 28, 
1837. The matter was vigorously discussed in the chamber, and 
was considered by several committees, by whom a plan for 
suitable legislation was proposed. Attention was called to the 
survival of the old measures and their general use, and to the 
fact that the mesures usuelles, while they had contributed much 
to increasing the use of the metric system, nevertheless, being 
founded on the measures of Paris, were not particularly useful 
where these measures had not been previously employed, as 
was the case in certain parts of the realm. A general 
discussion of nomenclature, systems of division, etc., took place, 
but the advocates of the metric system were most earnest in 
resisting any modifications, and it was argued that the yield- 
ing to prejudice manifested in the legislation of 1812 had 
been a serious mistake. It was also urged that people forced 
to employ the new system, in order to sell their goods, would 
soon learn, and that no new measures should be constructed 
whose contents were not in exact accord with the metric system. 
Accordingly, after considerable discussion, the following Act was 
passed by the Chamber of Peers and the Chamber of Deputies, 
and was promulgated July 4, 1837. 

Article I. — The decree of February 12, 1812, concerning weights 
and measures, is hereby repealed. 

Article II. — The use of instruments for weighing and mea- 
suring, constructed in accordance with Articles II. and III. 
of said decree, shall be permitted until January 1, 1840. 

Article III. — After January 1, 1840, all weights and measures, 
other than the weights and measures established by the laws of 
18 Germinal, year III., and 19 Frimaire, year VIII., constituting 



68 EVOLUTION OF WEIGHTS AND MEASURES 

the decimal metric system, shall be forbidden, under the penalties 
provided by article 470 of the Penal Code. 

Article IV. — Those possessing weights and measures, other 
than the weights and measures above recognized, in their ware- 
houses, shops, workshops, places of business, or in their markets, 
fairs, or emporiums, shall be punished in the same manner as 
those who use them, according to article 479 of the Penal Code. 

Article V. — Beginning at this same date all denominations 
of weights and measures other than those given in the table 
annexed to the present law, and established by the law of the 
18 Germinal, year III., are forbidden in public acts, documents, 
and announcements. They are likewise forbidden in acts under 
private seal, commercial accounts, and other private legal docu- 
ments. Public officers violating this law are subject to a fine 
of 20 francs, which shall be collected compulsorily as in a matter 
of registration. The fine shall be 10 francs for other violators, 
and shall be imposed for every single act or writing under 
private signature, but in commercial accounts there shall be only 
one fine for every case in which the prohibited terms are used. 

Article VI. — Judges and arbitrators are forbidden to render 
any judgment or decision in favor of any particular items in 
the accounts or writings in which the denominations forbidden 
by the preceding article shall have been inserted until the fines 
provided by the preceding article shall have been paid. 

Article VII. — The inspectors of weights and measures shall 
discover violations provided for by the laws and rules concerning 
the metric system of weights and measures. They may proceed 
to seize weights and instruments whose use has been prohibited 
by the said laws and rules. Their testimony in a court of 
justice shall be considered as direct proof. The inspectors will 
take oath before the tribunal of the arrondissement. 

Article VIII. — A royal ordinance shall regulate the manner 
in which the inspection of weights and measures shall be 
accomplished. 

As the metric system gradually became firmly established 
in France, the French Government, through diplomatic channels, 
called attention of the various nations to its many advantages, 
and, at the same time, distributed a number of copies of the 
Meter of the Archives, which had been prepared at the Con- 



DEVELOPMENT OF THE METRIC SYSTEM 69 

servatoire des Arts et Metiers, where now the work of preparing 
standards and of carrying on other operations in connection with 
the weights and measures took place. For this bureau, a new 
comparator, capable of exact measurement and facilitating the 
operation of comparison, had been constructed by Gambey, and it 
enabled a large number of accurate standards to be prepared for 
commercial and industrial use, though in most cases no remark- 
able degree of precision was obtained. Important work, however, 
was done in the study of platinum standards of the meter for the 
Prussian Government, preparatory to the general adoption by 
that country, of the metric system. This work was carried 
on by Eegnault, Le Verrier, Morin, and Brix. 1 

With the growing use of the metric system for scientific work, 
not only in France, but throughout Europe, the importance of 
the accuracy of its fundamental units became a matter of 
interest to mathematicians and geodesists in several countries. 
Increased activity in geodesy had brought about a number of 
measurements of arcs of meridian, and with the resulting data 
it became possible to compute anew the shape of the earth 
and the length of the quadrant. Any change in this last quantity, 
of course, affected the length of the meter as the fundamental 
unit of length, and called it into question as an absolute and 
natural standard. That such was the case was early demon- 
strated by Bessel, 2 while General T. F. De Schubert of the 
Eussian Army, Colonel George Everest of the British Army, and 
Captain A. E. Clarke of the British Ordnance Survey, made 
geodetic measurements and studies, which enabled them more 
accurately to determine the shape of the earth. As a result of 
this work, it was found impossible to depend upon the accuracy 
of the determination of the measurement of the quadrant of a 
great circle, as it would vary in different places, and required 
a most exact knowledge of the shape of the earth. 

These questions, it must be remembered, were purely scientific, 
and did not influence the practical development of the system 

^enolt, "De la Precision dans la Determination des Longueurs en 
Metrologie," Rapports Congr&s International de Physique, Tome 1, 1900, p. 45. 

2 "Ueber einen Fehler in der Berechnung der Franzosischen Gradmessuug und 
seinen Einfluss auf die Bestimmung der Figur der Erde." Schum. Ast. 
Nachrichten, 1844, vol. xix. No. 438, pp. 98-1160. 



70 EVOLUTION OF WEIGHTS AND MEASURES 

either in France or abroad, but they provoked much discussion 
among scientific men. With the series of world's expositions, 
which began with that at London in 1851, an opportunity was 
given to the people at large to examine and appreciate the 
benefits of an international system of measures, while statistical 
and scientific congresses saw the advantages resulting from the 
use of uniform weights and measures. Important among these 
was a convention formed largely of the official delegates to the 
Paris Exposition of 1867, which adopted a series of resolutions in 
which the superiority of the metric system of weights and 
measures was conceded, the benefits of uniformity stated, and its 
adoption by the civilized world urged. Furthermore, the con- 
vention deemed it advisable to advocate the study of the metric 
system in the public schools, and to recommend its use for 
scientific publications, public statistics, postal service, in customs, 
and in all works carried on by the governments. 

In the same year the International Geodetic Association, com- 
posed of delegates from the leading countries of Europe, met at 
Berlin, and was engaged in the discussion of topics of great 
concern to all interested in scientific measurement. Inasmuch as 
many of the standards of length used for base measurements were 
all end standards, 1 which doubtless had become worn, or possibly 
were inexact, these geodesists considered it of the utmost import- 
ance that there should be new and common standards as abso- 
lutely correct as then existing conditions of metrological science 
could make them. This having been done all base measurements 
could be referred to the same linear standard, thus insuring that 
all European geodetic work could be comparable, and could be 
reduced so that a degree of a great circle of the earth could 
be determined with accuracy from a number of different measure- 
ments. This convention decided that the interests of science in 
general, and of geodesy in particular, demanded a uniform decimal 
system of weights and measures throughout Europe, and recom- 
mended the adoption of the metric system without essential 
change, and especially without the metric foot. 2 In order to 

1 There were by this time a few geodetic line standards, among others those of 
Spain, Egypt, and probably that of Clarke. 

2 Berieht iiber die Verhandlungen der von 30 September bis 7 Octobre, 1867, zu 
Berlin abgehaltenen allgemeinen Conferenz der Europaischen Gradmessung, Berlin, 
1868, p. 126. 



DEVELOPMENT OF THE METRIC SYSTEM 71 

secure such a uniformity of measures the convention decided in 
favor of the construction of a new European prototype meter 
differing in length as little as possible from the Meter of the 
Archives at Paris, and compared with it to the highest degree of 
accuracy possible. In its construction there would be observed 
all refinements secured by the advance of metrological science, 
and especially there would be considered its availability for 
comparisons with secondary standards of length. The con- 
struction of the new standard was to be undertaken by an 
international commission appointed by the respective governments, 
and the desirability of establishing an international bureau of 
weights and measures was expressed. Thus the metric system 
came to be recognized as something of international concern, and 
its preservation and improvement a matter that concerned the 
world at large as well as France. 

The action of the Association G-eod6sique was echoed by the 
St. Petersburg Academy of Sciences, and this body expressed the 
interest of the scientific world at large in a proper standard of 
mass, as well as a new standard of length, in a communication to 
the Paris Academy of Sciences in 1869, in which they suggested 
taking common steps towards the establishment of an inter- 
national metric system. This proposition was not enthusiastically 
received in France, where many of the scientific men thought 
that the meter and the kilogram were the work of French 
savants, and looked upon them as something that should not be 
tampered with, especially by alien scientists ; but those more 
especially interested in metrology perceived that the application 
of recent advances in the theory and practice of the science of 
weighing and measuring was desirable, and that new standards 
•could be constructed with profit, provided that the original 
standards should remain as the underlying basis of the system. 
Accordingly, on the representation of the Paris Academy of 
Sciences, the French Government took up the matter, and after 
an examination of the question in its different aspects by a 
•committee consisting of representatives from the Academy of 
Sciences and the Bureau of Longitude, a report was made in 
favor of the proposed plan, and the Minister of Agriculture and 
Commerce (Alfred Leroux) brought the matter to the attention 
of the Emperor, Napoleon III., in a long and comprehensive 



72 EVOLUTION OF WEIGHTS AND MEASURES 

statement, dated September 1, 1869, favoring the calling of an 
international conference. 1 

This report was approved by the Emperor, and the French 
Government communicated through diplomatic channels with the 
various nations, inviting them to send delegates to a conference 
to be held at Paris to discuss the construction of a new prototype 
meter as well as a number of identical standards for the various 
participating nations. This action was especially important as 
emphasizing the international character of the system by allowing 
the participation of a number of nations in the construction of a 
standard that would serve for all, France included. It was also 
an admission on the part of the French Government that a new 
(line) standard (mMre a trait) was necessary, and that every 
means should be taken to conserve the metric system by putting 
its standards on a permanent basis. 

The invitation was accepted by the nations to which it was 
extended, and in August, 1870, delegates from twenty -four States 
met at Paris. In the meantime, in order to make suitable 
preparations, and to lighten the work of the International Com* 
mission as much as possible, the French members had assembled, 
and since September 1st, 1869, had been actively engaged in 
studying the subject, especially on its scientific side, and preparing 
a working basis for the conference. 2 Owing to the breaking out 
of the war between Germany and France this session was of 
short duration, but it was decided that instead of a single new 
standard a number of identical standards should be constructed 
for the nations participating in the convention, and that one of 
the number should be chosen as the international standard, and 
should be deposited in some convenient place accessible to all the 
participating countries, and under their common care. 

Summoned anew by the French Government, the International 
Commission met under more peaceful auspices at Paris, on Sep- 
tember 24, 1872, thirty States being represented by fifty-one 
delegates, among whom were included many distinguished 
scientists, and, as was natural, the foremost metrologists of the 
world. By reason of the previous session, and the activity of 
the French committee in the interval that had elapsed, the 
work of the Commission was very clearly mapped out, and 

1 Bigourdan, Le Systeme Mitrique (Paris, 1901), pp. 265-272. * Ibid. p. 273. 



DEVELOPMENT OF THE METRIC SYSTEM 73 

little time was spent in mere preliminary discussion. The first- 
and most important announcement was the report of the French 
Committee, that after a careful examination had heen made of 
the standards of the Archives, the Meter was found in a. 
very satisfactory state of preservation, and in such condition 
as to inspire all confidence in any operations for which it might 
serve as a base. Likewise, the Kilogram of the Archives also- 
was found to be perfectly preserved. Comparisons which were 
effected between the prototype meter and its contemporaries of 
the Conservatory and the Observatory demonstrated that the- 
Meter of the Archives had not appreciably altered in length. 1 

The Commission was divided into eleven committees composed 
of delegates specially qualified for the separate branches of the- 
work, and the subjects assigned to each committee were as follows: 
Study of the ends of the meter of the Archives, material for the- 
new meter, its form and method of support, thermometry and 
expansion, normal temperature of the meter and kilogram, weights- 
in vacuum or in air, comparator, creation of an international bureau 
of weights and measures, weight of a cubic decimeter of water r 
material and form of the standard kilogram, balances and 
methods of weighing, and preservation of the standards and 
providing for their invariability. 

Addressing themselves to the consideration of these topics, the 
commission speedily reached satisfactory conclusions, and specific- 
resolutions were adopted outlining the plans to be followed and 
the direct decisions which the Commission had arrived at. 2 

These resolutions were in substance as follows : The Mttre des- 
Archives was to be the point of departure, and was to be repro- 
duced by a mMre a traits (line standard), it having been found 
that the ends of the platinum bar of the historic meter were 
sufficiently well preserved to warrant employing it as an original 
standard. This last matter, however, would be finally determined 
when the actual work of comparison had commenced. The- 
identical copies of the standard meter to be furnished to each of 

1 Bigourdan, Le Systtme Metrique, p. 274. 

2 For complete text of resolutions and discussion, see Bigourdan, Le SysQme 
Mdtrique, pages 299-313. A translation of the same will be found pages 52-55, 
"Report of the Committee on Coinage, Weights and Measures," of the House of 
Representatives, 46th Congress, first Session, Report 14, 1879. 



74 EVOLUTION OF WEIGHTS AND MEASURES 

the countries were to be metres a traits, but at the same time a 
number of end standards {mhtres a bouts) whose equations would 
also be determined, would be constructed for such countries as 
specially desired them. The new standards were to represent 
the length of a meter at degree centigrade, and the material 
was to be an alloy of platinum 90 per cent, and iridium 10 per 
cent., with a tolerance of 2 per cent, either in excess or defici- 
•ency. The measuring bars were to be constructed from a single 
ingot produced at one casting and carefully annealed. Their 
length in the case of the metres a traits was to be 102 centi- 
meters, and their cross section was carefully designed according 
to specification by Tresca. 1 Detailed instructions were also 
.adopted for the determining of the expansion, the marking, and 
the calculation of the equations of the different standards. The 
.action of the Commission in reference to the kilogram was as 
follows (Section xxii.) : " Considering that the simple relation 
which was established by the originators of the metric system 
.between the unit of weight and the unit of volume is represented 
by the actual kilogram in a manner sufficiently exact for the 
•ordinary uses of industry and of commerce, and even for most 
of the ordinary requirements of science ; considering also that the 
exact sciences have not the same need of a simple numerical 
relation, but only of a determination of such relation as perfect as 
possible ; and considering the difficulties that would arise from a 
^change in the actual unit of the metric system, it is decided that 
the international kilogram shall be derived from the kilogramme 
<des Archives in its actual state." The international kilogram was 
to be determined with reference to its weight in a vacuum, and 
the material of the standards was to be the same alloy of 
platinum-indium as was employed for the standard meters. In 
form the international kilograms were to resemble the Kilo- 
gram of the Archives, being cylindrical, with height equal to 
the diameter, and with the edges slightly rounded. It was also 
decided that the determination of the weight of a cubic decimeter 
of water should be made by the Commission, and that a new 
balance of extreme precision should be constructed and employed. 
The method of weighing and determining the volume of the 
kilograms was outlined, but it was decided that, as also in the 

1 See chapter x., p. 254. 



DEVELOPMENT OF THE METRIC SYSTEM 75 

case of the mUre des Archives, the kilogramme des Archives should 
not be placed in a liquid until the end of the operations. 

The plan for actually carrying out the work of the Commis- 
sion involved the construction of as many identical standard 
meters and kilograms as were needed by the countries interested, 
all of which should be made and compared by the Commission, 
and required that a standard meter and a standard kilogram 
should be selected as international prototype standards in terms 
of which the equations of all the others should be expressed. 
The actual construction of these new standards, the tracing of 
the denning lines, and the comparison with the standards of the 
Archives, were entrusted to the French section of the Commission, 
which was to perform the work with the concurrence and under 
the general direction of a permanent committee of twelve mem- 
bers duly appointed to have general supervision of the work. 

The Commission also advocated the founding of an inter- 
national bureau of weights and measures, to be located at Paris, 
which would be both international and neutral, and supported by 
the common contributions from the nations party to a treaty 
creating such an establishment. It was proposed that it should 
be under the supervision of the permanent committee of the 
International Metric Commission, and should be used for the 
comparison and verification of the new metric standards, for 
the custody and preservation of the new prototype standards, and 
for such other appropriate comparisons of weights and measures 
as might come before it in proper course. In accordance with 
the suggestions of the Commission, the French Government again 
communicated diplomatically with the various governments rela- 
tive to the establishment of such a bureau, and the reports of 
the various delegates having in the meantime been made, and the 
project in all its details thoroughly understood, on May 20, 1875, 
a treaty was concluded at Paris, in which the recommendations 
of the Commission were put into effect. 1 This treaty was duly 
signed by accredited representatives of the following countries : 
United States, Germany, Austria-Hungary, Belgium, Brazil, 2 

^ee Bigourdan, Le Systeme M&rique, pp. 328-337. U.S. House Representa- 
tives, Committee on Coinage, Weights and Measures, 46th Congress, 1st Session, 
Heport No. 14, pp. 43-50. 

2 Brazil did not ratify the treaty. 



76 EVOLUTION OF WEIGHTS AND MEASURES 

Argentine Confederation, Denmark, Spain, France, Italy, Peru r 
Portugal, Kussia, Sweden and Norway, Switzerland, Turkey, and 
Venezuela. Of the countries present at the conferences, Great 
Britain and Holland declined to participate in the treaty or to 
contribute to the expense of an international establishment for 
the metric system. The British Government, in explanation of 
this action, stated that they could not recommend to Parliament 
any expenditure in connection with the metric system, inasmuch 
as it was not legalized in that country, nor could it support a 
permanent institution established in a foreign country for its 
encouragement. A change of feeling, however, took place in 
England, and in September, 1884, Great Britain joined the 
Convention. With the treaty were signed at the same time a 
series of regulations for the newly created bureau, and a set 
of temporary or transient provisions referring to the work already 
in hand which had been undertaken by the French section under 
the direction of the conference of 1872. * 

The treaty provided for the establishment and maintenance, 
at the joint charge of the contracting parties, of a scientific 
and permanent international bureau of weights and measures, to 
be located at or near Paris, in a territory to be kept strictly 
neutral. The bureau was to be installed in a special building, 
supplied with the necessary instruments and apparatus, and was 
to be conducted by an international committee, composed of 
fourteen delegates, each from a different country, with a personal 
scientific staff of a director with assistants and workmen. The 
first duty of the bureau would be the verification of the new 
international metric standards then in progress of construction, 
but, in addition, it would have such permanent functions as the 
custody of the new international metric prototypes, all future 
official comparison with those of the national standards, com- 
parisons with the metric standards of other units, the stan- 
dardizing of geodetic instruments and other standards and scales 
of precision, and, in short, to undertake such scientific work 
connected with metrology as would be possible with its equip- 
ment, and which would supply the greatest benefits to the 
supporting nations. The expense of the new establishment was 
to be met by contributions from the various signatories to the 
convention, on the basis of their respective population, multiplied 



DEVELOPMENT OF THE METRIC SYSTEM 77 

by the factor 3 for countries where the metric system was 
obligatory, by 2 where it was legalized but not obligatory, and by 
1 where it was not yet legalized. 1 

The treaty was ratified by the various contracting governments, 
and the international committee from the conference of 1872 was 
continued under the presidency of General Ibanez of Spain, and 
authorized to begin the preliminary operations. The first 
question was to find a suitable location for the laboratories of 
the bureau, and this was solved by the offer of the French 
Government to turn over, without charge, the Pavilion de Breteuil, 
including a tract of land about two and a half hectars in extent, 
situated on the bank of the Seine near Sevres, at the entrance 
of the Park of St. Cloud. 2 This building, which is on a hill, 
dates back to the time of Louis XV., and was used by kings 
and emperors as a palace and place of resort, especially by 
Napoleon I., who, it is said, was at times wont to study here. 
The pavilion itself was in bad repair, having been damaged in the 
siege of Paris, but the walls were in good condition, and it was 
decided to put the building in order to be used for the offices of 
the bureau and the residence of the staff, and to construct a new 
and special building for the actual scientific work and for the 
safe keeping of the international prototypes. The latter obser- 
vatoire or laboratory, a one-story building, was completed and 
the apparatus installed from 1878, and has been in constant use 
ever since. Its equipment has for the most part been specially 
provided, and includes, without doubt, the most complete and 
accurate instruments of precision in existence. Each of these 
merits a complete description, which is of course not possible 
in these pages, but some of the essentials of the more im- 
portant instruments will be found described in the chapter on 
Standards. 3 

The construction of the new standards involved greater 
difficulties than had been anticipated. The French section 
had melted an ingot of the platinum-iridium alloy specified by 
the conference of 1872, but it was found to contain impurities 

1 It has recently (1906) been proposed by the Committee to drop the coefficients. 
8 For description see Bigourdan, Le Systeme Me'trique (Paris, 1901), pp. 353-362. 
Ouillaume, La Convention du Metre (Paris, 1902), pp. 21-25. 
3 See chapter x. 



78 EVOLUTION OF WEIGHTS AND MEASURES 

in the form of slight admixtures of rhodium, ruthenium, and 
iron. This, accordingly, provoked a controversy, which, however, 
was settled by obtaining eventually material which satisfied 
all the requirements. 

From time to time, as occasion demanded, 1 the International 
Committee held various meetings connected with the maintenance 
and operation of the Bureau International, and in 1887 a 
resolution was passed denning the unit of mass as follows : 

" The mass of the international kilogram is taken as unity for 
the international use of weights and measures." 2 

This definition enabled a more perfect statement of the funda- 
mental basis of the metric system to be made, and produced an 
increased exactness which was most desirable. In 1889 a second 
International Conference was assembled, which passed on the 
work of the International Committee, and approved the standards 
which were submitted for their examination, together with a 
record of all experiments and investigations that had been made 
in their preparation. The conference definitely adopted the 
international prototypes of the meter and of the kilogram as the 
standards of length and mass respectively, and the centigrade 
scale of the hydrogen thermometer was adopted for their 
definition and determination. The national prototype standards 
were also approved, and were distributed by lot to the various 
countries contributing to the Bureau, and, finally, a committee 
was appointed to deposit the international standards, — meter 
and kilogram, — in the safe of the vault of the Observatory 
at Breteuil designed for their reception, and this was accom- 
plished with the observance of all due formality, — the various 
keys of the apartment being distributed to different officers, 5 
whose joint presence was necessary for any examination of the 
standards. 

Mention might properly be made of the elaborate scientific 
researches carried on at the Bureau, and the valuable memoirs 4 

1 Formerly every year ; now every two years. 

2 Proces-verbaux du Comite" International des Poids et Mesures pour 1887, 
p. 88. 

, 3 The president of the International Committee, the director of the French 
Archives, and the director of the Bureau. 

4 See Travaux et Me" moires du Bureau International des Poids et Mesures 
(Paris, 1881—). 



DEVELOPMENT OF THE METRIC SYSTEM 79- 

published at frequent intervals in which these are described. 
With the determination of the prototype standards for the meter 
and the kilogram accomplished, many other problems in metrology, 
such as the study of temperature measurements, the determina- 
tion of the meter in terms of the wave-length of light, the 
construction of standards for electrical measurements, the study 
of alloys for standards, especially those used in geodesy, etc.,, 
have received attention from the scientific staff, and the work 
accomplished has been of marked and permanent value. 



CHAPTER III. 
DEVELOPMENT OF THE METRIC SYSTEM IN EUROPE. 

While an international system of weights and measures was 
■contemplated by the French scientists, yet in the formulation of 
the metric system comparatively little general interest was 
manifested by other nations, and comparatively little aid was 
given by their scientific men. We have seen how an international 
•commission of scientists examined and approved the determination 
of the meter and kilogram, and the important parts played by 
Van Swinden and Tralles in this work of verification. 1 These 
foreign delegates appreciated the advantages of the new system, 
as did other men of science, but the times were unpropitious for 
innovations which would unsettle and change the ordinary habits 
.and customs of the people. Inasmuch as France was at war 
with the greater part of Europe during the opening years of the 
nineteenth century, the mere mention of the source of reforms in 
weights and measures was in many instances an argument against 
their adoption. Furthermore, the actual governments themselves 
were changing constantly in many parts of Europe, and the 
struggle for territory and national existence was of more im- 
mediate importance than such minor matters as those concerning 
commerce and the domestic life of the people. Indeed, had the 
change been attempted generally at this time it would hardly 
have met with success ; for, as we have seen in the case of France, 
not only was compulsory legislation eventually necessary, but an 

1 The names of nine foreign scientists were attached to the documents accom- 
panying the standard meter and kilogram when given to the French Government 
for deposit in the Archives. 



THE METRIC SYSTEM IN EUROPE 81 

able and active administration working on some wise and per- 
manent plan was required to put it into effect. Consequently, 
before any general consideration of adopting the new system 
could take place, it was necessary that there should be perman- 
ence and stability in the various governments. 

As the fixing of weights and measures is manifestly an 
attribute of government, so any successful reforms must depend 
upon the character and strength of a particular government, and 
in order to influence neighboring countries the territory affected 
should be comparatively large and the number of its inhabitants 
considerable. Consequently the adoption of the metric system, 
in a half-hearted way, by a petty kingdom here and a principality 
there, likely at any time either to be absorbed by its neighbors, or 
to conquer and to rule them, would and did have little influence 
on the general ultimate use of the new weights and measures. 
This, however, must not be understood as implying that at the 
beginning of the nineteenth century there was no need for 
reforms either in Europe at large or in particular states. 
Mediaeval conditions survived, and the same evils that prevailed 
in France were experienced throughout Europe. The same name 
was applied to measures whose values varied considerably not 
only in different states but even in different cities of the same 
state. Lack of uniformity, both in units and standards, was 
universal, with the natural result of hindering commerce and of 
generally cheating the less intelligent party to any transaction. 
True, French conquest had carried with it the metric system, but 
it was used merely under compulsion, and so soon as there was a 
change in political conditions the old measures were resumed. 
Aside from the scientific propaganda, due to the undisputed 
pre-eminence of French workers in exact and applied science, 
comparatively little could be done towards forcing the issue, and 
the adoption of the metric system waited largely on political 
circumstances which affected the life and commerce of the people 
at large, and which were duly appreciated by statesmen. These 
conditions were brought about by the decline of war, and the 
resulting opportunity for the people to turn to the pursuits of 
farming, commerce, and manufacturing. If a number of states or 
cities were brought into closer political relations, forming a larger 
state or possibly a confederation, their commercial relations 

F 



82 EVOLUTION OF WEIGHTS AND MEASURES 

naturally developed, and in order to increase the wealth and 
resources of the state, both material and military, it was essential 
that the government should take such measures as would best 
stimulate commerce and manufactures. Accordingly, it was early 
recognized that uniformity of weights and measures within the 
boundaries of a state not only contributed but was essential to 
the welfare of its inhabitants, while, furthermore, its foreign 
commerce was increased by having the same weights and 
measures as its neighbors. When we join to these considerations 
the fact that the separate systems in nearly all cases were 
illogical, inconvenient, and lacking in uniformity and facility of 
use, we have the explanation of the eventual spread of the metric 
system in Europe. 

On the return of Tralles from Paris he endeavored to introduce 
into Switzerland the metric weights and measures, and on March 
4th, 1801, a law was passed adopting these measures ; but, against 
his advice, special names were given^ to the various measures. 
Likewise, Van Swinden, after his return to Holland from Paris, 
attempted to bring about the adoption of the metric weights and 
measures in his own country, and in 1802 the Corps Legislatif 
decided in part on the new system. Yet so many features were 
lacking from their plan, that the completeness and general 
availability characteristic of the system were much impaired, to 
the great regret of the scientist. No record has been found to 
.indicate whether the law was repealed or never came into effect, 
but with the invasion of Holland by Napoleon, a decree of 
January 11, 1811, referred the weights and measures of that 
country to those of the metric system. 1 

In Milan, in 1803, the meter and the kilogram were adopted as 
the basis of a series of measures arranged on a decimal scale, but 
new and local names were given to them. Thus the braccio, as 
the unit of length, was equivalent to the meter, while the kilogram 
was known as a libbra metrica, or metric pound. In Baden, in 
1810, a^jfund, equal to one-half of the kilogram, was adopted as the 
unit of weight, and was decimally subdivided. The unit of linear 
measure was the ruthe, which was equivalent to three meters, 

1 Bigourdan, Le Systeme M&rique, p. 241. On August 21, 1816, a law was. 
enacted establishing the metric system, and later additional Acts were passed 
which will be alluded to in the course of a few pages. 



THE METRIC SYSTEM IN EUROPE 83 

while the dry and liquid measures of capacity were also defined 
in terms of the French metric measures. However, subsequent 
legislation was required, and by an order dated August 21, 1828, the 
new measures were made compulsory with the year 1831. Some- 
what similar steps were taken also in Hesse-Darmstadt in 1821, 
the pfund and the shoppen being made equal to one-half a kilogram 
and one-half a liter respectively, while the fuss, or linear unit, was 
one-fourth of the meter, and the elle four-fifths. In Switzerland, 
in 1828, it was proposed to adopt a common system of weights and 
measures for the various cantons, and in 1835 twelve of these 
divisions entered into an agreement known as the " Maass 
concordats," to which reference will be made later. This plan 
consisted essentially of the usual measures defined in terms of the 
metric units. 

The French Government, as we have seen, having experienced 
difficulty in securing the exclusive use of the metric system by its 
own people did not take active measures towards extending its use 
abroad until after the passage of the law of 1837, which rendered 
the system universal and compulsory throughout France. In 1841 
the Minister of Agriculture and Commerce, Cunin-Gridaine, con- 
sidered that much good would be accomplished by the exchange 
of standards of weights and measures between France and the 
important commercial countries of the world. He was supported 
by the Minister of Foreign Affairs, Guizot, who arranged for such 
an exchange through the diplomatic channels of the various 
governments. 1 Accordingly these standards were duly sent, and 
in 1853 the United States received a complete series of French 
standards, which included a steel meter that had been compared 
with the platinum standard at the Conservatoire des Arts et 
Metiers, and likewise a gilt kilogram whose constants had been 
determined in terms of the kilogram of the Archives. 

The beginning of a general feeling in favor of the universal 
adoption of a single system of weights and measures, and the 
opinion that for this purpose the metric system was the most 
suitable, may be considered to date from the London Exposition 
of 1851, to which reference has already been made. Despite 
the fact that metric weights and measures had been used, and 
their adoption advocated by scientific workers, it cannot be said 

1 Bigourdan, Le Systeme M6trique, p. 245. 



84 EVOLUTION OF WEIGHTS AND MEASURES 

that before this time the importance of the subject was recognized 
generally, and that economists and statesmen had thoroughly 
realized the benefits that would ensue from a single and 
universal system of weights and measures, as well as a common 
and universal basis for coinage, in which there should be a 
single, and preferably decimal, principle of division. But from 
such a beginning the agitation spread, and nearly every nation 
soon had a group of earnest advocates of the metric system, 
which included not only such scientific men as chemists, 
physicists, astronomers, and engineers, not to mention economists 
and statisticians, but also merchants and manufacturers. This 
was due to the bringing together from many quarters of the 
globe of a large number of representative merchants, producers, 
and manufacturers, with their various wares and products, and 
also scientific men and others who were called to pass upon the 
comparative merits of the various articles on exhibition. At 
the conclusion of the London Exposition, the Society of Arts, 
in a communication addressed to the Lords of the Treasury, asked 
if it were not possible that some arrangement could be made 
whereby a universal decimal system of moneys, weights, and 
measures could be adopted in common for all the nations of the 
world. This was possibly the first expression in England, outside 
of scientific circles, of the general advantages of universal weights 
and measures, and particularly those that would accrue to com- 
merce by the adoption of a uniform decimal system. In 1855 
an international statistical congress was held at Paris, and on 
the motion of James Yates, a member of the Eoyal Society 
of London, it was decided to form an International Association, 
to advance the adoption of a decimal system of weights and 
measures and moneys. This association made an examination of 
the different systems employed throughout the earth, and decided 
that the metric system, on account of its scientific character and 
general availability for international trade, was to be preferred, 
and accordingly made a recommendation in its favor. The 
sentiment was further echoed by members of the International 
Jury of the Paris Exposition of 1855, who formally adopted 
resolutions in favor of the metric system, recommending it to 
the attention of their respective governments, and urging its 
adoption on the ground that it would not only promote commerce, 



THE METRIC SYSTEM IN EUROPE 85 

but also peace and unity of feeling throughout the world, praising 
especially its decimal basis. 1 

A Committee of Weights and Measures and of Moneys, com- 
posed of delegates of various countries to the Paris Exposition 
of 1867, was formed at the initiative of these delegates, and took 
action in favor of the decimal system, and urged the adoption 
of uniform weights and measures throughout the world. While 
this committee enjoyed no official standing, yet it adopted reso- 
lutions recommending the study of the metric system in all the 
schools, and its recognition in all public meetings. Furthermore, 
its exclusive use in scientific and statistical publications, for 
postal purposes, in the customs, as well as in public works, 
and in all other branches of government administration was 
recommended. 2 

In the meanwhile, the inconvenience and confusion caused by 
different weights and measures throughout Central Europe had 
reached a point where positive action was necessary. Under 
more peaceful conditions, commerce and industry were beginning 
to flourish, and the lack of uniformity in weights and measures 
was proving a serious hindrance to trade. In a comparatively 
small territory there was a considerable number of different 
states with different systems of weights and measures, as well as 
with different tariff and customs regulations, which seriously 
interfered with the easy transaction of international business. 
The multiplicity of these measures involved the employment of 
an inordinately large number of clerks and computers in custom 
houses and counting rooms to change from one system to another 
weights, measures, and moneys, as specified in invoices, and other 
documents. It was doubtless also realized that to carry on 
commerce there must be an easy standard of comparison between 
the goods of the home country and those of other foreign coun- 
tries. The money alone was recognized as a sufficient cause of 
trouble, and extensive reforms, such as the decreeing of uniform 
(Metric) weights for metallic currency by the Vienna Coin 
Treaty of January 24, 1857, and a similar action by the so-called 
Latin Union of 1865, improved materially conditions in this 
respect, and it may be remarked that in both instances the 
currency was put on a decimal basis. 

1 Bigourdan, Le Systeme Mttrique, p. 248. 2 Ibid. p. 248. 



86 EVOLUTION OF WEIGHTS AND MEASURES 

With the weights and measures, however, the first steps to- 
ward uniformity were taken when the metric system was adopted 
for customs purposes, some time before its legal adoption for 
general use in the separate states. Thus the German Zollverein 
(Customs Unions) 1 adopted for use in the customs a standard 
metric pound {zollpfund) which was one-half of a kilogram, and 
with it a centner of 50 kilograms. These units of weight came 
into effect January 1, 1854, and the pfund, which was divided 
into 30 loth, was adopted by the German- Austrian Zollverein, for 
postal purposes, on the same date. In 1856 the use of the metric 
pound and centner was further extended, and in 1857 a coin 
pound or munzpfund (500 grams) was employed for coinage 
purposes. The railways also followed the example set by the 
customs, and throughout the countries constituting the Zoll- 
verein all freight was weighed by the metric pound. Thus it 
will be seen that the entering wedge of the metric system in 
Europe outside of France was in the adoption of uniform weights 
for international trade, which led to a general knowledge of its 
merits and appreciation of the advantages of uniformity. 

The natural and immediate result was the adoption of the 
" zollpfund " as the unit of weight in a number of states, and with 
this came a general understanding of the inconvenience attending 
the use of different standards for measures of length, capacity, 
etc. In consequence, a commission of scientific men was 
appointed from the federated German states to examine the 
question thoroughly, and formulate a national system of weights 
and measures. They reported in 1861 that the metric system 
already possessed the advantages sought after, and that greater 
benefits would ensue from its adoption as a whole than by 
devising a new system or by endeavoring to harmonize existing 
standards. 

The method of the change in Germany is well worth careful 
study from the student of metrology and of public affairs, inas- 
much as here were represented most of the problems which 

1 The Zollverein, or union of German states to secure among themselves freedom 
of trade and uniformity of duties on foreign imports, was proposed by Prussia in 
1818. The North and South German Unions, formed for this purpose, were 
united in 1829 by a treaty which became effective in 1834, and in 1854 a strong 
union of nearly all the German states was brought about. 



THE METRIC SYSTEM IN EUROPE 87 

would be encountered were the same change to be made in the 
near future either in the United States or in Great Britain. In 
fact, the conditions may be said to be practically the same, for 
although standards and processes based on Anglo-Saxon measures 
have since developed to such an extent that a change would be a 
serious matter, yet, at the same time, the use and knowledge of 
the metric system have also increased, so that on this score the 
change would be far less difficult now than it was for Germany 
in 1870. Furthermore, reforms in arbitrary gauges and methods 
of measurement are now required in various lines of industry and 
manufacturing, which make the present an especially appropriate 
•time for a general change in measures. Consequently, by study- 
ing methods and conditions in Germany at the time of this 
change, it is fair to say that an accurate knowledge of the general 
features of any present problems of this description will be gained, 
and it is also safe to say that the final advantageous outcome 
would be reproduced in either the United States or Great Britain, 
though the time necessary to accomplish such a consummation may 
reasonably be a subject for difference of opinion and argument. 

The first legislative step in the introduction of the metric 
system into Germany was the adoption of resolutions to that 
effect by the Federal Council and the Parliament of the North 
German Confederation, which were published under the date of 
August 17, 1868. 1 These resolutions provided that the metric 
system should be adopted in place of the weights and measures 
previously in use, and that the system should be optional on 
January 1, 1870, and obligatory on January 1, 1872. No change 
in the nature or execution of this plan occurred when in April, 
1871, the confederation was superseded by the empire. There 
was duly established the " Normal- Aichungs-Kommission," which 
was charged with the work of furnishing detailed directions and 
specifications as to the material, shape, and other characteristics 
of the weights and measures, and also with supplying the 
*' marking " office and its various local branches with such imple- 
ments as would enable it to mark and stamp all weights and 
measures which should be presented to it. It was also ordered 

1 W. Foerster (former Chief of the German Bureau of Weights and Measures, 
and President of the International Committee of Weights and Measures), pp. 12, 
13, House of Representatives, Paport No. 2885, 54th Congress, 2nd Session, 1897. 



88 EVOLUTION OF WEIGHTS AND MEASURES 

that the confederated governments publish the calculations giving 
the figures for the legal equivalents of the new weights and 
measures as compared with the old. 1 The Commission had charge 
of the introduction of the new system throughout the confedera- 
tion, supervising all measures to facilitate its speedy acceptance, 
and with definitely carrying it into effect. The various states of 
the confederation appointed officials for the actual marking and 
stamping of the measures and weights, and prescribed regulations 
for the administration of such bureaus. In the ten months 
previous to the date assigned for the beginning of the optional 
use of the metric weights and measures, the Commission provided 
all the marking offices with standards for the verification of such 
weights and measures as should be presented to them for legaliza- 
tion, and immediately after these needs had been met the 
manufacturers were provided with proper standards, so that they 
could at once commence the manufacture of weights and measures 
for general sale and use. Such weights and measures, adequate 
in number and of high accuracy, were soon forthcoming, and by 
the end of the first half of the year 1870 a large part of the 
people of Germany became well acquainted with the new 
measures, their decimal division appealing particularly to the 
industrial and technical workers. 

In 1870 occurred the war with France, and, while it prejudiced 
many of the people against the new weights and measures, never- 
theless it more closely united Germany and thus offset any 
difficulties on this score. In short, on the arrival of the 
specified date, January 1, 1872, when the use of the old weights 
and measures must cease and the metric system be the only 
legal system, not only were the new weights and measures 
supplied to all places throughout Germany where merchandise 
was sold, but the various tradesmen and others concerned had 
actually learned the use of meter sticks, liter measures, and the 
series of gram weights. This record is somewhat remarkable,, 
as in Germany there was not one system of weights and 
measures, but, as has been shown, a large number of different 
systems which the new measures had to supplant. Germany, 
however, enjoyed one great advantage in the adoption of the 
metric system in the extensive use in a number of the 
1 Same Report, pp. 7, 8. 



THE METRIC SYSTEM IN EUROPE 89- 

states of the " zollpfund " or customs pound, above mentioned, 
which we have seen was the weight of 500 grams or a half 
kilogram. Weights of this denomination were actually in 
existence in considerable numbers and were widely employed, 
but the subdivisions were not usually on a decimal or metric 
basis, and only in one state, Hanover, was there a division into 
1000 half grams. Two of these pfund weights immediately 
furnished a legal kilogram, and, while their use interfered 
somewhat with the development of the decimal principle, never- 
theless it served to accustom the people at large to the new 
mode of reckoning. The liter measures were accepted even 
more readily than those of mass. The relation between the 
unit or liter and the measure of length and the weight of water 
served to commend the new system readily to those dealing- 
with fluids, while a number of simple tables were prepared 
officially to explain the simplicity of the system. 

In contrast to the ease with which the liter and the gram 
series were adopted, mention must be made of the change 
in the measures of length. The principal measures of length 
were the ell and the foot, which, though varying greatly among 
the various German states from a metrological standpoint, were 
approximately the same, or sufficiently so at least, to conveys 
to the ordinary person a certain rough idea of extension which 
for many purposes sufficed. Furthermore, the foot and ell 
differed so much from the meter and its subdivisions that the 
purchasing public could not transfer readily the price of cloth or 
other material when conceived or expressed in these units to the 
meter, and thus obtain even an approximate idea of value. It 
was also argued that the meter was not as convenient to think 
in as the foot for architects and mechanics, by some of whom 
opposition to the new measures was manifested ; but this feeling 
soon died away, and the new measures were soon universally 
employed in all works and calculations. 

That the metric system has contributed materially towards the- 
upbuilding of German commerce and industry is universally 
conceded, but, of course, since its adoption so many causes have 
acted to this end, that it is not possible to state precisely just 
what part the international measures have played. Suffice it to 
say, that in manufacturing, especially of articles where precision 



r 



90 EVOLUTION OF WEIGHTS AND MEASURES 

of measurement, and interchangeability of parts are essential, 
the Germans have vastly improved and increased their output, 
which must in a certain degree be due to this cause. Inasmuch 
as the metric system was employed extensively in scientific 
work previous to its general adoption, the increased activity of 
German investigators in fields where measuring is essential is 
not necessarily a result, but the readiness with which industrial 
workers have availed themselves of the scientists' labors has 
doubtless been facilitated by the fact that their processes and 
results were expressed in a language that readily could be 
understood. 1 

Austria, where there was much the same variation of feet, 
pounds, etc., as in Germany, followed that country's example, 
and on July 23, 1871, the Parliament passed a law providing 
for the permissive use of the metric system after January 1, 
1873, and its compulsory use after January 1, 1876. At 
the same time it published official tables of equivalents 
between the old and new measures, and established a standard 
meter, which was an end standard of glass, and a standard 
kilogram of rock crystal, these being legally supplanted in 
1893 by the copies of the international standard meter and 
kilogram received from the International Bureau. The old 
measures, especially those known as the " Lower Austrian 
System," were quite unlike those of the metric system, and at 
first it would appear that there would have been great difficulty 
in bringing about a change ; but for a while a binary system 
of division was tolerated, and certain weights and measures 
approximate in value to the older ones temporarily were 
employed. In the meantime newspapers and schools were 
zealously educating the people to the new order, while the 
government prepared an adequate number of approved weights 
and measures, as well as supervised the construction of others 
according to standard regulations. The four years appointed 
for the transitional period proved ample, and there was no 
expressed or obstinate resistance on the part of the people. 
In fact, it was the general opinion that any lack of completeness 

1 See Promemoria of German Imperial " Normal- Aichungs Kommission " in 
House of Representatives, Report No. 2885, 54th Congress, 2nd Session, 1897, 
pp. 7-9. 



THE METRIC SYSTEM IN EUROPE 91 

in the adoption of the system was due rather to laxity on the 
part of the municipal authorities than to any pronounced feeling 
of the public at large. 1 

In Hungary, by the law of 1874, Article VIII., the metric 
system was established to be in force from January 1, 1876, but 
its use was sanctioned six months earlier, and finally, in 1901, the 
international standards were duly established by law. The 
method of making the change was in the main the same as in 
Austria, and the new weights and measures were quickly 
naturalized and adopted by the people generally, though in 
isolated districts the old usage was maintained for many years. 

Outside of France, Belgium is one of the earliest countries to 
use the metric system, as it was established there by the law of 
August 21, 1816, at a time when that country was united with 
Holland. 2 The names of the old units were applied to the 
metric values, but instruction in the metric system was given in 
the schools, so that, after the system had been rendered com- 
pulsory from 1820, by 1836 it was possible to withdraw the 
Belgian names, and in 1855 the exclusive use of the French 

1 See pp. 9, 10, House of Representatives, Report No. 2885, 54th Congress, 
2nd Session, 1897. In addition to this report, which contains information 
furnished by European governments to ambassadors and ministers of the United 
States on the subject of the adoption of the metric weights and measures by 
the different countries, a summary of foreign legislation on the Metric System 
prepared by J. K. Upton, chief clerk of the Treasury Department, and later 
Assistant Secretary of Treasury, contained in Report No. 14, House of Repre- 
sentatives, Committee on Coinage, Weights and Measures, 46th Congress, 1st 
Session, 1879, has been drawn upon for dates and details given in the following 
pages concerning the adoption of the metric system by the nations of Europe. 
Somewhat more recent are the summaries contained in Guillaume, La Convention 
du Metre (Paris, 1902), Annexe iv. pp. 218-226; "Resume de quelques Legis- 
lations relatives aux Poids et Mesures," Annexe aux Proces-verbaux des Stances 
du Comite' international des Poids et Mesures, Session de 1901, 2e Serie, Tome 1 
(Paris, 1901) ; Reports from Her Majesty's Representatives in Europe on the Metric 
System, part i., July, 1900, English Parliamentary Accounts and Papers, 1900, 
vol. xc. ; Reports from Her Majesty's Representatives Abroad, part ii., February, 
1901, English Parliamentary Accounts and Papers, 1901, vol. lxxx. The latter 
are particularly full, and give an interesting account of the transition period, as 
well as the extracts from the laws in many instances. There is also available the 
Beizieme Rapport aux gouvernements signatoires de la Convention du Metre and the 
Comptes rendus de la deuxieme Conference generate des Poids et Mesures, 1895. 

2 See ante, p. 82. 



92 EVOLUTION OF WEIGHTS AND MEASURES 

names and measures was established by law. The Belgian 
standards of mass and length were copied from those in France, 
being legalized in 1848, but they were damaged in the fire of 
1883 at the Palais du Nation, so that the international prototypes 
which were received in 1894, and duly legalized, were most 
acceptable. 

The use of the metric system in Egypt is of interest, inasmuch 
as that country is so largely under British influences, both 
commercial and political. The metric system was established on 
a permissive basis in 1873, by a decree of Khedive Ismail, which, 
however, was not enforced, so that in 1886 a commission was 
appointed to consider the adoption of the metric system, and 
reported in its favor. By 1892 its use had extended, so that it 
was possible for the government to adopt it for use in all trans- 
actions between it and private parties, except for measurement of 
land and the tonnage of ships. It has been employed in the 
public works department, where large engineering projects have 
been supervised and executed by British engineers, who have 
recognized its many advantages, and also in the customs, post 
office, and railways. While the old native measures still remain 
in daily use, yet the metric system is being taught in the 
government schools, and as rapidly as is possible for an oriental 
people, with their traditions and conservatism, it is growing into 
increased use. 

Greece is an example of a country where the Government 
though having adopted the metric system is unable to secure 
its use by the masses of the people. The metric system was 
established by a royal decree of September 28, 1836, with Greek 
names for the different weights and measures; but its use is largely 
confined to the Government in its various transactions involving 
measures of distance and area, the Government in common with 
the general public employing the oke — T282 kilograms as a unit 
of weight, and a measure of the same name = 1*33 liters as a, 
unit of capacity. This is undoubtedly due to the fact that the 
amount of international commerce in Greece is comparatively 
limited, and that the people at large have but little interest 
in general commerce as such, while the Government is indisposed 
to press reforms of this character. 

The conquest of Lombardy and Venetia by Napoleon in 1803- 



THE METRIC SYSTEM IN EUROPE 93 

was the means of inaugurating the metric system in Italy, but 
its general use did not follow except in governmental transactions, 
and the bulk of the people resisted this effort on the part of 
foreign conquerors. In some of the various kingdoms and princi- 
palities it was found convenient to adopt the metric weights and 
measures, 1 but it required the establishment of the Kingdom of 
Italy in 1861 to ensure complete uniformity and the thorough 
adoption of the system. Here, again, we see that one of the 
consequences, or possibly a necessary attribute, of the establish- 
ment of a nation from a number of separate states is that there 
should be a single and uniform system of weights and measures. 
Accordingly, by the law of July 28, 1861, the metric system was 
rendered obligatory throughout the kingdom after January 1, 1863, 
and this was reinforced by a law passed in June 23, 1874; and 
on August 23, 1890, the international standards were established 
by a royal decree. 

The Japanese have for some time used metric weights in their 
coinage, and in 1891 a law was passed in which the ancient 
measures were reorganized and based on those of the metric 
system, which was also duly recognized. The various national 
units, which are divided either decimally 2 or sexagesimally, are 
defined in terms of the metric units, so that little difficulty 
would be experienced in passing from one to the other, and, 
in fact, tape measures are frequently graduated on both sides with 
the two scales, while on a map both scales are usually given. 

We have seen above 3 how the metric system was introduced 
into Holland when it formed one country with Belgium in 
1816, and it gradually enjoyed wider use until in 1869 the 
^French names were adopted to designate the different units, 
while permitting the older and national names to be used for 
ten years longer. The royal standards of the Netherlands were 
constructed by a commission of Dutch scientists, and while they 

1 Metric System was made compulsory in Piedmont in 1845 ; introduced into 
Modena in 1849, with eight years for its gradual adoption ; adopted in part 
of Papal States in 1859 ; in 1861 adopted in Sardinia ; in 1863 adopted in 
Neapolitan provinces, in 1869 in Venice, and in 1870 in Rome. 

2 Japanese measures below a shaku= -99421 feet = ^ meter are decimally 
divided, rendering their comparison with metric measures in the case of 
drawings or diagrams very easy. 

3 See ante, pp. 82 and 91. 



94 EVOLUTION OF WEIGHTS AND MEASURES 

resemble those of the International Commission, were derived 
directly from the standards of the Archives. The Dutch 
standard meter is 2 # 7 microns longer than the international 
standard. 

When a decree was issued in Portugal in 1852 providing for 
the introduction of the metric system, it was provided that it 
should be in full legal operation within a space of ten years. It 
was planned that the introduction should be by successive stages, 
beginning with the Government, and various schemes and tables 
of legal equivalents were to be prepared and distributed. It was 
not possible to bring about the change during the specified time, 
so that subsequent statutes were necessary, and it was not until 
1872 that the metric system was officially in universal use. The 
introduction of the new weights and measures was attended with 
no difficulty, save the lack of intelligence of the people of the 
lower and agricultural classes, and among them the force of 
custom and tradition has proved so strong that old weights and 
measures still remain, though they cannot be used in any receipt 
or legal document. The metric system is, however, greatly 
appreciated by the commercial interests, and is slowly but surely 
making progress among the people at large. In fact, it will be 
seen that among intelligent people such a change occasions 
comparatively small inconvenience and is quickly effected ; but 
where there is a low general standard of education, as in Portugal, 
the people are conservative and unwilling to accept innovations, 
as they are unable to appreciate their utility. 

Russia, no less than other countries, early felt the necessity for 
reforms in its systems of weights and measures, and in 1833 the 
original Russian units were denned in terms of English feet, — 
the legal unit being the sagdne, which was equal to seven English 
feet. The standard for this unit was constructed with great 
exactness, and was compared with the English yard, and from it 
the various other measures were derived. Nevertheless it was 
found necessary to replace the sagdne by the archinne, which is 
i sagdne or '71112 meter. The metric system is now permissive 
under the terms of the law of June 4-16, 1899, which became 
effective January 1, 1900 ; yet it is noteworthy that its inter- 
national character is recognized by denning the national stan- 
dards, the livre and the archinne, in terms of the international 



THE METRIC SYSTEM IN EUROPE 95 

prototypes. 1 The metric units are largely employed in Russia, as 
elsewhere, for scientific work, and there is said to be a strong 
feeling towards the complete adoption of the system, which for a 
number of years has been used by the pharmacists of the empire, 
and since 1896 by the medical departments of the Russian army 
and navy. The metric system is also used in the customs ser- 
vice, with indications of further extensions. In Finland, where a 
higher standard of education prevails, the metric system has been 
employed with considerable success since 1892, and no difficulty 
attending its introduction was experienced. 

Notwithstanding the fact that a large part of the preparatory 
work in determining the length of the earth's quadrant had been 
done in Spain, that country did not adopt the metric system until 
1849, though previously it had been under discussion, and so early 
as 1807 a number of metric scales had been constructed at Madrid. 
The law of 1849, which provided that the system should go into 
force in 1853, and actually became operative throughout the entire 
kingdom in 1855, defined the meter in terms of the dimensions of 
the earth, and the other units as deduced from the meter. These 
definitions remained in force until 1892, when the receipt of the 
copies of the international prototype meter and kilogram, prepared 
by the Bureau International, necessitated the restatement of the 
law in which these standards and their relation to the inter- 
national prototypes of the Bureau were duly recognized. 

In Sweden a royal decree was issued November 22, 1878, by 
which the use of the metric system was made optional from the 
following January 1 , and after ten years was to be made compulsory. 
The usual official tables and information in various and convenient 
forms were distributed during this transition period, but it was not 
until the end of the appointed time that the metric system came 
to be used generally. After that its employment became prac- 
tically universal and no difficulties or opposition were experienced. 

In Norway the metric system was employed in the postal 
service, by the Act of May 3, 1871, and in the same year the gram 
was adopted as the unit of weight by the medical profession of 
that kingdom. In 1879, on July 1, the use of the metric system 
for all private business became optional, but from this date it was 

1 See Proces-verbavx dn Comity international des Poids et Mesures, Session 1897, 
p. 155. 



96 EVOLUTION OF WEIGHTS AND MEASURES 

to be used exclusively by the Government in all its transactions, 
such as the collection of customs duties, public accounts, taxes, 
etc. Then on July 1, 1882, the use of the metric system was 
made obligatory in all transactions, both public and private, and 
no other weight, measure, or coinage other than metric was 
permitted. It is interesting to note that during the three years 
of the transitional period the government altered certain of the 
older weights and measures, making them conform to the 
metric system. Thus all weights of one pound and over during 
the first two years were regulated and made over free of cost, so 
that the old Norwegian " skaal-pund " and the old " bismer-pund " 
used with the steelyards were slightly increased so as to weigh 
half-kilograms. Likewise the old " korn-tonde," or corn measure, 
was adjusted to hold 140 liters, and a half measure to hold 70 
liters. In the third year of the change period, however, a fee was 
required for these alterations, and after the compulsory use of the 
new weights and measures they were absolutely prohibited. 

In the case of Norway we have an approximate statement 1 of 
the cost of the introduction of the metric system as given in a 
statement of the value of instruments sold in the years 1877-84 
by the Weights and Measures Office, but this does not of course 
include the private sale of metric weights and measures. In this 
€onnection it must be borne in mind that the population of 
Norway at this time was somewhat less than 2,000,000. 2 The 
statement is as follows : 

Public expenses — 

Purchase of standards, weights and measures 

and apparatus ----- £2,844 
Plans and drawings- - - - - 217 

Models 306 

Controlling apparatus for town and country 

police - 1,650 

Adaptation of old instruments to the metric 

equivalents - - - - 3,111 

£8,128 

1 Reports from Her Majesty's Representatives in Europe on the Metric System, 
part i., July, 1900, pp. 63, 64 ; E.P.P., 1900, vol. xc. 

2 Dec. 31, 1882, 1,913,000. 



THE METRIC SYSTEM IN EUROPE 97 

Private expenses- 
Adaptation of old instruments to the metric 

equivalents - £2,044 

Purchase of new metric instruments - - 35,761 



Total cost of introduction £45,933 

In Switzerland there was even more than the usual diversity of 
weights and measures in the different cantons, but after 1822 in 
some of these divisions a system based on the metric measures and 
having a foot of 30 centimeters and a pound of 500 grams was 
established. By an agreement known as the " Maass concordats," 
dated August 17, 1835, twelve cantons united in establishing this 
system, and by subsequent additions to the convention and by 
legislation it became operative throughout the nation, being by an 
Act of Dec. 24, 1851, the national and compulsory system through- 
out the confederation after December 31, 1856. In this system 
the legal unit of length was the pied or foot, equal to 30 centi- 
meters, divided decimally, and having such multiples as the brache, 
2 feet ; the mine, 4 feet ; the toise, 6 feet ; the perche, 10 feet ; 
and the lieue, 16,000 feet. The livre or pound equal to 500 grams 
could be divided either on a binary or a decimal system, while 
for dry capacity the unit established was the quarteron, equal 
to 15 liters, and for liquid capacity the pot, equal to one and 
a half liters. On July 3, 1875, the Federal Chamber passed a 
law providing that the complete metric system should be used 
after January 1, 1877, and that the standards then in course 
of preparation by the International Commission should be the 
legal and national standards. These international prototype 
standards were received in 1889, and were duly substituted for 
the older standards. 

In Turkey, metrological, like other reforms, have not 
achieved the success deserved, largely on account of the char- 
acter of the people and the Government. In 1886 a law was 
passed providing for the establishment of the metric weights and 
measures in Constantinople, and making their use compulsory 
after five years, and in 1891 ancient measures were confiscated 
and destroyed ; but it has been recognized as practically impossible 
to enforce the system, and old and new units and standards have 
nourished side by side. In fact, experience demonstrates the 

G 



98 EVOLUTIOxN OF WEIGHTS AND MEASURES 

strength of the proposition that weights and measures and their 
preservation intact and uniform are correlatives of government, 
and where the latter is weak or deficient in character, a satis- 
factory condition of these necessary adjuncts to commerce cannot 
be maintained. Nevertheless, in 1900, it was reported 1 that all 
scales imported into the Ottoman Empire must be marked in the 
metric system, and all weights and measures marked according to 
the old systems were liable to confiscation. 

In England the need of an international and decimal system of 
weights and measures was realized as early 2 as 1783 by James 
Watt, who had considerable difficulty in reducing the weights 
and measures used by Lavoisier and Laplace in some experiment 
to the English weights and measures used by Kirwan in some 
similar work. Writing to the latter under date of November 14, 
1783, he said : 3 "It is therefore a very desirable thing to have 
these difficulties removed, and to get all philosophers to use 
pounds divided in the same manner, and I flatter myself that 
may be accomplished, if you, Dr. Priestley, and a few of the 
French experimenters will agree to it ; for the utility is so 
evident that every thinking person must immediately be con- 
vinced of it. My proposal is briefly this : 

Let the philosophical pound consist of 10 ounces or 10,000 grains. 
„ „ ounce „ „ 10 drachms or 1000 „ 

„ „ drachm „ „ 100 grains. 

Let all elastic fluids be measured by the ounce measure of water, 
by which the valuation of different cubic inches will be avoided, 
and the common decimal tables of specific gravities will im- 
mediately give the weights of these elastic fluids." Farther on 
in the letter he says, " I have some hopes that the foot may be 
fixed by the pendulum, and a measure of water, and a pound 
derived from that ; but in the interim let us at least assume a 
proper division which from the nature of it must be intelligible, 
as long as decimal arithmetic is used." 

1 Board of Trade Journal (London, Feb. 22, 1900), vol. xxviii. p. 449. 

2 In 1620 Edmund Gunter had proposed a decimal measure for land with a 
surveyor's chains of 100 links. 

3 A. Siemens, Journal Institution of Elect. Engineers of Great Britain, vol. xxxiL 
pp. 278-9. 



THE METRIC SYSTEM IN EUROPE 99 

A few days later (Nov. 23, 1783), Watt wrote to M. de Luc 
calling attention to the difficulties of comparing the work of 
investigators in different countries on account of the diversity in 
weights, and also on account of " the absurd subdivisons used by 
all Europe," even if the weights were the same. He describes 
the plan outlined above, and suggests dividing the Paris pound 
into 1000 parts. M. de Luc was asked to communicate with 
Laplace on this subject, and three years later when Watt visited 
Paris he met Lavoisier, Laplace, Monge, and Berthollet, whom we 
have seen were deeply interested in the reform of weights and 
measures. It is fair to assume that the subject was discussed by 
Watt among them, and that they listened to the suggestions and 
ideas of the English engineer, and this view is strengthened by 
the provision inserted in the bill for the reform of the French 
weights and measures that the French Academy and the Royal 
Society appoint a joint committee to discuss universal weights 
and measures. 1 

England, however, declined to co-operate with the International 
Commission which examined the work of the French scientists on 
which the metric system was based, and this attitude, as well as 
a subsequent antipathy to the French system, was doubtles due 
to the national feeling towards France. Mention, however, 
should be made of the fact that in 1789 Sir John Riggs Miller 
called the attention of Parliament to reforms in weights and 
measures, moving for the appointment of a committee " to 
investigate and report on the best means for adopting an 
uniformity of weights and measures." He, too, had in mind the 
length of the second's pendulum as a basis of linear measure, and 
his plan was supported by the Rev. George Skene Keith, who 
further urged that any new system should be a decimal one. 
The desirability of a decimal system that should include not only 
weights and measures, but also coinage, began to be felt, and in 
1814 Sir John Wrottesley brought such a scheme to the notice of 
Parliament. The result of the agitation was that in 1819 a 
commission which included Dr. Thomas Young, William H. 
Wollaston, and Captain Henry Kater reported adverse to the 
adoption of the decimal scale, but the cause continued to be 

1 See M'Leod, "Notes on the History of the Metrical Measures and Weights," 
Nature (London, 1904), No. 1792, vol. lx. pp. 425-427. 



100 EVOLUTION OF WEIGHTS AND MEASURES 

argued, and at every discussion of changes in weights and 
measures, the metric system had its advocates in increasing 
numbers. 

In 1816 a resolution was passed in Parliament providing for a 
comparison of the imperial standard yard with the Trench 
standard meter, this duty being assigned to the Eoyal Society. 
That body received from Paris two platinum meters which had 
been compared by Arago with the French standard. One was an 
end standard which was exactly equal to the meter at the 
temperature of melting ice, while the other was a line standard 
which at the same temperature was short by "01759 mm. These 
meters were carefully compared by Captain Kater with the 
Shuckburgh scale, and when referred to the Parliamentary 
standard the true length of the meter was determined at 39*37079 
British inches, a value which was legalized by Parliament in its 
Act of 1864 which permitted the use of the weights and measures 
of the metric system. 

Meantime the scientists and others had called for reforms in 
the British system which would involve more than merely the 
construction of new standards. In considering this subject, and 
especially in its bearing on the adoption of a decimal system, a 
committee of the House of Commons, reporting in 1862, stated 
that " it would involve almost as much difficulty to create a 
special decimal system of our own, as simply to adopt the metric 
decimal system in common with other nations. And, if we did 
so create a national system we would, in all likelihood, have to 
change it again in a few years, as the commerce and intercourse 
between nations increased, into an international one." The 
scientific men, and those who had been careful observers at 
international expositions and conventions, were now making their 
influence felt, and in 1864 was passed the Act mentioned above, 
which allowed the use of the metric system of weights and 
measures. Not satisfied with this step, the metric advocates in 
1868 proposed a bill making the system compulsory, but after a 
second reading it was dropped. In the meanwhile the Standards 
Commission, of which Sir G. B. Airy, the astronomer-royal, was 
chairman, carefully studied the subject of weights and measures 
for the kingdom, and their second report, dated April 3, 1869, is 
devoted to the metric system 



THE METRIC SYSTEM IN EUROPE 101 

The status of the metric system was defined in 1878 by the 
Weights and Measures Act, under the terms of which (clause 32) 
the Board of Trade was authorized " to verify metric weights and 
measures which are intended to be used for the purposes of 
science or of manufacture or for any lawful purpose, not being 
for the purpose of trade within the meaning of this Act." 

The legislation of August 8, 1878, still left much to be desired, 
and in 1895, in response to demands for further action, a com- 
mittee was appointed from the House of Commons to investigate 
the matter anew. This committee heard numerous witnesses and 
carefully considered their testimony, giving ample opportunity for 
both sides of the question to be discussed. In their report they 
recommended : 

" {a) That the metric system of weights and measures be at 
once legalized for all purposes. 

" (b) That after a lapse of two years the metric system be 
rendered compulsory by Act of Parliament. 

" (c) That the metric system of weights and measures be 
taught in all public elementary schools as a necessary and 
integral part of arithmetic, and that decimals be introduced at an 
earlier period of the school curriculum than is the case at 
present." 

Parliament acted on that portion of the report providing for 
the legalization of the metric weights and measures for all 
purposes, passing a bill to that end May 27, 1897, but hesitated 
when it came to making the system compulsory. On the 
following year in an Order in Council dated May 19, 1898, after 
an investigation by a committee of the Royal Society, the various 
units were defined and their legal equivalents in the customary 
weights and measures given. These differ by minute amounts 
from those of the United States. 

In 1903 it seemed to the members of the Decimal Association, 
an influential organization which had been formed to further the 
adoption of the metric system and of a decimal system of coinage, 
that popular feeling in favor of radical reforms in the system of 
weights and measures was increasing, and that it was an oppor- 
tune time to make another attempt. Accordingly Lord Belhaven 
and S ten ton introduced such a bill, which was supported on its 
introduction by Lord Kelvin and later by Lords Rosebery, 



102 EVOLUTION OF WEIGHTS AND MEASURES 

Spencer, and Tweedmouth, and after a third reading was passed 
and sent to the House of Commons, where, however, it was never 
brought up for passage. 

This bill was endorsed by a large number of town, city, and 
county councils, and by over fifty chambers of commerce, includ- 
ing some of the most important in the kingdom. Furthermore, 
in addition to petitions from forty-two trades unions, representing 
some 300,000 members, received while the bill was in the House 
of Lords, there was a resolution unanimously passed by the 
Congress of Trades Unions meeting at Leeds in September, 1904, 
and representing some 5,000,000 workmen, in which it was 
resolved to petition the House of Commons in favor of the bill. 
There were also petitions from sixty Teachers' Associations, 
Inspectors of Weights and Measures in eighty districts, and 
thirty Ketail Trades' Associations, besides numerous Chambers 
of Agriculture and Farmers' Associations. Thus it will be seen 
that the bill was supported by eminently practical people as 
well as scientists and theorists, and it is interesting to state that 
in Great Britain retail tradesmen and workmen have been alive 
to the many merits of the metric system. 

The bill of 1904 provided for the establishment of the standard 
kilogram and meter from the first day of April, 1909, as the 
imperial standards of weight and of measure, though for sufficient 
cause this date could be postponed by an Order in Council. It 
also provided for Parliamentary copies of the substituted imperial 
standards, and that future deeds, contracts, etc., must be in terms 
of the metric system. The bill also made due provision for 
various adaptations made necessary by the change, and prescribed 
the general method in which it should be carried out. 

In Australia an active demand was made for the introduction 
of the metric system, and in 1905 it was proposed to introduce 
into the Federation Parliament a bill with this object. In the 
same year the neighboring colony of New Zealand adopted the 
metric system as its legal system of weights and measures. 

Great Britain, however, played an important part in the de- 
velopment of scientific measures, namely, in working out the 
C.G.S., or Centimeter-Gram-Second system, as was done by the 
British Association for the Advancement of Science. This system 
was based, as the name implies, on the metric units of length 



THE METRIC SYSTEM IN EUROPE 103 

and mass, and has been of the greatest benefit to science, being 
universally adopted by physicists and engineers, and will be 
found discussed more at length farther on in this volume. 1 

In Mexico the Metric System came into effect on the first 
of January, 1862, in accordance with the terms of a law of 
March 15, 1857, and a second law of March 15, 1861, which 
provided for the exclusive use of the Metric Weights and 
Measures for all purposes. While the new system was adopted 
by the Government, yet private individuals did not take it 
up, and there was needed an imperial decree, issued in Nov- 
ember, 1865, which declared the Metric System alone valid 
throughout the country. For a number of years the old and 
new measures were used side by side, and also, with the 
introduction of railways and of machinery for mining and other 
purposes from the United States, the English foot and pound; 
but gradually the Metric measures asserted their supremacy, and 
now they are almost exclusively used. Mexico became a party 
to the International Convention of Weights and Measures in 
1890, and in 1896 it formally adopted the international standards 
for the meter and kilogram. 

Throughout South and Central America the Metric System 
is largely employed, and in nearly all cases it is the legal 
system of the different countries. There has been, however, 
great difficulty in maintaining this system as the only one, 
since in numerous instances the people have preferred to use 
the older units derived from Spanish and other sources, while 
exporters doing business with Great Britain and the United 
States have made use of the Anglo-Saxon units. This, of 
course, is due in great part to the lack of stability of the 
South American governments, but conditions in this respect 
are improving, and the use of the metric weights and measures 
is now practically universal throughout South America. It 
was on this account that representatives of these countries 
assembled at the International American Conference at Washing- 
ton in 1890 advocated the adoption by the United States of 
the Metric Weights and Measures. Beyond the dates of 
adoption, as given by the accompanying table, there is but 
little to say as regards the individual countries 

1 See Chapter ix. p. 205, 



104 EVOLUTION OF WEIGHTS AND MEASURES 

While in the foregoing paragraphs an attempt has been 
made to summarize briefly when and how the metric system 
was adopted by the more important nations of the world, it is 
possible to obtain this information for the remaining countries 
of the world by reference to the accompanying tables, which 
indicate the time at which metric measures were first adopted, 
when made compulsory, and, so far as can be ascertained and 
briefly stated, the extent to which they have replaced other 
and older measures. These tables speak for themselves, and 
illustrate most forcibly the spread of the system. They are 
based on a somewhat similar table published as an Appendix, 
p. 67, of a Eeport from the Select Committee on the Weights 
and Measures (Metric System) Bill [H.L.], May 5, 1904, to be 
found among the Parliamentary Papers of that year, on the 
Reports of British Consular officials abroad, to which reference 
has already been made (see footnote, p. 91), and other official 
sources of information. 



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CHAPTEK IV. 
WEIGHTS AND MEASUKES IN THE UNITED STATES. 

) In the early days of the American colonies the weights and 
| measures, like the coinage, were based almost entirely on those 
of the mother country, and where statutes were enacted pro- 
viding for standards, these were derived from the standards 
of the Exchequer of England. Inasmuch as that country was 
the chief source of supply as well as a market for merchandise, 
and the commercial dealings were very largely with its 
inhabitants, such a condition was most natural, and inasmuch 
as trade was not particularly extensive, such a system of 
weights and measures amply sufficed. 1 During the Eevolution, 
however, it was realized that all possible means should be taken 
to secure uniformity in commercial practices, and the need of 
a single national system of money and weights and measures 
was early appreciated. In the Articles of Confederation adopted 
by the Continental Congress, November, 15, 1777, it was pro- 
vided in section 4, article ix., that " The United States in 
Congress assembled shall also have the sole and exclusive 
right and power of regulating the alloy and value of coin 
struck by their own authority, or by that of the respective 
states ; fixing the standard of weights and measures throughout 
the United States ; . . ." By the Federal Constitution, Congress 
is explicitly given the power to fix the standard of weights 
and measures, the fifth paragraph of section 8 of article i. 
stating that the Congress shall have the power " to coin money, 

1 See John Quincy Adams, " Report on Weights and Measures" (Washington, 
1821), for summary of colonial, state, and territorial legislation, pp. 94-117. 



110 EVOLUTION OF WEIGHTS AND MEASURES 

regulate the value thereof and of foreign coins, and fix the 
standards of weights and measures." It is somewhat curious 
that the fixing of the standards of weights and measures is 
almost the only power expressly and specifically conferred on 
Congress which that body has refrained from exercising down 
to the present time, notwithstanding its constant and most 
active interest in the coinage of money, as evinced by a vast 
amount of discussion and legislation. 

In the days before and during the Eevolution the coinage of 
various nations as well as from different state mints passed in 
circulation, causing an inexpressible confusion of values and rates 
of exchange, and it was but natural that uniformity and sim- 
plicity should be desired. That this could best be attained by a 
decimal system was appreciated as early as 1782, when Eobert 
Morris, the Superintendent of Finance, an office corresponding to 
that of the present Secretary of the Treasury, wrote to the 
President of Congress " that it was desirable that money should 
be increased in the decimal Eatio, because by that means all 
calculations of Interest, exchange, insurance, and the like are 
rendered much more simple and accurate, and, of course, more 
within the power of the great mass of people. Whenever such 
things require much labour, time, and reflection, the greater 
number who do not know, are made the dupes of the lesser 
number who do." x In accordance with the suggestions made, an 
elaborate report on the question of a system of currency for the 
United States was prepared by Thomas Jefferson, and on July 6, 
1785, a decimal system of coinage was adopted. 2 In the following 
year, August 8, the complete system was duly determined, and 
the amounts, nomenclature, and value of the various coins fixed. a 
The success of the new currency was soon assured, and it received 
favorable commendation both at home and abroad. 

The reasons influencing its adoption would seem to have 
demanded a similar system of weights and measures, and it is 
perfectly evident that clear thinkers like Morris and Jefferson 

1 Watson, History of American Coinage (New York, 1899), p. 10, quoting 
from Wharton's Diplomatic Correspondence, vol. v. pp. 103-110. 

2 See Watson, p. 16 ; also MS. Reports of Committee on Finance of the Continental 
Congress, No. 26, pp. 537-560. 

3 Journal of Congress, vol. xxxviii. No. 1. 



WEIGHTS AND MEASURES IN UNITED STATES 111 

were alive to its advantages; but even at these early times, as 
well as subsequently, there was considerable disinclination on 
the part of Congress to take any measure looking toward the 
establishment or reform of these important adjuncts to commerce. 
In fact, while there have been numerous suggestions on the 
subject of weights and measures from Presidents in their messages, 
there has been comparatively little legislation, and more has been 
accomplished in the way of establishing and changing standards 
oy Executive order than by direct legislation. 

President Washington, however, early realized the importance 
of the matter, and in his first speech or message to Congress,, 
delivered January, 8, 1790, he said, " Uniformity in the currency, 
weights, and measures of the United States is a subject of great 
importance, and will, I am persuaded, be duly attended to." 
Accordingly, the House of Eepresentatives referred the matter to 
the consideration of the Secretary of State, Thomas Jefferson, and 
requested him to prepare a report dealing with the subject. Mr. 
Jefferson had been in Paris as Minister of the United States, and 
doubtless was well acquainted with the measures to reform the 
weights and measures of that country which had been and were 
then under discussion. For this reason, as well as on account of 
his connection with the establishment of the national currency on 
a decimal basis, his selection was most fortunate, and within a 
few months (July 4, 1790) a report was submitted containing two 
complete and distinct plans. 1 He suggested as the standard of 
linear measure a uniform cylindrical rod of iron of such length 
that in 45 degrees latitude at sea level and constant temperature 
it should perform its vibrations in small and equal arcs in one 
second of mean time. Such a rod would have a length of 58*72368 
inches, corresponding to a length of a seconds' pendulum of 
39*14912 inches. In one of the plans proposed he adapted the 
existing system to this standard, thus securing uniformity and 
stability, while in the other, which he considered available for 
future use, he proposed a new and strictly decimal system which 
was remarkably complete and comprehensive. Mr. Jefferson was 
convinced of the utility of the decimal system, and in his proposed 
scheme of weights and measures for the American people he aimed 

1 See The Works of Thomas Jefferson (edited by H. A. Washington, New York, 
1884), vol. vii. pp. 472-495. 



112 EVOLUTION OF WEIGHTS AND MEASURES 

to reduce " every branch to the same decimal ratio already estab- 
lished in their coins, and thus bringing the calculation of the 
principal affairs of life within the arithmetic of every man who 
can multiply and divide plain numbers." The success which has 
attended the decimal currency of the United States shows that 
•Jefferson was wise in his plan for a similar division for weights 
and measures, and had his proposals been adopted much confusion 
and inconvenience would have been spared the people of the 
United States. Furthermore, but little difficulty would have 
attended its adoption, as the fundamental unit, the foot, differed 
but slightly from the foot then in use. This foot was derived by 
Jefferson by taking one-fifth of the length of the rod forming the 
second's pendulum and then employing multiples and sub-multiples 
in building up a series of measures of length. A table of these 
units would read as follows : 1 

10 points make 1 line. 
10 lines make 1 inch; 
10 inches make 1 foot. 
10 feet make 1 clecad. 
10 decads make 1 rood. 
10 roods make 1 furlong. 
10 furlongs make 1 mile. 

Naturally the squares and the cubes of these units formed the 
units for area and volume, while for capacity the cubic foot was 
selected forming the bushel, which was then divided and multi- 
plied decimally to give other measures. Likewise the cubic foot 
of water, which weighed 100 pounds of 10 ounces each, gave the 
basis of the measures of weight, and these also were arranged 
decimally. Hardly too much in praise of this system of Jeffer- 
son's can be said, and its adoption by Congress would have 
exerted a wonderful effect on metrology, not only in the United 
States but also in the world at large. It will be remembered 
that at this very time France was constructing its metric system, 
while England, appreciating the confusion attending its complex 
and unwieldy system of measures, was in good temper for a 
change. Jefferson's system, although designed to have certain 
points of contact with the then existing system so as to make 

1 The Works of Thomas Jefferson (New York, 1884), vol. vii. p. 488. 



WEIGHTS AND MEASURES IN UNITED STATES 113 

it easy of adoption, nevertheless was perfectly uniform and 
symmetrical, and while possibly less scientific and precise than 
the French system, yet it possessed all the characteristic features 
of convenience, symmetry, and completeness. Congress received 
this able report, but did not adopt either of Jefferson's suggestions, 
doubtless on account of the similar agitation for changes in 
weights and measures then taking place in France and England, 
and its desire to await their outcome. 

The pressing need of some action for this country, neverthe- 
less, was realized by the executive branch of the Government, 
and again in his annual message to Congress on October 25, 1791, 
President Washington reverted to the subject, stating that "A 
uniformity in the weights and measures of the country is among 
the important measures submitted to you by the Constitution ; 
and, if it can be derived from a standard at once invariable and 
universal, must be no less honorable to the public councils than 
conducive to the public convenience." 

A committee of the Senate appointed November 1, 1791, then 
took the matter under advisement, and on April 5, 1792, presented 
a report 1 favoring the adoption of Jefferson's decimal plan, and 
containing directions for the scientific construction of a standard 
of length which would be divided into five equal parts, each of 
which would correspond to a foot. The report also contained 
information relative to the measures for the survey of land, units 
of weights, etc. Several reports were submitted by this committee, 
and it was finally decided (1793) " that the Standards should be 
the mean of those found in the country." No legislative action 
was taken by the Senate, and for several years there is apparently 
no record of any great interest manifested in the subject by 
Congress. In the meantime France had adopted the Metric 
System with a hope that it would become universal, and on 
January 8, 1795, the President transmitted to Congress a com- 
munication 2 from the Minister of the French Eepublic, describing 
in detail the new system of weights and measures, the standards 
of length and weight, and the method of dividing the standards 
into decimal parts. A committee from the House of Eepresenta- 
tives proceeded to study this plan, together with that of Jefferson, 

1 Journal of the Senate, Second Congress, First Session, pp. 173, 174. 

2 Executive Docs. , Third Congress, Second Session. 

H 



114 EVOLUTION OF WEIGHTS AND MEASURES 

and reported in the following year ; but their recommendations 
were of a general character, and involved experimental work by 
scientists, which was never authorized by Congress. It may be 
said in passing, Jefferson did not advocate the adoption of the 
French system, as he did not approve of the use of a fundamental 
unit derived from an arc of meridian in preference to the length 
of a seconds' pendulum. 1 As to his own plans, he was not a 
zealous advocate of either of the propositions he had advanced, 
and was willing to leave the entire matter to Congress. 

The difficulties with France, the war with Great Britain, and 
the consideration of various matters, political and otherwise, left 
little time for Congress to act on matters of weights and measures, 
and accordingly there was no legislative action for a number of 
years. In the meantime the Coast and Geodetic Survey requiring 
some standard of length, imported from England, in 1814, an 
82-inch brass bar scale made by Troughton of London. Thirty- 
six inches taken on this scale, between, divisions 27 and 63, were 
adopted as the standard yard for the United States by the 
Treasury, and this distance was used by other departments. 2 The 
meter, however, was selected at the outset for actual surveying 
operations by the Coast and Geodetic Survey, and for this purpose 
has since been continuously employed in its various triangulations. 
The metric standards were a brass meter bar constructed in Paris 
by Lenoir in 1813 for Mr. Hassler, and one of the original 
secondary iron-bar standards constructed by the same maker for 
the French Metric Committee in 1799, and presented to Mr. 
Hassler by Tralles. 3 This latter standard was employed by the 
Coast Survey until the receipt of the international standards in 
1890, and is now to be seen in the vault of the Bureau of 

1 This is shown plainly in several of Jefferson's letters contained in the Works 
of Thomas Jefferson (New York, 1884), particularly those to William Short 
(vol. iii. p. 276), Dr. Robert Patterson (vol. vi. p. 11), and John Quincy Adams 
(vol. vii. p. 87). 

2 See F. R. Hassler, Report on Weights and Measures, Document 299, 22nd 
Congress, 1st Session, 1832, p. 40. Also U.S. Coast and Geodetic Survey Report, 
1877 ; Appendix 12. 

3 See Hassler, loc. cit., p. 75, for translation of Tralles' description of these 
standards. Also Transactions of American Philosophical Soc. (Phila., 1825), vol. 
ii. p. 252 ; and Special Publication No. 4, U. S. Coast and Geodetic Survey, p. 31 
(Washington, 1900). 



WEIGHTS AND MEASURES IN UNITED STATES 115 

Standards at Washington. It is of rectangular cross section 
9 mm. x 29 mm., and is, of course, an end standard. 

Eeforms in weights and measures were not proceeding any more 
satisfactorily abroad than in the United States. Great Britain 
had been unable " to reduce into any simple order the chaos of 
their weights and measures," 1 as Jefferson wrote to Secretary of 
State Adams in 1817, while in France the Metric System was not 
securing the ready adoption that was desired. The countries 
conquered by Napoleon and compelled to adopt it, returned to 
their old ways once compulsion was removed; and even in France, 
as we have seen, there was considerable doubt as to the practical 
and ultimate success of the new system, while the decimal division 
of time and the decimal measurement of the circle had proved 
distinct failures. Therefore, it is not hard to explain the hesita- 
tion in the United States about adopting the French system. 
That some measures were needed we learn from the message of 
President Madison to Congress in 1816, when he said: 

" Congress will call to mind that no adequate provision has 
yet been made for the uniformity of weights and measures con- 
templated by the Constitution. The great utility of a standard 
fixed in its nature, and founded on the easy rule of decimal pro- 
portions, is sufficiently obvious. It led the Government at an 
early stage to preparatory steps for introducing it, and a com- 
pletion of the work will be a just title to the public gratitude." 

Congress referred the matter to the Secretary of State, John 
Quincy Adams, and that official undertook a thorough analysis 
and study of the whole subject. To him Jefferson wrote in the 
letter already quoted : 2 " I sincerely wish you may be able to rally 
us to either standard, and to give us an unit, the aliquot part 
of something invariable which may be applied simply and con- 
veniently to our measures, weights, and coins, and most especially 
that the decimal divisions may pervade the whole." Adams 
realized that the matter was one of extreme importance that 
could not be settled offhand, and on his own account examined 
the question in all its many aspects, his conclusions being given 
in a report 3 submitted on February 22, 1821, that has since been 

1 Works of Thomas Jefferson, vol. vii. p. 89. 

2 Ibid. 

3 J. Q. Adams, Report upon Weights and Measures, Washington, 1821. 



116 EVOLUTION OF WEIGHTS AND MEASURES 

considered almost a classic in American metrology. While the 
Secretary of State was so engaged, a committee from the House 
of Kepresentatives also considered the question of weights and 
measures, and, January 25, 1819, submitted a report virtually 
advising the adoption of the first plan proposed by Jefferson, and 
recommending that models of the yard, bushel, and pound, con- 
forming to those in most common use, be made under the 
direction of a commission to be selected by the President, and 
which, if satisfactory to Congress, should be declared the standard 
weights and measures of the United States. Again, Congress 
failed to take action on this recommendation, and when, two years 
later, Secretary Adams submitted his report, in which he recom- 
mended that no present change in the weights and measures of 
the country be attempted, but that the standards should remain 
as they were, that body had no disposition to oppose his sug- 
gestions, and nothing was accomplished. 

The report, however, is worth more * than passing notice, for 
although Adams did not believe that the introduction of the 
Metric System into the United States at that time was prac- 
ticable, nevertheless he was as alive to its symmetry, complete- 
ness, and general desirability, as he was to the many advantages 
attending the introduction of a universal system of weights and 
measures throughout the great countries of the world. While it 
is, of course, impossible to do justice to the completeness and 
philosophic treatment of the subject in this report by any 
summary or brief extracts, nevertheless a few passages will show 
how keen was Mr. Adams' understanding of the matter, and how 
well he appreciated the advantages of the French system. He 
said : ! " This system approaches to the ideal perfection of 
uniformity applied to weights and measures, and whether destined 
to succeed or doomed to fail, will shed unfading glory upon the 
age in which it was conceived, and upon the nation by which its 
execution was attempted, and has in part been achieved. In the 
progress of its establishment there it has often been brought in 
conflict with the laws of physical and of moral nature, with the 
impenetrability of matter, and with the habits, passions, pre- 
judices, and necessities of man. It has undergone various 
important modifications. It must undoubtedly submit to others 

1 J. Q. Adams, Report, p. 48. 



WEIGHTS AND MEASURES IN UNITED STATES 117 

before it can look for universal adoption. But, if man upon 
earth be an improvable being ; if that universal peace, which was 
the object of a Savior's mission, which is the desire of the 
philosopher, the longing of the philanthropist, the trembling hope 
of the Christian, is a blessing to which the futurity of mortal 
man has a claim of more than mortal promise ; if the spirit of 
evil is, before the final consummation of things, to be cast down 
from his dominion over men, and bound in the chains of a 
thousand years, the foretaste here of man's eternal felicity, then 
this system of common instruments, to accomplish all the changes 
of social and friendly commerce, will furnish the links of 
sympathy between the inhabitants of the most distant regions ; 
the meter will surround the globe in use as well as multiplied 
extention, and one language of weights and measures will be 
spoken from the equator to the poles." 

As regards the metric or, as he terms it, the French system in 
the abstract or as an ideal system, no one could be more 
enthusiastic than Mr. Adams. He says : 1 " The single standard, 
proportional to the circumference of the earth ; the singleness 
of the units for all the various modes of mensuration ; the 
universal application to them of decimal arithmetic ; the un- 
broken chain of connection between all weights, measures, 
moneys, and coins; and the precise, significant, short, and 
complete vocabulary of their denominations : altogether forming 
a system adapted equally to the use of all mankind ; afford such 
a combination of the principle of uniformity for all the most 
important operations of the intercourse of human society ; the 
establishment of such a system so obviously tends to that great 
result, the improvement of the physical, moral, and intellectual 
condition of man upon earth ; that there can be neither doubt 
nor hesitancy in the opinion that the ultimate adoption and 
universal, though modified, application of that system is a con- 
summation devoutly to be wished." 

The strongest praise for the French system is for the time 
that it will save, and here Mr. Adams states, 2 " Considered 
merely as a labor-saving machine, it is a new power offered 
to man incomparably greater than that which he has acquired 
by the new agency which he has given to steam. It is in 

1 J. Q. Adams, Report, p. 90. 2 Ibid., p. 91. 



118 EVOLUTION OF WEIGHTS AND MEASURES 

design the greatest invention of human ingenuity since that 
of printing." 

Mr. Adams, while he realized the desirability of universal 
measures, believed that they could only come " by consent and 
not by force," and mindful of the difficulties attending the intro- 
duction of the metric system in France, and of certain of its 
features being susceptible of further improvement, thought it to 
be the best policy for the United States first to confer with 
foreign nations as regards the future and ultimate establishment 
of universal and permanent uniformity, and, meanwhile, to 
secure for the weights and measures in use throughout the 
United States a more perfect uniformity by suitable legislation 
especially avoiding for the time being any innovations. The 
conclusion of the report is no less interesting than its other 
sections : It states, 1 " France first surveyed the subject of weights 
and measures in all its extent and all its compass. France first 
beheld it as involving the interests, the comforts, and the morals 
of all nations and of all after ages. In forming her system she 
acted as the representative of the whole human race, present and 
to come. She has established it by law within her own terri- 
tories, and she has offered it as a benefaction to the acceptance of 
all other nations. That it is worthy of their acceptance is 
believed to be beyond question. But opinion is the queen of the 
world, and the final prevalence of this system beyond the 
boundaries of France's power must await the time when 
the example of its benefits, long and practically enjoyed, shall 
acquire that ascendancy over the opinions of other nations 
which gives motion to the springs and direction to the wheels 
of power." 

It is doubtful if a stronger statement of the abstract merits of 
the metric system could be made than is contained in this report. 
Mr. Adams, however, was in error in believing that concerted 
action was necessary to secure the adoption of a universal system, 
as it has come about gradually, and has been adopted by the 
various nations of the world at such times as seemed to them 
suitable and convenient. Again, experience has shown the error 
of Mr. Adams' view on the decimal division of the United States 
coinage. He says (page 81), "The convenience of decimal 

l J. Q. Adams, Report, p. 135. 



WEIGHTS AND MEASURES IN UNITED STATES 119 

arithmetic is in its nature merely a convenience of calculation ; 
it belongs essentially to the keeping of accounts ; but it is merely 
an incident to the transactions of trade. It is applied, therefore, 
with unquestionable advantage to moneys of account, as we have 
done : yet even in our application of it to the coins, we have not 
only found it inadequate, but in some respects inconvenient." 

This famous report has been quoted most extensively by 
writers on American metrology, and passages are cited with great 
enthusiasm by both metric and anti-metric advocates in support 
of their respective positions. While conceding its great breadth 
and philosophical character, yet at the present time it is worth 
considering whether too much stress has not been laid on this 
celebrated document. Although President Adams was a zealous 
student, errors of statement are to be noted, while at the same 
time advances in the science of metrology have made it necessary 
to look at certain matters in a new light. 

There was at least one department of the U.S. Government — 
namely, the Mint — where any uncertainty of weight could not for 
obvious reasons be tolerated. Accordingly, Minister Gallatin 
was instructed to procure from England a copy of the imperial 
standard Troy pound which had been adopted in 1825. This he 
did, and the standard, after having been most carefully compared 
by Captain Kater, was transmitted to the United States, and by 
Act of Congress of May 19, 1828, 1 was duly established as the 
coinage standard of the United States, the Act being remarkable 
in that it is the only legislative Act legalizing any of the 
•customary measures, and establishing a standard for such purpose. 
The Act provides, that " For the purpose of securing a due con- 
formity in weight of the coins of the United States to the 
provisions of this title, the brass troy -pound weight procured by 
the minister of the United States at London, in the year eighteen 
hundred and twenty-seven, for the use of the Mint, and now in 
the custody of the Mint at Philadelphia, shall be the Standard 
troy pound of the Mint of the United States, conformably to 
which the coinage thereof shall be regulated." 2 

1 C. 131, Sec. 50, 17 statutes 432. Revised statutes 3548. 

2 A description of this standard, together with the various certificates of 
individuals concerned with its construction, testing, receipt, etc., including 
Oaptain Henry Kater, Minister Gallatin, and President John Quincy Adams, 



120 EVOLUTION OF WEIGHTS AND MEASURES 

On May 29, 1830, the Senate passed a resolution ordering the 
comparison of the standards of weights and measures used by the 
different custom-houses, and when these measures or copies were 
called in to the Treasury Department for examination, it was 
found that there was the greatest lack of uniformity throughout 
the various customs districts. In many cases the various state 
or local sealers of weights and measures were appealed to not 
only for purposes of comparison, but even for the correction of 
the standards. 1 

The resulting diversity of weights and measures naturally was 
not without its effect on the revenues of the Government, in 
addition to violating that section of the Constitution which pro- 
vides that taxes shall be uniform throughout the United States. 
The national standards upon which the measurements made in 
the custom-houses were based are thus described in the following 
extract from the report of S. D. Ingham, Secretary of the 
Treasury, March 3, 1831 : 

" Among the instruments which had been procured, some years 
ago, under the direction of the President, for the survey of the 
coast, was a standard measure of length, exactly corresponding 
with the British Parliamentary standard, as established in 1758, 
with which that of 1760 is identical, as tested by Sir George 
Shuckburgh in 1798, and by Captain Kater in 1821, on the 
occasion of the last determination of the weights and measures in 
England, when it was adopted as the legal unit. This standard 
measure has, by means which will be explained in a future 
report, been compared with the pendulum vibrating seconds in 
London, and also with the French meter, which is based upon 
measurements of arcs of a meridian of the earth. With such, 
evidence of its character, and such an opportunity of correcting 
any alteration by reason of decay, it was without hesitation, 
adopted as the unit for the comparison of measures of length. 

" The troy pound used in the Mint is known to be identical 
with the latest established standard troy pound of Great Britain, 
as regulated by the British laws, and standarded by Captain 

will be found contained in an interesting history of the weights and measures of 
the United States, by 0. H. Tittman, in the United States Coast and Geodetic 
Survey Report for 1890, Appendix 18, pp. 736-8. 

1 Hassler, p. 6 (House of Reps. Doc., No. 299, 22nd Congress, 1st Session). 



WEIGHTS AND MEASURES IN UNITED STATES 121 

Kater in 1824, having been constructed by him at the special 
request of Mr. Gallatin, upon the same principles and in the 
same manner that he had employed in the construction of the 
British standard." 1 

Preparations were duly made to construct from these standards 
the standards for the custom-houses, and on June 14, 1836, a joint 
resolution was adopted by both Houses of Congress providing 
that there should be constructed in the office of the Coast 
Survey for every state and territory, complete sets of standards 
equal to those made for the custom-houses, " to the end that 
a uniform standard of weights and measures may be established 
throughout the United States," and in July, 1838, it was ordered 
that balances for the accurate comparison of weights should be 
similarly constructed and distributed to the states and territories. 
The standard weights were given to the custom-houses in 1836, 
and in the following years the standard yards, which were based 
on the Troughton scale, and liquid measures were distributed. 
By 1856 the various states of the Union were supplied with 
sets of standards, and shortly after their receipt the individual 
states enacted statutes establishing them as the standards of 
weights and measures. 2 This work was important, as being 
the first practical and systematic attempt to secure general 
uniformity of weights and measures throughout the country,, 
and as an early example of refined constructive scientific work 
being carried on by the national government for the benefit 
of the people at large in their commercial relations. 

It should be said in passing that the early work of estab- 
lishing the standards of weights and measures for the United 
States was done by Professor F. E. Hassler, the superintendent 
of the Coast Survey, from its inception to his death, and during 
these years many interesting reports dealing with the scientific 
and other features of the work were prepared by him. 3 To 

Extract from the report of S. D. Ingham, Secretary of State, March 3, 1831 1 
House of Representatives, Doc. No. 299, July 2, 1832, 22nd Congress, 1st 
Session. 

2 See Laws Concerning the Weights and Measures of the United States, an official 
compilation of the United States Bureau of Standards of legislation on this- 
subject (Washington, 1904). 

3 See partial bibliography in House of Representatives, Report No. 3005, 56th 
Congress, 2nd Session. 



122 EVOLUTION OF WEIGHTS AND MEASURES 

Professor Hassler was due the derivation of the standard avoir- 
dupois pound from the standard Troy pound, and so accurately 
was the work accomplished that when the British Government 
sent over in 1856 a copy of the standard avoirdupois pound, there 
was found a difference of '001 of a grain between British and 
American standards. He also connected the units of capacity 
with those of weight, by using in his experiments, which were 
begun in 1830, distilled water at its temperature of maximum 
density, and thus was able to determine and construct accurate 
standards. 

On the death of Mr. Hassler in 1843, Professor A. D. Bache 
became the head of the Coast Survey, and manifested consider- 
able interest in the work of the Office of Weights and Measures, 
supervising the completion and distribution of the state standards 
begun by Mr. Hassler, and in his reports making recommenda- 
tions looking towards the improvement of the United States 
system of weights and measures, and also the establishment of 
a universal system. 

With the distribution of the standard weights and measures, 
there resulted the natural inquiries as to their origin and value, 
and the legal enactments upon which they were founded. Pro- 
fessor Bache in his report for 1848 1 summarizes the essential 
facts relating to them. The actual standard of length is the 
8 2 -inch Troughton scale (which has been already described) ; 
" the units of capacity measure are the gallon for liquid and the 
bushel for dry measure. The gallon is a vessel containing 
58,372*2 grains (8*3389 pounds avoirdupois) of the standard pound 
of distilled water, at the temperature of maximum density of 
water, the vessel being weighed in air in which the barometer 
is 30 inches at 62° Fahrenheit. The bushel is a measure 
containing 543,391 '89 standard grains (77'6274 pounds avoir- 
dupois) of distilled water at the temperature of maximum 
density of water, and barometer 30 inches at 62° Fahrenheit." 
The gallon is thus the wine gallon of 231 cubic inches nearly, 
and the bushel the Winchester bushel nearly. The temperature 
of maximum density of water was determined by Mr. Hassler 
to be 39'85° Fahrenheit. The standard of weight is the Troy 
pound copied by Captain Kater in 1827 from the imperial Troy 

^Oth Congress, 1st Session, Senate Executive Doc. 73 (1848), p. 8. 



WEIGHTS AND MEASURES IN UNITED STATES 123 

pound for the United States Mint, and preserved in that 
establishment. The avoirdupois pound is derived from this : 
its weight being greater than that of the Troy pound, in the 
proportion of 7000 to 5760 ; that is, the avoirdupois pound is 
equivalent in weight to 7000 grains Troy. The multiples, as well 
as subdivisions of the pound, are based upon this standard, the 
weight of which was determined by the best means attainable at 
that time, in grain weights, by Troughton, at the Mint, and at 
the Office of Weights and Measures, in presence of Mr. Hassler, 
and of the Director of the Mint, Dr. Moore. From these 
determinations resulted the pound weights of the Office of 
Weights and Measures, which are therefore copies of the Troy 
pound of the United States Mint or derived from it. The 
pound is a standard at 30 inches of the barometer and 62° 
Fahrenheit thermometer. The Troy pound of the Mint was 
found, in the comparisons of Captain Kater, to be heavier than 
the imperial Troy pound by only '0012 of a grain. 

" The measures of length and capacity, and the weights just 
referred to, have been adopted by the Treasury Department as 
standards for the measures and weights of the custom houses of 
the United States, and reported as such to Congress in 1832. . ." 

That the system was then unsatisfactory in many respects we 
have abundant testimony. The simplification of the existing 
weights and measures, and the issuing of correct standards had 
been provided for as Adams had suggested, but nothing had been 
done to improve the system or towards co-operating with foreign 
nations in establishing a universal system, as Adams had also 
suggested. On the conditions as they then existed Professor 
Bache's observations are of interest. In a report made in 1848 
he says : x 

" No one who has discussed the subject of weights and 
measures in our country has considered the present arrangement 
as an enduring one. It has grown up with the growth of 
European society, and is deficient in simplicity and in system. 
The labor which is expended in mastering the complex denomi- 
nations of weights and measures is labor lost. Every purpose 
for which weights and measures are employed can be answered 
by a simple and connected arrangement." 

1 Executive Document 84, Thirteenth Congress, 1st Session, July 30, 1848. 



124 EVOLUTION OF WEIGHTS AND MEASURES 

Professor Bache believed that inasmuch as it was the prac- 
tically universal opinion of all who had studied and written on 
American weights and measures that the system then in use 
must be considered temporary, and eventually be replaced by a 
more convenient and systematic arrangement, and wrote in 
reference to Adams' plan for an international conference on the 
subject as follows : " The present time seems especially to invite 
an effort of this kind. In England the subject of weights and 
measures is under consideration by a commission ; and on the 
Continent the new relations of states hitherto separated appears 
to be favorable to this object. Such changes can be readily 
effected by suitable means in one generation, by introducing the 
new measures through the elementary schools." In a subsequent 
report Professor Bache asks, " Has not the time arrived, in the 
general progress of commercial and international intercourse, and 
the rapid advance of our own country in science, wealth, and 
power, when her voice should be heard in an important matter 
like this ? Should not Congress make the proposition to all 
nations, to meet, by their representatives, and consult for the 
purpose of establishing uniformity of weights and measures ? 
Such action could not fail to meet with a response due to the 
greatness of the subject, and if the great object be attained, to 
lead to results productive of vast and lasting benefit to the 
human race." 

While it is quite natural that opinions in favor of the adoption 
of the metric system should be given by officials of the bureau of 
weights and measures, and by Secretaries of the Treasury, it is 
possible to recognize the beginning of a distinct general feeling 
and movement in favor of reforms in American weights and 
measures. This may be traced largely to the increasing numbers 
of scientific and professional men who were sent to Europe for 
education, and, who having used the metric system in the schools 
and laboratories of France and Germany, became enthusiastic 
advocates of the system, with the result that on their return 
to the United States they adopted it for their own scientific 
work, and taught it to their students. In chemistry especially 
its pre-eminence was early recognized, and American chemists 
soon fell in with the universal system which by this time 
was employed in all the European journals and standard 



WEIGHTS AND MEASURES IN UNITED STATES 125 

works. 1 American diplomats and representatives to various inter- 
national conferences also became convinced of the desirability of 
a uniform system of weights and measures, and their influence 
was also exerted in stimulating a feeling in favor of reforms. 

In February, 1854, the American Geographical and Statistical 
Society, of which George Bancroft, the historian and Minister to 
Spain, was then president, presented a memorial to Congress in 
which the appointment of a joint scientific commission to consider 
a uniform system of weights and measures based on a decimal 
system was urged. This was one of the earliest of a number of 
similar resolutions which have since been addressed to Congress. 
Of more importance, however, as coming from the people at large 
rather than from scientific bodies, were the resolutions adopted 
by the legislatures of various States. The legislature of New 
Hampshire, by joint resolution approved on June 28, 1859, re- 
quested their senators and representatives to urge upon Congress 
the adoption of a decimal system, while the legislature of Maine, 
March 20, 1860, by joint resolution, expressed in still more 
decided language, their desire for a uniform international system 
of weights, measures, and coins. This action was soon followed 
by a similar resolution by the legislature of the State of Con- 
necticut, which in June, 1864, took an important step in recom- 
mending to the proper school officers, that they should provide 
for the teaching of the metric system in all the schools of the 
State. From this time interest in the metric system in con- 
nection with the study of the arithmetic in the schools increased, 
so that the pupils within a few years became aware of the 
existence of the system, although often in the method of pre- 
sentation of the subject in text-books, and by teachers there was 
little to commend it to the young mind. The problems were 
usually those involving conversion from the common system to 
the metric, and as such, were not likely to inspire any great 
degree of appreciation for the latter. 

The Civil War so occupied the legislative and executive 
departments of the Government that there was little opportunity 

1 The use of the metric measures in American College text-books, in physics and 
chemistry, dates from 1868-1870. In similar works for high schools the new 
system was used from 1878. R. P. Williams before Am. Chem. Soc, June, 
1900. 



126 EVOLUTION OF WEIGHTS AND MEASURES 

for any marked progress on the part of Congress or the officials. 
The condition of affairs is stated by Salmon P. Chase, Secretary 
of the Treasury, in his annual report December 9, 1861, where he 
writes : " The Secretary desires to avail himself of this oppor- 
tunity to invite the attention of Congress to the importance of a 
uniform system and a uniform nomenclature of weights and 
measures, and coins to the commerce of the world in which the 
United States already so largely shares. The wisest of our 
statesmen have regarded the attainment of this end so desirable 
in itself as by no means impossible. The combination of the 
decimal system with appropriate denominations in a scheme of 
weights, measures, and coins for the international uses of com- 
merce, leaving, if need be, the separate systems of nations 
untouched, is certainly not beyond the reach of the daring genius 
and patient endeavor which gave the steam engine and the 
telegraph to the service of mankind. The Secretary respect- 
fully suggests the expediency of a small appropriation to be 
used in promoting interchange of opinions between intelligent 
persons of our own and foreign countries on this subject." 

In 1863 the United States was represented abroad at two 
important international congresses, both of which took action on 
the matter of weights and measures which commended itself to 
the American delegates. At the International Statistical Con- 
gress held at Berlin, a committee appointed at the Paris meeting 
three years previously, to consider the question of uniform 
international weights, presented a report in which the subject 
was carefully considered and as a result of which the Congress 
resolved that the same measures for international commerce was 
of the highest importance, and that the metric system was the 
most convenient of all that could be recommended for inter- 
national measures. 1 At a previous session this body had 
recommended that the countries which employed weights and 
measures other than the metric should give in adjoining columns 
the metric equivalents of all statistics. 

The other international congress referred to was a postal 
congress held at Paris in May, 1863, and which resulted in 
important measures towards securing uniformity of weights 

1 Samuel B. Ruggles, Report on International Statistical Congress at Berlin in, 
respect to Uniform Weights, Measures, and Coins (Albany, 1864), pp. 43, 44. 



WEIGHTS AND MEASURES IN UNITED STATES 127 

throughout the world. It was here recommended, that, " Sec. 7. 
The rates upon international correspondence shall be established 
according to the same scale of weight in all countries," that 
" Sec. 8. The metrical system, being that which best satisfies the 
demands of the postal service, should be adopted for international 
postal relations, to the exclusion of every other system " ; and 
that " Sec. 9. The single rate upon international letters shall be 
applied to each standard weight of 15 grams or fractional part of 
it." This proposition proved satisfactory to the various nations 
and accordingly was incorporated in the International Postal 
Convention. 

In 1866, when the resolutions authorizing the use of the 
metric system of weights and measures was passed by the 
Congress of the United States, which is referred to at more 
length below, an Act was also passed enabling the Post Office 
Department to use the metric weights and measures for foreign 
and other purposes, and the law was re-enacted in 1872 and 
now reads {Revised Statutes of the United States, Sec. 3880), 
" The Postmaster-General shall furnish the post-offices ex- 
changing mails with foreign countries, and to such other 
offices as he may deem expedient, postal balances denoted in 
grams of the metric system, fifteen grams of which shall be 
the equivalent for postal purposes of one half ounce avoirdupois, 
and so on in progression." The interchange of mail by all 
the civilized countries of the world represents the most extensive 
use of a uniform system of weights and measures in the world 
and has been carried on for many years without the slightest 
confusion or embarrassment. All mail matter transported be- 
tween the United States and the fifty or more nations, 
signatories of the International Postal Convention, including 
the United States and Great Britain even, is weighed and paid 
for entirely by metric weight. 

The serious consideration of the metric system in the United 
States by the people at large may be said to date from 1866 
when Congress passed a Bill which was approved by the 
President authorizing the use of the metric system of weights 
and measures. In this action Congress had the advice of 
the National Academy of Science, which had appointed in 
1863, at the request of the Secretary of the Treasury, a special 



128 EVOLUTION OF WEIGHTS AND MEASURES 

committee to consider the matter. In its report, which was 
adopted by the Academy, occurs the following passage, which 
seems to sum up the situation : " The committee are in favor 
of adopting, ultimately, a decimal system : and in their opinion, 
the metrical system of weights and measures, though not 
without defects, is, all things considered, the best in use. 
The committee therefore suggest that the Academy recommend 
to Congress to authorize and encourage by law the introduction 
and use of the metrical system of weights and measures, and 
that, with a view to familiarize the people with the system, 
the Academy recommend that provision be made by law for 
the immediate manufacture and distribution to the custom- 
houses and States, of metrical standards of weights and 
measures : to introduce the system into the post-offices by 
making a single letter weigh 15 grammes instead of 14^^, 
or half an ounce : and to cause the new cent and two cent 
pieces to be so coined that they shall weigh respectively 
5 and 10 grammes, and that their diameters shall be made 
to bear a determinate and simple ratio to the metrical unit 
of length." 1 Accordingly, by the law of May 16, 1866, the 
weight of the 5 cent copper nickel piece was fixed at 5 grams. 
This idea was extended to the silver coinage, and by the law 
of Feb. 12, 1873 {Revised Statutes of the United States, Sec. 
3513), it was provided that "The weight of the half dollar 
shall be twelve grams and one-half of a gram; the quarter 
dollar and the dime shall be, respectively, one-half and one- 
fifth of the weight of said half dollar." The Act passed 
by Congress (Revised Statutes of the United States, Sec. 3569) 
on July 28, 1866, making the metric system permissive, pro- 
vided that "it shall be lawful throughout the United States 
of America to employ the weights and measures of the metric 
system, and no contract or dealing, or pleading in any court, 
shall be deemed invalid or liable to objection because the 
weights and measures expressed or referred to therein are 
weights or measures of the metric system." The Act further 
provided a series of legal tables of equivalents, and upon them 
are based in the United States all conversions from one system 

1 House of Representatives, Report of the Committee on Coinage, Weights, 
and Measures, 46th Congress, 1st Session, Report No. 14, p. 23, part i. 



WEIGHTS AND MEASURES IN UNITED STATES 129 

to the other, as, for example, those contained in the tables in 
the Appendix of this book. To further the use of the metric 
system Congress passed an Act, approved July 27, 1866, 
authorizing and directing the Secretary of the Treasury to 
furnish to each State one set of the standard weights and 
measures of the metric system. With this start the metric 
system has grown in the United States, and various measures 
looking towards its final adoption have been urged in Congress 
and among the people generally. 

The delegates to the Paris Exposition of 1867 were par- 
ticularly enthusiastic in this respect, and among them Professor 
F. A. P. Barnard, President of Columbia College, who, with 
.a number of other advocates of reforms in weights and measures, 
formed December 30, 1873, the American Metrological Society, 
and was its president until his death in 1889. 1 This society, 
while interested in such kindred subjects as the adoption 
of standard time and international currency, carried on an 
active propaganda in behalf of the metric system, while the 
Metric Bureau which was organized July, 1876, with head- 
quarters in Boston, supplied material both in the way of 
literature and actual weights and measures, charts, tables, 
etc., that was of the greatest assistance to the general public, 
especially teachers, who were now called upon in many States 
to explain and teach the principles of the system. 

Sufficient interest was manifested in the subject for the United 
States Government to accept the invitation of the Government 
of France to send delegates to Paris to form an international 
commission to construct new metric standards. America was 
accordingly represented by Professor Joseph Henry and J. E. 
Hilgard, the latter being an active member of various important 
committees concerned with the construction of the standards. 
When this commission, after reassembling in 1872, decided that 
an International Bureau of Weights and Measures should be 
established in Paris, the plan had the approval of the delegates 
of this country and of the American scientific world generally, 
the National Academy of Sciences formally favoring the scheme 
and recommending to the Government the signing of such 
a treaty. The work of the Commission has already been 

a See Proceedings, American Metrological Society, 1873-1888 (New York). 

I 



130 EVOLUTION OF WEIGHTS AND MEASURES 

discussed, 1 and in this connection it is necessary merely to record 
the fact that when the American Minister to France, Mr. E. B. 
Washburne, signed the convention, together with delegates from 
sixteen other nations, agreeing to establish and support the 
International Bureau of Weights and Measures, the United 
States became committed to the principle of international weights 
and measures, and privileged to participate in the benefits accru- 
ing from a common system and common standards. 

In 1889, after accurate and careful construction and adjustment 
and comparison, the international prototype standards of the 
standard meter and kilogram were completed by the bureau, and 
were distributed to the various countries supporting the Com- 
mission. In a distribution by lot, the United States received 
meters Nos. 21 and 27, and kilograms Nos. 4 and 20. The seals 
of meter No. 27 and kilogram No. 20 were broken by President 
Benjamin Harrison on January 2, 1890, and they were straight- 
way deposited in a fireproof room at the Office of Weights and 
Measures in the Coast Survey Building. 2 These standards were 
immediately adopted as the national prototype meter and kilo- 
gram, and the primary standards for the United States, and were 
employed as fundamental standards for deriving customary 
units, the yard and the pound, as well as for constructing and 
standardizing secondary metric standards. To obviate any 
possible misunderstanding, however, a formal order, approved by 
the Secretary of the Treasury, was issued on April 5, 1893, 
recognizing " the International Prototype Meter and Kilogram 
as fundamental standards, and the customary units, the yard and 
the pound, will be derived therefrom in accordance with the Act 
of July 28, 1866." 3 

Here, again, we find a matter of fundamental importance 
settled by Executive order, and the United States firmly com- 
mitted to the metric system as the basis of all measures in use, 

1 See pp. 72-77. For text of treaty, diplomatic correspondence, reports, etc , 
see chapters ii. and iv., Report No. 14, 46th Congress, 1st Session, House of Repre- 
sentatives, Committee on Coinage, Weights, and Measures (Washington, 1879). 

2 For technical description of the standards, certificates, reports, etc., consult 
Report U.S. Coast and Geodetic Survey, 1890, Appendix 18, pp. 746-758. 

3 Bulletin No. 26, U.S. Coast and Geodetic Survey, "Fundamental Standards 
of Length and Mass." Republished as Appendix No. 6, 1893, U.S. Coast and 
Geodetic Survey Report. 



WEIGHTS AND MEASURES IN UNITED STATES 131 

no matter what their source. So far as fundamental standards 
go, the only ones used by the United States are metric and 
international, and to them must be referred all measures, whatever 
their nature. These standards are known in their relation to 
the standards of the International Bureau at Sevres, and to 
those of the various foreign countries, so that in case of their 
destruction they could readily be reproduced, thus guaranteeing 
the permanency of weights and measures founded upon them. 

In fact, meter No. 27 was transported to Paris in 1904 for 
comparison with the standards of the International Bureau, 
and after several series of careful observations its value was 
redetermined in terms of the international standard prototype. 
It was found that No. 27 at 0° centigrade was too short by 
2 microns, a discrepancy greater by '55 microns than that 
obtained in 1888, when it was tested with the other national 
prototypes. This change, however, was so minute that the 
U.S. Bureau of Standards decided to employ the old value 
in all of its determinations until an opportunity had been 
given to compare standard No. 27 directly with the international 
prototype meter and with other national prototypes. Inasmuch 
as the relation of No. 27 to No. 21 is accurately known, as 
also are the values of various secondary standards in terms 
of both national standards, it will be seen that the Bureau 
of Standards is now in a position to guarantee the accuracy 
and permanency of the measures of the United States. 1 

That progress was being made in the use of the metric system 
is shown by the fact that when Congress, on March 3, 1893, 
passed an Act 2 establishing a standard scale for the measurement 
of sheet and plate iron and steel, it was expressed in terms of 
both the customary and metric measures. Of perhaps greater 
importance was the Act approved July 12, 1894 {Revised 
Statutes of the United States, Supplement, vol. ii. chap. 131, 
1894), which denned and established the units of electrical 
measure. These were the international electrical units based on 

1 See L. A. Fischer, " Recornparison of the United States Prototype Meter," 
Bulletin of the Bureau of Standards (Washington), pp. 5-19, No. 1, vol. i. 
1904. The discrepancy mentioned has since been accounted for through a 
small error in the coefficient of expansion of No. 27, which was compared at 
different temperatures in 1888 and 1904. 

2 Bevised Statutes, 3570, c. 231, Sec. 1, 27 Statute, 746. 



132 EVOLUTION OF WEIGHTS AND MEASURES 

the metric system which were in use by electrical engineers 
throughout the world, having been definitely settled at a congress 
held at Chicago in 1893. 1 

In 1901 the National Bureau of Standards was established by 
Act of Congress to take over the duties of the old Office of 
Weights and Measures of the Coast and Geodetic Survey, and 
to have somewhat broader functions, especially in carrying on 
standardization and other scientific work of general public 
advantage. To this bureau was assigned the custody of the 
national standards and the construction and comparison of 
secondary and other standards of weights and measures of all 
kinds. In the event of the adoption of the metric system, it 
would fall to this bureau to oversee the construction and certify 
to the correctness of the many new standards that would be 
required in science, commerce, and the arts. This it is well 
equipped to do, and has large laboratories with every facility for 
such work. 

When new territories were added to the United States as a 
result of the Spanish war in 1898, it was found that the metric 
system of weights and measures was employed in both Porto 
Eico and the Philippine Islands, and the status of the system in 
these possessions was duly confirmed. In the proclamation of 
the Military Governor of Porto Rico, March 18, 1899, it was 
stated, " 1. The use of the metrical system of weights and 
measures and its nomenclature are obligatory. 2. Its use is 
enforced in all transactions, sales, contracts, ... 3. Wholesale 
and retail mercantile establishments shall sell their goods to 
the public conformably to the metric system." The Political 
Code of Porto Rico (1902), sections 230-246, definitely fixes the 
metric systems and gives the legal definitions. The Philippine 
Tariff Act (No. 230, September 17, 1901, sec. 9) contained a pro- 
vision that " The metrical system of weights and measures as 
authorized by sections 3569 and 3570 of the Revised Statutes of 
the United States, and at present in use in the Philippine 
Islands, shall be continued." In the Government Bill of 1902 it 
was provided that " Sections (of the former 2 Act) are hereby 
amended by reducing all measurements therein, whether of dis- 
tance, area, or value, to the metric system." 

1 See p. 208, chap. ix. 2 Philippine Government Act of 1902. 



WEIGHTS AND MEASURES IN UNITED STATES 133 

Since the first permissive legislation in 1866 there have been 
various Bills introduced into Congress to establish the metric 
system, and each successive one has come before Congress with 
stronger support, and likewise with stronger opposition on the 
part of those opposed to any change. The matter of weights and 
measures has been investigated most carefully by various House 
Committees on Coinage, Weights, and Measures, and their reports 
are replete with information on the subject treated from different 
standpoints. In 1896 two interesting reports 1 were prepared 
after the committee had made a careful consideration of the 
subject extending over two sessions, and a Bill to establish the 
metric system was unanimously recommended for adoption, 
but, however, did not pass a third reading. Again in 1901 a 
somewhat similar Bill was reported from the Committee, accom- 
panied by a brief report 2 in which its passage was recommended, 
but unfortunately this Bill was received too late to be considered 
by the Congress then in session. Once more, in 1902 and 1903, 
the subject was discussed in committee and numerous hearings 
were held, the record of which was embodied in an interesting 
report 3 in which the establishing of the metric weights and 
measures as the legal standards of the United States was 
recommended. 

The general tendency of all these Bills was the same. It was 
proposed that within a few months after their passage, usually 
at the commencement of the next calendar year, that the national 
Government in all its business relations, as well as in all its 
constructive work, should adopt the metric weights and measures 
exclusively, while for the public at large two or three years 
should elapse, after which they would become the legal system 
of the country. It was not proposed to resort to compulsory 
measures, but to so establish the new system that it would 
gradually extend into universal use. In the Littauer Bill intro- 
duced in 1905 it was provided only that the metric system 
should be employed by the Government in all its transactions 
and activities. 

^H.R. Report No. 795, and H.R. Report No. 2885, February 10, 1897, 
54th Congress. 

2 H.R. Report No. 3005, 56th Congress, 2nd Session, March 1, 1901. 
Z H.R. Report No. 1701, 57th Congress, 1st Session, April 21, 1902. 



134 EVOLUTION OF WEIGHTS AND MEASURES 

Secretaries of State and Treasury, irrespective of political 
party, as well as other executive officers of the Government, have 
urged the adoption of the international system, and diplomats 
and consuls have repeatedly called attention to the benefits to 
commerce that would ensue. Scientific men and educators have 
unanimously urged the desirability of the change, as have many 
engaged in foreign commerce. Against any innovation at the 
present time are many manufacturers and mechanical engineers, 
many of whom have secured in their work a considerable accu- 
racy of construction, especially as regards patterns based on the 
English measures, which they assert could only be abandoned at 
an expense entirely incommensurate with any possible benefit. 1 
At Congressional hearings, in the scientific press, and at meetings 
and conventions, the question has been thoroughly debated by 
those interested, and the material for information is most ample. 
It is now, however, a matter for the American nation at large, 
and when the people are thoroughly convinced of the great 
benefits that will ensue, there will be no outcry against temporary 
inconvenience. The adoption of the metric system is surely in 
the line of progress, and when once it is realized, the United 
States, with its superior school system and general high order of 
intelligence possessed by its people, especially its workers, can 
make the change with a minimum of embarrassment and can 
avail themselves of its benefits more quickly than has been done 
in the past by European nations. 

1 This point of view will be found strongly represented in Halsey and Dale, 
The Metric Fallacy, New York, 1903, one of the ablest of the anti-metric books, 
and one that attracted considerable attention at the time of its publication on 
account of the bitterness of its attacks on the metric system and its advocates. 
It furnished material for many reviews and discussions in the technical press, 
both favorable and hostile. Of the latter possibly the most interesting and able 
were those in the Electrical World and Engineer (New York), vol. xliv. No. 19, 
pp. 784-794, Nov. 5, 1904, and in The Physical Review (Ithaca), 1904. 

A somewhat more scholarly, though less argumentative paper from a 
similar point of view, by George W. Colles, entitled " The Metric versus the 
Duodecimal System," will be found in the Transactions of the American Society of 
Mechanical Engineers, vol. xviii. pp. 492-611, 1896-1897. See also a paper by 
J. H. Linnard, "The Metric System in Shipbuilding," Transactions of the Society 
of Naval Architects and Marine Engineers (New York, 1903), vol. ii. pp. 168-188. 



CHAPTEE V. 

THE METRIC SYSTEM OF TO-DAY—ITS ESSENTIAL CHAR- 
ACTERISTICS AND FUNDAMENTAL PRINCIPLES. 

The metric system to-day represents a complete, uniform, and 
simple international system of weights and measures, and as such 
may be considered briefly in its entirety, and with a view of the 
relation of the various units to one another. In the beginning 
it must be understood that any particular metric unit as such 
does not possess any intrinsic superiority over other units, but 
by reason of being united into a system which is strictly symme- 
trical and systematized on one base ratio throughout, and with 
that base ratio 10, metric units have many and preponderating 
advantages over those of other systems. Nevertheless, bearing in 
mind the two conditions mentioned, which are fundamental, there 
is nothing to prevent other systems being constructed with other 
units which would no doubt be equally satisfactory. But in reply 
it may be said, Why should this be done, when a system exists, 
used not only by men of science generally but by a large part of 
the civilized world, the abandonment of which would surely accom- 
plish no particular purpose. " For," says Professor R. H. Smith, 1 
" no other can possibly be better in practical essentials except in 
substituting for ten the base twelve or thirty for measures and 
written numeration alike, and this latter is humanly impossible." 
For ordinary purposes of simple measurement, units are 
grouped into five different classes, those pertaining to measures of 

1 Professor R. H. Smith in Journal oj Institution of Electrical Engineers, quoted 
by A. Siemens in Proceedings, Royal Statistical Society (London), p. 693, vol. lxvi. 
1903. 



\ 



136 EVOLUTION OF WEIGHTS AND MEASURES 

length, surface, volume, capacity, and weight, or, as regards the 
last, speaking more exactly and scientifically, mass. These all 
depend upon the meter as the fundamental unit, and as a primary 
and essential condition of the system, all must bear a strictly 
decimal relation to each other. Inasmuch as in the metric 
system all are referred to one primary standard, the Meter, there 
must be necessarily absolute uniformity, and as means have been 
taken to preserve this standard from any deterioration due to- 
time or other causes, there is every guarantee of the stability of 
the system and of its standards. Furthermore, what was once- 
deemed desirable but found to be impossible of realization,, 
namely, the definition of a standard by some object or circum- 
stance in nature, has been accomplished, and to-day we have the 
meter precisely defined in terms of the wave-length of cadmium 
light by a method which is described elsewhere. 1 Thus in the 
event of the loss or the destruction of the International Prototype 
Meter or of the copies thereof, it would be possible to reproduce 
the exact length by experiments that to the practised physicist 
involve no serious difficulty. 

With the fundamental unit, the International Prototype Meter, 
defined as the distance between two fine lines on a particular 
platinum-iridium bar, at the temperature of melting ice, and 
reproduced by national standards accurately copied therefrom and 
duly recognized by the laws of the countries owning them, by 
simply multiplying by ten successively or by a similar simple 
process of decimal subdivision, is built up a system of measures 
of length which have been demonstrated as sufficient for the 
needs of science, commerce, and industry. Each unit is 
either ten, one hundred, one thousand, ten thousand, or a million 
times as great as the fundamental unit of length, the meter, or a 
similar fraction or sub-fraction. This relation for many purposes 
it is convenient to express by means of the number 10 and the 
appropriate exponent or index, and then speak of a certain 
number of meters multiplied by 10, 10 2 , 10 3 , 10 4 , 10 6 , or for the 
sub-multiples 10" 1 , 10 ~ 2 , 10" 3 , etc. Consequently, in a number 
expressing a length in a metric unit, it is possible to change the 
unit merely by moving the decimal point or adding a requisite 
number of zeros to correspond with the necessary decimal multi- 

1 See chapter x. pp. 261-266. 



THE METRIC SYSTEM OF TO-DAY 137 

plication or division. Thus, as will be seen from the following 
table, 1 kilometer may be written as 1000 meters simply by adding 
three zeros to the 1, while 1 decimeter may be expressed in 
terms of the meter simply by moving the decimal point one 
place to the left. Taking fundamental units other than those of 
length, which, however, are derived from the meter, a similar 
method of decimal multiplication and subdivision enables us to 
derive complete sets of units for surface, volume, capacity, and 
mass measurements. For the first two we use the square meter 
and the cubic meter as the fundamental units, and for capacity 
the liter, and for mass the gram. 

For the multiples of its principal units the metric system 
employs prefixes derived from the G-reek as follows : 

Deca meaning 10 times derived from Greek Seica. = 10 
Hecto „ 100 „ „ €kclt6v= 100 

Kilo „ 1000 „ „ x^ a = 1000 

Myria „ 10000 „ „ fwpia = 10000 

Similarly, prefixes derived from the Latin are employed for the- 
submultiples of the various units. These are as follows : 

Deci meaning ^ derived from Latin decern = 10 
Centi „ y^ „ „ centum = 100 

Milli „ TJ }^ U „ „ mille=1000 

These seven prefixes always used in the same relation supply the 
means of obtaining units of a size convenient for the work in 
hand, and alway instantly available for conversion into units of 
another denomination. To facilitate remembering the fact that 
the Greek prefixes indicate multiples, and the Latin the sub- 
multiples, one has merely to think of the word " Gild," and 
understand that it stands for the initials of the motto, " Greek 
increases, Latin decreases." With the three primary units, in- 
volving the three names meter, liter, aud gram, and the two 
more arbitrary units are and stere, together with the seven 
prefixes given above, it is possible to construct all the metric 
units in ordinary use, inasmuch as their relation to each other- 
is perfectly uniform and simple. 



138 EVOLUTION OF WEIGHTS AND MEASURES 



Metric Measures of Length. 



Unit. 


Abbrevia- 
tion. 


Where Employed. 


Value in Terms 
of Meter. 


Power 
of 10. 


Megameter, - 




Astronomy 


1,000,000m. 


lO^m. 


Myriameter, 


Mm. 


Geography 


10,000m. 


10 4 m. 


Kilometer, - 


Km. 


Distance 


1,000m. 


10 3 m. 


Hectometer, 


Hm. 


Artillery 


100m. 


10 2 m. 


Decameter, - 


Dm. 


Surveying 


10m. 


10m. 


Meter, 


m. 




lm. 




Decimeter, - 


dm. 


[Commerce 


•lm. 


lO^m. 


Centimeter, - 


cm. 


-j Industry 


•01m. 


10" 2 m. 


Millimeter, - 


mm. 


1 Science 


•001m. 


10" 3 m. 


Micron = /*, - 




(Metrology 


•000,001m. 


10~ 6 m. 


Millimicron, 




■I Spectroscopy 
[Microscopy 


•000,000,001m. 


10-9m. 



While the foregoing represent the various units of length in 
the metric system, and indicate the principal departments of 
knowledge in which they are used, it does not follow that all of 
them are used, or that a given length is expressed in terms 
of more than one. For example, a distance is not expressed as 
34 kilometers, 9 hectometers, 3 decameters, and 4 meters, but 
as 34*934 kilometers, and all measures of length, where it is 
desirable to use kilometers, are expressed in that unit and a 
decimal fraction. Thus, for each class of measurements, as a 
general rule, there is used but one of the above units, as will be 
discussed below, and any measurement is expressed in whole 
numbers and decimal fractions. Each of the above units is well 
suited for a number of varieties of measurements, and a few of 
these may be conveniently outlined. The megameter, which has 
not received legal sanction, is but rarely encountered, and then only 
in astronomical work where distances of considerable magnitude 
are discussed. As it appears only in calculations it does not 
possess much general interest, and the same holds true for the 
myriameter formerly used in geographical work. The kilometer, 
on the contrary, as a unit of distance such as would be used in 
the measurement of the length of a railway or road, is of vast 



THE METRIC SYSTEM OF TO-DAY 139 

importance, and is universally employed both scientifically, as by 
engineers, and also in non-technical matters. It is a unit whose 
use presents very little difficulty to those accustomed to Anglo- 
Saxon measures, in that it corresponds so closely to six-tenths of 
a mile that such an approximation suffices for most purposes and 
is readily made. 

The hectometer does not find extensive practical application, 
and is encountered chiefly in the calculations of artillerists ; but 
even here it is preferable to use meters, and velocities, etc., are 
now usually calculated in the latter units. The decameter is 
used in surveying where it forms a base for the measure of land, 
since the decameter squared gives the are, which is the principal 
unit of land measure. The classes of measurement for which the 
meter is available are numerous and apparent. For the measure 
of cloth and similar fabrics it is eminently suitable, and as the 
yard is approximately '9 of the meter there is no very violent 
break in passing from one to the other, as would be done by 
the purchaser of cloth for a dress. The meter would be used by 
the stone mason in the measurements of a length of wall, or by a 
carpenter or architect in his specifications and plans for structural 
work, and is in every way as suitable a unit as the yard, aside 
from the inherent merits of its connection with the metric 
system. In the decimeter there is a unit intermediate between 
the meter and the centimeter, and on that account not as much 
used as either. Furthermore, the decimeter does not correspond 
to any unit that has been in recent use by non-metric countries, 
and in the Anglo-Saxon system its nearest equivalent is the hand 
of four inches, long obsolete, except in measuring the height of 
horses. The decimeter is too short to fill the place of the foot 
and too long to supplant such a unit as the inch. Nevertheless, 
it is at the disposal of those who desire such a unit, and as 
three decimeters will approximate a foot, it may find increased 
application, but its use has never been great in the countries 
employing the metric system. The centimeter, on the other hand, 
is a most useful and convenient unit, and is susceptible of wide 
application. For the carpenter or cabinetmaker in giving the 
dimensions of a door or window, the size of a plank, that is, its 
breadth and thickness, or the dimensions of any ordinary objects, 
such as tables, chairs, etc., the centimeter fills every requirement, 



140 EVOLUTION OF WEIGHTS AND MEASURES 

and in scientific work it is customary to express dimensions of 
apparatus and all ordinary measurements in its terms. For 
many years in the United States library catalogue cards and 
other furnishings, such as pamphlet cases, have been standardized 
and sold according to metric measure, and the centimeter has 
been the unit adopted. It takes the place of the inch, and while 
it requires a larger number to express a given distance, yet it is 
likely to lead to greater exactness where it is not desirable to 
employ fractions. The millimeter is the unit of science and 
exact mechanical work. It affords an integral unit for minute 
measures, speaking comparatively, and its decimal subdivision is 
peculiarly suitable for this class of work. In ordinary life its 
chief application is to the measurement of thickness, such as 
metals, paper, glass, etc., and particularly in the measurement 
of diameters of wire, tubing, and other materials which enter 
into mechanical construction. Thus, measurements in millimeters 
are designed to take the place of arbitrary gauges where the 
problem of original standards, which in turn are based on 
standards of length, works against general uniformity and con- 
venience. For the measurement of screw-threads the millimeter 
is also employed, and in France, Germany, and Switzerland 
millimeter sizes for screws and thickness and diameters have 
been found to be far more convenient than arbitrary gauges. 
While the millimeter answers many purposes of the scientist, 
yet it does not carry him far enough, and accordingly there is 
the micron, which is one-thousandth part of it. This affords a 
convenient unit for the microscopist and the spectroscopist when 
they venture into the regions beyond the range of the human 
eye ; and to secure a still greater refinement we have the 
millimicron, or again the thousandth part. 

With such units as the foregoing, the next point is how are 
they applied, and how are they concretely represented by scales 
or other devices ? The longest scale is that of the geodesist 
or engineer employed in measuring his base line for trigono- 
metrical surveying of greater or less accuracy as the occasion 
may warrant. The best modern practice involves the use of a 
steel tape or wire, or one made of an alloy of steel with a smaller 
tendency to expand and contract with changes in temperature, 
which under a constant tension gives an exact representation of 



THE METRIC SYSTEM OF TO-DAY 141 

a distance as determined with a standard of length. 1 Such tapes 
or wires are usually of 100, 200, or 300 meters, while the ordinary- 
chain or tape of the land surveyor is either a double or single 
decameter on which are marked the meters and such other 
subdivisions as are desired, the double decameter being known as 
a metric chain. The next measure of length in point of size 
is the double meter, which may be either a rod or tape. If a 
rod, its material and subdivision are dependent on the use for 
which it is designed, as a metal scale lends itself more readily to 
permanent and accurate graduation, and is less susceptible to 
change with time and temperature ; the latter condition, in fact, 
may be accurately and satisfactorily accounted for by knowing 
the coefficient of expansion of the bar and the temperature at 
which it is used. The tape may be either of metal or linen, 
and is a convenient measure for many purposes. There are also 
constructed meter scales, half-meter scales, double and single 
decimeter scales, the shape and material as well as the accuracy 
of graduation depending on the purposes for which they are to 
be used. When it comes to the division of millimeters it is 
necessary to employ a dividing engine, 2 and the finest scales are 
ruled on glass or upon a smooth and even substance, such as 
speculum metal platinum-iridium, or nickel steel. The glass 
scales are, of course, to be used with the microscope, and similar 
scales can be constructed photographically by reducing in a 
desired proportion. 

1 There are also standard bars used in the most refined base measurements, such 
as that at Holton, Mich., which was of 5 meters length. These bars require the 
most careful levelling, are packed in ice at the time of making the measurement, 
and are only used when the greatest accuracy is desired, as the refinements of a 
laboratory are involved in a field operation. See Woodward, "The iced bar and 
long tape base apparatus and the results of measures made with them on the 
Holton and St. Albans bases," part ii. of Appendix No. 8 of Report of United 
States Coast and Geodetic Survey for 1892, pp. 334-489. Professor Woodward 
also discusses "Long Steel Tapes" in a paper presented to the International 
Engineering Congress of 1893, and printed in the Transactions of the American 
Society of Civil Engineers, vol. xxx. p. 81. 

2 See chapter x. — Standards and Comparison, p. 225. 



142 EVOLUTION OF WEIGHTS AND MEASURES 





Number of Square 


Abbreviation. 


Meters. 


km 2 . 


1,000,000m 2 . 


ha. — hm 2 . 


10,000m 2 . 


a. — dm 2 . 


100m 2 . 


ca. or m 2 . 


lm 2 . 


dm 2 . 


•01m 2 . 


cm 2 . 


•0001m 2 . 


mm 2 . 


•000,001m 2 . 



Measures of Surface. 



Square kilometer, 
Hectar (square hectometer), 
Ar (square decameter), - 
Centiar or square meter, 
Square decimeter, 
Square centimeter, 
Square millimeter, 

For the measurement of surfaces it is customary to employ 
as a unit a square or quadrilateral figure bounded by four equal 
sides at right angles to each other. In such a unit the sides are 
usually made equal to the linear unit, hence in the metric system 
a square of this nature would have for each side a meter, and 
would be known as a square meter, forming the principal unit 
for the measurement of surface. The next greater unit would be 
formed by a square whose bounding sides were each equal to a 
decameter, and consequently would include 100 of the principal 
units. If our units of length increase by a ratio of 10, it is 
obvious that the unit of surface based on these same units of 
length must increase by the square of 10 or by 100 as is indicated 
by the table. The same nomenclature is retained, but the word 
square is prefixed, and in the case of the units formally adopted 
for the measure of land, the terms hectar and ar have been 
selected to designate respectively the square hectometer and the 
square decameter. In writing and converting the measures of 
area it is necessary to multiply or divide by 100 when changing 
to a larger or smaller unit, consequently in the decimal fraction 
each metric unit must be given two places of figures. For 
example, to write as square meters 984*8963 square decimeters, it 
would be necessary to move the point two places to the left and 
we would have 9*848963 square meters, which also could be 
written 9 square meters, 84 square decimeters, 89 square centi- 
meters and 63 square millimeters, or even 9848963 square milli- 
meters if it was so desired. The square kilometer is employed 
in topographical work on a large scale, or in cartography in 
summing up the area of a country or large region. For fields 



THE METRIC SYSTEM OF TO-DAY 143 

the hectar is used, and is parallel to the acre, which contains 
•4047 hectars. For land of smaller dimension, such as city lots, 
it is customary to use the are. The measurement of surfaces, as 
of walls by the painter or paperhanger, or of floors by the dealer 
in carpets, is naturally made by the square meter. Such measure- 
ments as the square decimeter and the square centimeter are 
useful for purposes that will naturally suggest themselves, but 
again attention may be called to the fact that scientific men 
prefer to use the square centimeter and the cubic centimeter 
also as much as possible. 

Measures of Volume. 

The volume of a body, or the amount of space that it occupies, 
is usually measured by a unit known as a cube, which is a 
parallelopipedon bounded by six equal squares. In the metric 
system the principal unit is the cubic meter, a cube each of 
whose faces is a square meter, and consequently whose edges are 
each a meter in length. The cubic meter is the largest unit of 
volume in the metric system, though logically there is no reason 
why cubic decameters, hectometers, and kilometers should not be 
employed were there any necessity for their use, which there is 
not. Therefore we have only to concern ourselves with the sub- 
multiples of the cubic meter. On the decimal principle the 
next smaller unit must be one in which the size is determined 
by the tenth of the meter, or the decimeter, or a cube each of 
whose edges is a decimeter. Obviously, to make a cubic meter 
ten rows of these cubes, arranged so that they are ten in 
length, will have to be placed ten deep, or one thousand of our 
cubic decimeters must be used. So that where the unit of area 
required a ratio of 100 to pass from a smaller to a greater, the 
units of volume need a ratio of 1000 ; that is, three figures of 
integers or of the decimal fraction are required for each unit. 
Thus a cubic meter will contain 1000 cubic decimeters, or 
1 000 000 cubic centimeters, or 1 000 000 000 cubic millimeters. 
We may read 76'854 673 2 cubic meters as 76 854*673 cubic 
centimeters, or, were it desirable, 76 854 673 cubic millimeters. 
Or we could read the above expression as 76 cubic meters, 
854 cubic decimeters, and 673 cubic centimeters. 



I 



144 EVOLUTION OF WEIGHTS AND MEASURES 

The cubic meter is employed in all cases where any con- 
siderable quantity of a substance must be considered. Thus 
the amount of material excavated from a foundation, railway 
cut, or canal, would be expressed in cubic meters, as would be 
blocks of marble or the contents of a tank or reservoir. When 
the cubic meter is applied to the measurement of firewood it 
receives a new name, stere ( = 35*317 cubic feet or *27 cord), and 
as a pile of wood can be divided or increased readily, the name 
of decistere is given to the one-tenth part, and that of decastere to 
ten times the unit quantity. The cubic decimeter is an inter- 
mediate unit like the corresponding decimeter and square 
decimeter, but it possesses importance, inasmuch as it is the 
volume of the liter (very nearly), and as such is frequently 
employed in calculations where it is desired to obtain the 
capacity of a given space, as will be explained further on under 
measures of capacity. The cubic centimeter answers for many 
purposes, and is the usual unit for scientific work. Thus in 
pharmacy by the volumetric method (see page 194) almost all 
liquids are compounded by taking the desired quantities in cubic 
centimeters, while to determine standard pressure reference is 
made to that of a column of 75 cubic centimeters of mercury at 
0° centigrade. 

Measures of Capacity. 

Hectoliter, - 
Decaliter, - 
Liter, - 

Deciliter, - 
Centiliter, - 
Milliliter, - ml. -001 liter. 

The close connection between measures of volume and capacity 
is obvious, and the founders of the metric system took as their 
unit of capacity the volume of a cubic decimeter. Subsequent 
measures of the kilogram, and the mass of water necessary to 
amount to this weight, resulted in the conclusion that for strictly 
scientific purposes this was inaccurate, and consequently the legal 
definition is in the words of the International Committee, " The 
liter is the volume occupied by the mass one kilogram of pure 



hi. 


100 liters. 


dal. 

1. 

dl. 


10 liters. 


•1 liter. 


cl. 


•01 liter. 



THE METRIC SYSTEM OF TO-DAY 145 

water at its maximum density and under normal atmospheric 
pressure," and this decision was duly sanctioned by the general 
conference of 1901. As the result of a large number of careful 
experiments it was found that a mean value for the mass of a 
cubic decimeter of water at 4 degrees centigrade (its temperature 
of maximum density) would be '999974 kilogram, and that the 
error of assuming the liter equal to the cubic decimeter would be 
only about one part in 30,000, an amount only appreciable in the 
most refined measurements. The liter is subdivided on a 
decimal basis, while its multiples are similarly arranged, and 
from what has preceded it will be possible to understand the 
various units merely by referring to the table. In actual practice 
the liter and the hectoliter are the units chiefly employed, as for 
many reasons it is preferable to employ cubic centimeters for 
smaller measures, while the decaliter, being an intermediate 
measure, does not come into wide use. The liter and all the 
measures of capacity are used for both dry and liquid substances ; 
but it is a tendency of modern metrology quite independent of 
the metric system to do away so far as possible with dry 
measures of capacity and buy and sell such substances by weight. 1 
^ The liter, however, can be used to measure all liquids (such as 
water, milk, wine, beer, oil, etc.), vegetables, grains, seeds, etc., in 
ordinary retail transactions. When large quantities of the 
commodity are dealt in or discussed, then it is customary to use 
hectoliters. The liter corresponded so closely to the ancient 
French pinte ('981 liter) which it supplanted that its use did not 
occasion any difficulty, and as it is intermediate in value between 
the American dry ( = 1*1012 liter) and liquid quarts ( = '94636 
liter) its employment would result in a simplification of measures, 
and would involve no inconvenience. 

The adoption of metric measures of capacity in the United 
States would result in important simplifications, as the present 
measures differ from those of Great Britain, and possess no 
intrinsic merits of their own. In fact, in the Anti-metric 
Argument of the Committee of the American Society of Mechanical 
Engineers (vol. xxiv. New York, 1902), which opposes most 
bitterly any attempt at the introduction of the metric system, it 
is stated (p. 676), " That there is no reason for the English 

1 In Europe the practice of selling liquids by weight is also increasing. 

K 



\ 



146 EVOLUTION OF WEIGHTS AND MEASURES 



.z 



system retaining the gallon and the bushel except that they are 
in such common use. For convenience in computation it would 
be well if the gallon were 216 cubic inches, or the cube of 6 
inches, and the bushel 1728 cubic inches, or 1 cubic foot." 

In constructing the actual measures of capacity their range is 
extended by binary subdivision and doubling, so that all possible 
capacities can be measured and substances sold on a basis of the 
simplest mental process, namely, that of halving. Actual measures 
in the form of wooden vessels for measuring grain with a capacity 
of one hectoliter and less are constructed with their internal 
height and diameter equal, while for measuring liquors, wines, 
and alcohol, the French laws provide that the internal height 
should be twice the internal diameter. Oil and milk measures 
are of tin, and their internal height and diameter are equal. 



Measures of Mass. 



Metric ton, 


t. 


10 Quintals 


1000 Kilogran 


as 1,000,000 


grains 


io 6 g. 


Quintal, 


q- 


10 Myriagrams 


100 


100,000 


n 


10%. 


Myriagram, 




10 Kilograms 


10 


10,000 




i 


10*g. 


Kilogram, 


kg. 


10 Hectograms 


— 


1,000 




)i 


io 3 g. 


Hectogram, 




10 Decagrams 


— 


100 




i 


io 2 g. 


Decagram, 




10 Grams 


— 


10 




i 


lOg. 


Gram, 


g- 


10 Decigrams 


— 


1 




i 


E- 


Decigram, 


d g . 


10 Centigrams 


— 


•1 




, 


io-ig 


Centigram, 


eg. 


10 Milligrams 


— 


•01 




i 


io-V 


Milligram, 


mg 


— 


— 


•001 




i 


10" 3 g. 



V 



By mass is meant the actual quantity of matter which a body 
contains, and it is to be distinguished from weight, which is the 
force with which a body is attracted to the earth. Now, as this 
force of attraction depends upon the mass of a body, it follows 
that the weight of different bodies at the same place is pro- 
portional to their respective masses. But as the force of 
attraction or gravity varies at different points on the earth's 
surface, it is obvious that bodies of the same mass will have 
different weights at different places. Originally, as we have 
seen, the gram was defined by the decree of 18 Germinal, year 
III., 1 as " The absolute weight of a volume of pure water equal to 
a cube of the one-hundredth part of a meter and at the temperature 

1 See p. 54. 



THE METRIC SYSTEM OF TO-DAY 147 

of melting ice," and on this basis the Kilogram of the Archives 
was constructed. However, after the construction of the Inter- 
national standard kilogram it was deemed desirable to define 
formally the kilogram, and at a meeting of the International 
Committee on October 15, 1889, it was decided that "The mass 
of the international kilogram is taken as unity for the inter- 
national system of weights and measures," and this decision was 
confirmed at the third general conference held at Paris in 1901. 
While the gram is the fundamental unit of mass, yet in actual 
practice, as in the construction of the standard, it has been found 
rather small for most weighings, and consequently the kilogram 
is employed as a practical unit. 

There is, of course, the same wide range of units of weights as 
in other classes of measures, and on precisely the same decimal 
basis, as the table plainly sets forth. The same considerations 
govern their use, and we find that the number of units in actual 
use is but a small part of those available. Thus, for large 
weights the metric ton is the unit employed, and is used in the 
weighing of ore, coal, hay, and other substances dealt in in 
large quantities. It is employed in estimating the mineral pro- 
duction of the world, being a convenient weight to which the 
output of different nations may best be reduced for purposes of 
comparison and statistical study. It corresponds so closely with 
the long ton of 2240 pounds (a metric ton equals 2204*62 lbs.) 
that for many purposes it is practically equivalent. The quintal 
has the same line of uses as the hundredweight, which either 
as 112 pounds or 100 pounds is still employed in some branches 
of trade. It would be substantially equivalent to twice the 
former, and would not vary greatly from the American barrel of 
flour, which contains 196 pounds net. / 

The myriagram is rarely, if ever, used, but the kilogram is a 
unit which is found universally. Being the weight of a cubic 
decimeter of water it enables one instantly to determine the 
weight of a body whose volume and specific gravity are known, «/ 
and for that reason is very convenient in calculation, such as to 
determine the weight of cut stone, etc. It is the unit most 
frequently employed in trade and industry for the sale of 
merchandise of all descriptions. By using the half kilogram 
there is a weight which approximates the pound, and being 



148 EVOLUTION OF WEIGHTS AND MEASURES 

slightly larger there is an element in favor of the purchaser. 
Instead of using hectograms and decagrams it is found more 
convenient to express such quantities in terms of fractions of 
kilograms or as grams, and such is the usual practice. The gram 
is extensively employed in science, as by the chemist, and by 
those dealing in small and valuable materials, as jewellers and 
coiners. In multiples of ten it affords a convenient substitute 
for the ounce, 30 grams (28*3495 exactly) corresponding to one 
ounce avoirdupois. Its relation to the cubic centimeter of water 
makes it a useful unit for the physicist or chemist, and unless 
there is reason to the contrary it is always used to record and 
describe the results of his experimental and other work. As the 
gram is so constantly used for measures of weight of this nature 
by those having to do with masses of a size convenient for its 
use the adoption of this part of the metric system would work no 
hardship, as apothecaries' weight, which it would supplant, has few 
defenders, and is destined to disappear: Decigrams, centigrams, 
and milligrams are used in the form of fractions of the gram, 
though milligrams are employed to a certain extent, especially as 
the riders or smallest weights of a fine balance enable weighings 
to be made in milligrams and fractions of a milligram. 

In the actual weights there is not only the diversity indicated 
by the table, but also others obtained by doubling or halving the 
various units there mentioned. The construction and design of 
these weights as also their accuracy depends upon the purpose 
for which they are intended, and vary from the platinum iridium 
and rock crystal copies of the international standard down to the 
cast-iron weights of the retail dealer. The cast-iron weights 
range from 50 kilograms to 50 grams or J hectogram, while the 
brass weights, which are usually cylindrical in shape, with the 
upper part fashioned into a knob for more convenient handling, 
range from 20 kilograms to 1 gram. Fractions of a gram are 
usually made of sheet metal, such as platinum, german silver, or 
aluminium, as in this shape they are more readily handled with 
the forceps employed to transfer them from their case to the 
pans of the balance. The very smallest or milligram weights are 
known as " riders," and are twisted loops of wire which may be 
placed at any desired position along the graduated beam of the 
balance, and thus enable the observer to read to fractions. 



THE METRIC SYSTEM OF TO-DAY 149 

While there have been enumerated under each class of 
measures a number of units, yet it is necessary to state again that 
only a comparatively small number are employed. In this 
respect the metric system is similar to the United States 
monetary system, where there are mills, dimes, and eagles, as well 
as quarters and halves, in addition to dollars and cents, but in 
computation everything settles down to a dollars and cents basis. 
This is precisely the case with the metric system, and while the 
intermediate units appear in the tables we have taken care to 
explain how infrequently they are employed. In fact, it is a 
tendency in metrology to eliminate from use as many units as 
possible, and all existing measures are on a far less liberal scale 
in point of numbers than those of a century ago, not to speak of 
those of ancient times or of the middle ages. With the metric 
system this elimination can be done without any trouble, as it is 
the work of but a moment to change from one unit to another 
for any purpose whatsoever. 



CHAPTEE VI. 
THE METRIC SYSTEM FOR COMMERCE. 

Feom what has been said regarding the development and present 
conditions of the metric system, the advantages of its use by 
all nations would seem apparent ; nevertheless, as its employ- 
ment is not as yet universal, it would seem desirable here to 
deal first with the benefits to the commercial world at large of 
a single system of weights and measures, and second with the 
profit that would accrue to an individual nation from the adop- 
tion of the metric system. It is a mere truism to say that 
anything that enlarges the circle of exchange of either ideas or 
commodities works for the welfare of the world, and the happiest 
and most prosperous nations are those that have the advantages 
of such interchange with their fellows most firmly established. 
A striking example of this is seen when it is considered that 
the improvements in navigation following the application of steam 
have not redounded to the benefit of any one nation to the 
exclusion of others, but have stimulated trade and prosperity in 
all parts of the world. Likewise by means of the telegraph and 
submarine cable the exchange of ideas and rapid transaction of 
business between distant places have been made possible, and that 
again has brought about benefits confined to no single nation. 
Furthermore, international banking has also contributed to extend 
and develop trade, and here we find that through the pre-eminence 
of Great Britain in this field pounds sterling are adopted as a 
universal measure of value. Facilities have been supplied by 
the British merchant and banker which have resulted in no 
small profit to him, simply because he has been able to occupy 
the world with his commercial machinery and force the use of a 
standard of value adequate for a large part of the world's trade. 



THE METRIC SYSTEM FOR COMMERCE 151 

On the other hand, a result of international co-operation is the 
International Postal Union, where mails from all countries of 
the world are exchanged with equal and proportionate expense 
and advantage to all. Here, as we have seen, 1 it was necessary 
at the outset to find a common system of weights and measures 
to regulate the payments and the exchanges of mail, and it was 
found desirable to adopt the metric system, which has since been 
employed for many years with complete success even among 
non-metric nations. In general, wherever there has been inter- 
national co-operation to secure uniformity in commerce, as in 
cable and telegraph conventions, treaties to establish uniform 
classifications and definitions, etc., the results have invariably 
resulted in promoting general prosperity and in increasing 
business. Furthermore, an international language, as well as 
an international currency, would serve to increase commerce and 
from many points of view would be an important benefit. 
However, international language and international currency are 
outside the province of the present consideration, but inter- 
national weights and measures must be discussed, especially as 
the metric system is destined eventually to hold such a position, 
even in a fuller sense than at present. The reasons for this 
present pre-eminence, as we shall soon see, are obvious. First, 
in different contiguous countries, there was the realization of a 
need of a single system of measures that would conform to those 
of the other nations ; and second, there was the natural desire 
for the best and most useful system. The result was that in 
every instance where a change was made, save that of Russia 2 in 
1835, the metric weights and measures were adopted in preference 
to those of any other system, and in no case have they been 
given up, nor is the slightest desire for any change expressed. 3 

For the benefits of a single and international system of units, 
we have only to refer in passing to the electrical units which 
are subsequently discussed at some length, 4 For the measure- 
ment of electrical quantities throughout the world a single system 

1 See ante, p. 127. 

2 Russia adopted as a unit of length 7 English feet, but neither multiples or 
submultiples were as in the British system. Furthermore the British pound was 
not adopted. 

3 See chapter iii. ante. 4 See chapter ix. 



152 EVOLUTION OF WEIGHTS AND MEASURES 

of units is employed, and this system, based on the metric 
units, was developed in Great Britain, and has been adopted by 
scientists and engineers universally. When great industries 
were established to apply to the everyday uses of mankind the 
discoveries and inventions of men of science in this field, these 
same units were retained, and were later sanctioned by inter- 
national agreements. No voice has ever been heard to dispute 
the advantages of such a system, and the result has been that 
there has been more progress in electricity through the inter- 
change of ideas than in any other branch of applied science. 
When electrical congresses meet every communication is in- 
telligible at once to every member so far as the expression 
of quantities goes. When tenders are asked for electrical 
machinery, materials, or apparatus, the manufacturers of every 
nation of the world are on the same footing as regards under- 
standing the specifications and utilizing materials for a desired 
output. Accuracy in measurement is not restricted to any 
single nation or its scientific workers, as the work of the latter 
can be put immediately at the disposal of the world, and the 
highest precision can be secured by joint effort and co-operation. 
In fact, when the Physicalisch-Technische Keichsanstalt at Char- 
lottenburg, near Berlin, was the only important governmental 
testing bureau and physical laboratory, it received apparatus and 
materials from many nations outside of Germany to be examined 
and standardized according to the common system. To-day elec- 
trical measuring instruments certified to by the Keichsanstalt, the 
Laboratoire Central d'Electricite* at Paris, the National Physical 
Laboratory of England, or the U.S. Bureau of Standards, can be 
used for electrical measurements anywhere in the world, as the 
units employed depend for their derivation on the same defini- 
tions. In fact, so much a matter of course is the single system 
of electrical units that no one would think of proposing any other, 
and its existence is so taken for granted that its advantages are 
rarely spoken of or even considered until the possible chaos of sub- 
stituting a number of systems in its place is mentioned. Indeed, 
while the various units are frequently criticized, no electrician 
or physicist would venture to propose the adoption of new units 
locally, despite the fact that universal reforms in units and 
standards are advocated before international congresses. 



THE METRIC SYSTEM FOR COMMERCE 15S 

Looking at the question of weights and measures from a 
strictly commercial standpoint it is clear that, as commerce 
involves primarily the exchange of quantities of various com- 
modities, the use of a simple and convenient method for the 
rapid calculation of weight, length, and capacity must promote 
ease and security of commercial intercourse. The metric system 
being decimal, and consequently the most easily grasped and 
applied, is therefore the best for commerce, and when to this 
is coupled the fact that its use is all but universal and is em- 
ployed in the major portion of international commercial trans- 
actions, it is easy to see that a great saving of time in business 
operations must result from its adoption. That this saving of 
time and simplicity is real, and not the mere hope or opinions 
of reformers, can be demonstrated by reference to the reports of 
American and British consular and diplomatic officials who are 
acquainted with both the Anglo-Saxon and the metric systems. 
These reports, notable among which, as being most comprehen- 
sive and complete, are those presented to Parliament in 1900' 
and 1901, 1 to which reference has already been made, speak 
emphatically in this respect, and in a communication from 
Portugal appears the statement that " The large amount of time 
saved in commercial houses by the simplicity of the metric 
system, as well as by the uniformity now existing in place of 
the former chaos, is in itself a valuable factor in considering 
the advantages of the new system." 2 

The successful prosecution of foreign commerce requires a 
complete understanding between merchants in different countries 
as to each other's standing, methods of payment, and, most 
important, as to the goods themselves which form the subject of 
the transaction. Aside from standards of quality, quantities and 
dimensions must be considered, and it is here that universal 
measures and standards are needed. It is also of importance for 
both buyer and seller to know the quantity of the commodity in 
existence at different places, the quantity produced and consumed 
in previous years, and other statistical information. As regards 

1 English Parliamentary Accounts and Papers: 1900, vol. xc. ; Reports from Her 
Majesty's Representatives in Europe on the Metric System: 1901, vol. lxxx. ;. 
Reports on Metric System, part ii. 

2 Ibid, part i. p. 54. 



154 EVOLUTION OF WEIGHTS AND MEASURES 

the latter, it will readily be seen that the collection and diffusion 
of such knowledge would be facilitated if the same units were 
used in every country and port of the globe, and trade could then 
be carried on in a more intelligent manner, and with the elimina- 
tion of speculative elements, while tariff laws and custom regula- 
tions, etc., could be more intelligently framed through the better 
and more uniform character of the statistical information. Such 
benefits accrue to trade throughout the world generally, and are 
generally recognized. 

But with no uniform system of weights and measures which 
may be applied to the description of goods, it is inevitable that 
there is a lack of clear understanding between buyer and seller, 
and one of these parties is at a disadvantage. Especially is this 
true if there is a competitor who is ready to trade on a basis more 
readily understood. Thus, if a man is in doubt as to certain 
elements concerning goods which he desires to buy or sell, he 
naturally assumes that there are other points about which he is 
equally ignorant, and consequently he is unwilling to undertake 
the transaction. True, he may compute in his own system the 
quantities or dimensions of the article or articles, or may receive 
these figures in whole or in part from the other merchant or 
agent ; but the basis of trade is unsatisfactory, and it is natural 
for men to buy or sell according to their usual measurements even 
if the goods must be imported from a greater distance. This, 
furthermore, is emphasized by the extensive use of standards 
which, at first designed for a single country and trade, have 
gradually crept abroad so that if either English or Continental 
goods, such as pipe or nuts and bolts, for example, have secured 
a foothold in a certain country, it is quite certain that in all 
subsequent orders they will be demanded, and a newcomer in the 
field will have to conform to styles and standards already estab- 
lished. Thus to compel trade in a large and unusual number of 
sizes is a most wasteful economic process, and results in forcing 
the manufacture into the hands of a comparatively small number 
of producers, who can so control their business as to occupy 
certain fields exclusively rather than to establish wholesome 
competition between all the manufacturers of the world. 

A striking example of the evils attending lack of standardiza- 
tion in measures, materials, and machinery, is to be found in 



THE METRIC SYSTEM FOR COMMERCE 155 

the mining districts of South Africa, where mining and other 
engineering operations are carried on in a cosmopolitan manner 
by engineers from various countries. Machinery and supplies are 
imported, for specific purposes, from all over the world, and con- 
sequently they vary in dimensions, often in parts that properly 
should be interchangeable. 1 The result is that considerable fitting 
is required in order to make the various parts of a plant work 
harmoniously. This of course involves time and expense without 
accompanying benefit to anyone, whereas by a system of inter- 
national standards such waste would be avoided. Furthermore, 
a proper system of standardization would enable the specifications 
of machinery and supplies to be prepared in such a way that 
manufacturers and dealers would know exactly what was wanted, 
and make their bids accordingly, to the benefit of all concerned. 
If the standardization was universal a simple description of the 
desired articles could be circulated, and manufacturers and dealers 
all over the world could submit prices and estimates. Thus the 
whole world could participate in the competition, and not only 
would the supplies be cheaper to the purchaser, but manufacturing 
and commerce would be stimulated. 

Now, the first principle of standardization is the defining of 
sizes in a regular and systematic manner, and conforming to a 
permanent standard, and this in the ultimate analysis must 
depend on a standard of length or mass. Consequently, if the 
dimensions of articles are referred to one and the same system, 
and that the international or metric system, it is comparatively 
simple to reach a point where all articles of a class are reduced to 
certain sizes determined by conference and mutual consent of the 
makers and consumers of the commodities in question. There is, 
in short, a survival of the fittest and most convenient sizes, and 
machinery and materials, involved in making the various articles, 
are soon conformed to these standards of size. 2 It will be seen, 
therefore, that the standardization which is a benefit, national or 
international in accordance with its scope, follows from a well- 
defined system of units, and when such a system is single and 

1 See Presidential Address of R. M. Catlin before Mechanical Engineers' 
Association of the Witwatersrand, abstracted in Engineering and Mining Journal 
<New York), vol. lxxix. 1905. 

2 See p. 173, chap. vii. 



156 EVOLUTION OF WEIGHTS AND MEASURES 

universal there is bound to result a single set of standards in all 
important industries. Such a result is bound to promote com- 
merce and industry by facilitating the manufacture and exchange 
of commodities, and the same benefits would be experienced by 
the world at large as have been realized in the United States 
where this policy has been followed in many lines. 

International weights and measures soon would produce truly 
international standards, both of size and of quality, and the trade 
of the world would be on a far more wholesome and active basis, 
as there would not be material tied up in odd sizes, and con- 
sequently unavailable to other users except at increased expense, 
but there would be a common world stock. As trade would be 
stimulated and diversified a further division of labor would take 
place, and there would be greater general prosperity. To become 
thoroughly convinced of this, one has only to refer to the reports of 
American and British consuls, which are unanimous and constant 
in reiterating the assertion that the lack of an international 
system of weights and measures acts most strongly against the 
extension of trade between their home countries in those places 
in which they serve. This, of course, implies a reciprocal loss, as 
the wider the distribution of a nation's commerce the more 
extensive it must be, as also the more profitable. 

That there is need of an international system of weights and 
measures which is universal and invariable is shown by the fact 
that the United States and Great Britain, which claim the same 
sources for their various weights and measures, now have units 
that figure constantly in trade relations which are quite unlike in 
value. For example, wheat and other grain from America is sold 
by a bushel which differs materially from the British bushel, as 
does also the gallon used in the measurement of petroleum, while 
the hundredweight of 112 pounds and quarter of 56 pounds are 
rarely used in America. These weights were abandoned in 
Liverpool in 1903 for a weight of 50 pounds, the use of which in 
trade was authorized by an Order in Council of October 9, 1903. 
Since that time a standard for this amount has been constructed 
and verified, and there is an increasing tendency towards using 
the cental of 100 lbs. as a commercial unit. Here are examples 
of the inconvenience where two countries employ measures and 
weights apparently the same, but which must be adjusted even for 



THE METRIC SYSTEM FOR COMMERCE 157 

transactions between themselves, when by the adoption and use of 
the metric system they would be put on the same basis as regards 
one another as they would enjoy towards the rest of the world. 

Foreign commerce presents many difficulties unknown to 
business between two parties in more or less proximity. There 
is the question of time and of freight, both important items in 
any commercial transaction, but especially so when weeks or 
months must elapse before a delivery can be effected. Misunder- 
standings or mistakes are most costly and cannot be rectified 
promptly ; consequently there should be the most complete 
understanding between the parties to the transaction. This must 
involve an easy standard or basis of comparison, for the present 
differences in money and exchange are troublesome enough. The 
extent of this difficulty is best illustrated by modern methods of 
doing business where catalogues, price-lists, and other printed 
matter are used so extensively, and are such an important adjunct 
to the work of the salesman, who naturally is unable to carry 
with him a complete line of samples, even of agricultural tools, 
not to mention dynamos and steam engines. If these descriptions 
and prices are understood, and if the sellers have a good 
reputation, much has been done towards effecting a sale, as the 
prospective buyer can tell at a glance whether character, quality, 
and size are such as he desires and uses, and especially whether 
they will correspond in size with present or future stock or plant. 
Furthermore, in case of an immediate demand for the goods, 
business can be transacted satisfactorily by cable or telegraph. 
When, however, various articles are presented to a foreign pur- 
chaser described in strange units, the latter is compelled to 
employ conversion tables, and even then fails at a complete, not 
to speak of quick, comprehension of the goods. With a single 
system the case would be different, and no nation would enjoy 
any advantage over another in this respect, save in the actual 
merit of its goods, and the increased circulation and use of such 
•catalogues would provoke keener competition, and would result 
in a higher grade of tools and other articles, as the world markets 
would be aimed at where general excellence and price would 
carry the day. 

The question whether a country's export business would be 
helped by an international system of weights and measures must 



158 EVOLUTION OF WEIGHTS AND MEASURES 

be considered, no matter whether that country is on a protection 
basis or enjoys free trade. In the latter case the advantages are 
obvious, but where there has been protection the result in many 
nations is that the product is often greater than the needs of the 
home market, consequently the manufacturer, in order to keep up 
his production on the largest, and therefore most economical 
scale, must seek to market his surplus in a foreign field. A 
glance at our table (page 105) will soon show that with the 
exception of Great Britain and its dependencies, Eussia, Denmark, 
and China, the vast majority of nations are on the metric basis, 
and for reasons we have already advanced it is quite necessary 
that business with them should be done according to the inter- 
national measures. That this is essential is shown by the fact 
that in the United States certain manufacturers, and the number 
is constantly increasing, not only describe their goods in metric 
measures, but so construct them, and stand ready to increase 
their business in this respect. If the surplus product is made so 
that it can be utilized in any country, it is of course obvious that 
the manufacturer has a far wider range of market, and is likely 
to secure better prices. 

Possibly the best testimony as to the advantages to commerce 
of an international system of weights and measures should come 
from countries where the metric system has supplanted the local 
system or systems, though the latter still survive. Such is the 
following extract, which sums up the conditions in Spain, and 
which is typical of the enlightened opinion in nearly all metric 
countries : " The facility and security afforded to the sending of 
orders, owing to the amount ordered being subject to the same 
measure in the different countries, the conformity in transport, 
custom-house, and commission tariff, etc., attract, tighten, increase 
commercial relations." 1 This is the answer of the Spanish 
Geographical and Statistical Institute attached to the ministry of 
Public Instruction, Agriculture, Industry, and Public Works, in 
reply to a question as to how the adoption of the metric system 
had affected its commerce, and it is also the experience of other 
countries. The importance of the adoption of the metric system 

1 Report of Her Majesty's Representatives in Europe on the Metric System, pre- 
sented July, 1900, part i. p. 61 ; Parliamentary Accounts and Papers, 1900, 
vol. xc. 



THE METRIC SYSTEM FOR COMMERCE 15£ 

to international trade has been noted formally by various com- 
mercial and statistical conferences and conventions, but of a more 
official character was the action taken by the International 
American Conference which was held at Washington in 1890, 
where the following resolution was adopted : " Resolved that the 
International American Conference recommends the adoption of 
the metrical decimal system to the nations here represented 
which have not already adopted it." James G. Blaine, then 
Secretary of State, whose last important official work was towards 
the extension of American commerce through reciprocity treaties 
with the South American countries, urged upon the United States 
Government the adoption of that system for the customs service, 1 
and his recommendations were concurred in by Secretary of the 
Treasury Windom (Report, Dec. 1, 1890), and by Secretary of 
State Foster, in his reports for 1891 and 1892. Likewise, in 
Great Britain there was a conference of Colonial Premiers at 
London in 1902, and a resolution was formally adopted favoring 
the use of the metric system for all the British colonies. Fol- 
lowing up the matter the Colonial Office then communicated with 
the various Colonial governors, asking what action was likely to 
be taken with regard to this resolution. Mauritius and 
Seychelles already used the system, but the following colonies 
were reported as favorable to its adoption : Australia, New 
Zealand, 2 Cape of Good Hope, Transvaal, Orange River Colony, 
Southern Rhodesia, Gambia, Northern Nigeria, Gibraltar, British 
Guiana, Trinidad, Leeward Islands and Windward Islands. 
Sierra Leone, Southern Nigeria, Ceylon, and the Falklands 
stipulated that they were in favor of it if adopted by the United 
Kingdom or in the Empire generally. The Australian states, 
while favorably disposed, thought that the matter should be 
settled by the government of the commonwealth, while Jamaica 
and British Honduras required the adoption of the system by the 
United States. Fiji and British New Guinea would have to 
follow Australia, just as the Straits Settlements and Labuan were 
dependent on India. The Bechuanaland Protectorate would be 
compelled to be in harmony with the rest of South Africa. 
Opposition to the plans was evinced by St. Helena, Cyprus, Lagos, 

1 Sen. Exec. Doc, No. 181, 51st Congress, 1st Session. 

2 Metric System adopted by New Zealand in 1905. 



160 EVOLUTION OF WEIGHTS AND MEASURES 

Wei-hai-wei, Barbados, and Bahamas, while the Gold Coast 
Colony and the State of Queensland were ready for the system, 
but anticipated inconvenience in its adoption. Natal reported 
that some definite general plan was necessary before an opinion 
could be expressed. Of the remaining colonies definite answers 
were not given by Newfoundland, Malta, or Bermuda, and no 
reply whatsoever was received from Canada, though it is 
sufficiently obvious that the latter country would be compelled to 
follow the example of the United States. 

It will be seen from the foregoing that these colonies, widely 
scattered over the world, were for the most part alive to the 
-advantages attending the adoption of the metric system, as by so 
doing the great trade of the British Empire would then be put 
on the same terms as that of the rest of the world. This, of 
course, leaves out of consideration the trade of the United States 
■and its possessions, which, if brought into harmony with the 
above, would greatly facilitate in the development and prosecution 
of commerce. 

An additional consideration is that new discoveries of mineral 
wealth and supplies of raw materials of one class or other have 
within comparatively few years greatly extended the range of 
commerce, and many nations once thought uncivilized and un- 
productive are becoming great consumers as well as producers, 
requiring the most varied supplies and machinery. These 
markets are destined to prove among the most valuable of the 
world, and to pre-empt them is the task of the highest wisdom. 
In South America and in all non-British colonies we find the 
metric system used, though with it are often various native or 
local nondescript units. It is the opinion of the consuls to these 
places — and they at least must be admitted to be competent 
judges — that the use of the metric system would greatly increase 
trade of these countries with America and Great Britain. 

Having pointed out that the adoption of a single system of 
weights and measures throughout the world would be most 
advantageous, and would facilitate commerce, therefore benefiting 
each and every nation to a greater or less extent depending on 
its location and the amount of its foreign trade, it is now 
necessary to consider just what advantages a country not using 
the metric system would secure by its adoption, and what dis- 



THE METRIC SYSTEM FOR COMMERCE 161 

advantages, if any, are likely to be experienced. These advantages 
must be practical, especially in a country like the United States, 
and must appeal to the small shopkeeper and farmer, as well as 
to the professor of physics, the merchant, and the statistician. 
Large, as the question seems, it is possible to simplify it by 
eliminating a certain number of elements. Thus, we know that 
workers in science in America, Great Britain, and Russia have, 
for a long time, universally employed metric weights and measures 
in their daily work, and have urged their adoption for general 
use, confident of their great utility and superiority. Also, that 
other scientific men, whose work is of a more practical nature, 
such as electrical engineers, who constantly use the metric 
weights and measures in their work, have also urged their general 
adoption. Consequently, the change would be a distinct advan- 
tage to workers in this field, and there is no opposition to the 
step to be anticipated from them. 

At the other end of the scale must be considered the average 
citizen who does business on a small scale, and who, with his 
household, uses weights and measures daily. In fact, looking at 
the question as a national one, this seems to be the most 
important aspect, and should be most carefully considered, both 
in the light of the experience of foreign countries and according 
to local conditions. Reflection, however, soon establishes the 
fact that most of these transactions take place where the actual 
goods are transferred in the presence of the buyer and seller, and 
some approximate idea of the measure desired is in the mind of 
both of the parties to the transaction. Thus a man buying sugar 
sees the amount he is receiving, and knows the price paid, so 
that with properly sealed weights there is no opportunity for 
injustice, as the man is free to buy sugar where he will, and at 
the most favorable price, the latter being governed by the law of 
supply and demand as modified by trade conditions. When his 
wife mixes the sugar to make cake her methods of measurement 
are purely relative, and neither ounces nor grams are employed, 
but approximate measures, such as tea-cups, which are quite 
independent of any laws of metrology. In fact, the question has 
been excellently summed up by one of the most distinguished 
opponents 1 of the introduction of the metric system into the 

1 Dr. Coleman Sellers, Cassier's Magazine, vol. xvii. p. 365, 1900. 

L 



162 EVOLUTION OF WEIGHTS AND MEASURES 

United States, as follows : " To the great bulk of mankind engaged 
in trade, in buying and selling, in bartering and exchanging, it 
matters little what system of weights and measures they adopt : 
it matters little whether they are obliged to use a yard-stick or 
a meter rod, pounds or kilograms, quarts or liters. The cost to 
them is the cost of the few devices needed in weighing and 
measuring ; the rationale of the system may never enter into 
their thoughts." Thus, there is no reason why, so far as this 
class of people is concerned, a change should not be made if the 
new system supplied is superior for their purposes. This the 
metric system is, on account of its great simplicity, doing away 
as it does with all compound relations for the single ratio of ten, 
connecting weight and measures by the weight of a volume of 
water as a unit, thus eliminating all odd equivalents such as the 
fact that a cubic foot of water weighs 62 \ pounds, and finally 
doing away with such anomalies as dry and liquid measures of 
capacity, avoirdupois, Troy, and apothecaries' weight, long tons 
and short tons, hundredweight of 112 pounds, and other weights 
and measures equally arbitrary, and not susceptible of being put 
into simple relation with other quantities. 

Indeed, the full complexity and absurdity of the present 
" system," so called, is hardly realized until we stop to consider 
that in the United States copper is weighed by one standard, 
silver by another, medicines by a third, diamonds and other 
precious stones by a fourth, and platinum and chemicals by a 
fifth, none of which are interchangeable with one another except 
by means of fractions. Nor is the condition less striking in the 
case of the measures of capacity. One unit is used for wine, and 
bears the same name as a dissimilar one used for grain, while 
gas is measured by still a third unit. In fact, the condition as 
regards the last-named groups of units is summed up in the 
Anti-metric Argument of the committee of the American Society 
of Mechanical Engineers, where it is stated in a passage already 
quoted : l " There is no reason for the English system retaining 
the gallon and the bushel, except that they are in such common 
use." For convenience of computation it would be well if the 
gallon were 216 cubic inches, or the cube of 6 inches, and the 

1 See pp. 145, 146 ante; Transactions American Society of Mechanical Engineers, 
vol. xxiv. 1902, No. 972, " Anti-Metric Argument," vii. p. 676. 



THE METRIC SYSTEM FOR COMMERCE 163 

bushel 1728 cubic inches, or 1 cubic foot. A few lines later in 
this interesting argument some comments on the various units of 
weight are concluded by the remark, " Both Troy weight and 
apothecaries' weight might be abandoned." Here, from a source 
unfriendly to the metric system, and opposed to any fundamental 
changes in the weights and measures, is to be found a frank 
admission that the measures of capacity are inconvenient, and 
could be greatly improved, and that no reason other than use 
exists for retaining the Troy and apothecaries' weight. Accord- 
ingly, they propose to reconstruct the measures of capacity into a 
new system which would occasion all the inconvenience attendant 
on a transition from one system to another, and yet would not 
yield the advantages of a decimal basis, and division, or relation 
between weights and measures of the metric system, nor would it 
have the least international value. 

Likewise in England a society was formed in 1904 under the 
title of the British Weights and Measures Association, which 
had as it object " the defence, standardizing, and simplifying 
(italics ours) of British weights and measures," and to oppose 
the introduction of the meter as a British standard. Further- 
more, this society proposed the introduction of "simplified and 
scientifically related weights and measures based upon existing 
British measures " (again italics ours). Now, with such an 
admission that the Anglo-Saxon weights and measures need 
" simplification " and to be " scientifically related," it is proposed 
to proceed on a new basis, and construct and try a system 
that has not been tested by actual use, as has the metric system, 
and which in addition must be pushed against the latter, despite 
the fact that it will doubtless contain neither the decimal basis 
nor the relation between measures of length and weight. In 
other words, there would be experienced all the inconvenience 
which would attend a change to the metric system, and at the 
same time the advantages obtained would be infinitely small in 
comparison with what would follow a decision to adopt the 
latter completely. 

Moreover, such a proposition is by no means new, for we 
have seen how Sir John Kiggs Miller, at the end of the 
eighteenth century, advocated a decimal division of the British 
weights and measures, while on October 27, 1863, Sir John 



164 EVOLUTION OF WEIGHTS AND MEASURES 

Herschel, the eminent scientist and astronomer, in an address 
before the Leeds Astronomical Society, advocated the readjust- 
ment of the British Imperial weights and measures on a decimal 
basis according to a plan that at least appeared scientific and 
methodical. He proposed to take as the standard of length the 
earth's polar axis, which in imperial inches was computed to 
be 500,482,296, and as a new, or as he termed it, " geometrical " 
inch, employ the 5~o~o~tj oo 000 P art of tnis > wnicn would differ 
by less than a thousandth from the customary inch, and be 
at the same time related to a natural quantity. The unit 
of weight would be a cubic foot of water, and would be 
approximately equal to 1000 ounces avoirdupois. Herschel says : 
" Thus the change, which would place our system of linear 
measure on a perfectly faultless basis, would at the same time 
rescue our weights and measures of capacity from their present 
utter confusion, and secure that other advantage, second only 
in importance to the former, of connecting them decimally with 
that system on a regular, intelligible, and easily remembered 
principle ; and that by an alteration practically inperceptible in 
both cases, and interfering with no one of our usages or 
denominations." 

It might be said in passing that the length of the polar 
radius, as calculated by Sir John Herschel, was no more 
accurate or permanent than the original determination of the 
length of the earth's quadrant by the founders of the metric 
system, while similar, though greater, errors have been found 
in his fundamental unit of weight. It is now conclusively 
recognized in metrology that no terrestrial dimensions can be 
relied upon to furnish an accurate standard of length. 1 Thus 
we see that a simple and albeit excellent step at reforming 
British weights and measure did not meet with any greater 
favor than the complete change to the metric system advocated 
about the same time, and it is quite probable that a like fate 
would to-day befall any similar proposition. So that the 
question seems to be not to reform weights and measures by 
gradual and slight improvements, but, if any changes can be 
made, to adopt the best possible system, notwithstanding the 

x See Mendenhall, "The Metric System," Appleton's Popular Science Monthly, 
October, 1896. 



THE METRIC SYSTEM FOR COMMERCE 165 

drawback of temporary inconvenience, and for the sake of the 
future benefits which must unmistakably follow. 

Perhaps the most important question in connection with 
the adoption of the metric system is whether the change 
would occasion any temporary inconvenience or expense to the 
people at large. In the United States the great majority of 
the people have been educated in the public schools, in most 
of which since 1880 the metric system has been taught more or 
less effectively as an integral part of arithmetic. Everyone 
is used to the decimal system as employed in the national 
currency and coinage, and, furthermore, it must be granted that 
a higher standard of intelligence and adaptability prevails in 
the United States than in Germany and other European 
countries, where but little inconvenience was experienced and 
practically no injury was done at the time of the change. True, 
there would be in some cases the cost of new scales, weights, 
and measures, but it must be remembered that these are under- 
going constant deterioration, and in constant use the life of 
scales and weights is only about two years. Therefore, any such 
expense would be in actuality practically negligible, and doubtless 
would result in distributing over the country weights and 
measures of increased accuracy. Indisputably some time would 
be required for the complete assimilation of metric measures and 
weights, as we have seen was the case in Europe, but at the same 
time the advantages attending their use would begin, and there 
would be employed tables of legal equivalents which would soon 
educate all to the necessary proficiency. Then, also, we would 
see for a few years before and after any legislative establishment 
of the metric system, all books for common use containing 
formulas, recipes, etc., printed with all quantities in both English 
and metric measures, so that the transition from one to the other 
either ideally or actually would be attended with no inconvenience. 

In addition to the marked advantages in the actual measuring 
and weighing of everyday life, due to the simplicity of the 
metric system, there would be the great saving of time in the 
schools where the complete metric system taught in connection 
with decimals would require but a fraction of the time now given 
to compound numbers. In fact authorities on education have 
estimated that at least one year of the child's school course could 



166 EVOLUTION OF WEIGHTS AND MEASURES 

be saved by the adoption of the metric system, as after its 
employment in our practical everyday life, the Anglo-Saxon 
measures would be of little more use than those of the Greeks 
and Eomans, and would have scarcely more interest than the 
old measures of France have to-day. 

It is not necessary here to refer to the great saving of time in 
making calculations involving quantities of produce of various 
kind, although it is by no means unimportant, for with the class 
of citizens we are now considering, while bookkeeping usually 
plays but a secondary part in their life, yet it is employed, and 
the farmer or petty shopkeeper will appreciate the saving of 
time as much as the clerk or accountant whom we will consider 
later. For the mechanic it is amply demonstrated that a change 
in measurements makes but little difference as foreign workmen 
educated to the metric system are able to work in the Anglo- 
Saxon system without any difficulty whatsoever and vice versa, 
ample testimony being forthcoming on both sides of this pro- 
position. 

In short, there are no serious drawbacks so far as the average 
man and woman are concerned why America and Great Britain 
should not adopt the metric system, and when it is recalled, how 
practically no inconvenience was experienced in Canada when the 
change was made from shillings and pence to dollars and cents, 
or in the early days of the United States when its system of 
currency was established on lines quite new, it is not reasonable 
to anticipate any embarrassment or difficulty. 

We are then brought face to face with the question, how will 
the adoption of a metric system affect the internal commerce of a 
country using the term as referring to the exchange of com- 
modities on a somewhat larger scale than we have discussed 
above. While such commerce depends for its prosperity on the 
individual purchaser, yet anything which facilitates it acts to the 
latter's benefit in reduction of prices and promptness of delivery 
and improvement of quality. This exchange is accomplished 
through an intricate system of machinery in which credits, banks, 
transportation, and other factors all enter to a large degree. Yet, 
with the extension of commerce constantly going on, there has 
been no backward step, and in its progress simplicity and 
accuracy in business transactions have been the chief essentials 



THE METRIC SYSTEM FOR COMMERCE 167 

which have been aimed at and attained. Thus the use of 
banking facilities, and the telegraph, for the exchange of money 
have contributed to save time and trouble, which in business are 
definitely measured by money, while typewriter, telephone, cal- 
culating machines, and new methods of bookkeeping have played 
their part in releasing the mind of the business man to new and 
original activities, and to the extension of his business along such 
directions as his experience tells him are most profitable. With 
such innovations must be considered the adoption of the metric 
system, as a step in advance, since it will simplify all calculations 
and bookkeeping by the elimination of useless multiplications 
which are involved in the use of the compound numbers employed 
in the ordinary weights and measures. One immediate result 
would be the ease in determining errors and the decrease in their 
number through less multiplication. Undeniably, the simplest 
mathematical process for man is decimal multiplication, corre- 
sponding as it does to his fundamental notation, and this simplicity 
has been established uncontrovertibly in an experience of over a 
century with the decimal system of American money, where there 
has been demonstrated its applicability to all pecuniary trans- 
actions, both large and small, from the actual handling of the 
currency to the booking of credits and the computation of 
discounts, interest, etc., not to mention the ease with which such 
mental calculation as the determination of the price for a quantity 
from a price for an individual article or vice versa can be made. 

Consequently there has resulted the widespread use of per- 
centages and a decimal division wherever possible. Thus, it is a 
matter of convenience that railway and other shares shall be 
valued on a percentage basis, and still more convenient that the 
par value should be $100*00, and this practice has largely prevailed. 
For mining or other shares where a smaller par value is desired, 
it is usual to employ $10'00 or $1*00, while bonds are con- 
veniently arranged on a basis of $1000*00 each. Likewise with 
such commodities as sugar and cotton, 1 where it is necessary 
to express intermediate values between even cents, it has been 
found desirable to give up common fraction and use a decimal 

1 The Liverpool Cotton Association since October 1, 1902, has quoted cotton 
values in hundredths of a penny instead of sixty-fourths. A similar practice is 
observed in America. 



168 EVOLUTION OF WEIGHTS AND MEASURES 

division to facilitate computation and bookkeeping. 1 These 
changes have been the result of an evolution which has been 
independent of any theory, but which has considered merely the 
commercial availability of the method. For shop costs a decimal 
hour is often employed, and such clocks are used in some 
factories. 

An instance of this in American weights and measures is 
found in the tendency to eliminate as many units as possible, and 
to use larger numerical figures, as 1000s of pounds instead of 
tons. Another example was the introduction of the short ton of 
2000 pounds to facilitate calculation, and this unit soon came to 
be more extensively used than the long ton of 2240 pounds 
inherited from Great Britain. No difficulty was experienced in 
making the transition from the long to the short ton, in com- 
mercial usage, and there is no reason why any inconvenience 
should attend the change to the metric ton. In fact, in one of 
the largest chemical works in the United States, — that of the 
Solvay Process Company, — where the metric system is used 
exclusively, it is customary to weigh the coal and other supplies, 
when received, in metric units, despite the fact that they are 
bought and invoiced in ordinary weights and measures. This 
company has found it a distinct advantage in its internal 
economy to make use of the metric system, and employs it in all 
calculations, except for specifications of machinery and wood-work 
that must be constructed outside of their factory by people to 
whom the metric weights and measures are practically unknown. 
An interesting example of the superiority of the metric system for 
purposes of accounting and bookkeeping may be cited in the 
experience of the Brighton Bailway in England, which for a 
number of years has employed the kilogram as its unit of weight 
for all its European business, and the French decimal monetary 
system for its accounts. 2 It is the opinion of the officials of this 
road that the keeping of all accounts would be simplified by using 
metric weights and measures. In the foreign business it would 

1 The Stock Exchanges, however, still use common fractions and commissions 
are usually in eighths and sixteenths of a per cent. 

2 See testimony of Charles A. de Pury, chief accountant of Brighton Railway in 
Report by Select Committee on Weights and Measures (Metric System) Bill 
[H.L.] 1904, p. 25. 



THE METRIC SYSTEM FOR COMMERCE 169 

have been possible, of course, to have changed the French weights 
and currency to English, but the auditors of this corporation 
believed that the metric system would be the more convenient,, 
and such it has proved in practice. 

The elimination of the middleman is one of the tendencies of 
modern trade, and the more direct relation of consumer with 
producer requires that business should be done on the simplest 
possible basis by the contracting parties. Now the middleman 
in the past was the one who usually made the transformations of 
weights and measures, buying by one system and selling by 
another. Inasmuch as often now he is considered superfluous, 
in many transactions where the buyer and seller come together 
directly, it is essential that a single system, which must also be 
the simplest, should be employed. Thus there is no reason why 
coal should be sold at wholesale by the long ton and retailed by 
the short ton of 2000 pounds, or that the dealer in drugs and 
chemicals imported by metric weights should dispose of them by 
avoirdupois or apothecaries pounds. In fact, transformations of 
weights and measures, or the use of double systems, are and 
always have been a fruitful source of complaint and controversy. 
Indeed, it was well said by a British diplomatic official in 
speaking of conditions in Belgium, " The disputes which were 
formerly so numerous, and which rendered long and complicated 
calculations necessary, have become few and far between. In 
short, the adoption of the metric system has done much to ensure 
honesty in commercial transactions." ! 

With the decimal system can be used such important labor 
saving device as slide-rules and calculating machines, the latter 
in particular now being a feature of every well equipped office, 
and resulting in increased accuracy and speed of operation. So 
that the way is in part prepared for the introduction of the 
metric system to denote units of quantity on account of its 
decimal features, which would fit in completely with modern 
business computation, and America could make the change with 
greater facility than Great Britain, or even than that experienced 
by any foreign country, on account of its simple currency system. 
With the advent of the metric system would come the release 

1 Reports from Her Majesty's Representatives in Europe on the Metric System> 
part i. p. 8 ; English Parliamentary Accounts and Papers, 1900, vol. xc. 



170 EVOLUTION OF WEIGHTS AND MEASURES 

from the various heterogeneous arrangements of tables of length, 
surface, volume, capacity, and mass in which binary, duodecimal, 
and other relations are maintained and abandoned in accordance 
with no consistent theory or system, constantly requiring refer- 
ence to unwieldy tables and tedious calculation. Not only is 
there saving in the time required to learn the metric system over 
all others (and it is safe to say that any clerk working at a new 
task where quantities or dimensions of a substance were involved 
would have to brush up his knowledge of compound numbers 
and tables, or proceed with extreme slowness and caution), but in 
its application there is a most important gain of time. The 
result is that more business can be transacted with a smaller 
office force, and that the activity of clerks and computers can be 
turned in other directions. 

The disadvantages attending the introduction of the metric 
system will be entirely of a temporary character, and if we may 
take the experience of Germany as a guide, will prove far less 
than is feared by the timid. The time lost by making trans- 
formation from the old into the new weights and measures will 
in reality prove much less than is anticipated, as such operations 
doubtless will be performed with the aid of tables, such as will 
be found in the appendix, which not only the government but 
every industry doubtless will prepare to facilitate such work, 
while for new calculations employing metric weights and measures 
throughout there will be a great saving. 

The difficulty of minds learning to think in a new system of 
weights and measures is not so easily disposed of, but we have 
seen how convenient and easily applied are some of the approxi- 
mations, and we have only for most purposes to consider a yard 
equal to ^ of a meter, two pounds equal to *9 kilogram, a liter a 
quart, a long ton equivalent to a metric ton, etc. The relation 
between volume and capacity should be appreciated greatly in 
commercial work, as the capacity of a tank, reservoir, bin, or car 
in appropriate units can readily be computed from its dimensions, 
and then, knowing the specific gravity, by simple multiplication 
the weight of its contents can be ascertained. 

With all the inconveniences of the Anglo-Saxon systems of 
weights and measures we are forced to consider a still more 
serious difficulty, namely the growth of a dual system due to the 



THE METRIC SYSTEM FOR COMMERCE 171 

increased use of the metric system as permitted by statute. It 
cannot be denied that the metric system has made great progress, 
and that by the close connection of science with industry that it 
is destined to be even more widely employed. Both systems 
being legal, and the metric measures coming into more wide 
spread use, there would result the perpetual necessity of con- 
verting from one to the other in commercial transactions, and 
while the nation was waiting for the ultimate survival of the 
fittest system, or the birth of an ideal scheme, incalculable 
inconvenience and damage would ensue, as has been shown many 
times in the past where a nation at other times than at a 
transition period has employed a double standard. 



CHAPTEK VII. 

THE METRIC SYSTEM IN MANUFACTURING AND 
ENGINEERING. 

The application of the metric system to manufacturing and 
mechanical and other forms of constructive engineering, where 
there has been long use of units of other systems, presents con- 
fessedly the most serious aspect of the question of adopting the 
international weights and measures. These branches of human 
activity, it must be remembered, had their beginnings in most 
humble and commonplace sources, such as the village smith, the 
local carpenter, or even the aboriginal savage with his primitive 
loom. In this respect they differ from electrical and civil 
engineering, and applied chemistry, where the applications of 
science and discovery have resulted in vast industries and 
important technical professions. From their very inception these 
latter have been dependent on the work of scientific men, using 
the term broadly, and it has been possible to use such units and 
measurements as they have recommended. That these units 
can be developed rationally and systematically, as well as with 
extreme simplicity we can see from the electrical units which 
will be discussed in a subsequent chapter. But in mechanical 
engineering and manufacturing simple processes and methods 
have gradually been developed by the aid of scientific men, 
and by applying their discoveries to every- day work, con- 
sequently the engineers have been forced to use the units 
and measures of the people rather than to develop and 
rationalize such systems as would best commend themselves to 
their judgment. 



THE METRIC SYSTEM IN MANUFACTURING 173 

Improved methods of manufacturing, however, have brought 
about machinery and processes marked by simplicity and 
efficiency, and while the advantages that will ensue ultimately 
from the adoption of international weights and measures will 
more than compensate for any temporary inconvenience, never- 
theless, it must be admitted that the transition will involve some 
serious problems and expense. Inasmuch as comparatively few 
manufacturing processes, or at least individual plants, remain 
stationary, but are constantly undergoing improvements either of 
method or machinery, the possibility of adjustment to new 
conditions, such as a new system of weights and measures, is not 
so difficult as might at first be imagined. Oftentimes changes of 
styles or classes of product are made that are far more funda- 
mental than any changes that would be involved by new 
measures, and natural wear and tear to machinery require 
constant renewals and substitutions at intervals, and in many 
shops it is considered good economy to strive for a maximum 
output at the expense of individual machines and tools. Further- 
more, conformation to standards, so necessary for successful 
manufacturing, does not involve the blind adherence to such 
standards, however honored and however universally observed, 
after better standards have been evolved. That such a change in 
units or standards can readily be made we know from numerous 
instances in the past where various gauges, screw threads, screws, 
etc., have been changed without undue confusion and expense. A 
notable instance, inasmuch as the change was radical and funda- 
mental, was made by the printers of the United States in 1883, 
when the nomenclature of the different sizes of type was changed, 
and a system of measuring by points adopted to take the place of 
names in use for years. In fact, the adoption of various screw 
threads in different countries, either in the interest of standard- 
ization or to obtain a better screw, and even their modification, 
has worked no great hardship, and such changes in car coupling 
and other devices recommended from time to time in the United 
States by the Master Car Builders' Association, involving as they 
often do marked departures from sizes or styles in use by 
different railroads, seem to be made speedily and effectively, and 
without such expense as would occasion objection from controlling 
officials. 



174 EVOLUTION OF WEIGHTS AND MEASURES 

Numerous instances where changes of systems and standards 
dealing with actual concrete things may be cited to show how 
readily changes in manufacturing and mechanical engineering 
have been brought about, proving that it is not only under ideal 
conditions, such as the change from local to standard time, or 
in an improved calendar, that scientific reforms can be effected. 
Once the people concerned are convinced of the need of the 
change and the superiority of a new system, history shows that 
the change can be made effectively and expeditiously, so that at 
present it remains for the adherents of the metric system to 
convince the manufacturing public by demonstrating its superiority 
for their work, and to show how it may be adopted with the 
smallest amount of inconvenience. Possibly this will best be 
understood by considering briefly the relation of weights and 
measures to manufacturing and constructive engineering. If a 
single piece of machinery or a single fabric is to be produced, 
it is of little moment what units of weight and measures are 
employed by the designer, and what are used by the maker, 
provided that both can understand each other, and provided that 
time and expense are subordinate. That this is true is shown by 
the ease with which American and English workmen can and do 
work from continental designs prepared according to the metric 
measures and vice versa on special orders. But when thousands 
of the manufactured article are required, and time and economy 
must be considered, or in other words, when the commercial 
conditions of successful manufacturing have to be met, then the 
influence of weights and measures as reflected in standards, 
processes, and in numerous more or less direct ways, is felt. 

We may start with the raw material, which may be in bulk as 
in the case of ore, pig iron, crude chemicals, baled cotton or wool, 
logs, etc., to cite but a few examples, or we may consider as raw 
material, wire, sheet metal, structural shapes from the rolling mill, 
yarn, boards, and other sawed or milled timber, to mention some of 
the innumerable articles that enter into manufacturing processes. 
In the case of the former class we have to consider the same 
principles discussed in the last chapter, as the purchase of the 
materials would be greatly simplified by having all invoices and 
calculations of prices made in the metric system, consequently 
there would be a saving of time to the office. The actual 



THE METRIC SYSTEM IN MANUFACTURING 175 

weighing would be the same under any system, though easier 
with metric weights, but for the computations involved in mixing 
or otherwise treating raw materials there would be a great saving 
effected by using the metric system, as it would avoid the 
employment of different classes of units, and would be throughout 
on a strictly decimal basis. However in this no particularly 
serious questions arise, but with the other class of raw materials 
used in manufacturing, experience has shown and convenience 
enforces the demand that they must be supplied of certain 
dimensions which must be of sufficient variety to fill all reason- 
able needs, prepared according to certain standards, and packed in 
certain quantities. The dimensions or weights are taken, of 
course, in conventional units, and the law of supply and demand, 
modified by co-operative action and trade customs among manu- 
facturers, consumers, and dealers, has resulted in the establishment 
of certain standard sizes which not only are regularly carried in 
stock, but for which have been calculated many tables dealing 
with their weight, strength, elasticity, resistance, and other 
characteristics useful to designer and maker alike. As a result 
the majority of articles used in manufacturing and construction 
are made only in standard sizes, for making which special 
machinery has been prepared and adjusted, while articles of other 
dimensions must be specially made at considerably greater 
expense. 

This policy of making articles in standard sizes has been 
productive of the highest benefit to the manufacturer, and 
the specialization that has been brought about in American 
works and factories has contributed in no small degree to the 
position in manufacturing that the United States now occupies 
among the nations of the world. This system of standardiza- 
tion is also advantageous to the consumer, who in turn 
may be just as important a manufacturer, only turning out a 
more finished or more complex article. Let us see how the 
metric system would apply here. First, let us take the purely 
arbitrary standards which have no even dimensions. For 
example, flour is manufactured and usually sold 196 pounds net 
to the barrel, yet there is no particular reason for this quantity, 
since flour sold in sacks for export, where it may be stowed the 
more readily in a vessel's hold, usually is packed 140 pounds to 



176 EVOLUTION OF WEIGHTS AND MEASURES 

a sack. Now, if there was any reason for preserving these 
particular quantities they could be used in metric weights just as 
readily as at present, but appreciate the convenience if barrels of 
100 kilograms and sacks of exactly half that amount were 
employed. True, the miller would have to adjust his automatic 
scales for weighing his flour, but the product would be turned out 
in even quantities, and the weight of carload or cargo would be told 
at a glance from the number of barrels or sacks. Every trans- 
action from the time that the flour left the mill until it was divided 
by the retail grocer into 10 kilogram lots would be facilitated. 

Then let us consider wire and sheet metals for which there 
have been a number of gauges. These, for the most part, have 
been and are, not only arbitrary but irregular and inconsistent, and 
have stated the thickness in decimal fractions of inches, some of 
which are expressed to the fifth or sixth place. If these numbers 
are to be retained it is certainly just as easy to express the 
thicknesses in fractions of a millimeter as^ of an inch, and in fact 
this was officially done in the Act of March 3, 1893, when a 
standard gauge for sheet and plate iron and steel was established 
by Congress l in which the numbers were defined by equivalent 
values in inches and millimeters. Consequently, under the 
existing legal gauge, the adoption of the metric system would 
cause no difference whatever in the making of sheet iron and 
steel, and the customer would find the same legal sizes under the 
metric system as before. While no wire gauge has been legalized, 
yet, if any of the standard gauges is to be used, it is quite as 
easy to consider the metric as the inch values since the decimal 
fractions are no greater. The gauge system at best is bad in its 
general aspect as it always requires an act of memory, and in 
practice so inexact and unsatisfactory that certain large consumers 
in the United States, notably the Great Electric Companies, 
have instructed their draughting rooms and purchasing depart- 
ments to always specify by actual dimensions in thousandths 
of an inch expressed decimally. But so long as gauges are 
generally used, it is necessary to consider just what they 
signify and what part they play in mechanical operations. 
Formed as they are of plates of sheet steel or other metal, with 
holes or openings with which to test the various samples of 
1 C. 221, Sec. 1, 27 Stat., 746, K.S. 3570. 



THE METRIC SYSTEM IN MANUFACTURING 177 

materials, they are in practice often at the outset very inexact in 
their graduations, and in any event they sooner or later become 
so by the wear of constant use. As regards their graduation and 
division the various standard gauges differ widely from one 
another, and in individual cases, as has been said, they are hardly 
■ever arranged systematically or methodically. This can readily 
be appreciated by examining the tables in almost any standard 
engineer's reference or so-called pocket book, but a hint can be 
given by the following list, which shows the dimensions in 
decimal parts of an inch for the same number (No. 2) of the 
various gauges that are all in use in the United States. 

Dimensions of No. 2 gauge according to different standards : 

Inch. 

American or Brown & Sharpe, - '25763 

Birmingham or Stubs' Wire, - '284 

Washburn & Moen M'fg Co., Worcester, Mass., - '2625 

Imperial Wire Gauge, - - - - '276 

Stubs' Steel Wire, " '219 

U.S. Standard for Plate, ... - -265625 

Twist Drill and Steel Wire Gauge, - - - '221 

Screw Gauge for Machine and Wood Screws, - '08416 

Thus it will be seen that material made according to any of the 
•above gauges is not suitable to be used with that made by 
another gauge, as for example there is no correspondence between 
the gauge sizes of wire and th.€ twist drill which would make the 
hole in which the wire might be inserted, or the size of the wire 
and the wood or machine screw into which it might be made. 
Consequently the present tendency is to abandon all arbitrary 
gauges and work to decimal parts of an inch requiring all 
materials to be furnished of such dimensions, a condition which 
can be easily determined with great exactness by a micrometer 
caliper of low cost. Now, the use of decimals presents no 
inconvenience whatsoever to the average mechanic, so that at such 
a transition period as regards standard sizes of materials, there is 
every reason for adopting the metric system rather than waiting 
until further standardization on an inch basis shall have occurred. 
Instead of arbitrary gauge numbers millimeters and decimal 
fractions could be employed, and there would be the advantage of 
having a larger number of integral numbers and division by 

M 



178 EVOLUTION OF WEIGHTS AND MEASURES 

tenths and hundredths, amply sufficing for all ordinary mechanical 
work. The workmen, in their measurements, would employ the 
same form of micrometer, the reading of which would be even 
more simple, and much greater interchangeability would result 
as soon as materials were furnished in a smaller number, but 
standard sizes. 

The tendency would be towards a more exact arrangement on 
a metric basis. Such a movement would be gradual, and there 
would be few occasions where any difficulty would be experienced. 
Metric wire gauges were introduced in France in 1894, and have 
proved satisfactory, their use increasing very rapidly. In fact, in 
much work done with such materials, as sheet metal and wire, as 
well as with other material, it is rarely necessary to look for the 
strictest exactness in conforming to a certain gauge as the purpose 
can be satisfied by an approximation, and the customary method 
of payment being made on a basis of weight prevents any 
imposition or injustice. As, however, new dies or rolls were 
required, these would be carefully adjusted to metric gauge, and 
the older sizes would gradually become obsolete, unless there 
arose some special demand, while in the case of sheet metal it 
would only be necessary to have a new setting of the rolls. It is 
impossible to conceive of any injury being done the manufacturer, 
for at the worst he has only to provide himself with a few new 
adjuncts to his larger tools and a limited number of smaller tools,, 
which are constantly being replaced. 

Then take the case of the lumber mill, where planks, boards, 
joists, etc., are turned out on an inch basis. How near do these 
dimensions correspond in reality with the sizes they are sold for ? 
In fact, in many instances planed boards of a certain dimension 
do not gauge that dimension at all, but represent what remains- 
after a board sawed approximately to that thickness has been 
planed. The carpenter and the cabinetmaker do not demand so 
high a degree of precision from the lumber dealer that the *4 of a 
millimeter, between 25 millimeters and an inch (25*4 mm.) cannot 
be disregarded, and here again it is found that most standard 
sizes of lumber can be readily described in metric measures- 
without the use of decimal fractions, and no new machinery 
will be required except as new styles or sizes are demanded. 

In actual manufacturing, after the adoption of the metric 



THE METRIC SYSTEM IN MANUFACTURING 179 

system, the first step would be the provision of facilities for 
making various articles, such as sheet metal, paper, wire, cloth, 
etc., according to metric dimensions. This would be to meet the 
requirements of the government and other consumers, who 
desired goods according to metric specifications. In other words, 
the same process would be gone through with as occurs when a 
large new or special order is received. As these orders would be 
in metric sizes, and conformable approximately to those that 
experience had taught were most serviceable for the particular 
use for which they were designed, they would gradually become 
standards, and would supplant the older sizes. In many cases 
where materials are sold by weight, as paper and wire, the effect 
of a change of dimensions would have no effect on the price, 
while a minute change sufficient to adapt the material to a 
regular metric dimension would in no way affect its usefulness to 
the consumer, and should there be a slight increase in some 
instances it would be balanced by a slight decrease in others. 
Indeed, in many instances only the trimming or finishing would 
be involved, and here it is probable that the waste material would 
just as likely be less than the amount produced in making the 
present sizes as it would be greater, and at any rate it could 
doubtless be worked or utilized in some way, the difficulties can 
hardly be called serious. 

Linear measures and standards play a prominent part in all 
mechanical operations, and here the superiority of the metric 
system and its ready applicability may be shown. It has been 
the practice to measure by successively halving the unit, and in 
the case of the inch this has brought us down to such fractions as 
^ and -^g, which are awkward both for computation and 
observation on a scale. While it is quite natural to halve or 
quarter a unit, yet to pursue this policy of binary subdivision too 
far is extremely inconvenient. With the metric system in linear 
as in other measurements it is possible to make use of any 
decimal multiple or submultiple of the meter from the micron to 
the myriameter as the base, according to the nature of the 
measurement involved, and it is quite possible to use the half of 
it simply by writing "5, or the quarter by writing *25, both 
expressions requiring no more figures than the corresponding 
common fractions, and involving no difficulty in case it is desired 



180 EVOLUTION OF WEIGHTS AND MEASURES 

to transpose to a higher or lower unit. Now, it has been found 
better in actual experience when other fractions than a half or 
quarter are desired, to divide decimally, and where accurate work 
is demanded it has become the almost universal custom in the 
United States among engineers and machinists to work in 
hundredths and thousandths of inches, the practice being followed 
from draughting room to shop. This practice involves the ex- 
pression of all quantities in terms of a single unit, such as feet, 
inches, or pounds, with the appropriate decimal fraction, and 
demonstrates the availability of the decimal system for such 
practical work, as well as for mere computation. This practice is 
rapidly on the increase, due largely to the use of calipers and 
gauges thus divided, so that the matter of decimal fractions 
presents no disadvantage, but rather a convenience, to the 
workman who has to make measurements. 

As regards the linear units themselves ; if the workman 
employs millimeters he has a unit which is a whole number, and 
is superior to ^, as the latter is too large, and represents coarse 
measurement and work. On the other hand ^ is too fine a 
division for an ordinary scale, especially for a draughtsman, and 
is only useful on a steel scale, with which few mechanics are 
equipped, consequently the centimeter and millimeter are quite as 
convenient as the inch, while the foot, which is rarely used in 
modern mechanical engineering, is in no way missed. Even if we 
consider the inch as the principal unit we are forced to use, either 
its sixteenth part, or its tenth, hundredth, or thousandth, and in 
reality we make such a fractional part our standard unit, and we 
have the odd relation between such units and the greater ones, 
the inch, and the foot, as compared with the simple decimal 
relation of the metric linear measures. The yard and the meter 
wherever desired are units of the same class, and what can be 
done with one is equally possible with the other, not to mention, 
of course, the advantage of the decimal relation of the meter to 
its sub-multiples. But the great gain is that all calculations are 
made in the same unit as the original measurement, and no 
reductions, save the transfer of a decimal point, are ever 
necessary. Contrast this with the English system where 
measurements made in inches must be changed to feet or yards 
for use with tables or vice versa. 



THE METRIC SYSTEM IN MANUFACTURING 181 

But in most manufacturing there is comparatively little or no 
measuring for the workman to do, inasmuch as he is required 
merely to make his work according to gauges, or templates, 
or jigs, which are supplied to him by the tool room, where 
they have been carefully worked out from the specifications 
of the draughting room. Holes are bored and reamed to a 
certain gauge, drills are set so that several will come down on 
the piece of work at places previously determined by the jig, and 
planers, shapers, milling machines, etc., are all operated in the 
same way. But there must be some consideration of standards 
and units in the draughting room and tool room, is the suggestion 
immediately made, and here possibly would be one of the points 
where difficulty might be encountered. It has been shown in 
actual experience that the work of the draughtsman in preparing 
plans according to metric measures is not only no harder, but is 
facilitated considerably in actual drawing, and immeasurably so 
if there are computations to be made. Now, in the construction 
of gauges and tools the highest intelligence of the mechanical 
force is employed, and here there are men not only having a 
knowledge of current sizes and standards, but perfectly capable of 
working in any kind of measures. In fact, the dimensions of 
many gauges are merely nominal, and there is a greater or less 
deviation from the stated dimensions, but which concern neither 
draughtsman nor workman if all tools and gauges are harmonized 
as they must be to these dimensions throughout the work. This, 
of course, involves the use of micrometers and other adjuncts to 
fine measuring, and this class of work can be done with greater 
facility in the metric system, as is shown by its adoption by 
makers of instruments of precision, opticians, and watchmakers 
universally. 1 If tools and gauges in the factory are to remain as 
before the introduction of the metric measures, as they can be 

1 The Swiss watchmakers were the first to employ a metric thread for small 
screws, and the basis of the system was to start with a pitch or distance between 
threads of one millimeter, and to decrease the pitch of each succeeding size by 
ten per cent. In 1869 not only were metric threads adopted by the American 
Watch Company for watches, but also throughout their factory, and all their 
watchmaking machinery has been constructed on that basis. In Great Britain a 
Committee of the British Association for the Advancement of Science appointed 
to determine a gauge for small screws used in telegraph and electrical apparatus 
reported in favor of the Swiss series of small screws, and the same was adopted. 



182 EVOLUTION OF WEIGHTS AND MEASURES 

without the slightest inconvenience, it is only necessary to 
designate them by their metric values for purpose of computation, 
and to continue employing them with their various shop numbers 
as before. Where new standards and gauges are to be con- 
structed, as they must be from time to time, then it would prove 
desirable to use the metric measures, and the tendency will be to 
work toward even dimensions and universal standards. Such a 
tendency will be general, and if the manufacturer need tools, 
which he must buy, he will soon find that the new ones carefully 
standardized will be forthcoming in metric sizes, wherever any 
changes are made from existing patterns and numbers. To such 
a degree of exactness is this work now carried on in well- 
organized American shops, that the highly skilled man in charge 
of the tools will find little trouble in adopting the metric 
dimensions. 

Making the supposition now that a machine shop or factory is 
required to work to actual correct dimensions in the metric 
system, which, of course, is not contemplated by any movement 
for the introduction of the new system, it does not mean that a 
new equipment of tools must be procured. None of the larger 
tools would be changed, as even in the case of the lathes a single 
gear wheel connected to the lead screw enables metric threads to 
be cut on an ordinary lathe with an inch lead screw and vice 
versa, while the only important changes would be such small 
tools as drills, reamers, taps, dies, etc., where in certain dimensions 
a new size might be demanded, and these, if not already made 
and in stock, as are gear cutters for cutting metric pitches x at 
the present time in the United States and England, would soon 
be provided by tool makers. 

In this connection the cutting of screws may be discussed 
more at length, as it is one of the principal undertakings in a 
machine shop, and involves the greatest care in order to secure 
high precision and interchangeability. Screw threads originally 
are made upon a lathe where a cutting tool is given a lateral 
motion by means of a screw known as a lead screw which 
revolves in a nut attached to the tool carriage, and thus gives a 
lateral motion to the tool. The object on which the screw is 
being cut is also revolved, and the proper ratio of revolution 

1 Bevel gears can be cut to metric pitch with the usual tools. 



THE METRIC SYSTEM IN MANUFACTURING 183 

between the two is maintained by suitable gearing. In the 
United States and England lathes are usually designed to work 
on an inch basis, and consequently the lead screw is so divided 
and the corresponding gears furnished. But, by the use of one 
change wheel with 127 teeth 1 it is possible to arrange a lathe so 
that with a lead screw divided on an inch basis metric threads 
may be cut with an error that can only be detected by the most 
refined methods, if at all, and such screws are entirely suitable 
for all ordinary use, being correct to one part in 6350. By such 
means are made the taps of hard steel with which holes are 
threaded, and the dies that are used for the more rapid cutting 
of threads on a large scale in the actual manufacture of screws 
in quantities. 

While the adoption of the metric system does not necessarily 
involve the doing away with the present systems of screw threads 
in the United States and England, which, however, are purely 
arbitrary, and could be measured in millimeters with equal 
facility, yet there is a metric thread which was approved at a 
congress of engineering societies held at Zurich in October, 1898, 
and again at an international conference held in October, 1900, at 
Paris, delegates being present from all the important metric 
nations of the Continent, including France, Germany, Switzerland, 
and Italy. This form of thread was evolved by the Socidte* 
d'Encouragement pour lTndustrie Rationale of France, having been 
devised by M. Ed. Sauvage, and used for a number of years on 
the French railways previous to its adoption by the society. 
With slight modifications it was adopted as an international 
standard for shape of thread and pitch, and is now known as the 
Systeme International, abbreviated to S.I. or S.J. The shape of 
this thread is practically the same as that of the U.S. standard 
adopted by the U.S. Navy Department in 1868, and also known 
as the Franklin Institute or Sellers Standard, from the name of 
its inventor, William Sellers. The thread of the bolt or screw 
consists in cross section of an equilateral triangle, giving an angle 
of 60 degrees as compared with 55 degrees in the Whitworth 
(British) standard, and the edges and bottom of the thread are 
flattened by an amount equal to -^ the height. A modification 
and improvement over the Sellers thread, as well as over the 

1 This represents five times the ratio of the inch to the millimeter. 



184 EVOLUTION OF WEIGHTS AND MEASURES 

Whitworth thread, consists in allowing for clearance between the 
base of a nut thread and the top of a bolt thread, though in 
American machine shop practice it has been usual so to make 

Common Sizes of Screw Threads. 





Whitworth. 






S.I. 






(Inches.) 


Diam. 




(mm.) 


Diam. 


Diam. 


Thds. per inch. 


Increment. 


Diam. 


Pitch. 


Increment. 


i 


20 


i 


6 


1 


2 


f 


16 


i 


8 


1-25 


2 


i 


12 


1 


10 


1-5 


2 


1 


11 


i 


12 


1-75 


4 


J 


10 


i 


16 


2' 


4 


i 


9 


i 


20 


2*5 


4. 


i 


8 


i 


24 


3* 


6 


i* 


7 


1 
4 


30 


3'5 


6 


H 


7 


i 


36 


4- 


6 


i* 


6 


i 


42 


4*5 


6 


. it 


5 


i 


48 


5 


8 


2 


*J 


i 


56 


5-5 


8 


n 


4 


i 

2 


64 


6 


8 


n 


4 


i 


72 


6-5 


8 


2f 


H 




80 


7' 




3 


H 











the thread that there is such a clearance, the sides of the thread 
and nut receiving the fit. In the S.I. thread this clearance amounts 
to -^ of the thread in the form of a circular fillet tangent to the 
thread's side, while the thread itself has a flat top. The pitches 



THE METRIC SYSTEM IN MANUFACTURING 185 

or distances between the threads increase regularly by a half 
millimeter, with a "25 millimeter interval in some cases, as 
between 1 and 2 millimeters. The rate of increase is much more 
regular and simpler than in the case of the United States 
standard thread, where in many places awkward fractions are 
introduced. The pitch of the latter is finer, thus making a bolt 
constructed on the Systeme International a trifle weaker, but the 
difference is not serious, and no disastrous effects have been 
experienced in actual use. The underlying symmetry and the 
regularity are, however, features of great value, and the system at 
the time of its adoption was thought worthy of widespread use, 
even to supplant the Whitworth thread, which despite its English 
basis has been in wide use for years even in metric countries. 1 

In watchmaking the metric thread is employed universally, the 
Swiss system being taken as the standard ; while for small 
machine screws used in electrical and other apparatus there is 
the B.A. (British Association) standard, which is also metric 
The latter thread was devised by a committee of distinguished 
electricians and experimental physicists, and since its adoption 
the regularity and symmetry of its divisions have been thoroughly 
appreciated. 

The change to the Sellers thread in the United States was 
made without any paralysis of manufacturing industries or 
serious injury to machine work, and the same was true when the 
railroads adopted a standard screw thread and gauge on the 
recommendation of a committee of the Master Car Builders' 
Association, which reported in 1882. This report 2 shows the 
advantages to be gained by adopting and adhering to one system, 
and outlines the problem that was solved by the late Professor 
William A. Eogers and the Pratt and Whitney Company in 
preparing suitable standards for adoption by all railroads. This 
change was made in the course of a few years without undue 
difficulty or expense, and since has been found amply justified, 
illustrating most strikingly the advantages of a common standard 
in a single industry. 

1 Henry Hess, "The S.J. Standard Metric Thread in Continental Europe," 
American Machinist, p. 422, vol. xxiii. No. 18, May 3, 1900. 

2 M. N. Forney, Chairman, Railroad Gazette (New York), July 7, 1882, vol. xiv. 
p. 407. 



186 EVOLUTION OF WEIGHTS AND MEASURES 

The adoption of the metric system, however, does not 
necessarily involve the changing of the present excellent screw 
system of the United States, as it is perfectly possible to get 
along with arbitrary names and gauges based on original 
standards, and well denned in terms of metric as well as the old 
measures. Just as " tenpenny " nails are now spoken of, so 
screws could be denned by number even if they were based on 
obsolete linear measures and standards. On the other hand, if 
the tendency should be towards a new international gauge it will 
come gradually, and without undue inconvenience, as similar 
changes have been made in the past. 

In Great Britain, where possibly the standardizing of screws 
and screw threads has not been developed so highly as in the 
United States, the situation has been most excellently summed up 
by Alexander Siemens, the well-known electrical engineer and 
manufacturer. In his Presidential Address l before the (British) 
Institution of Electrical Engineers, delivered November 10, 1904, 
he said : 

" As a last resort the expense of changing the screw threads 
is urged against the change to the Metric System, and the 
Continental practice of calling their system ' Whitworth thread ' 
is considered an incontrovertible proof that the metrical screw 
thread is impracticable. If all taps and dies and leading screws 
had to be exchanged at once, it would certainly be a costly affair, 
but such a measure is not likely to be adopted, as no advantage 
could result from it. For the real difficulty with screw threads 
is that giving dimensions on paper is not sufficient to ensure that 
the screws, manufactured according to such instructions in 
•different works, are really interchangeable. This subject has 
been investigated by a committee from the War Office, and their 
conclusions throw a very interesting light on the controversy. 
In their opinion it is only possible to obtain interchangeable 
■screws, if the leading screws by which they are made have all 
been cut on the same screw-cutting lathe, or are at least cut on 
benches which are fitted with a leading screw manufactured on 
the same original bench. If another link is interposed, differences 
in the screws turned out become perceptible. As a consequence 
of the finding of the committee a screw-cutting lathe has been set 

1 Electrician (London), Nov. 11, 1904, p. 149. 



THE METRIC SYSTEM IN MANUFACTURING 187 

up at the National Physical Laboratory, where leading screws 
for screw-cutting lathes are to be manufactured. 1 The same 
experience has been had in other countries, where nominally 
* Whitworth's threads ' are used. It is not possible to make 
screws interchangeable by prescribing their dimensions, the only 
way is to obtain taps and dies or leading spindles cut by the 
same tools. If it is a case of extreme accuracy, there is no 
difficulty in cutting English thread by means of a metric lathe, or 
vice versa." 

To appreciate just what would be the immediate effects of 
the adoption of the metric system in mechanical engineering it 
is interesting to study the experience of a large engine works 
and machine shop in England — Messrs. Willans and Robinson, of 
Rugby — which enjoys a reputation for extremely accurate work 
together with progressive ideas associated with the best engineer- 
ing practice. This firm employs in its works the metric measures 
of length, and not only are they preferred by their draughtsmen 
and engineers, but also by the workmen in the shops, who did 
not experience the slightest difficulty in accustoming themselves 
to the new system or to employing it interchangeably with the 
customary measures. Inasmuch as this shop has been and is 
now experiencing some of the conditions attendant on a transition 
period from the customary to the metric measures its experiences 
are of interest. They employ bolts whose diameter is turned to 
the nearest even millimeter larger than the size of thread and on 
them cut a thread of the standard Whitworth pattern. One of 
their engineers, Mr. Ernest R. Briggs, in describing the use of the 
metric system in the shop's work has written: 2 "I have seen new 
machines built in the metric system side by side with existing 
lines built in the English system, and I have seen standard 
parts of one set of machines made to work in with standard 
parts of the other set, and I have also made and sent into the 
shops drawings in which a single large and complicated casting 
has been figured in each system. I can make no defence for 

1 The screw of this lathe is six feet in length, and is made of compressed steel, 
the thread being cut with such accuracy that it is said to be correct to rjj^nr of 
an inch at 60° Fahrenheit. The lathe is installed in a constant temperature 
room at Bushy House. [Authors.] 

2 Ernest R. Briggs, p. 450, vol. xxv. American Machinist, 1902; also a second 
jaaper by the same author on p. 1347 of the same volume. 



188 EVOLUTION OF WEIGHTS AND MEASURES 

this latter, but it shows what can be done in working the two 
systems side by side during the transition period." 

In England there is at present the beginning of a lack of 
uniformity, as during recent years much improved machinery has 
been imported from the United States and from Germany and 
Switzerland. The former has screws cut to the Sellers thread, 
while in the latter the S.I. system is being widely and increas- 
ingly used. Consequently, so long as English engineers will go 
into the market for the best machinery irrespective of its source, 
as is now the tendency of the best and most progressive manu- 
facturers, there is bound to be an increasing lack of uniformity in 
screws and screw-threads. 

As to the effect of the introduction of the metric system into 
the manufacture of machinery, we cannot do better than conclude 
by quoting from the remarks of Mr. S. M. Vauclain, the superin- 
tendent of the Baldwin Locomotive Works of Philadelphia, Pa. 
Mr. Vauclain's testimony is not only interesting and most 
valuable from his high reputation as a mechanical engineer, but 
from the position that his company enjoys in the manufacturing 
world. Locomotives from its works have been shipped all over 
the world, while the actual manufacture has been systematized 
and specialized to such an extent that unrivalled speed of con- 
struction as well as largeness of output has been attained. Mr, 
Yauclain says i 1 "So far as the metric system is concerned from 
a manufacturer's standpoint, it certainly should have no terrors. 
Where — in what workshop — can you find a 'dozen men who will 
measure the same piece of work and find the same result with 
the ordinary 2-foot rule, or such scales as are ordinarily provided 
for their use ? Could any manufacturer in America to-day rely 
upon the accuracy of the measurement of its employees in its 
products ? Instead of having first-class fits and interchange- 
ability he would have first-class misfits and ruination of his 
trade." Eeferring to the vast amount of fitting involved at the 
Baldwin Works, where there is an output of five locomotives 
daily and a force of workmen aggregating 11,500, Mr. Yauclain 
goes on to say, " . . . it can readily be understood how poorly 
these locomotives would be fitted together if we relied upon each 
and every one of these 11,500 men to do the measuring necessary 

1 S. M. Vauclain, p. 414, vol. cliii. Journal of Franklin Institute, 1902. 



THE METRIC SYSTEM IN MANUFACTURING 189 

to fit these parts together with the drawings furnished by the 
draughtsmen in their hands." 

Discussing the actual relation of the measures to the work of 
designing and construction, he says : " What is the natural 
proceeding, then, in a workshop of this kind ; you receive the 
drawings from the drawing room ; they are all made to, we will 
say, the English measure — 12 inches to the foot, 3 feet to 
the yard, or whatever you please — no matter how you may see fit 
to speak of it ; but really and truly these drawings are not made 
to the ordinary English measure: they are made to a scale which 
is adopted, and which represents 12 inches to the foot, or 3 feet 
to the yard, or so many sixteenths inches to an inch. The scale 
that we have adopted in our draughting room is a scale of 
2 inches to the foot, and in comparing everything that we look 
at, we do not consider the foot at all : but if it is 2 inches long it 
is a foot long." 

"When a change of this kind would commence in any manu- 
facturing establishment, it would first commence in the drawing- 
room (because unless the drawings were made in accordance with 
the metric system, the men in the shop could never work to it), 
and there would be very few gauges in use in the shop that 
would have to be changed, because the gauges do not depend 
upon the figured dimensions on the drawings ; the drawings 
would all be figured for the gauges. A certain gauge would be 
called for instead of a certain dimension. In our works to-day 
there is not a single hole drilled in a connecting rod where the 
straps are fitted oh the stub ends of the rods, that is drilled to 
a dimension ; the drawings do not refer to any dimensions ; we 
have no use for dimensions, but we have for gauges. They are 
marked to be drilled with a certain gauge and a certain bushing 
piece. You could not use an inch and a quarter drill in a inch 
and an eighth bushing. Whatever bushing you use determines 
the size of the drill you are going to use ; and whatever gauge 
you use determines the distance apart the holes may be and the 
number of them, and the distance they are from the end to the 
stub. The workman goes ahead and drills regardless of the 
consequences in accordance with the gauge that is ordered on the 
drawing ; and the result is that these parts are perfectly inter- 
changeable, and hundreds and thousands of these parts are 



190 EVOLUTION OF WEIGHTS AND MEASURES 

duplicated from time to time and shipped to almost every country 
on the face of the earth, and that without a single dimension 
either metric or English on the card — simply the gauge number 
calling for that part. This may be met with the remark that 
those people who do not do their work with gauges would not 
find it so easy to change ; but that is easily confronted by stating 
that no first-class shop, or any shop, no matter how small it 
might be, that desired to enter into competition with the world 
would ever do its work in any other way and expect to succeed; 
it would die a natural death sooner from the fact that it failed to 
use gauges or jigs for the output of its work — even though it had 
only one of a kind to make — much sooner than it would if it 
undertook to use the metric system." 1 

1 S. M. Vauclain, p. 417, vol. cliii. Journal of the Franklin Institute. 



CHAPTEE VIII. 

METEIC SYSTEM IN MEDICINE AND PHAEMACY. 

In no branches of scientific work is there greater need for 
uniformity of weights and measures than in pharmacy and 
medicine, where the entire world is drawn upon for drugs and 
chemicals for therapeutic purposes, and where the latest dis- 
coveries of such agents, or new methods of their use, are immedi- 
ately communicated to the medical profession in every civilized 
country. With uniformity of measures there would result uniformity 
of treatment, and the ability to compare various methods in 
different cases. In fact, there is no reason why the medical 
profession should not be able to write and speak in the same 
language as concerns their weights and measures throughout the 
world just as much as the chemist and other workers in pure and 
applied science; such a condition would also facilitate the exchange 
of scientific information, which in the case of medical intelligence 
would be of incalculable value. In addition to this must be 
considered the commercial advantages to the general wholesale 
drug trade, the manufacturing chemist, and the retail pharmacist, 
due to the fact that many drugs are produced in metric-using 
countries, and are there sold and exported according to such 
measures. These same drugs, when they reach English-speaking 
countries, customarily are sold according to avoirdupois weight, 
and are then compounded according to apothecaries' weight — a 
system which is a survival from mediaeval times, and which finds 
few, if any, defenders on grounds other than its customary usage. 
The fact, however, must be considered that the manufacture and 
distribution of pharmaceutical products is a trade that is self- 



192 EVOLUTION OF WEIGHTS AND MEASURES 

contained, as it were, and we do not find the retail consumption 
of drugs and chemicals save for medicinal purposes, where the 
measurements are by spoonfuls or similar devices, and are usually 
at the direction of a physician, a matter of great interest in the 
daily life of the public. In other words, the buying, selling, and 
compounding of drugs and chemicals concerns the physician and 
pharmacist rather than the general public, who, however, are the 
ultimate consumers, but whose wants are not such as to require 
the use of any particular system of weights and measures, much 
less to insist upon it. The use of the metric system among the 
manufacturers and dealers in drugs and chemicals has been 
constantly on the increase, in fact some of them furnish their 
products altogether according to metric units. On the other 
hand, the European chemical manufacturer must provide special 
containers for all of his products intended for the American 
market. Therefore, it is a fact that manufacturers and dealers in 
drugs and chemicals are more than willing to adopt metric 
weights and measures exclusively, if they are not already in use. 
Furthermore, we know that the pharmacist is convinced of the 
availability of the metric system inasmuch as it has been adopted 
universally in continental Europe (in Germany since 1858), and 
figures exclusively in the United States Pharmacopoeia, and con- 
jointly in the British Pharmacopoeia of 1898. This brings us to 
the medical profession, and here we find that in English-speaking 
countries there has been great progress in the use of metric 
weights and measures in writing prescriptions, but that owing to 
the conservative tendencies of medical colleges it is by no means 
general, and while the majority of pharmacists stand ready to 
compound metric prescriptions, comparatively few American 
practitioners write them. That there is no difficulty involved is 
shown by the ease with which the system was adopted by the 
United States Marine Hospital Service, the Medical Department 
of the United States Army, and the Medical Department of the 
United States Navy, as will be further explained below ; while the 
fact that it is eminently desirable is demonstrated not only from 
the testimony of those that have used it, but from resolutions 
adopted at various times by representative national organizations 
of physicians and surgeons. Despite the fact that there has been 
no active campaign in behalf of the metric system waged among 



METRIC SYSTEM IN MEDICINE 193 

physicians there has been great progress, and when its advantages 
-are more thoroughly realized it is believed there will be little 
opposition to completely dropping the absurd antiquated apothe- 
caries' weights. The science of medicine to-day is closely con- 
nected with chemistry, physiology, biology, microscopy, and other 
sciences in which measurement plays a most important part. For 
example, in all experimental medicine the doses given to animals 
are measured in metric measures, in pathology the dimensions of 
an organ or any part of it are always stated in centimeters or 
millimeters, while the oculist employs metric measures in all his 
measures of focal length. In short, wherever medicine comes 
into contact with natural or exact science we find that the metric 
system is employed, and there is no reason why it should not be 
used universally. The only excuse advanced is that the practi- 
tioner has learned all his doses on the basis of the old measures, 
and that any change not only might result in inconvenience but 
in possible danger to the patient, inasmuch as a mistake that 
might prove fatal could be made in writing out the quantities. 
This is indeed a very weak objection, as the pharmacist or his 
clerk is constantly on the lookout for errors of this or any other 
kind in prescriptions. Furthermore, the more advanced physician 
is constantly reading in medical journals of new methods of treat- 
ment employed in Europe, where of course the metric weights 
and measures are altogether employed, and desiring to adopt such 
remedies in his own practice he must either employ the metric 
measures, or translate them into English, either operation requir- 
ing a knowledge of the metric system. 

In pharmacy there are two different methods of compounding 
prescriptions according to the metric system, which, while 
fundamentally different, in their actual results do not occasion 
any very serious discrepancies. In Continental Europe and in 
countries where the metric system is exclusively used, it is the 
practice to measure all substances entering into a prescription, 
whether solid or liquid, by weight, and this consequently is 
known as the gravimetric method. That is, the quantities are 
denoted by grams, and in Germany no designation of the unit 
follows the number, grams being understood in every case, as 
no other units are employed for this purpose. This, of course, 
furnishes a very accurate method; but in the United States and 

N 



194 EVOLUTION OF WEIGHTS AND MEASURES 

Great Britain, where the metric system is used it is customary to 
employ what is termed the volumetric method, where the fluids 
are measured by volume or capacity measure, the quantities 
being indicated in cubic centimeters. The solids, of course, are 
weighed in grams, and it is usual to write after the number the 
abbreviation gm. to distinguish from gr. denoting grains, as used 
in the older system. Inasmuch as the specific gravity of water 
is taken as unity, and one cubic centimeter of water at its 
temperature of maximum density weighs one gram, it will be 
seen that for water and other liquids of approximately the same 
specific gravity there is no difference between the two methods, 
and the majority of the liquids used in compounding prescrip- 
tions are so near to water in specific gravity that little trouble 
is occasioned; but there are a few instances in which this 
difference is material, according as the liquid is either con- 
siderably lighter or heavier than water. These few should be 
borne in mind in comparing formulae on the gravimetric system 
with those on the volumetric. Of the substances lighter than 
water the most important are ether, whose specific gravity is '736 
at 0°C. and spirits of nitrous ether, whose specific gravity is "837. 
Consequently, speaking approximately, four parts by weight of 
these liquids will occupy an equivalent space to five parts by 
weight of water. Alcohol (proof spirit) sp. gr. 0*79 at 20° 
Centigrade is another substance similar in this respect. On the 
other hand, dealing with liquids heavier than water, we find 
that glycerin stands in such a ratio that five parts by weight 
of it occupy the same space as four parts of water, while with 
syrup this ratio is four to three, and with chloroform three 
to two. It is, of course, possible to indicate on the prescription 
that the quantities are to be taken by weight; but except in 
such cases as above noted, or in those of an extraordinary- 
character, the volumetric method is employed, and not only 
corresponds more closely with the older method, but also is 
much more expeditious, as the fluids may be poured from 
graduated measuring glasses in much less time than they could 
be weighed. 

The profession at large was not so quick to see the advantages 
of the metric system as the medical departments of the United 
States Government, and the first of these to adopt the innovation 



METRIC SYSTEM IN MEDICINE 195 

was the Marine Hospital Service, where, in accordance with 
Department Circular 39, dated April 27th, 1878, it was ordered 
that " The Medical Officers of the Marine Hospital Service will 
hereafter, for all official, medical and pharmaceutical purposes, 
make use of the Metric System of Weights and Measures." 

This action, which was the first Government order issued in 
the United States to make the use of the metric system obli- 
gatory for any purpose whatever, 1 followed the report made 
to Surgeon-General John M. Woodworth, which was prepared 
by Oscar Oldberg, Phar.D., then Chief Clerk and Acting Medical 
Purveyor, U.S. Marine Hospital Service, in which he called 
attention to the advantages of the metric system, and provided 
the necessary rules for expressing quantities in that system, 
and also described the necessary methods to be followed in 
writing metric prescriptions. 

In 1881 the Bureau of Medicine and Surgery in the U.S. 
Navy adopted the system, as on April 15th of that year there 
was approved by Secretary William H. Hunt a small volume 
entitled, Instructions for Medical Officers of the United States Navy, 
prepared by Medical Director Philip S. Wales, U.S.N". On 
page 10, Article 2, Section 1, was the official direction that "the 
Metric System of Weights and Measures shall hereafter be 
employed in the Medical Department of the Navy." Accordingly, 
the " Supply Table " in this volume was prepared on a metric 
basis, and supplies have since been issued in accordance with 
this system. 

In 1894 the metric system was adopted by the medical 
department of the United States Army, and was put into 
operation under the provisions of the accompanying order. 

WAR DEPARTMENT, 

Surgeon General's Office, 

Washington, April 13, 1894. 
CIRCULAR : 

Upon the publication of the new Supply Table and receipt of the new 
forms, all requisitions, invoices, receipts, and returns pertaining to medical 
supplies will be in accordance with the metric system of weights and 
measures. 

After the 30th day of June, 1894, the use of this system in writing 

1 See Oldberg, Weights, Measures and Specific Gravity, Chicago, 1888, p. 18. 



196 EVOLUTION OF WEIGHTS AND MEASURES 

official prescriptions is desired ; on and after the 1st day of January, 1895, 
such use is hereby ordered. 

Metric measures, weights, and prescription blanks will soon be issued 
to all posts without requisition. 

Until medical supplies now in stock in troy and avoirdupois weights 
are exhausted, the following approximate values may be considered as 
equivalent in transferring original packages : 

1 ounce = 30 grammes. 

1 pound = \ kilogram. 

1 fluid ounce = 30 cubic centimeters. 

1 pint = 500 cubic centimeters. 

1 quart = 1 liter. 

1 yard = 1 meter. 

GEO. M. STERNBERG, 

Burgeon General, U.S. Army. 
Approved : 

Daniel S. Lamont, 

Secretary of War. 

This order was promptly carried out on the dates specified, 
and all supplies were not only handled within the department, 
but were purchased from dealers according to metric weights and 
dimensions. In addition, the army surgeons began writing their 
prescriptions on the metric basis without protest or difficulty, 
and the system was soon in successful operation, and in 1902 
was pronounced by Surgeon-General Sternberg as eminently 
satisfactory, the General testifying before the Committee on 
Coinage, Weights and Measures, Congress, February 15, 1902, 
when asked why he would not go back to the old system : 

" Because it (the metric system) is so decidedly superior. It is 
working smoothly, and we have no difficulty whatever — no 
protests on the part of the people we deal with, from whom 
we purchase. The wholesale druggist must necessarily be 
familiar with it." 1 

General Sternberg also said that the principal reason for 
the adoption of the system was the greater simplicity of the 
decimal system, and furthermore it was successfully used in 
other countries, and was a better system than the one in use. 
An important test came in the Spanish-American War, when the 

1 Page 83, The Metric System of Weights and Measures. Committee on Coinage, 
Weights and Measures (Hearing), February 15, 1902. 



METRIC SYSTEM IN MEDICINE 197 

medical department was increased by a number of volunteer and 
contract surgeons ; but the latter experienced no difficulty in 
conforming to the regulations. 

In England the feeling of the advanced members of the 
medical profession has been most favourable to the metric * 
system, and in 1904 the General Medical Council adopted 
the following resolution in reference to the Bill then before 
the House of Lords : " That the President (with the Chairman 
of the Pharmacopoean Committee) be requested to inform the 
Lord President of the Privy Council that in the opinion of 
the Council it is desirable that, after a sufficient period to 
be fixed by law, the metric system of weights and measures 
should become the one legal system for the preparation and 
dispensing of drugs and medicines ; that the Council would 
view with favour the passing into law of a Bill such as that 
now before Parliament, entitled the 'Weights and Measures 
(Metric System) Bill ' ; and that in that event the Council 
would be prepared to take all necessary steps to give effect 
to the law by making the proper modifications in the British 
Pharmacopoeia." 

The correctness of the prescription when written in metric 
units is much more likely to be ensured, as there is no possi- 
bility of mistaking the various units, since but two are used 
— the gram for solids, and the cubic centimeter for liquids. 
In a prescription written in apothecaries' weights and measures, 
on the other hand, not only are there numerous units — as 
pounds, ounces, drachms, scruples, grains, minims, etc. — but 
these are denoted by alchemistic characters which, at least in 
the case of ounces and drachms, are susceptible of confusion. 
Thus, not only is there the danger of errors in figures which 
is common to both methods, but in the case of the older 
system there are also the characters. Furthermore, with 
apothecaries' weights it is customary to denote the quantities 
by Roman figures or letters, which are much more readily 
confused than the Arabic figures employed in metric prescrip- 
tions. If the decimal line is used, as in a cash account, the 
danger of a misplaced decimal point, or of an occasional dot 
being taken as a point, is obviated. In fact, these possible 
errors attributed to the metric system have been found by 



198 EVOLUTION OF WEIGHTS AND MEASURES 

experience to be altogether imaginary, for a misplaced decimal 
point decreases or increases a dose ten-fold. The dispenser 
would therefore detect the error at a glance. Then there is 
the further advantage that it is possible to send by telegraph 
• a metric prescription with far greater facility than one where 
the Eoman characters are employed. 

While the gravimetric method may be the most scientific 
and exact, yet it must be remembered that the dose cannot 
be administered to the patient in the great majority of cases 
with anything like scientific accuracy, and it is usual to 
employ various domestic glasses and spoons, which of course give 
a volumetric measurement. In general certain rough equivalents 
amply suffice, and the following measurements are used in the 
United States and France: 

A tea-spoonful = 1 fluid drachm, = 5 grams of water 

A dessert-spoonful = 2 fluid drachms, = 10 

A table-spoonful = J fluid ounce, = 15 

A tumblerful = 8 fluid ounces, = 240 

A wine glass (U.S.A.) = 2 „ „ =60 

A wine glass (French) = 5 „ „ =150 



CHAPTER IX. 
INTERNATIONAL ELECTRICAL UNITS. 

Beside the units incident to our every-day life which we 
have already discussed, it is possible to derive from the 
metric system in connection with the ordinary unit for the 
measurement of time employed throughout the civilized world, 
a complete system of units that will answer for the measure- 
ment of any and all physical quantities. For such a system 
it is necessary to have as the bases certain fundamental units, 
and with them we may build up and extend the system as 
occasion demands. It has been found that, starting with 
units of length, mass, and time, a satisfactory system can be 
evolved; and though there have been several such systems 
proposed, yet the one founded on the centimeter as the unit 
of length, the gram as the unit of mass, and the second as 
the unit of time, has met with the greatest favour. It has 
for many years been the only one employed in scientific 
work, and has served as a basis for other and practical 
units when such have been required or desired. As the 
units mentioned have been adopted for most scientific work, 
being as small as were convenient to employ in ordinary 
measuring processes, it is easy to see why they were chosen 
eventually as the basis of a system of units that should be 
complete and symmetrical. From the names of the funda- 
mental units this system is known as the C.G.S. system, 
and it is our purpose to outline briefly its development in 
order that we may trace the derivation of some of the ordi- 
nary electrical units now in every-day use, and which are 



200 EVOLUTION OF WEIGHTS AND MEASURES 

essentially metric in their origin. The first suggestion of 
such a system of units was due to Carl Friedrich Gauss, who 
in 1832 proposed a system of so-called absolute units, which. 
had as its base the fundamental units of length, mass, and 
time. This system was devised by Gauss while engaged in 
the study of terrestrial magnetism, in which the intensity of 
the earth's magnetism, as well as the declination and dip, 
was to be measured at different points in Europe. For this 
purpose a German Magnetic Union had been organized by 
Gauss and Alexander Von Humboldt, and was actively engaged 
in magnetic studies from about 1834 to 1842. Previously there 
had been no unit for the intensity of magnetism, and English 
physicists had taken the intensity at London as the standard. 
Gauss believed that it would be more scientific, as well as 
more practical, if a system were devised which would be 
independent of season or place, as well as of instruments and 
external conditions. Accordingly, as the system which he 
proposed in 1832 was based merely on the three fundamental 
units mentioned, he termed it the Absolute System. In this- 
system it was possible to derive all necessary units from the 
three selected as fundamental ; thus a unit of velocity was 
obtained by defining it as such a velocity as a body would 
have in travelling unit distance in unit time. Unit accelera- 
tion was the acceleration that a body would experience when 
it gained or lost unit velocity in unit time. Then, for the 
unit of force, it was only necessary to take such a force as 
would impart unit velocity to unit mass in unit time — that 
is, the unit acceleration. Consequently, when it came to 
defining a unit of intensity of magnetism, Gauss took such a 
quantity of magnetism as would exert unit force on a similar 
quantity at unit distance. 1 Now, as magnetic force was mani- 
fested by the attraction or repulsion of a magnetic pole when 
placed in a magnetic fluid, it would be possible to measure- 
the force by mechanical methods, and for this he deduced 
the necessary equations. 

In this way, by mathematical processes which are interesting but. 

i Resultate aus den Beobachtungen des Magnetischen Vereins, 1836-1842; Soc. 
Gott. viii. 1832-1837; Pogg. Ann. xxviii. §§ 241, 591 (1833); Gauss, Werke,. 
v. § 79-118. 



INTERNATIONAL ELECTRICAL UNITS 201 

need not be discussed here, it was possible for Gauss to determine 
the intensity of the earth's magnetic field at any given point on 
its surface. While the process of derivation was the same as for 
the modern C.G.S. system, yet Gauss employed as the funda- 
mental units in his Absolute System the millimeter as the unit 
of length, the milligram as the unit of mass, and the second as the 
unit of time. By similar reasoning, it was possible to define the 
unit charge of electricity as such a charge as would act on a 
similar charge at unit distance with unit force. So useful was 
this idea of absolute measurement that it was straightway 
adopted by Wilhelm Weber, (1804-1891) and found application in 
his experiments to measure the intensity of an electric current,, 
the intensity of electromotive force and of resistance ; the latter 
investigation being further developed by Eudolf Kohlrausch 
(1809-1858) in some most valuable investigations. Weber's work 1 
is remarkable not only for the fact that he applied absolute 
measurements in electricity, but for his showing that electricity 
was but a manifestation of mechanical energy, and consequently 
could be measured in terms of length, mass, and time. There was,, 
however, an important difference, in that it was not possible to 
measure directly quantities of electricity, but it was necessary to 
make such measurements by the effect on some external object. 
For example, when Weber came to determine the intensity of an 
electric current in absolute measurement, he found three ways 
open to him. The first was to determine the strength of current 
by its chemical or electrolytic effect. In other words, a unit 
current would be that which decomposed a unit mass of water 
into its chemical elements in unit time. Secondly, the magnetic 
effect of the electric current also served as a basis for measuring 
a current of electricity, and a unit of intensity of current he 
defined as such a current as would exert, upon a magnet pole, the 
same force as an infinitely small magnet of unit moment, placed 
at the center of a closed circuit of unit area around which the 
current should flow, and perpendicular to its plane. In other 
words, he defined his unit of current according to the measure- 
ments which could be made with a tangent galvanometer, as will 
be described below. Then thirdly, the intensity of current could 

1 Rosenberger, Geschichte der Physik, vol. iii. pp. 302, 514-519. Braunschweig,. 
1890. Weber, Pogg. Ann. xcix, p. 11, 1855. 



202 EVOLUTION OF WEIGHTS AND MEASURES 



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204 EVOLUTION OF WEIGHTS AND MEASURES 

also be measured by the effect of two currents flowing along 
parallel conductors distant from each other by a unit length. 

Following out these three methods, Weber made a series of 
absolute measurements and found that they possessed a certain 
ratio to each other. He also found that, with the galvanometer, 
he was able to measure the quantity of electricity with which a 
conductor was statically charged, by allowing it to be discharged 
or flow to the earth through the galvanometer. Having thus 
been able to measure the intensity of current in absolute units, 
which (following the example of Gauss) were based on the 
millimeter, milligram, and second, Weber then proceeded to make 
absolute measurements of electromotive force. The absolute 
unit of electromotive force he defined as that induced by unit 
magnetic force in a circular conductor of unit area, if this 
circular conductor were turned from a position parallel to the 
direction of the magnetic force into one perpendicular to it in the 
time of one second. 1 Inasmuch as he was able to use the 
magnetic field of the earth, whose intensity could be measured 
accurately, and as by his previous experiments he was able to 
measure the intensity of the current, using the apparatus known 
as the earth inductor, he was soon able to make a direct 
measurement of electromotive force. The earth inductor, it 
may be said in passing, consisted of a large coil of wire whose 
axis of revolution was perpendicular to the lines of magnetic 
force, so that when the coil was revolved a current was induced 
in it which could be measured by the galvanometer. 

With methods for the absolute measurement of current and 
electromotive force already known and defined, it only remained 
to measure the resistance in absolute units, and this, of course, 
followed from Ohm's law, which had been known since 1827. 
According to this statement, the current was equal to the electro- 
motive force divided by the resistance, and consequently it followed 
that a unit of resistance would be that through which unit 
electromotive force would produce unit current. This determina- 
tion of the unit of resistance involved most elaborate experiments, 

1 Rosenberger, vol. iii. p. 517; " Electrodynamische Massbestimmungen ins 
besondere Widertandsmessen, " Abhandl. der K. 8. Gesellsch. I. § 197, 1852; Pogg. 
Ann. lxxxii. § 337. Weber, Abhandl. bei Begriindung der K. S. Gesellschaft der 
Wissenschaft, 1846 ; Abhandl. der K. 8. Gesellschaft d. Wissenschaft, I. 1852. 



INTERNATIONAL ELECTRICAL UNITS 205 

which are among the most celebrated in all experimental physics, 
and their result was firmly to establish the absolute system on a 
thoroughly scientific basis. 

There were, previous to this, various arbitrary electrical units 
suggested, and in more or less limited use. 1 Thus various 
lengths of copper, iron, or German silver wire of specified length, 
weight, and cross-section were suggested and employed as units. 
Perhaps the most conspicuous of these was the copper wire of 
prescribed dimensions and weight which was recommended by 
Jacobi, 2 of St. Petersburg, in 1846, to the physicists of Europe as 
the standard of normal resistance. This standard was determined 
in absolute units of resistance by Weber, but it did not prove 
entirely acceptable, owing to the changes taking place in the 
copper with time, and owing to the difficulties experienced in 
obtaining standard conditions. Accordingly, Werner Siemens, of 
Berlin, proposed, in 1860, following the suggestion of Marie- 
Davy made in 1843, to use mercury in defining the unit of resist- 
ance, and as a standard, a column of this substance one meter in 
length and one square millimeter in cross-section, measured at 
0°C. 3 This also was measured by Weber in 1861, and later 
by Kohlrausch. 

For electromotive force, it was customary at this time to 
employ the electromotive force of a constant battery, such as the 
Daniell cell, and in the case of a current, to make use of various 
arbitrary units. With the increase in the scientific knowledge of 
electricity, as well as in its industrial applications, such as the 
telegraph and submarine cable, it was realized that, for practical 
use, there should be a systematic and comprehensive system of 
electrical units, which would be based on certain fixed standards, 
and would be universally employed by electricians. This subject 
was accordingly taken up in Great Britain by the British 
Association for the Advancement of Science, and in 1861 a strong 
committee, composed of leading physicists and electricians, was 
appointed to investigate the subject and to report on suitable 
units. The subject was discussed in all its many bearings by 

1 For a list with bibliography, see Eosenberger, Geschichte der Physik, vol. iii. 
pp. 519-520. 

2 Jacobi, Comptes Rendus (Paris), p. 277, vol. xxxiii. 
3 W. Siemens, Poggendorff's Annalen, ex. p. 1, 1860. 



206 EVOLUTION OF WEIGHTS AND MEASURES 

this committee, Weber's and other experiments were repeated, and 
the result was that an absolute system was adopted, only the 
centimeter, gram, and second were employed as the fundamental 
units in place of the millimeter, milligram, and second of Gauss 
and Weber. This committee not only reported in favor of the 
establishment of the C.G.S. system, but also fixed a certain 
number of so-called practical units, which, with slight modifica- 
tions, are now in universal use. 

The reason for this was that a number of the C.G.S. absolute 
units are either too large or too small to be employed in practical 
work. For example, the electromotive force of an ordinary 
Daniell cell would represent about 10 8 absolute units, and as the 
electrician of that time dealt with electromotive forces of this 
magnitude, rather than with those represented by a quantity so 
much smaller, it was convenient to multiply the absolute unit by 
10 8 to obtain a convenient practical unit, which was designated 
by the name volt. Likewise with the ohm, or practical unit of 
resistance, which represented 10 9 absolute units. But in the case 
of the ampere, or unit of current, which, as we have seen, must 
follow from Ohm's law, the difference was not so large, and the 
absolute unit had merely to be divided by 10 to give the practical 
unit. This Commission decided on the coulomb as the unit of 
quantity, being 10 _1 absolute units, and being the quantity of 
electricity conveyed by one ampere in one second. As a unit of 
capacity, the farad, or 10 ~ 9 absolute units, was taken, and measured 
the capacity of a condenser charged to a potential of one volt by 
one coulomb. As a more useful unit still, the micro-farad, or 10 " & 
part of a farad, was also established. For work, the joule was 
taken, representing 10 7 ergs or absolute units of work, and 
equivalent to the energy expended in one second by one ampere 
flowing through a resistance of one ohm. As a unit of power, 
the watt, or 10 7 ergs per second, represented the power of a 
current of one ampere flowing under a pressure of one volt, or 
one joule per second, and when multiplied by 1000 it gives the 
kilowatt, which soon became common in electrical work in place 
of the old familiar horse-power. 1 

i For an interesting historical presentation which includes the text of recent 
legislation, see Wolff, " The So-called International Electrical Units," a paper 
presented at the International Congresses of Electricians at St. Louis, 1904. 



INTERNATIONAL ELECTRICAL UNITS 207 

In 1865 this committee made a determination of the ohm, and 
constructed a standard of platinum-silver to represent its value. 
This standard, by law, represented the legal unit of resistance in 
Great Britain, and was also known for many years as the B.A. 
(British Association) unit ; in fact, holding its own, especially in 
English-speaking countries, until the adoption of the international 
ohm by the Chicago Congress of 1893. 

Soon after this, the invention by Latimer Clark, in 1873, of a 
constant cell, which was found to have, under certain conditions, 
an electromotive force of 1*434 volts, furnished a standard of 
electromotive force which, while not legally defined until some 
years later, became widely used, and figured in many determina- 
tions. 

So thoroughly was the C.G.S. system thought out by the 
British Association Committee, and so systematically were the 
practical units determined and denned that, despite minor in- 
accuracies, as shown by the experiments of German physicists, the 
system was favorably considered at the International Congress of 
Electricians held in Paris in 1881, and resolutions were adopted 
in which the C.G.S. electro-magnetic units were chosen as the 
fundamental units in terms of which the practical units should be 
defined. At a meeting held in 1884 an international commis- 
sion decided on the length of the column of mercury for the 
standard ohm, and the legal ohm was denned as the resistance of 
a column of mercury of one square millimeter section, and of 106 
centimeters length at a temperature of melting ice. 

The ampere was defined as a current corresponding to 10 -1 
absolute C.G.S. electro-magnetic units, while the volt was defined 
as an electromotive force which produced a current of one 
ampere in a conductor whose resistance was a legal ohm. This 
definition of the ohm did not carry with it universal acceptance, 
and the legal ohm was not made legal in Great Britain or in the 
United States ; but in the meantime a number of prominent 
physicists, including Professor Henry A. Eowland in America and 
Lord Eayleigh in England, carried on further investigations to 
evaluate the true ohm, with the result that the length of the 
mercury column was found to be nearly 106*3 centimeters, which 

Reprinted in Bulletin No. 1, Bureau of Standards, Washington, D.C. See British 
Association Reports on Electrical Standards (London, 1873). 



208 EVOLUTION OF WEIGHTS AND MEASURES 

accordingly was adopted by the British Association Committee in 
1892, together with the definition of the column in length and 
mass, rather than by length and cross-section. 

Meanwhile, in 1889, another international congress of elec- 
tricians was held at Paris, at which, in addition to a number of 
decisions involving nomenclature, definitions of units of energy, 
power, and inductance were adopted. The joule was selected as 
the practical unit of energy and was defined as equal to 10 7 C.G.S. 
units, being equivalent to the energy disengaged as heat in one 
second by a current of one ampere flowing through a resistance 
of one ohm. As a practical unit of power the watt was taken, 
and was equal to 10 7 C.G.S. units, being the power of one joule 
per second. For inductance the quadrant was chosen as the 
practical unit, and was defined as equal to 10 d centimeters. This 
-congress also took the important step of recommending that the 
power of various electric machines, such as dynamos, motors, 
transformers, etc., should be rated in watts and kilowatts instead 
of horse-power, and this practice has generally prevailed even in 
non-metric countries such as Great Britain and America. 

In 1893, in connection with the World's Columbian Exposition 
at Chicago, an International Congress of Electricians was held, 
and a Chamber of Delegates, composed of officials appointed by 
the various Governments, proceeded to define and name the 
various electrical units. By this time, owing to the increased use 
of electric lighting, various forms of power transmission, electric 
railways, and other important applications of electricity, the 
subject was one of prime interest, and required the most careful 
oonsideration of the Chamber of Delegates, which consisted of 
many of the world's most eminent physicists and electrical 
engineers. Its deliberations resulted in a series of recom- 
mendations which were reported to the Congress, and referred to 
the various nations of the world, by many of whom they were 
subsequently embodied to a greater or less extent in legal 
■enactments making the use of the new units obligatory. In the 
United States such an Act was passed and approved, July 12, 1894. 1 
These resolutions contained the following recommendations : 

" Resolved, — That the several Governments represented by the 
delegates of this International Congress of Electricians be, and 

1 Revised Statutes of the United States, Supplement, vol. ii. chap. 131, 1894. 



INTERNATIONAL ELECTRICAL UNITS 209 

they are hereby, recommended to formally adopt as legal units of 
electrical measure the following: As a unit of resistance, the 
international ohm, which is based upon the ohm, equal to 10 9 
units of resistance of the Centimeter-Gramme-Second System of 
electro- magnetic units, and is represented by the resistance offered 
to an unvarying electric current by a column of mercury at the 
temperature of melting ice 14*4521 grammes in mass, of a constant 
cross-sectional area, and of the length of 106*3 centimeters. 

" As a unit of current, the international ampere, which is one- 
tenth of the unit of current of the C.G.S. system of electro- 
magnetic units, and which is represented sufficiently well for 
practical use by the unvarying current which, when passed 
through a solution of nitrate of silver in water, and in accordance 
with accompanying specifications deposits silver at the rate of 
0*001118 of a gram per second. 

" As a unit of electromotive force, the international volt, which 
is the electromotive force that, steadily applied to a conductor 
whose resistance is one international ohm, will produce a current 
of one international ampere, and which is represented sufficiently 
well for practical use by \^% of the electromotive force between 
the poles or electrodes of the voltaic cell known as Clark's cell, 
at a temperature of 15° C, and prepared in the manner described 
in the accompanying specification. 1 

" As a unit of quantity, the international coulomb, which is the 
quantity of electricity transferred by a current of one international 
ampere in one second. 

" As a unit of capacity, the international farad, which is the 
capacity of a condenser charged to a potential of one international 
volt by one international coulomb of electricity. 

" As a unit of work, the joule, which is equal to 10 7 units of 
work in the C.G.S. system, and which is represented sufficiently 
well for practical use by the energy expended in one second by 
an international ampere in an international ohm. 

" As a unit of power, the watt, which is equal to 10 7 units of power 
in the C.G.S. system, and which is represented sufficiently well for 
practical use by work done at the rate of one joule per second. 

1 No report was ever made by the committee to which the preparation of the 
specifications was entrusted. Its members were Professors Helmholtz, Ayrton, 
and Carhart, but the death of the first prevented the work. 

O 



210 EVOLUTION OF WEIGHTS AND MEASURES 

" As a unit of induction, the henry, which is the induction in a 
circuit when the electromotive force induced in this circuit is 
one international volt, while the inducing current varies at the 
rate of one ampere per second." 



Specifications for Construction and Use of the Silver Voltameter. 

• In the following specifications the term silver voltameter 
means the arrangement of apparatus by means of which an 
electric current is passed through a solution of nitrate of silver in 
water. The silver voltameter measures the total electrical 
quantity which has passed during the time of the experiment, 
and by noting this time the time average of the current, or if the 
current has been kept constant, the current itself, can be deduced. 

In employing the silver voltameter to measure currents of 
about one ampere the following arrangements should be adopted : 

The kathode on which the silver is to be deposited should take 
the form of a platinum bowl not less than 10 cms. in diameter 
and from 4 to 5 cms. in depth. 

The anode should be a plate of pure silver some 30 sq. cms. in 
area and 2 or 3 mms. in thickness. 

This is supported horizontally in the liquid near the top of the 
solution by a platinum wire passed through holes in the plate at 
opposite corners. To prevent the disintegrated silver which is 
formed on the anode from falling on to the kathode, the anode 
should be wrapped round with pure filter paper, secured at the 
back with sealing wax. 

The liquid should consist of a neutral solution of pure silver 
nitrate, containing about 15 parts by weight of the nitrate to 85 
parts of water. 

The resistance of the voltameter changes somewhat as the 
current passes. To prevent these changes having too great an 
effect on the current, some resistance besides that of the volta- 
meter should be inserted in the circuit. The total metallic 
resistance of the circuit should not be less than 10 ohms. 

In the United States the foregoing recommendations were 
duly given force of law by an Act of Congress approved 
July 12, 1894, one section of which provided that the National 



INTERNATIONAL ELECTRICAL UNITS 211 

Academy of Sciences should prepare detailed specifications for 
the practical application of the definitions of the ampere and 
volt. Such specifications were accordingly prepared by a com- 
mittee x of the Academy, and were adopted by that body on 
February 9, 1895. They are given in full below. 

REPORT. 

In the preparation of this report, in order to have the specifications accord 
with international usage, free use has been made of the English Govern- 
ment specifications and of certain papers prepared by Dr. K. Kahle of 
Germany, and Prof. H. S. Carhart of this country. 

SPECIFICATIONS FOR THE PRACTICAL APPLICATION OF THE 
DEFINITIONS OF THE AMPERE AND VOLT. 

Specification A. — The Ampere. 

In employing the silver voltameter to measure currents of about 1 ampere, 
the following arrangements shall be adopted : 

The kathode on which the silver is to be deposited shall take the form of 
a platinum bowl not less than 10 centimeters in diameter, and from 4 to 5 
centimeters in depth. 

The anode shall be a disk or plate of pure silver some 30 square centi- 
meters in area and 2 or 3 millimeters in thickness. 

This shall be supported horizontally in the liquid near the top of the 
solution by a silver rod riveted through its center. To prevent the dis- 
integrated silver which is formed on the anode from falling upon the 
kathode, the anode shall be wrapped around with pure filter paper, secured 
at the back by suitable folding. 

The liquid shall consist of a neutral solution of pure silver nitrate, con- 
taining about 15 parts by weight of the nitrate to 85 parts of water. 

The resistance of the voltameter changes somewhat as the current passes. 
To prevent these changes having too great an effect on the current, some 
resistance besides that of the voltameter should be inserted in the circuit. 
The total metallic resistance of the circuit should not be less than 10 ohms. 

Method of making a measurement. — The platinum bowl is to be washed 
consecutively with nitric acid, distilled water, and absolute alcohol ; it 
is then to be dried at 160° C, and left to cool in a desiccator. When 
thoroughly cool it is to be weighed carefully. 

It is to be nearly filled with the solution and connected to the rest of the 
circuit by being placed on a clean insulated copper support to which a 
binding screw is attached. 

1 Henry A. Rowland, Chairman ; Henry L. Abbot, George F. Barker, Charles 
S. Hastings, Albert A. Michelson, John Trowbridge, Carl Barus. 



212 EVOLUTION OF WEIGHTS AND MEASURES 

The anode is then to be immersed in the solution so as to be well covered 
by it and supported in that position ; the connections to the rest of the 
circuit are then to be made. 

Contact is to be made at the key, noting the time. The current is to 
be allowed to pass for not less than half an hour, and the time of breaking 
contact observed. 

The solution is now to be removed from the bowl and the deposit washed 
with distilled water and left to soak for at least six hours. It is then 
to be rinsed successively with distilled water and absolute alcohol and 
dried in a hot-air bath at a temperature of about 160° C. After cooling 
in a desiccator it is to be weighed again. The gain in mass gives the silver 
deposited. 

To find the time average of the current in amperes, this mass, expressed 
in grams, must be divided by the number of seconds during which the 
current has passed and by 0*001 11 8. 

In determining the constant of an instrument by this method, the current 
should be kept as nearly uniform as possible, and the readings of the 
instrument observed at frequent intervals of time. These observations 
give a curve from which the reading corresponding to the mean current 
(time-average of the current) can be found. The current, as calculated from 
the voltameter results, corresponds to this reading. 

The current used iu this experiment must be obtained from a battery, 
and not from a dynamo, especially when the instrument to be calibrated is 
an electrodynamometer. 

Specification B.— The Volt. 

Definition and properties of the cell. — The cell has for its positive electrode, 
mercury, and for its negative electrode, amalgamated zinc ; the electrolyte 
consists of a saturated solution of zinc sulphate and mercurous sulphate. 
The electromotive force is 1*434 volts at 15° C, and between 10° C. and 25° C, 
by the increase of 1° C. in temperature, the electromotive force decreases by 
0*00115 of a volt. 

1. Preparation of the mercury. — To secure purity, it should be first treated 
with acid in the usual manner and subsequently distilled in vacuo. 

2. Preparation of the zinc amalgam. — The zinc designated in commerce 
as " commercially pure " can be used without further preparation. For the 
preparation of the amalgam, 1 part by weight of zinc is to be added to 
9 parts by weight of mercury, and both are to be heated in a porcelain dish 
at 100° C, with moderate stirring until the zinc has been fully dissolved in 
the mercury. 

3. Preparation of the mercurous sulphate. — Take mercurous sulphate, pur- 
chased as pure ; mix with it a small quantity of pure mercury, and wash the 
whole thoroughly with cold distilled water by agitation in a bottle ; drain 
off the water and repeat the process at least twice. After the last washing, 



INTERNATIONAL ELECTRICAL UNITS 213 

drain off as much of the water as possible. (For further details of 
purification, see Note A.) 

4. Preparation of the zinc sulphate solution. — Prepare a neutral saturated 
solution of pure recrystallized zinc sulphate, free from iron, by mixing 
distilled water with nearly twice its weight of crystals of pure zinc sulphate 
and adding zinc oxide in the proportion of about 2 per cent, by weight of the 
zinc sulphate crystals to neutralize any free acid. The crystals should 
be dissolved with the aid of gentle heat, but the temperature to which 
the solution is raised must not exceed 30° C. Mercurous sulphate, treated 
as described in 3, shall be added in the proportion of about 12 per cent, 
by weight of the zinc sulphate crystals to neutralize the free zinc oxide 
remaining, and then the solution filtered, while still warm, into a stock 
bottle. Crystals should form as it cools. 

5. Preparation of the mercurous sulphate and zinc sulphate paste. — For 
making the paste, 2 or 3 parts by weight of mercurous sulphate are to 
be added to 1 by weight of mercury. If the sulphate be dry, it is to 
be mixed with a paste consisting of zinc sulphate crystals and a con- 
centrated zinc sulphate solution, so that the whole constitutes a stiff mass, 
which is permeated throughout by zinc sulphate crystals and globules 
of mercury. If the sulphate, however, be moist, only zinc sulphate crystals 
are to be added ; care must, however, be taken that these occur in excess 
and are not dissolved after continued standing. The mercury must, in 
this case also, permeate the paste in little globules. It is advantageous 
to crush the zinc sulphate crystals before using, since the paste can then be 
better manipulated. 

To set up the cell. — The containing glass vessel, . . . shall consist of 
two limbs closed at the bottom and joined above to a common neck fitted 
with a ground-glass stopper. The diameter of the limbs should be at 
least 2 centimeters and their length at least 3 centimeters. The neck 
should be not less than 1*5 centimeters in diameter. At the bottom of 
each limb a platinum wire of about 0*4 millimeter diameter is sealed 
through the glass. 

To set up the cell, place in one limb pure mercury and in the other 
hot liquid amalgam, containing 90 parts mercury and 10 parts zinc. The 
platinum wires at the bottom must be completely covered by the mercury 
and the amalgam respectively. On the mercury place a layer 1 centimeter 
thick of the zinc and mercurous sulphate paste described in 5. Both this 
paste and the zinc amalgam must then be covered with a layer of the 
neutral zinc sulphate crystals 1 centimeter thick. The whole vessel must 
then be filled with the saturated zinc sulphate solution, and the stopper 
inserted so that it shall just touch it, leaving, however, a small bubble 
to guard against breakage when the temperature rises. 

Before finally inserting the glass stopper it is to be brushed around 
its upper edge with a strong alcoholic solution of shellac and pressed firmly 
in place. (For details of filling the cell, see Note B.) 



214 EVOLUTION OF WEIGHTS AND MEASURES 

NOTES TO THE SPECIFICATIONS. 

(A) The mercurous sulphate. — The treatment of the mercurous sulphate 
has for its object the removal of any mercuric sulphate which is often 
present as an impurity. 

Mercuric sulphate decomposes in the presence of water into an acid and 
a basic sulphate. The latter is a yellow substance — turpeth mineral — 
practically insoluble in water ; its presence, at any rate in moderate 
quantities, has no effect on the cell. If, however, it be formed, the acid 
sulphate is also formed. This is soluble in water, and the acid produced 
affects the electromotive force. The object of the washings is to dissolve 
and remove this acid sulphate, and for this purpose the three washings 
described in the specification will suffice in nearly all cases. If, however, 
much of the turpeth mineral be formed, it shows that there is a great 
deal of the acid sulphate present, and it will then be wiser to obtain a 
fresh sample of mercurous sulphate, rather than to try by repeated washings 
to get rid of all the acid. 

The free mercury helps in the process of removing the acid, for the 
acid mercuric sulphate attacks it, forming mercurous sulphate. 

Pure mercurous sulphate, when quite free from acid, shows on repeated 
washing a faint yellow tinge, which is due to the formation of a basic 
mercurous salt distinct from the turpeth mineral, or basic mercuric sulphate. 
The appearance of this primrose-yellow tint may be taken as an indication 
that all the acid has been removed ; the washing may with advantage 
be continued until this tint appears. 

(B) Filling the cell. — After thoroughly cleaning and drying the glass 
vessel, place it in a hot-water bath. Then pass through the neck of the 
vessel a thin glass tube reaching to the bottom, to serve for the introduction 
of the amalgam. This tube should be as large as the glass vessel will 
admit. It serves to protect the upper part of the cell from being soiled 
with the amalgam. To fill in the amalgam, a clean dropping tube about 
10 centimeters long, drawn out to a fine point, should be used. Its lower 
end is brought under the surface of the amalgam, heated in a porcelain 
dish, and some of the amalgam is drawn into the tube by means of the 
rubber bulb. The point is then quickly cleaned of dross with filter paper, 
and is passed through the wider tube to the bottom and emptied by pressing 
the bulb. The point of the tube must be so fine that the amalgam will 
come out only on squeezing the bulb. This process is repeated until the 
limb contains the desired quantity of amalgam. The vessel is then 
removed from the water bath. After cooling, the amalgam must adhere 
to the glass, and must show a clean surface with a metallic luster. 

For insertion of the mercury, a dropping tube with a long stem will 
be found convenient. The paste may be poured in through a wide tube 
reaching nearly down to the mercury and having a funnel-shaped top. 
If the paste does not move down freely it may be pushed down with a 



INTERNATIONAL ELECTRICAL UNITS 215 

small glass rod. The paste and the amalgam are then both covered with 
the zinc sulphate crystals before the concentrated zinc sulphate solution 
is poured in. This should be added through a small funnel, so as to 
leave the neck of the vessel clean and dry. 

For convenience and security in handling, the cell may be mounted in 
a suitable case, so as to be at all times open to inspection. 

In using the cell, sudden variations of temperature should, as far as 
possible, be avoided, since the changes in electromotive force lag behind 
those of temperature. 

Somewhat similar specifications were prepared by the Board of 
Trade of Great Britain and were promulgated in an Order 
in Council, August 23, 1894. The chief points of difference 
besides phraseology were in the specifications for the Clark cell, 
but these were in no way radical. Canada also adopted regula- 
tions essentially in harmony with the above, as did France, 
Austria, and Belgium ; while in Germany the measure of current 
was made of prime importance, and the specifications for the 
silver voltameter and the method of measurement are somewhat 
modified. 1 

At the Paris International Electrical Congress of 1900 it was 
decided to give the name of Gauss to the C.G.S. unit of magnetic 
field intensity, or to such a field as would be produced by the 
unit of magnetism at the distance of one centimeter, or, in other 
words, such a field as would act on a unit pole with the force of 
one dyne. Likewise the same congress gave sanction to the 
name of Maxwell to denote the C.G.S. unit of magnetic flux or 
the number of magnetic lines within a tube of force. The 
magnetic flux would consequently be equal to the product of the 
intensity of the field by the area, and the unit would be a single 
magnetic line. Thus magnetic flux would correspond to current, 
being dependent on the magnetomotive force and the magnetic 
reluctance. This step was taken as these C.G.S. units were 
employed in actual practice and apparatus was in common use 
by means of which field intensities could be measured directly. 
The name Jcilogauss is also employed to denote a thousand times 
the unit. Other propositions have been made for names for the 
C.G.S. magnetic units, but they have not yet been adopted legally 

1 The full text of the various laws and regulations will be found in the 
Appendix to Wolff's paper on the "So-called International Electrical Units," 
Bulletin of the Bureau of Standards (Washington, 1901), No. 1, vol. 1, pp. 61-76. 



216 EVOLUTION OF WEIGHTS AND MEASURES 

as they have not been considered essential, though strenuously 
urged by many prominent electricians. 

After the adoption of the resolution defining the electrical 
units, at the Electrical Congress held at Chicago in 1893, and 
their subsequent ratification, either in whole or in part, by various 
governments, it was found that there were slight errors in these 
definitions, especially in the electromotive force of the Clark 
cell, which has been found to be nearer 1*433 volts than 1*434 as 
defined. It was stated by some physicists that a cadmium 
(Weston) cell 1 was more constant, had a lower temperature 
coefficient, and could be defined with greater accuracy, while 
further researches on the Clark cell itself gave a value for its 
electromotive force somewhat different from that stated in the 
resolutions ; and, in fact, in Germany the value 1*4328 volts was 
adopted as corresponding to the realized value of the ohm and 
ampere. There was also a demand for new units, and for changes 
in the nomenclature in the existing units. Consequently, at the 
Electrical Congress held in connection with the St. Louis Exposi- 
tion, 1904, a chamber of representatives of various governments 
was in session to pass upon these propositions. It was the 
opinion of the Chamber of Delegates that these propositions were 
of sufficient character to warrant a thorough discussion, but, at 
the same time, the delegates did not seem to be of the opinion 
that they should be settled at such a meeting. Accordingly, they 
resolved that a permanent Commission, consisting of representa- 
tives from various governments, should be convened, and that to 
such an International Commission should be entrusted the decision 
of the matter. Such an international body would have much the 
same duties as the International Commission of Weights and 
Measures, and, without doubt, its deliberations and decisions 
would be equally acceptable and important to electricians and 
physicists. 

In concluding this chapter on electrical units it is hardly 
necessary to more than call attention to the great benefits that 

1 The Weston cell has for its electrodes cadmium amalgam covered with a 
layer of crystals of cadmium sulphate, and pure mercury in contact with a paste 
of mercurous sulphate, cadmium sulphate crystals, and metallic mercury, while 
the electrolyte is a saturated aqueous solution of zinc sulphate and mercurous 
sulphate. 



INTERNATIONAL ELECTRICAL UNITS 217 

have been conferred on the electrical industry throughout the 
world by the employment, in all countries, of one and the same 
system of units of measurement. In fact, this condition has been 
advanced as one of the reasons for the rapid growth of the 
industry, and while various modifications of units have been 
demanded and discussed, they have only been adopted after they 
have been determined by an International Congress. No nation 
or group of electricians or engineers has ever found fault with 
the extensive use of the decimal system, and by the close con- 
nection of electrical units with the metric system such workers 
have been enabled to appreciate the advantages of the latter, so 
that in non-metric countries the electrical professions unanimously 
are found eagerly demanding its adoption. In fact, it has been 
truly said by a British electrical engineer, 1 than whom there is 
no one more competent to discuss the subject in its many aspects, 
that " so far as I am aware nobody has ever suggested that it 
would be to the advantage of any country to start a system of 
electrical units of its own." 

1 Alexander Siemens, Presidential Address before the Institution of Electrical 
Engineers of Great Britain, Nov. 10, 1904, Electrician (London), Nov. 11, 1904, 
p. 149. 



CHAPTEE X. 
STANDARDS AND COMPARISON. 

In all systems of weights and measures based on one or more 
arbitrary fundamental units, the concrete representation of the 
unit in the form of a standard is necessary, and the construction 
and preservation of such a standard is a matter of primary 
importance. The reference of all measures to an original standard 
is essential for their correctness, and such a standard must be 
maintained and preserved in its integrity for purposes of com- 
parison by some responsible authority, which is thus able to 
provide against the use of false weights and measures. Accord- 
ingly, from earliest times, standards were constructed and pre- 
served under the direction of kings and priests, and the temples 
were a favorite place for their deposit. Later, this duty was 
assumed by the government, and to-day in addition we find the 
integrity of standards of weights and measures safeguarded by 
international agreement. 

The progress of the science of metrology is not only well 
exemplified in these actual representations of various units, but 
is intimately connected with the construction of the prototypes of 
the fundamental standards. The mechanical processes and other 
features involved in their construction have so improved with 
time and with the growth of physical science, especially as it 
involves a constantly increasing degree of exactness in measuring, 
that the subject is one which warrants attention in even a brief 
treatise on weights and measures. In fact, metrology has been 
defined as : " That part of the science of measures which applies 
itself specially to the determinations of prototypes representative 
of the fundamental units of dimensions and of mass, of the 
standards of the first order which are derived from the same, and 
are employed in experimental researches, aiming at a high 



STANDARDS AND COMPARISON 219 

exactitude, as well as to the operations of diverse natures which 
are the necessary corollaries." 1 

That a standard should exactly represent a unit is of course 
obvious, and what is usually the case, the definition of the unit is 
derived from the standard, as is the definition of the British 
imperial yard or the modern definition of the meter. Therefore 
it is essential that the standard should be so constructed as to be 
as nearly permanent and invariable as human ingenuity can con- 
trive. As an example of the lack of permanence experienced in 
standards, attention might be called to the fact that the secondary 
standards of the British yard of 1855, which were distributed to 
the various nations and laboratories, have since undergone careful 
comparisons and remeasurements, and it is believed that in many 
cases their lengths are not the same as when they were first 
constructed. 2 

While it is physically impossible to secure absolute invari- 
ability in standards, yet in their construction a material should be 
chosen whose variations are well-determined functions of one or 
more independent variables easy to measure. In practice, these 
variations themselves ought to be very small, and the variables 
upon which they depend susceptible of being determined with 
high precision. The realization of these conditions represents 
essentially what has been accomplished by the advance of metro- 
logical science so far as exactness in standards is involved. In 
the past, as we have seen, an extreme degree of precision in 
measurement was not essential, nor could it be obtained with the 
means at the disposal of the scientist or mechanician, but 
improvements in this branch of science have been made to such an 
extent that within two centuries the precision of standards of length 
has been increased nearly a thousand fold. With the growth of 
knowledge, it was realized that matter varied to a marked degree 
under the influences of temperature, pressure, time, and other 
conditions, so that in consequence, not only a unit must be defined 
precisely, but the appropriate standard and its copies be so con- 

1 J. Rene Benoit, " De la Precision dans la Determination des Longuers en 
Metrologie," p. 31, Rapports pre'sente's au Congres International de Physique, tome 
1, Paris, 1900. 

2 See Report, Superintendent U.S. Coast and Geodetic Survey, 1877. Appendix 
12, pp. 180-181. 



220 EVOLUTION OF WEIGHTS AND MEASURES 

structed that they would be permanent, invariable and exact. In 
designing and constructing a standard to fill these demands there 
would be, consequently, a number of conditions to be satisfied. 
First, there would be the natural wear of time, which would alter 
easily the length of a measure or the mass of a weight, and could 
only be guarded against by selecting a hard and durable material 
which would resist abrasion. Then, there would be the question 
of temperature effects, most important in all metrological work, 
but hardly realized before the beginning of the 18th century. For 
it will be remembered that, at different temperatures, a body 
varies in length and volume, so that a standard of length, for 
example, is only of unit length at one stated and defined tempera- 
ture, being too long at a higher temperature and too short at a 
lower temperature. Consequently, it is desirable that a standard 
should be of a material affected as little as possible by heat, or, 
in scientific language, having a low and regular coefficient of 
expansion, and it is essential that this amount of expansion 
should be known accurately, so that in case the standard is used 
at other temperatures than that of the definition, the amount that 
it is too large or too small may be taken into consideration and 
allowed for, as by knowing accurately and applying the factor 
which represents the variation in length, a measurement may be 
made as exact as the original measurement on which the standard 
is based. It is therefore necessary to exclude from consideration 
materials having coefficients of expansion which vary con- 
siderably at different temperatures, or which expand at a 
different rate from that with which they contract. 

The prime condition of a standard of length, and the same is 
essentially true of standards of mass, is that it should consist of a 
single bar, or piece of a single material, avoiding any joining of 
several elements, such as by screws or by soldering. In fact, the 
method used at the beginning of the 19th century, whereby a strip 
of silver was inlaid on a brass bar, as in the Troughton scale, after 
the fashion of the graduated circles of various modern instruments, 
was soon found unsuitable for the standards of higher precision 
which were demanded. The material selected should not only be 
hard and highly elastic, but should have a surface that can be 
polished readily, and engraved with the marks of terminal limits, 
or of the divisions of the unit. For many years it was customary 



STANDARDS AND COMPARISON 221 

to construct the standards of iron or of brass — materials which 
were easily oxidizable, and which were with difficulty obtained in 
a pure and constant condition. For the standard of the meter, 
known as the Meter of the Archives, platinum was used ; but later, 
the material best suited for a standard was found to be an alloy 
of platinum and iridium, and such was used for the international 
prototype meter and kilogram and the national standards copied 
therefrom. This material, however, being extremely expensive, 
cannot be used generally where secondary standards for ordinary 
exact measurements are desired, nor can rock crystal of which a 
few standards of mass have been constructed. 

A recent study of alloys, however, has resulted in finding 
materials which possess many of the desired properties, such as 
hardness and durability, and at the same time have a low 
coefficient of expansion. One of the most recent of these, known 
as invar, has resulted from experiments carried on at the 
International Bureau of Weights and Measures, and has been 
developed to a high degree of usefulness by M. Guillaume. This 
metal, which consists of 36 parts of nickel to 64 of steel, has been 
found available for measuring rods and wires for use in geodetic 
operations, and seems destined to occupy a much wider field in 
the future. Wires for measuring base lines made of this alloy 
have been found to possess a coefficient of expansion in some 
cases as low as '0000001 for a degree centigrade. 1 In 1900 invar 
standards and gauges were put on the market, and for all prac- 
tical purposes permitted the disregarding of temperature effects. 
In fact, it has been proposed to employ a heavy bar of this 
material as the support of the observing microscopes in a com- 
parator. Invar, however, is not quite steady and constant and 
cannot be used for primary standards. In accurate surveying 
such standards should be determined just before and after using 
in the field. 

From the early standards of length rectangular or cylindrical 
in form, much improvement has been made and care is now 
taken that the cross-section of the bar shall be of such design 

1 See Guillaume, " Les Procedes Rapides de la Geodesie Moderne," La Nature 
(Paris), 1904, No. 1640, p. 339, and No. 1643, p. 395; id., Les Applications des 
Aciers au Nickel, avec un Appendice sur la The'orie des Aciers au Nickel (Paris, 
1904) ; id., La Convention du Metre (Paris, 1902), pp. 127 and 233. 



222 EVOLUTION OF WEIGHTS AND MEASURES 

that not only it shall possess maximum strength, but especially 
that it will resist deformation by bending, which in accurate 
measurements may cause considerable error. Thus in a linear 
scale of considerable length as compared with its breadth and 
thickness and, let us say, of rectangular section, where the 
divisions are on the upper surface, it will be obvious that if it is 
so supported that the ends hang lower than the centre, the upper 
surface will form a convex curve, and the particles of the material 
lying in such a surface will be stretched apart, and the distance A 
to B will be greater than when the bar is straight as under 
normal conditions. 



If the ends of the scale were supported, rather than the centre, 
the opposite conditions would prevail, and the marked distance 
will be too short. This was recognised by Captain Kater, who 
proposed the employment of a scale of small thickness which was 
placed on a base whose surface was perfectly plane. 1 A better 
solution of the difficulty was to use the neutral fibres, as shown 
by the dotted line CD, and for this purpose the British standard 
of 1855 was constructed, as shown on pages 245 and 246, where the 
unit distance is measured between lines on polished gold plugs, set 
in two holes or wells, so that they lie in this so-called neutral plane. 
This idea was more perfectly carried out in the standards of 
the International Metric Commission, having the X-section as 
shown on page 254, where the construction is such that the bar 
possesses maximum rigidity with the minimum material and the 
neutral plane in the line standard is easily accessible for measure- 
ments throughout its length. In standards for small lengths, such 
as the decimeter, such considerations as a desirable type of cross- 
section and the placing of the divisions in a neutral plane, 
naturally do not require careful consideration and can practically 

1 See Kater, "Investigation of the Curvature of Bars, produced by the In- 
equalities of the supporting surface," Phil. Trans., 1830, p. 359. See also W. A. 
Rogers, Proc. Amer. Acad. Arts and Sciences, vol. xv. 1879-80, p. 292. 



STANDARDS AND COMPARISON 223 

be neglected, but in meter or yard standards it is an important 
consideration. 

Then, as regards the actual means of denoting the distance, we 
may have end standards (Stalon a touts) and line standards (4talon 
a traits). The end standard represents the given unit by the 
distance between the extreme boundary surfaces, as in the case of 
any ordinary rule, or in the case of the inside measure, — the 
distance between the interior surfaces of two extended arms, — the 
object being to secure better protection for the surfaces employed 
for measurement, and at the same time, to furnish a ready means 
of comparing end measures with a standard, by simply bringing 
them within the space included between the terminal arms. 
With the other form of standard, the limits of the distance are 
indicated by lines or sometimes dots. The line standard, of 
course, can be used with a microscope with cross-hairs, or a 
micrometer microscope, much more readily than an end standard, 
as it is possible to effect an exact setting on even a coarse 
line with much greater accuracy than on an edge, which 
though imperceptibly worn to the naked eye, would appear 
rough and indistinct when magnified by the microscope. 

The line standard possesses a distinct advantage, where it is 
divided throughout its whole length, as is usually the case, since 
it is readily comparable with its own sub-divisions and with 
smaller standards. On the other hand, the end standard con- 
stitutes merely a standard for a single length, and does not lend 
itself to direct comparisons with the ordinary standards of other 
lengths in the laboratory or testing bureau, which in the case of 
metric scales are usually divided into millimeters, with the centi- 
meters and decimeters suitably marked. With a standard so 
divided, standards of measure for other distances besides the 
greatest one marked on its surface must be supplied. 

In spite of the general tendency to use a line standard, rather 
than an end standard, Bessel, in 1835, when he was preparing a 
standard based on the seconds pendulum at Koenigsberg, used a 
steel bar with sapphires set in its ends, to form a standard of length. 
This standard of Koenigsberg was used as a basis for numerous 
measurements of base lines in geodetic surveys in Europe. 1 

Though the line standard forms the most suitable, and in 

1 P. 9, Guillaume, La Convention du Metre. 



224 EVOLUTION OF WEIGHTS AND MEASURES 

fact the only, standard for a modern prototype, and even for 
secondary purposes, there are nevertheless occasions where stan- 
dards of the end type can be conveniently used. Especially is 
this the case in mechanical engineering, where various gauges 
and shop standards must be constructed so as to be used readily 
in the tool-room or machine shop for accurate measurements. 
The methods of comparison are essentially similar to those 
employed in comparing line standards. However, certain 
variations of methods have been introduced, since it is 
necessary to consider the terminal faces, which are susceptible 
of wear and must be protected carefully. In addition to the 
use of the microscope comparator, which is described below, 
in connection with line standards, there are three methods 
which can be used for this purpose, as follows : 

First, the method of direct contact, which, while the simplest, 
can also be made very accurate if properly used. 

Second, by reflection of an object at the terminal surface. 

Third, by interference fringes which are produced at the 
ends of the scale to be measured. 

In the method of contact, which is ordinarily employed 
where a high degree of precision is unnecessary, it is usual 
to employ such simple measuring devices as a screw micro- 
meter, or a spherometer, or some less accurate form of instru- 
ment, such as calipers or a beam compass. The second and 
third methods are optical, and must be executed by a trained 
physicist ; but they increase materially the range of precision, 
and can afford results more accurate than are obtained in 
comparing line standards. 

The method of reflection was employed in comparing the 
Meter of the Archives, an end standard, with the provisional 
meter for the construction of the international prototype, and 
also subsequently in the standardizing of certain end standards 
of platinum-iridium, which were given to such nations as had 
ordered them. This method consisted in observing the dis- 
placement of the reflection of a line at the terminal surface 
of the bar; and while under certain circumstances it was 
exact, it required a study of the objectives of the microscope 
and other features in order to insure its accuracy. 

Employing this method, in 1881-82, a series of comparisons 



STANDARDS AND COMPARISON 225 

of the new standards was made at the Conservatoire des Arts 
ot Metiers with the Meter of the Archives, taking into con- 
sideration most carefully the question of temperature. It was 
found that these comparisons, when reduced to degrees C, 
gave an accuracy of *6 of a micron for each standard. 

In the method of interference use is made of the phenomenon 
•of Newton's rings, whereby interference of light follows differ- 
ences in the path of a beam, such as may be produced by 
reflection from two different surfaces. It is necessary to have 
■a fixed and determined surface as a plane of reference, and then 
to consider the difference in the fringes that are produced 
by light falling on two other surfaces at different times. 

Considering now a line standard constructed, of approved 
material and cross-section, it is naturally of primary import- 
ance to provide the marks accurately limiting the distance. 
These marks or traces are usually made with a diamond, and 
are transverse to the axis of the bar. The method employed 
is to place the bar, with the standard by which it is graduated, 
•on the carriage of a special piece of apparatus, such as a com- 
parator or dividing engine, which will be described below more 
fully, with the cross-hairs of one of the microscopes accurately 
•over the line of the standard scale. After a mark is made 
on the scale to be graduated, both scales are moved until the 
second mark of the standard scale is under the cross-hairs, 
and another ruling is then made by the diamond. Or the 
scales may remain stationary and the microscope and tracing 
device be moved. 

To divide a scale into millimeters or other divisions the 
dividing engine is employed, an instrument in which the 
•essential feature consists of an accurately constructed screw, 
whose pitch (i.e. distance between threads), as well as its 
oonstant and periodic errors, are known to a high degree of 
precision. This screw, working in a suitable nut, moves a 
table along a heavy metal supporting bench, and a metal or 
glass bar on this table can be moved forward by regular and 
successive intervals of length. Above the table is a tracing 
device operating in a fixed vertical plane, and by this means 
the desired divisions may be inscribed on the bar. Apparatus 
of this kind has been constructed which is entirely automatic 

p 



226 EVOLUTION OF WEIGHTS AND MEASURES 

in its movements, and which is able to mark the divisions 
in millimeters on a scale a meter in length. Such machines 
have means of correcting the errors in the screw, whether 
they are constant or occur at different intervals of its length, 
and also devices permitting corrections for temperature. Often 
these machines are driven by an electric motor, and even the 
differences in length of the marks denoting divisions of the 
scale — as, for example, at every tenth millimeter — are made 
longer automatically. A meter scale divided into millimeters 
can be ruled with a machine of this description in the Inter- 
national Bureau of Weights and Measures, in about sixteen hours,, 
with an accuracy of two or three microns for each division. 1 

With the dividing engine or ruling machine of the late Pro- 
fessor H. A. Eowland of the Johns Hopkins University, designed 
for constructing diffraction gratings for spectroscopic work rather 
than for making linear scales, as many as 20,000 lines to the inch,. 
787*5 to the millimeter, could be ruled on speculum metal, and 
gratings having as many as 120,000 lines have been made where- 
the estimated error between any two lines was not thought to 
exceed 2000000 °^ an mcn > or nearly the 80 q q of a millimeter. 2 

To secure the best results, the surface of the standard or scale 
on which the lines are traced should be highly polished, and great 
care should be taken, not only in the choice of the diamond or 
tracing-tool, but in the actual operation. The line made should 
be clear and sharp, not broader than is absolutely necessary, and 
not appearing rough and indistinct when seen under the micro- 
scope. In the national standard prototypes of the meter this line- 
measures from 6 to 8 microns in width, but after it had been 
ruled, it was thought that a much narrower line, say 2 or & 
microns, could have been used with advantage, — securing, of 
course, a sufficient depth to insure the permanent preservation of 
the line. On both sides of the line at a distance of *5 mm. 
are two parallel and similar lines, the distance between them 

1 M. Guillaume says, "It is essential in order to get very good lines to trace 
very slowly, and in the studies made at the Bureau International it has been 
found useful to trace the 1000 lines of the meter in millimeters in about 16 hours. 
The inaccuracy in the position of either end line does not exceed two or three 
microns, but of course the error of every interval of 1 mm. is much smaller." 

2 See The Physical Papers of Henry A. Rowland (Baltimore, 1902), pp. 506-51 1„ 
691-697. 



STANDARDS AND COMPARISON 227 

forming a standard millimeter at each end of the scale, which 
furnishes a check on the micrometer of the microscopes of the 
comparator used to compare the scales. These transverse lines 
are crossed by two longitudinal lines parallel to the axis of the 
bar, and distant from each other *2 of a millimeter. Between 
the intersections of these lines with the transverse lines is where 
the standard distance is measured. 

The important part played by temperature in exact determina- 
tions and comparisons of standards of length, as well as of mass, 
of course involves a means of measuring such temperatures. This 
subject has received increasing attention in the course of time, 
and it has been realized that exactitude in constructing standards 
of length is only possible where the most accurate methods of 
temperature measurements are employed, as the changes in length 
or volume with temperature of course produces marked variations 
from the standard unit. Since a linear unit is represented by the 
length of a standard or bar of metal at a fixed and defined temper- 
ature, at no other temperature will this bar have the standard 
length, and consequently its exact length at such other tempera- 
ture can only be ascertained by knowing the amount that it 
expands for a unit (degree) of temperature, and the precise 
temperature at which the measurement is made. Accordingly, 
two thermometric measurements of great precision are involved, 
one in determining the expansion of the material forming the 
standard, or obtaining the coefficient of expansion of the bar, 
and the other, in measuring the temperature at which the bar is 
used. Now as the coefficient of expansion enters as a direct 
factor in determining the exact length of a standard, it is 
necessary to consider how far we can depend upon its accuracy, 
and to realize that if this factor cannot be trusted beyond a 
certain figure of decimals, then refinement of measuring with the 
micrometer is quite superfluous. 

In the first attempts at accurate measurement and comparison 
of standards, as soon as temperature effects began to be considered, 
mercury-in-glass thermometers were used, and in them for many 
years a confidence was placed, which has been since found 
entirely unwarranted. The gravity of this matter was realized 
by physicists toward the middle of the 19th century, and at the 
time of the construction of the international standards, it was 



228 EVOLUTION OF WEIGHTS AND MEASURES 

considered necessary to undertake a complete study of the 
mercury-in -glass thermometer, and find within what limits its 
accuracy could be trusted. So many sources of error were found 
in the instruments as then constructed, due to the material used, 
and to differences in its behaviour at different temperatures, as 
well as to the difference in the coefficient of expansion of mercury 
at different temperatures, that it was found necessary, after a 
most thorough investigation, to adopt a gas thermometer in which 
hydrogen was used as the expanding fluid. In this the expansion 
of the gas indicates the temperature, and within certain limits it 
is far more accurate than the mercurial thermometer. The latter, 
however, when carefully studied and calibrated, can be referred to 
the hydrogen scale with sufficient exactness for use at ordinary 
temperatures. For purposes of standardizing, it has been found 
necessary to refer all temperature measurements to the hydrogen 
thermometer, and the study of exact thermometry made at the 
International Bureau of Weights and Measures, has been one of 
its most important scientific works. It has served to increase the 
accuracy of the present standard of length and of mass, as well as 
to raise materially the degree of precision in all measurements in 
science in which temperature enters as a factor. 1 

Fundamental standards or prototypes are of course not avail- 
able for general work, even where high precision is demanded, 
but they must serve only as a basis for the construction and 
testing of secondary standards which are divided throughout their 
entire length. These are necessary for many purposes, and can 
be used under conditions involving more or less wear. 

The question of the permanence of these fundamental 
standards, or more particularly that of the international prototype 
meter is of primary importance. New methods involving greater 
exactness in measurements and comparisons would avail little if 

1 Good modern mercury thermometers made of hard glass alloy are of great 
accuracy at moderately high temperatui'es, but their scale though very well 
defined and reproducible is an arbitrary one and has no fixed relation with 
theoretical phenomena, as is the case with the gas thermometer — Guillaume. 
See Benoit, p. 75, Rapports Congres International de Physique, tome i. Paris, 
1900. Guillaume, La Convention du Metre, Paris, 1902, p. 26, etc., for resume 
of thermometric studies at the International Bureau of Weights and Measures ; 
Traite de la Thermome'trie de Precision. Paris, 1889. Travaux et Me'moires, 
Bureau International des Poids et Mesures, vol. i.-vi., x., xii., xiii. 



STANDARDS AND COMPARISON 229 

changes were taking place in the material of the standard bar 
which would produce variations in its length. Evidence that 
has accumulated in almost twenty years' experience with the 
national standard meter bars does not indicate any substantial 
changes that should give cause for anxiety in this respect, but at 
the same time, the physicist is hardly in a position to guarantee 
this permanence for a longer period of time, such as a century. 
Recourse must be had, therefore, to a series of comparisons 
of other standards among themselves and of providing new means 
by which the integrity of the standard may be safeguarded. 
The most satisfactory of these auxiliary means of protection is 
the reference of the standard meter to a wave-length of light, 
according to the method devised by Professor A. A. Michelson 
and applied at the Bureau International des Poids et Mesures, to 
which reference will be made in the course of a few pages. Thus 
to-day the permanence of the meter is assured in that it is defined 
in terms of a wave-length of cadmium light, with an exactitude 
of one part in 1,000,000 or, in other words, of a micron. 1 

In comparing standards of length the earliest scientific device 
employed was the use of some form of calipers or beam compass. 
Thus in comparing an outside end standard with an inside end 
standard, by placing the former between the projecting ends of 
the latter, a measurement could readily be made. For com- 
parisons of this kind, the inside end standards constructed of 
metal were frequently embedded in a masonry wall at some 
central and convenient point in a city. In comparing the toise 
of Peru with that of the Grand Chatelet, we are told by the 
Astronomer Lalande that the microscope, in connection with a 
beam compass having very fine points, was used as early as 
1735, and we also know that a similar device where the 
jaws or points were moved by micrometer screws with divided 
heads was employed in England by Graham, in 1742, in 
making his comparison of standards of length. 2 In the earliest 
comparisons involved in the original determination of the meter 
and the construction of the standard bars used for measuring 

1 Benoit, p. 68, Rapports Congres International de Physique, vol. i. Paris, 1900. 
2 See "Description of Standards and Use of Beam Compasses," Philosophical 
Transactions, 1742-1743, vol. xlii. London. 



230 EVOLUTION OF WEIGHTS AND MEASURES 

the bases, the various scales to be measured and compared 
were placed on a long plate of brass, having a fixed terminal 
piece at one end, with which the ends of the scales were placed 
in contact. Differences of length were determined by means of a 
moving contact block and a small scale carefully divided. This 
device, known as the rule of comparison, or the comparator of 
Borda and also of Lenoir, which was believed for many years to 
have been lost, was discovered by M. Wolf, 1 and is now preserved 
in the Observatory of Paris. It consists of a heavy strip of 
copper, some 13 pieds (4*225 meters) long, 30 lignes (6*78 centi- 
meters) in width, and 4 lignes ( - 9 centimeter) in thickness. The 
movable piece is a smaller scale of copper, about 6 feet in length, 
and divided into ten thousandths of a toise. It was movable 
along the copper bar, and with it an exact reading of the length 
of the scales to be compared could be made. There were verniers 
ruled on the copper bar at different points, such as 12 pieds from 
the extremity, for the comparison of geodetic base bars of 2 toises 
length ; at 6 pieds for the comparison of toise standards ; at 3 
pieds for the comparison of meters, etc. The verniers were 
divided to read to tenths, so that it was possible to obtain the 
Y^j part of the length of a toise. 2 

In this way a degree of precision equal to about ^tro °f a 
ligne ('01 mm.) was obtained, which was practically ten times that 
attained in the comparisons of the toise of Peru and that of the 
Grand Chatelet half a century before. However, even greater 
precision was demanded at this time, and accordingly, a lever 
comparator was constructed by Lenoir, in which the long arm of 
a lever magnified the distance traversed by a movable contact piece 
in connection with a shorter arm, with the result that it was pos- 
sible to read even smaller differences than those mentioned above. 3 

The next step marking progress and increased accuracy in the 
comparison of standards was the use of the micrometer-microscope 
which was devised by Troughton, of London, and was first em- 
ployed by Sir George Shuckburgh, in 1796-8, in the measurement 
of some line standards, which were then beginning to be employed 

1 See Annates de VObservatoire de Paris; Me'moires, vol. 17, p. C 32. 
2 Bigourdan, p. 86, Le Systtme Me'trique, Paris, 1901. 

3 Benoit, p. 34, Rapports pre'sentts au Gongres International de Physique, vol. i. 
Paris, 1900. 



STANDARDS AND COMPARISON 231 

in metrology. 1 This device has since played an important part 
in all such comparisons, and the micrometer-microscope, in 
improved form, figures in many instruments for this purpose. In 
•Shuckburgh's comparator, the two microscopes were arranged 
vertically on a metallic bar, and in one there were fixed cross- 
hairs, and in the other, a movable system of cross-hairs connected 
with the screw of a micrometer. The divisions of the head of 
this screw corresponded to ten thousandths of an English inch. 
The method of operating was to adjust one of the scales so that 
the image of its line should appear at the cross-hairs of one of the 
microscopes, the cross-hairs being set at the focus of the objective. 
The other microscope would be so adjusted that its cross-hairs 
would coincide with the image of the line at the opposite end of 
the scale, or in case of a comparison with end standards, the cross- 
hair would be set on the ends themselves. In making a com- 
parison, a second scale was substituted for the first, and was 
placed under the microscopes in the same position, one of the 
lines, or the extremity of the scale (in case it were an end 
standard) being made to take a position so that its image would 
■correspond with the cross-hairs of the first microscope. If the 
•other division were exactly equivalent to that of the first scale, it 
would occupy the same position in the field of the second micro- 
scope, but, in case there was a difference, this difference could be 
measured by moving the movable cross-hairs with the micrometer 
screw. The micrometer-microscope of Sir George Shuckburgh 
was capable of reading to '0001 of an inch, or the -^ of a milli- 
meter, and with this apparatus he made, in 1802, a comparison 
between the British and French standards. 

This idea for a comparator underwent subsequent improvements 
about 1804 at the hands of Baily, also of England, who employed 
in his apparatus, two microscopes, each provided with a micro- 
meter and with an achromatic objective, by means of which 
the image was made clearer and the magnification increased. 
He also devised a method whereby the scales could be slid 
under the microscopes, without touching them with the hands, 
by arranging a carriage on a frame independent of the microscopes. 
While this apparatus contained important improvements, never- 
theless, in its construction, it lacked in solidity, and at the 

1 Philosophical Transactions (London), 1798, p. 137. 



232 EVOLUTION OF WEIGHTS AND MEASURES 

same time was without adequate means of preserving the* 
temperature of the rules constant. Accordingly, the commission 
charged with the construction of the British Imperial Standards,, 
in 1843, made important improvements in the comparator^ 
supplying the desired rigidity and strength by means of a 
solid foundation for the microscopes, and providing for enclosing 
the rules to be compared in a double-lined box, whose tempera- 
ture was maintained constant at the desired temperature by 
a circulation of water. 

In France, also, the work of constructing and comparing 
standards of length developed, and the progress towards exact- 
ness made in that country during the nineteenth century, was 
due in large part to the placing the service of weights and 
measures in charge of the Conservatoire des Arts et Metiers- 
There was constructed for this institution, by Gambey, a com- 
parator with longitudinal displacement, which permitted the 
comparison of both end and line standards, and at the same- 
time allowed the defining lines to be marked upon them. The 
result of improvements and the activity of this establishment, 
was that much was accomplished in the semi-scientific and 
industrial application of exact measurements, and the weights 
and measures of France were brought to a higher degree of 
precision. 

In the United States, also, important comparisons were made 
of the various scales presented by the French and British 
Governments, with those in the Coast and Geodetic Survey.. 
But neither instruments nor methods represented any striking 
departures from European practice, though the work itself was. 
up to the high scientific standard maintained by this bureau 
and was favorably commented on abroad. A useful and 
accurate comparator, still in use, was constructed by Saxton 
and was employed in making the early standards of length. 1 

While there have been no fundamental improvements in 
the idea underlying the operation of comparing standards,, 
within the last half-century, nevertheless by various mechanical 
improvements and refinements, the range of accuracy has been 
notably increased, so that to-day the modern comparator 
represents an instrument susceptible of great precision in the 

1 Executive Doc. 27, 34th Congress, 3rd Session. 



STANDARDS AND COMPARISON 233 

hands of a competent observer. The prime requisite of a com- 
parator designed for such purposes as the comparison of a 
prototype with national or other standards, is its stability, and 
for that purpose the instrument is generally mounted on piers 
of solid masonry, which are independent of the structural walls 
of the building in which it is placed. It is essential that such a 
building should be located in a place free from vibrations and 
disturbances, such as would be produced by the traffic of a busy 
street, or by machinery, or by a railway. The micrometer- 
microscopes are mounted on heavy castings, set on separate piers 
placed at approximate distances, if the comparator is to be used 
for the comparison of standards of a single unit, as, for example,, 
meter-bars. If, on the other hand, the comparator is of a 
universal character, and must be used in the comparison of 
various lengths, then the microscopes must be mounted on 
solid carriages, which are capable of being moved along some 
sort of a solid frame-work or firmly mounted beam. Equally 
important with the microscopes is the arrangement for carrying 
the scales which are to be compared. Some means must be- 
provided to place them successively in the same position beneath 
the microscopes, so that the difference in their length may be- 
determined by means of the micrometers. These scales must be 
maintained at the same temperature, and must be examined 
under practically the same conditions. This involves, first, the 
absolute uniformity of the temperature of the apparatus itself, 
and for this purpose it should be installed in a room where 
direct sunlight cannot penetrate and be surrounded by corridors, 
enabling a constant temperature to be maintained. This requires, 
naturally, an apartment of a considerable extent, provided with 
thick walls, and specially designed doors and windows, as well 
as various devices for maintaining automatically the desired 
degree of temperature. The entire instrument may be surrounded 
by a box through which penetrate only the eye-pieces of the 
microscopes and the handles controlling the various parts of the 
mechanism. 

To keep the scales at the same temperature there is a movable 
carriage which carries a double-walled box containing water. 
In this box the scales are placed and the water is kept in 
constant circulation by means of small agitators electrically 



234 EVOLUTION OF WEIGHTS AND MEASURES 

driven and in motion except at the moment of reading. A 
number of thermometers arranged in close proximity to the scales 
enable a series of accurate readings of the temperature to be made 
with microscopes placed above for that purpose. It will readily 
be seen that by changing the temperature of the surrounding 
water, the amount of expansion of a scale can be measured. 1 

Improvements have been made in the micrometer-microscope 
as well as in the rest of the apparatus, and particularly in the 
screws which form the basis for moving the cross-hairs and 
for measuring the amount of motion. These improvements 
consist essentially of a frame carrying several sets of cross-wires 
in pairs, which occupy a vertical position in the field of view 
of the microscope. This frame is set at the focal plane of 
the objective, and can be moved laterally by means of a screw 
with a graduated head and handle. Such screws are so con- 
structed that they are practically free from constant or periodic 
error, and by means of a spring, any " back-lash " or lost motion 
between the screw and nut is guarded against. The head of 
the screw is graduated to a certain number of divisions, usually 
100, so that a fractional part of the revolution of the screw 
can be determined accurately. For example, if a pair of cross- 
wires are focussed over a line of a scale, it is possible, by noting 
the number of revolutions of the screw, to bring those cross- 
wires over the next line, to determine the value of a single 
revolution of the screw, and by means of its divided head and a 
vernier, of minute fractions of a single revolution. Where cross- 
wires of the ordinary or X type were once employed and a setting 
made on the centre of the magnified division, it is now usual to 
employ two vertical cross- wires, following a plan proposed by 
Kupffer when preparing the Eussian standards, and to arrange 
the setting with respect to the edges of the engraved line. This 
lends itself to greater accuracy, as by means of the bright borders 
of the image of the line a much sharper setting can be made 
than where the magnified line was bisected by a single cross- 
wire. The magnifying power of the microscope for accurate 
comparisons ranges from 80 to 250 times, and in some few rare 
cases even higher, the most serviceable power being determined 

X A description of the Brunner Comparator of the International Bureau will be 
found in Travaux et Mdmoires du Bureau International des Poids et Mesures, vol. 4. 



STANDARDS AND COMPARISON 235 

after considering the conditions, as, under many circumstances, 
increased magnification introduces errors and does not result 
in as satisfactory results as with the use of a lower power. 1 

There must also be considered the illumination of the face of 
the rule, and it is now usual to provide direct illumination, rather 
than oblique. This is accomplished by the use of a prism which 
will reflect light from a distant source, such as an incandescent 
lamp with a ground glass globe, to the scale and then to the 
objective of the microscope. A transparent plate of plane glass 
placed in the tube of the microscope at an angle of 45 degrees to 
the axis, will also produce the same result, and is preferred by 
some observers. 

As regards the manner in which the adjustment of the scale is 
•accomplished, two main divisions of comparators can be made, — 
those which give the transverse movement of the scales, and those 
in which the scales are moved longitudinally. A longitudinal 
comparator is so arranged that the divisions of a standard can be 
studied accurately ; for example, throughout the entire length ; or 
standards of different lengths, whose differences exceed the 
diameter of the field of the microscopes, can be measured with 
facility. Thus from a standard meter, a bar or tape of several 
times this length for use in measuring a base line or in surveying, 
•can be standardized. In a comparator of this kind the scales 
must be so adjusted that they lie with their axis either in a 
perfectly straight line or exactly parallel. 

In the comparators where the scales have a transverse move- 
ment, as is the case with an instrument designed for comparing 
two scales of the same length, the microscopes are mounted at a 
fixed distance, and the scales are adjusted so that their axes are 
parallel to a line connecting the two microscopes. The two 
scales should rest in a carriage protected from changes of 
temperature by means already described, and so arranged that 
after being adjusted parallel to each other, they can be moved 
under the two microscopes. Such an arrangement enables one to 
study the relative expansion of scales of different materials, as the 
measurement of the differences of length at a certain temperature 

1 See W. A. Rogers, " On the Present State of the Question of Standards of 
Length," Proceedings American Academy of Arts and Sciences, vol. xv. 1879-80, 
pp. 290-291. 



236 EVOLUTION OF WEIGHTS AND MEASURES 

can be made, and then, at a second temperature, obtained by 
varying the warmth of the circulating water. 

With standards of mass, the material of which they are com- 
posed is of primary importance. Not only must the standard be 
of a permanent character, hard and able to resist abrasion in actual 
use, but it must be such that it will not be affected by the oxygen 
of the air, or, in other words, have its surface oxidized and the 
weight increased. Other and more subtle chemical changes must 
also be provided against. On this account, platinum and rock 
crystal have been found to be the most useful materials, and the 
former posesses the merit of having a high specific gravity, so 
that when weighed in air the amount displaced is a minimum. 
Furthermore, the shape must be such that the volume can be 
measured with a high degree of exactitude, as on the volume 
depends the effect of buoyancy, and of temperature. Such cor- 
rections are often very small ; in fact, much less than in the 
case of a standard of length, but in constructing and using a 
standard of mass, the barometric pressure, temperature, and the 
humidity should be determined, as the density of the air must 
be known accurately and duly considered. 

In addition to possessing a geometrical figure easily measured, 
the standard should be so designed that there are no grooves or 
cavities to collect dust, and that when used in a balance it will 
conform to the needs of the mechanism used for changing the 
weights in the scale-pans. Taking all things into considera- 
tion, the cylindrical shape with round edges serves the best, 
and such is the form of the Kilogram of the Archives and of 
the International Prototype and its copies. 

For determining standards of mass, the modern physicist 
has recourse to the same instrument which was employed thou- 
sands of years ago by the ancients, viz. the balance with equal 
arms. But he has effected such improvements in its mechanical 
construction and operation that this instrument is now entitled to 
rank with the apparatus of precision of the first order. For 
accurate weighing, the balance must be of the finest and most 
accurate workmanship, and also there must be employed various 
methods and corrections evolved largely from mathematical 
considerations. 

In comparing standards of mass, and in all accurate weighings- 



STANDARDS AND COMPARISON 237 

with a balance, it is necessary to take into consideration the 
buoyant effect of the displaced air, as conditions are quite 
•different from those obtained when a body is weighed in a 
vacuum. This correction is especially necessary in making an 
■absolute determination, but in cases where the standard and 
the weights with which it is compared are of the same material, 
the effect is the same in both cases and does not enter into 
consideration at all. 

For accurate weighing it is possible to employ the method 
of double weighing of Borda, where the two objects whose masses 
are to be compared are successively placed in the same scale- 
pan and are counterpoised by weights on the opposite side, or 
the interchange of the weights on the scale-pans, as devised by 
Gauss. There must be considered, also, the effect of temperature, 
which can change the condition of balances and weights, just as 
much as in other physical operations, and it is accordingly 
necessary to have such a balance placed in a room with constant 
temperature, and to provide against currents of air, by means of a 
suitable case. Even the influence of the temperature of the 
•observer's body has its effect, and he must be placed as far as 
possible from the balance, observing the oscillation of the beam 
with a small telescope, and changing the weights, setting the 
beam in motion and bringing it to rest, and performing other 
necessary operations by suitable mechanical devices, which can 
be operated at a distance, without opening the casing of the 
balance. 

These conditions are realized in the balances used at the 
Bureau International, as well as at various governmental 
Bureaus of Standards, physical laboratories and like institutions. 
Typical, perhaps, as involving the greatest refinements, are the 
balances of the Bureau International, two forms of which are 
•described in outline below. 

Of these perhaps the simplest is the Ruprecht type of balance, 
which consists of a balance with equal arms carrying two scale- 
pans in which an opening is cut in the form of a cross, the edge 
being cut away at one of the branches. Beneath this is an axis 
carrying a cross-shaped piece of somewhat smaller dimensions 
than the opening in the scale-pan. Two supports similar in 
shape to the scale-pans and provided with like openings are 



238 EVOLUTION OF WEIGHTS AND MEASURES 

attached to the central column supporting the balance. When 
a weight is placed on the scale-pan by means of mechanism 
operated from a distance of over four meters, it is possible for the 
cross-shaped piece below to be raised, thus carrying the weight 
clear of the scale-pan, and then to be swung out through the 
opening clear of the latter, and into the plate placed on the 
central column where the weight may be deposited. The 
standard carrying the cross-shaped piece is then lowered 
and the weight is left on the rest. The weights can then be 
revolved around the central column carrying the beam and by the 
apparatus just mentioned placed on opposite pans from their 
original position. This operation is accomplished by means of 
gears and shafts, and is carried on simultaneously for both pans 
of the balance. Mechanism is also provided, so that the observer 
may release the pans and also the beam, by turning suitable 
cranks, and there is a telescope, whereby he may observe the 
deflections of the beam by means of a mirror and divided scale. 1 

The Bunge balance, at the Bureau International des Poids et 
Mesures, contains several features leading to further refinements. 
It is enclosed in a copper case, from which the air may be 
exhausted, so that the weights may be compared in vacuo. In 
addition to the means of changing the weights, and for releasing 
and arresting the scale-pans and beam, mechanism is provided 
whereby small additional weights can be added to one side or the 
other of the beam, as is found necessary. All of the controlling 
devices are so arranged that they may be operated by the 
observer from a distance of several meters, and with this balance 
the most accurate results may be obtained. 

In the determination of standards of mass, it is necessary to 
determine their specific gravity and the amount of water that 
they displace when immersed. For this hydrostatic balances 
are used, which, in their essential features, correspond with the 
balances of precision just described. The vessel containing the 
water in which the weight is immersed is placed directly below 

1 Guillaume's La Convention du Metre, p. 111. The balances have been pro- 
vided with suitable mechanism to add small differential weights, i.e. at the same 
time two weights say of 100 and 100*5 milligrams respectively, which give a new 
position of equilibrium and allow the determination of the sensitiveness. This- 
addition of small weights can be made without arresting the balance which con- 
stitutes a great saving of time. — Ch. Ed. Guillaume. 



STANDARDS AND COMPARISON 239 

the point of support of one of the arms of the balance. There 
is also provided a scale-pan, in which the body to be measured 
is placed, and connected with it — a device by which it can be 
supported when immersed in water — the whole forming a con- 
tinuous arrangement supported from one arm. The body is first 
placed in the upper pan and counterbalanced by weights on the 
opposite side of the balance. It is then removed and weights 
are added in its place until the equilibrium of the balance is 
secured. The sum of the weights so added gives, of course, the 
actual weight of the body. It is then immersed in water, and 
the same process is gone through with, the temperature of the 
water being noted by a carefully calibrated thermometer. Various 
devices are employed to secure a uniform temperature of the 
water, to diminish the effects of friction and capillarity, and to 
facilitate the handling of the body when immersed. 

The sensibility of an accurate balance depends on the load, 
and in making a weighing, this factor must be determined 
accurately, and it is likely to vary under different conditions. 
With the balances employed in comparing the standard kilo- 
grams, it is usual to have the sensibility equal to 25 to 50 
divisions for a milligram, or, in other words, an addition of 
weight equal to a milligram produces a deflection of the beam 
corresponding to this amount. This is useful, inasmuch as the 
differences of weight between the two standards compared are 
usually so small as to be measured only by the deflection, and not 
requiring the addition of the smaller weights to either scale-pan. 

In some cases, a reading of a tenth of a division of the 
deflection in either direction may correspond to some thousandths 
of a milligram. Thus, in comparisons of standard kilograms, the 
•01 of a milligram would be equal to a '000,000,01 of the mass 
measured, but other considerations do not permit this degree of 
precision to be maintained. Nevertheless, this represents a 
substantial gain in accuracy, as the fine balance used at the 
London Mint by Harris in 1743 was able to indicate only ^ of 
a grain on a Troy pound, or about one part in 50,000, while in 
adjusting the Kilogram of the Archives in 1779, Fortin employed 
a balance sensitive to one part in a million. 

As units of capacity are defined in terms either of linear 
measures or of mass, the construction of suitable standards does 



240 EVOLUTION OF WEIGHTS AND MEASURES 

not present any particular difficulty, nor is any high degree of 
precision required, save in a few cases. In fact, standard 
measures of capacity are usually adjusted by means of the 
weight of a liquid such as water, taken at a certain temperature. 
As these measures are used in few experiments or determina- 
tions where extreme accuracy is called for, there is no need 
of observing particular precautions, either in their construction 
or their calibration. The standards are usually of some metal, 
such as bronze or gun-metal, of a regular geometrical shape, 
and are adjusted with water at a certain temperature. The 
purpose for which a measure of capacity is to be used is borne 
in mind in determining its shape, as with liquids it is not 
necessary to take into consideration the question, of compres- 
sibility or of heaping the measure which would be involved in 
the measurement of grain or vegetables. This, of course, does 
not affect the actual cubical contents of the measure, but merely 
considers its actual application in commerce. Thus, in Great 
Britain there have been various shapes adopted for standards for 
the liquid and dry gallon, and for the coal bushel, and for other 
measures, the exact dimensions of which are defined. In view 
of the great inaccuracy in measuring goods by capacity measures 
being unavoidable, it is the present tendency of metrology to 
use capacity measures as little as possible, and to recommend 
the use of weights, especially in business dealings. In Europe 
this practice is rapidly increasing among the metric countries, 
and in some of them nearly all articles of food and other 
necessities for daily life, even liquids such as oil, are bought and 
sold by weight. 

There is, however, one kind of standard of capacity where 
accuracy is important, namely, flasks, burettes, or other vessels of 
glass employed in physical or chemical experiments. These are 
calibrated carefully with water or mercury, whose volume at any 
specified temperature is known with exactness. Such standards, 
however, are not specially and exclusively maintained by national 
bureaus and direct comparisons made with them, but as their cali- 
bration involves little difficulty to the trained physicist or chemist, 1 

1 The calibration of chemical and other graduated glass-ware is one of the 
regular routine duties of the National Bureau of Standards at Washington, and 
is done for the technical public at reasonable and established fees. 



STANDARDS AND COMPARISON 241 

they are usually constructed in any laboratory where their use 
is desired. 

In the case of other standards, such as those of electricity, the 
most important are the ohm and the standard cell, which involve 
the realization of the international definitions 1 by careful scientific 
work. These definitions for practical purposes are so exact and 
the modes of construction so well understood by physicists that 
such standards can be constructed at national or other physical 
laboratories and bureaus of standards by trained investigators, 
and the results represent refined methods of manipulation and the 
use of specific apparatus rather than scientific work of such 
character as was involved in the construction of the international 
standards of length and mass. It should not be understood, 
however, that from the purely scientific point of view that 
electrical engineers and physicists are altogether satisfied with 
the present definitions. Consequently there is at present much 
important investigation in progress which has as its object the 
determination of new standards or new definitions, and at the 
Electrical Congress held at St. Louis in 1904 it was decided that 
steps should be taken to form an international electrical com- 
mission composed of official representatives, much after the fashion 
of the International Commission of Weights and Measures. The 
call for a preliminary meeting of delegates has been issued and 
the formation of this international commission in the near future 
is probable. From the discussion of the electrical units in the last 
chapter their independence on each other will be appreciated, so 
that it is necessary to determine whether the voltameter operating 
under standard conditions shall give the unit of current from 
which, with the ohm, may be derived the unit of electromotive 
force, or whether the unit of electromotive force as given by a 
standard cell shall be considered the fundamental source of the 
standards. 

There have been constructed by the Physikalisch-Technische 
Reichsanstalt at Berlin and the English National Physical 
Laboratory, primary mercurial standards of resistance in which 
the international definition of the ohm has been realized and 
the apparatus of these two laboratories shows substantial 
agreement of measurement, being in harmony to a few parts in 

1 See chapter ix. ante. 
Q 



242 EVOLUTION OF WEIGHTS AND MEASURES 

IOOjOOO. 1 Furthermore there are in England, preserved at the 
Board of Trade Electrical Standardizing Laboratory in London, 
actual standards of resistance, current and electrical pressure 
which have been duly legalized (Order in Council, August 23, 1894). 
Thus the standard ohm is the resistance between the copper ter- 
minals of the platinum-silver coil marked " Board of Trade Ohm 
Standard, verified 1894," to the passage of an unvarying electrical 
current, when the coil of insulated wire forming part of the 
aforesaid instrument and connected to the aforesaid terminals is 
in all parts at a temperature of 15*4 degrees Centigrade. 

The standard ampere is the current which passes in and through 
the coils of wire of the standard ampere balance, marked " Board 
of Trade Ampere Standard, verified 1894," when on reversing the 
current in the fixed coils the change in the forces acting upon 
the suspended coil in its sighted position is exactly balanced by 
the force exerted by gravity in Westminster upon the iridio- 
platinum weight marked " A" and forming part of said instrument. 

The British standard volt is one-hundredth part of the pressure 
which, when applied between the terminals of a Kelvin electro- 
static voltmeter of the multicellular type marked " Board of Trade 
Standard, verified 1894," causes a certain exactly specified amount 
of rotation of the suspended part of the instrument. 

While various other standards are of course possessed by the 
different national laboratories and testing bureaus, yet they aim 
rather at representing specifically the definitions of the various 
units, than, as in the case of the British Board of Trade, employing 
as national standards the mere concrete apparatus. The same 
holds true for standard barometers, thermometers, polariscopes, 
and other instruments of precision which are used for standardizing 
similar instruments used in science and industry. 

Having considered the general principles underlying standards 
and their construction and comparison, it may be advantageous to 
discuss briefly the weights and measures that have served this 
purpose in France and England, as well as the present metric 
standards. While it was legally possible to establish the inch by 
taking " three barley corns round and dry " as was provided by 
the statute of Edward II. and to raise a pound from 7680 grains 

x The first standard ohm was constructed privately by M. Benoit of the 
Bureau International. 



STANDARDS AND COMPARISON 243 

of wheat as was enacted by the statute of the Assize of Bread and 
Ale (51 Henry III., stat. 1, 1266), yet such means on their very 
face were manifestly lacking in accuracy, as there was nothing to 
ensure that the corns or grains would conform to a uniform 
standard. Consequently as early as the fourteenth year of the 
reign of Edward III. (1340) a royal edict was published ordering 
" standard weights and measures to be made of brass, and sent 
into every city and town in the kingdom." This necessary and 
excellent law, however, merely followed the precedent made by 
Eichard I., who ordered that standard measures of length should 
be made of iron and that those for capacity should have iron 
brims, and that standard measures of every kind should be kept 
by the sheriffs and magistrates of towns. While it cannot be 
said that this law was enforced, yet it shows that the government 
was alive to the necessity of proper standards in order to 
secure the desired uniformity and that their construction was 
constantly in mind. 

The earliest English standard of length extant is the Exchequer 
standard yard of Henry VII., which dates back to 1496. It is a 
brass bar of octagonal cross section whose length furnished the 
standard distance, and which is divided both into inches and also 
into sixteen equal parts on the basis of binary division. It was 
used until 1588, when in the reign of Queen Elizabeth a new 
standard yard, also of brass, was constructed, which is still in 
existence after having served for a long period as an original 
standard. It is a rectangular bar one yard in length, on which 
are indicated the divisions of a yard and also a similar bar forming 
an ell of 45 inches (exact length 45*04 inches), there being a 
third and larger bar with two beds or matrixes into which both 
of the end standard bars could fit, and having at one end of the 
yard bed a subdivision into inches and half inches. It may be 
said in passing that both the standards of Henry VII. and of 
Elizabeth are essentially of the same length, and they are only 
about '01 inch shorter than the present British imperial standard. 
The Elizabethan standard did duty until well into the nineteenth 
century, in spite of the fact that some time between 1760 and 
1819 it had been broken and mended by means of a dovetail 
joint in a rather crude fashion. In fact this ancient standard has 
been spoken of most contemptuously by F. Baily, who examined 



244 EVOLUTION OF WEIGHTS AND MEASURES 

it in 1836, he even going as far as to call it disgraceful for the 
British government to issue certificates and construct copies 
based on it as representing the English standard. 1 

A line standard constructed by Bird in 1760, under the 
authorization of the Committee on Weights and Measures of 
the House of Commons, was based upon a standard made by 
the same maker in 1742 for the Royal Society, and on a line 
standard which he constructed in 1758. The former has been 
pronounced by H. W. Chisholm, an authority on British 
metrology, to be " the first scientifically constructed measure 
of length in this country " (England). 2 The Bird standard of 
1760 was approved by the Committee, and, though not at that 
time legally established, formed a basis for a number of 
secondary standards. It was eventually adopted as the legal 
standard of Great Britain by an Act of Parliament promulgated 
June 17, 1824, and served as such until its destruction in the fire 
which consumed the Houses of Parliament in 1834. The adop- 
tion of this standard, however, at this time was hardly warranted 
in view of the state of scientific knowledge, or by the actual 
character of the standard itself. It was a brass bar, 1*05 inch 
square and 39'73 inches in length, with gold plugs near the ends, 
on which were points or dots, the distance between which at the 
temperature of 62 degrees Fahrenheit (16*7 degrees Centigrade) 
represented the standard yard. This standard bar, however, in 
addition to being of comparatively crude construction, even at 
the time of its legal adoption had become badly worn by rough 
treatment. By the use of beam-compasses, and in various rough 
comparisons, the dots had become worn, so that under the micro- 
scope they were seen to appear like the craters of small volcanoes, 
and consequently rendered the bar quite unsuitable for exact 
scientific work. In the Act by which this standard was estab- 
lished it is clear that the idea of a natural standard was still 
cherished, since it provided that in the event of the loss of 
the standard yard it should be restored by means of a reference 

1 See H. W. Chisholm, ' ' Seventh Annual Report of the Warden of the Standards, " 
1872-3, English Parliamentary Papers, Reports from Commissioners, 1873, vol. 
xxxviii. pp. 25 and 34; also id. "Weighing and Measuring" (London, 1877), pp. 
50-54. See also footnote, p. 36, ante. 

2 See Chisholm in same Report, p. 10, for full description of this and other 
standards. 



STANDARDS AND COMPARISON 



245 



to a pendulum beating seconds in a 
vacuum, at the latitude of London 
and reduced to sea level, which would 
have the relation to the yard of 
391393 to 36; but in spite of this 
statutory provision, when the standard 
yard was destroyed ten years later no 
recourse was had to the seconds' 
pendulum, as that method seemed then 
incapable of furnishing the standard 
with sufficient exactness, and the stan- 
dard yard was reconstructed from other 
standards in the possession of the 
Government and scientific societies 
which had been compared with the 
standard of 1760. These included the 
five-foot brass standard scale of Sir 
George Shuckburgh which was made 
by Trough ton, of London, in 1796, two 
iron standards made for the Ordnance 
Survey in 1826-7, the brass tubular scale 
of the Royal Astronomical Society, and 
the standard yard of the Royal Society 
constructed under Captain Kater's 
direction in 1831. The Shuckburgh 
scale was based on a five-foot scale 
made and used by Troughton, which in 
turn was constructed from an accurate 
90-inch brass scale made by Bird. 1 

This imperial standard yard, as well 
as the imperial standard prepared 
under the direction of a Parliamentary 
Committee appointed in 1843, were 

x See W. Harkness, "Progress of Science as 
Exemplified in the Art of Weighing and 
Measuring," Bulletin, Philosophical Society of 
Washington, D.C., vol. x. ; Smithsonian Miscell- 
aneous Collection, vol. xxxiii. 1888, pp. 43 et seq. 
Present State of the Question of Standards of Length," Proceedings, American 
Academy of Arts and Sciences, vol. xv. 1879-80, pp. 273 et seq. 




British Imperial Yard. 



Also W. A. Rogers, " On the 



o 



246 EVOLUTION OF WEIGHTS AND MEASURES 

duly legalized in 1855 (18 and 19 Vict. c. 72) by an A.ct 
known as the Standards Acts, whose provisions as regards 
these standards were re-enacted in the Weights and Measures 




British Imperial Standard Yard. Cross-section. (Exact size.) 
1. — Section of Bar. 2. — Section through holes. 

Act of 1878. These standards, as they represent the best 
practice of the time of their construction, and as they are 
the present standards of Great Britain, may be briefly de- 
scribed. 1 The imperial standard yard is a solid square bar 
of a special bronze or gun-metal known as Baily's metal, 
composed of copper 16 parts by weight, tin 2 J, and zinc 1. 



Diagram Showing British Imperial Standard Yard from above, a— a=l yard. 

It is 38 inches in length, with a cross section one inch square, 
and has near its ends two circular holes or wells sunk to a 
point midway the depth of the bar. In these wells are inserted 
two gold studs, on which the fiducial lines are engraved, the 
distance between them forming the imperial standard yard of 36 
inches at a temperature of 62 degrees Fahrenheit (16j-° C). This 
imperial standard, as also the imperial standard pound, is pre- 
served in a strong fire-proof room at the Standards Office in 
Old Palace Yard, Westminster, and copies are deposited at 

1 G. Airy, ' ' Account of the Construction of the New National Standards of 
Length, and of its Principal Copies," Philosophical Transactions (London), 18th 
June, 1857. 



STANDARDS AND COMPARISON 247 

the Royal Observatory, Greenwich, the Royal Mint, the Royal 
Society, and the Houses of Parliament. The latter are specially 
designated by statute as Parliamentary copies, and must be com- 
pared with the imperial standard once in every ten years, since 
in the event of the possible destruction of the latter they would 
furnish the source from which a new standard would be derived. 
There were in addition thirty-five other standards made of the 
same size and of the same material, which were duly compared 
with the prototype, and were distributed to the various nations of 
the world and to scientific institutions in Great Britain and else- 
where. One of these standard bars, by Act of Parliament, June 
30, 1855, was presented to the United States Government, and 
was known as "Bronze Standard No. 11." It is '000088 inch 
shorter than Bronze Standard No. 1, which was chosen as the 
imperial standard. It was accompanied by a malleable (Low 
Moor) iron standard of length, No. 57, and standard weight No. 5, 
the correction for each standard being given over the signature of 
G. B. Airy, Astronomer-Royal. 1 

These two yards, particularly the bronze standard, were so 
much superior to the Troughton scale that they were accepted 
by the United States Office of Weights and Measures as the 
standards of the United States, and in this way comparisons 
of American measures of length were made with the imperial 
yard. In 1876, and again in 1888, they were taken to England 
and were compared with the British standards. 

In 1904, the late H. J. Chany, Warden of the Standards, caused 
to be constructed and standardized at the International Bureau a 
platinum-iridium bar similar in composition and section to the inter- 
national meter, and while this has not as yet any legal standing, 
it is perhaps the best representative of the British yard. 

The oldest authenticated British standards of weight date from 
the reign of Queen Elizabeth, and consist of three distinct sets. 
The first of these are bell-shaped standards of bronze for the 
heavier weights, and range from 56 lbs. to 1 lb. inclusive. They 
are of importance, as from the time of their construction in 1588 
until 1824 they were the standards of the kingdom. Then there 

1 See Report, Superintendent U.S. Coast and Geodetic Survey, 1877, Appendix 
12, p. 154, for description of these standards of length. See also Executive 
Document 27, 34th Congress, 3rd Session, p. 17. 



248 EVOLUTION OF WEIGHTS AND MEASURES 




is a series of flat circular avoirdupois weights from 8 lbs. to T ^ 
of an ounce, and a set of cup-shaped Troy weights which, with the 
exception of the very small weights, fitted into each other. These 
standards had been prepared under the direction of a committee 
of merchants and goldsmiths, who employed as the basis for 
avoirdupois weight a 56 lb. standard of the Exchequer dating from 
Edward III., and for Troy weight the 
ancient standard of the Goldsmiths' Hall. 

About 1758 the Parliamentary Com- 
mittee, to which we have before referred, 
caused to be constructed three standard 
Troy pound weights, but like the yard of 
the same period none of these was legalized 
until 1824, when one of the weights was 
chosen as the government standard, only 
to be destroyed by the fire of ten years 
later. On the recommendation of the 
Standards Committee of Parliament, made 
in a report submitted December 21, 1841, 
the British imperial standard of weight 
was changed from a Troy pound of 5760 
grains to an avoirdupois pound of 7000 
grains, and a standard representing the- 
latter was constructed in 1844 and duly 
legalized in 1855. After much discussion 
and a careful examination of existing 
standards it was found necessary to use 
almost exclusively two platinum weights, one belonging to the 
Eoyal Society and the other to Professor Schumacher, whose 
values were accurately known in terms of the lost standard. 
The new standard, which is indeed the present imperial standard, 
is of platinum, cylindrical in form, 1*35 inches in height, and 
1*15 inches in diameter. Its density as compared with distilled 
water is 21*1572, and it displaces *403 grains of air under 
standard conditions. 1 It has a slight groove or channel near its 
upper surface by which it may be moved with a fork of ivory, and 

1 W. H. Miller, "On the Construction of the New Imperial Standard Pound, 
etc.," Philosophical Transactions (London), 1st June, 1856. H. W. Chisholm,. 
Weighing and Measuring (London, 1877). 




British Imperial Standard 
Pound. (Exact size.) 



STANDARDS AND COMPARISON 249 

bears on its upper surface the inscription "P.S.I 844, 1 lb.," the letters 
signifying Parliamentary Standard. Copy No. 5 was presented to 
the United States in 1856. The British units of capacity, the 
gallon and the bushel, are based on the fact that an imperial 
gallon represents the volume occupied by ten imperial pounds of 
distilled water at 62 degrees Fahrenheit and a barometric pressure 
of 30 inches, while the bushel is eight gallons, 1 The imperial 
standard gallon bears the date of 1828 and is of brass, with a 
diameter equal to its depth. The imperial bushel standard is of 
gun-metal, with a diameter twice that of the depth, these latter 
dimensions being selected on account of the applicability to the 
use for the measure of grain. It dates from 1824, and was 
verified in the following year. 

The French standard of length previous to the completion of 
the Meter of the Archives was the Toise de Perou, to which 
reference has already been made. It was constructed for use in 
making the base measurements for determining the length of the 
Peruvian arc of the meridian and the verification of the arc 
passing through Paris, being derived from the Toise du Grand 
Chatelet, which dated back to 1668. This latter standard was a 
bar of iron which was fixed in the wall of the Grand Chatelet, 
forming an inside end standard by which all scales could be tested 
by simply placing them between the limiting ends. This naturally 
deteriorated from exposure and wear, and, as a result, the Toise 
de Perou was substituted for the Toise du Grand Chatelet, as the 
French standard of length, in 1766, and is now preserved at the 
Observatory in Paris. It is an end standard of polished iron, 
somewhat greater than a toise in length and of rectangular 
section, 17 lignes in breadth and 4-^ lignes in thickness. At each 
end of the bar a rectangular portion extending to a line midway 
of the breadth was removed, and the standard distance was taken 
between the edges of the remaining portion of the bar, at a point 
about one ligne from the median line. On the longer part of the 
bar two lines were traced, with points marked at their centers, so 
that the distance between them was exactly a toise, with the result 
that an end standard was combined in the same metal bar with 
the more exact line standard, — there being, however, a difference 

1 Henry Kater, "Verification of Standard Gallon," Philosophical Transactions 
(London), 1826. 



250 EVOLUTION OF WEIGHTS AND MEASURES 

between the two scales of about "1 of a millimeter, a quantity 
which was readily negligible in the metrology of those days. 
The bar was standard at a temperature of 13° Reaumur (16°*25 C. 
or 61°'25 F.) and has been found equal to 1-949036 meter at 0° C. 

The French standards of weight were a series of weights 
known as the Pile of Charlemagne, and dating back to the reign 
of that king (about 789). Together they aggregated 50 marcs, 
as the unit of the series was termed, or 25 livres poids de marc 
(pounds), and in standardizing weights the sum of the pile was 
usually taken as the standard. These weights are now preserved 
in the Conservatoire des Arts et Metiers at Paris, and have 
figured in many comparisons. 1 

With the experience which the French scientists had gained 
in their brilliant geodetic work during the 18th century, it was 
possible to employ new and more accurate standards of length 
in the measurements of the base lines. Accordingly, for the 
purpose of making this fundamental measurement in determining 
the length of the earth's quadrant, four compound standard bars 
of novel form were designed and constructed by Borda, each 
of which was two toises in length, six lignes in width and almost 
one ligne in thickness. 2 Each bar consisted of a strip of platinum 
connected permanently at one end with a strip of copper, which 
otherwise was free to move longitudinally as it expanded or 
contracted. At the opposite end the copper was cut away for 
a short distance and a movable rod of platinum was provided, so 
that an exact and variable setting could be made by means of 
a divided scale and vernier. As the two metals had unequal 
coefficients of expansion, it was possible, by determining their 
relative expansion, as indicated by a graduated scale and vernier, 
to obtain not only a true measure of length, but also the 
temperature of the bar. This was accomplished by first standard- 
izing the bars in the laboratory and measuring the relative 
expansion corresponding to a certain number of degrees. 3 In 

1 See C. Mauss, La Pile de Charlemagne (Paris, 1897). A mathematical 
discussion of these weights. 

2 See Borda, " Experiences sur les regies destinees a la mesure des bases de l'arc 
terrestre," Delambre and M^chain, Base du Systeme Me'trique, vol. iii. p. 313. 

3 These bars of Borda were studied and standardized by Lavoisier. See Chisholm 
in Nature (London), vol. ix. p. 185, Jan. 8, 1874. See also Dumas, Works of 
Lavoisier, vol. v. 



STANDARDS AND COMPARISON 251 

use in the field, these bars were placed end to end and were 
carefully levelled. One of them was considered as a standard, 
and to this all measurements were referred, including that of 
the seconds' pendulum, and when the length of the meter was 
evaluated, it was obtained in terms of the fraction ('256537) 
of this modulus. 1 

Compensated bars of this form found increased use in the 
measurement of base lines in geodetic surveys until well into 
the 19th century, though they have been largely displaced by the 
employment of bars of a single material, or steel tapes or wires 
whose temperature coefficients are accurately known. In the case 
of the metallic bars, in one of the most accurate base measurements 
to which reference has already been made, viz., that at Holton, 
Mich., which was made in connection with the transcontinental 
survey of the United States, the distance was measured by means 
of a bar carried in a trough of melting ice. 2 

In passing from these standards of Borda to the meter, use 
was made of the comparator of the Committee, and that of 
Lenoir, already described. A provisional standard of brass, first 
constructed, served as a means of connecting the two measure- 
ments. Finally, when sufficient data had been obtained and 
computed to justify the construction of a definite standard, it 
was made from a mass of platinum as nearly pure as possible 
and of a rectangular section. It was an end standard 4 milli- 
meters in thickness and 25 millimeters in breadth becoming the 
Meter of the Archives. 3 From the same material and at the 
same time were constructed two other standards, which differed 
only in having a thickness of 35 millimeters. These have since 
been known as the Meter of the Conservatory and the Meter 
of the Observatory. 4 

1 Benoit, " Dela Precision dans la Determination des Longueurs en Metrologie," 
Rapports presented au Congres International de Physique (Paris, 1900), vol. i. 
p. 34. Bigourdan, Le Systeme Metrique (Paris, 1900), p. 83. C. Wolf, " Recherches 
historiques sur les etalons des poids et mesures de l'Observatoire," Annales de 
I'Observatoire {Memoires), Paris, vol. xvii. p. C 36 et seq. 

2 See note ante, p. 141, chapter v. 

3 For Cross-section see illustration on p. 252. No. 1 is the Meter of the 
Archives. 

4 C. Wolf, "Recherches historiques sur les etalons des poids et mesures de 
l'Observatoire," Annales de V Observatoire (Me'moires), vol. xvii. p. 52. 



252 EVOLUTION OF WEIGHTS AND MEASURES 

The construction of the actual meter was accomplished by- 
using a number of auxiliary rules, which being placed end to 
end and compared both among themselves and with the modulus, 
enabled the true length of the meter to be obtained. This 
proceeding involved considerable careful mathematical work as 
well as manipulative skill, and was accomplished with a remark- 
able degree of precision, considering the apparatus at the disposal 
of the investigators. In fact, it is fair to say that modern work 
of this character is more exact only through the improved instru- 
ments that an advance in mechanical and scientific knowledge 
has made possible, rather than in any greater skill and carefulness 
on the part of the observers. 

Although a large number of standards of a secondary character 
were constructed by the different bureaus established for this 
purpose by the French Government as well as by instrument 
makers, but little advance was made as regards their form and 
general character. In most of them the rectangular shape was 
preserved, and though, by the use of the microscope, a more 
accurate division was possible, yet no standards of high precision 
were attempted. When, however, the custody of the standards 
and their verification was assigned to the Conservatoire des Arts 
et Metiers, more interest was taken in this work, and with the 
installation of new comparators, the scientific staff of that institu- 
tion began researches which led to substantial improvements. 
It was due to M. Tresca, who was Assistant Director, that a 
thorough study of the shape and material of standards was 
undertaken, the results of which were placed at the service of 
the International Commission, when it assembled in 1870. 1 

The French Committee, of which he was a member, recom- 
mended in preparing the specification for the international meter, 
that the new standard should be a line standard, having a cross- 
section sufficient in form and dimensions to preserve accurately 
the shape of the bar, and that its coefficient of expansion should^ 
be as nearly as possible that of the meter of the Archives. The 
platinum which went to make up this original standard contained 
also iridium, together with a small amount of palladium, and 
it was deemed desirable, in constructing a new prototype, to 

1 See Tresca, Appendix 7, Annates du Conservatoire des Arts et Mi '.tiers > 
vol. x. 1873. 



STANDARDS AND COMPARISON 



253 



employ an alloy of platinum, with one-tenth part of iridium, as 
devised by H. Sainte- Claire Deville, since as such a combination 
filled the required conditions of inalterability, homogeneity, 



r 



R 



u 



n 




H 



CI 



rj 



12 



df~ b 




Cross-Sections of Standards (Studied by Tresca). 
1. — Meter of the Archives. 8. — Provisional Standard of Platinum Iridium. 

9, 10, 12.— H Standards. 13, 14, 15.— X Standards. 

durability, and small expansibility under the influence of tem- 
perature. In addition, it was susceptible of taking a high polish, 
and possessed numerous other physical and chemical advantages 
which made it particularly suitable for this purpose. 1 

1 Bigourdan, Le Systeme M&rique, p. 274. 



254 EVOLUTION OF WEIGHTS AND MEASURES 

In preparing the standards of length, it was realized by the 
Commission at the outset that two essential conditions must 
be fulfilled, viz., that the metal bars should be as rigid as pos- 
sible, without employing such a quantity of the platinum alloy 
as would make their cost prohibitive, and, secondly, that the 
lines marking the divisions must be placed in the plane of the 
neutral fibres. M. Tresca, who had given the subject of 
standards careful study, reported to the Commission on their 
form, and stated the essentials which must be observed in the 
construction of a new standard meter. He called attention to 
the fact that it was necessary that the distance between the 
two limiting lines should lie entirely in a plane which would 
contain the various centres of gravity, and this condition could 
only be obtained by making the bar of such cross-section that 
it would have the greatest rigidity. He also deemed it essential 
that the cross-section should be uniform throughout the length 
of the bar, and that the median plane on which the lines were 
traced should be available for tracing the necessary divisions, 
and for observation with the microscope of the comparator. M. 
Tresca carried on a series of experiments and investigations with 
bars of different cross-sections for which he calculated the 
mechanical constants, and, as a result of the studies, he came 
to the conclusion that the most suitable form for the standards 
of length was the bar of X section, as shown in the accompany- 
ing figures. 

«.,, zo m ™. „ m 2o m ri m 



I I \ Li I I \ Li 

1 2 

Cross-Section of Standard Meter Bars. (Exact size.) 
1.— Line Standard. 2.— End Standard. 

It will be seen from the illustration that the median plane, 
or plane of the neutral fibres, lies exactly in the center of the 
bar, and is available for marking any necessary lines or 
divisions. This is the case with the line standard. For the end 



STANDARDS AND COMPARISON 255 

standard he adopted a somewhat similar section, but with the 
cross-bar relatively higher, so that the median plane passed 
through its center instead of being situated in its upper surface, 
as in the case of the line standard. The section in either case 
would be included in a square 20 mm. on each side, and the 
diagram represents accurately the actual size and figure of the 
section. 1 

As compared with the Meter of the Archives, the new stan- 
dard proposed by Tresca had a profile 1*509 times as great, 
so that the actual quantity of material involved was but slightly 
more than a third, but the form of construction made possible 
far greater strength and rigidity, while at the same time the 
standard distance was measured in the neutral plane. These 
recommendations were duly adopted, the material was prepared 
according to the above specifications, and the bars were delivered 
to the Conservatoire des Arts et Metiers, where the standards 
were constructed by the French section under the terms of the 
international agreement. 

In the comparison of the prototype meters among themselves 
and with the international standard, the first step was to con- 
struct a provisional meter, whose constants were determined 
directly in terms of the Meter of the Archives. For this purpose 
a comparator with a transverse movement was employed, while 
for making the definitive marks on the bars a longitudinal 
comparator was used. The comparisons between the Meter of 
the Archives and the provisional meter were made at the Conser- 
vatoire des Arts et Metiers. The standard bars were taken to the 
Bureau International, where was made a series of comparisons 
which established their relations to each other, as well as to the 
international prototype. 2 Of the thirty bars thus examined, the 
one that approached most nearly the length of the Meter of 
the Archives was selected as the international prototype, and 
a new scale was chosen to take its place in the series of 

^uillaume, La Convention du Metre (Paris, 1902), pp. 15-18; Benoit, " De 
la Precision dans la Determination des Longueurs en Metrologie," JRapports, 
Congres de Physique (Paris, 1900), tome i. p. 48. 

2 See U.S. Coast and Geodetic Survey Report, 1890, Appendix 18, pp. 743 et seq. y 
for a description of the construction of the standard meter bars ; also Bigourdan, 
Le Systeme Me'trique. 



256 EVOLUTION OF WEIGHTS AND MEASURES 

comparisons. As a result of these comparisons, the probable error 
of a single comparison was stated at ±0 - 12 /a — the probable error 
in the length of any one of the standards being stated at 
±0"04 jii} From the result of many years of comparison at the 
Bureau International, the conclusion is reached that the length 
of a standard can be absolutely guaranteed to an exactitude of 
about *2 micron at all usual temperatures. 2 

In the construction of standards of weights, the instrument 
makers of the eighteenth century had gradually become more 
proficient, and their work partook of greater precision, both in 
the weights themselves and in the balances. Nevertheless, no 
particular features are worthy of note until the kilogram of the 
Archives was constructed. This unit of weight, as we have seen, 
was defined as the "weight of a cubic decimeter of distilled water, 
taken at its maximum density and weighed in a vacuum." To 
realize such a definition in a standard would apparently involve 
the construction of a cubic vessel whose side was exactly a 
decimeter, and then ascertaining the weight of water contained 
therein. A measurement of this kind could be made by taking 
a vessel of regular form and known interior dimensions, but to 
determine its volume accurately by any process of measuring 
was a difficult, if not an impossible proceeding. Eecourse was 
had, accordingly, to the law of Archimedes, which states that a 
body immersed in a fluid loses an amount of weight equal to 
the weight of the volume of the fluid which it displaces. Con- 
sequently, in order to determine the weight of the displaced 
water, it was necessary to weigh a solid body of regular form, 
first in air, reducing to vacuum, and then in water, making 
suitable provision or correction for its temperature. * In order 
to determine exactly the volume of such a body, it must be 
constructed in a regular geometric form, such as a cube or a 
cylinder. The latter form was adopted in making the standard 
of weight by the Committee of the Meter, and Lefevre-Gineau, 
with the assistance of Fabbroni, standardized a hollow cylinder 
of brass, which was constructed for them by Lenoir. It was 
243*5 millimeters in height and diameter, and thus had a volume 

1 Benoit, Rapports, Congres International de Physique (Paris, 1900), vol. i. 
p. 63. 
Ubid. p. 66. 



STANDARDS AND COMPARISON 257 

slightly in excess of eleven cubic decimeters, and had a weight in 
water of about 200 grams. 1 The dimensions of the cylinder were 
•obtained with a lever comparator from a scale equal to the ^ 
part of the modulus (the double toise standard of Borda). As a 
result of these experiments, a theoretical value of 18827*15 grains 
{poids de marc) was assigned to the kilogram, and such a weight 
was constructed in pure platinum to be the prototype standard. 2 
Unfortunately, no record has been left to us of the methods 
employed in constructing such a standard. It is known, how- 
ever, that at the time when the platinum was prepared for the 
four standard meter bars, material was made ready for four 
cylinders destined for the standard kilogram. After adjustment, 
one of these was taken, and has since survived as the Kilogram 
of the Archives. It is unquestionable, however, that the same 
balance and weights employed in determining the weight of a 
cubic decimeter of water were used in these latter operations. 3 
During the first half of the 19th century, with the growth 
of experimental physics and with improvements of apparatus, 
new methods giving a high degree of precision were available for 
use with the balance. Consequently, in the construction of 
weights and in their reference to standards, much more precision 
was obtained than ever previously. This, however, did not cause 
any marked demand for new metric standards, although various 
physicists were of the opinion that the kilogram did not repre- 
sent accurately the mass of a cubic decimeter of water. These 
determinations, however, varying as they did — being both greater 
and smaller than the Kilogram of the Archives — did not inspire 
any greater degree of confidence. Accordingly, when it was 
proposed to construct new standards for the meter and the 
kilogram, it was decided to use the Kilogram of the Archives 
as the basis, and then by subsequent experiments determine 
its relation to the mass of a cubic decimeter of water at its tem- 
perature of maximum density. Accordingly, the International 
Commission made arrangements for such an investigation. 

^uillaume, La Convention du Metre, p. 5. 

2 For full description of the determination of the standard of mass, see 
Delambre and Mechain, Base du Systeme Me'trique, vol. iii. pp. 579-638 ; 
Bigourdan, Le Systeme Me'trique, p. 107. 

3 Bigourdan, Le Systeme Me'trique, p. 159. 

R 



258 EVOLUTION OF WEIGHTS AND MEASURES 

To this body, in 1879, three cylinders of platinum-iridium 
alloy, designed for standard kilograms, were delivered, and 
were then compressed in a powerful coining-press of the 
Paris Mint. They were then given to an instrument maker 
for approximate adjustment, and samples of the material were 
submitted to chemical analysis by Stas and Sainte-Claire 
Deville, it having been found by experiments at the Ecole 
Normale that the final density was 21*55. The first adjustment 
was made with the kilograms of the Paris Observatory, which 
were copied from that of the Archives, and for this purpose 
a balance of the Ecole Normale Superieure was employed. After 
the three standards had received their final adjustment at the 
hands of M. A. Collet, they were then compared with the Kilo- 
gram of the Archives, with the standards of the Observatory and 
the Conservatoire, and with the standard kilogram of Belgium,, 
and then final comparisons were made at the Paris Observatory, 
both the French section and the International Committee being 
duly represented. 1 

The volume of these three new standards was determined 
by hydrostatic weighings, and compared with that of the standard 
of the Archives, which, however, was determined by other methods, 
as it was not deemed advisable to place it in water. 2 The work 
was finished October 18, 1880, when the Committee submitted a 
report covering other duties. 

After a careful examination of these three kilograms among 
themselves, and with the standard kilogram of the Archives, the 
committee deemed it wise to select one which was known as 
Kill as the standard kilogram, rather than to make a series of 
additional comparisons with the other kilograms, to be constructed 
as national standards, in the course of which the platinum-iridium 
cylinder would doubtless experience a certain amount of injury. 
Accordingly, this was adopted in a formal resolution, at a meet- 
ing held October 3, 1883, and that kilogram has since been 
designated by |Ji, although it bears no mark. 3 

In the following year, after several attempts had been made to 
secure an alloy of the necessary purity, satisfactory material 

1 Guillaume, La Convention du Metre (Paris, 1902), p. 123. 

2 Ibid. p. 124. 

3 Bigourdan, Le Systeme Me'trique des Poids et Mesures (Paris, 1901), p. 365. 



STANDARDS AND COMPARISON 259 

suitable for the national prototypes was delivered in the form of 
forty cylinders. These were worked down to approximately the 
exact weight, and finished under the direction of the members of 
the commission and an elaborate series of comparisons was under- 
taken. 1 

The weighings were effected by means of the Rueprecht and 
Bunge balances already described, the latter being employed 
when comparisons were made with the international prototype, 
which, of course, was preserved most carefully from any deterio- 
rating influences. The constants were calculated separately for 
each standard, and they were found to agree within a limit of 
one milligram, and were accepted by the International Committee, 
this decision being formally sanctioned at the International Con- 
ference in 1889. Originally it had been determined to insist on 
an accuracy of '2 of a milligram for each kilogram, but in certain 
cases it was found that the polishing had been carried on too 
vigorously, and it was accordingly found necessary to fix the limit 
of accuracy at one milligram, within which limits the forty 
standards all fell. For example, those given to the United 
States, in the drawing by lot (Nos. 4 and 20) were found to have 
an error of — '075 milligram and — '039 milligram respectively. 2 

The permanence of the national standards of mass is no less 
important than that of the standards of length. After about 
ten years there was made at the Bureau International a com- 
parison of eight standards from seven different nations with the 
working standards of the Bureau, and it was found that the 
deterioration experienced was barely appreciable, ranging as it 
did from '027 milligram in the case of one of the Belgian 
standards, to '001 of a milligram in the case of that from 
Roumania. It was possible that the deterioration in the case 
of some of the kilograms which had experienced considerable 
usage, was as much as '04 of a milligram, but it was believed that 
the future would not show as great an amount of change. 3 

The idea of the founders of the Metric System to establish a 
unit of length which would be absolutely invariable, by means of 
its reference to the dimensions of the earth, and also by reference 

1 Guillaume, La Convention du Metre, p. 125. 2 Ibid. p. 126. 

3 Ibid. p. 127. Also Report by M. Benoit in Proces-Verbaux des Seances de 
1900, ComiUs International des Poids et Mesures. See also Proces- Verbaux, 1905. 



260 EVOLUTION OF WEIGHTS AND MEASURES 

to the seconds' pendulum, was not destined to survive. It soon 
was seen, in view of subsequent researches, that the trigono- 
metrical operations on which the length of the meter was based 
were not carried on with an exactitude required by modern 
methods of geodetic work, and that, as a result, the standard was 
in error by about *1 millimeter. This did not detract from the 
usefulness of the system, but it did require the abandonment of 
the idea of referring the meter to the ten-millionth of the earth's 
quadrant as a natural standard. A century after the Metric 
System was established, it was found possible to realize the 
condition of reference to a natural and invariable standard, which 
was at that time thought so fundamental, and the meter was 
defined in terms of wave-length of light, after a series of most 
elaborate experiments carried on at the International Bureau of 
Weights and Measures by Professor A. A. Michelson, later of the 
University of Chicago, who had previously distinguished himself 
by his accurate determination of the velocity of light. 

The fundamental idea of using a wave-length of light was by 
no means new, as a unit of this nature had been proposed by 
J. Clerk Maxwell, 1 who suggested that a system of absolute 
units could be founded on the following basis : 

As a unit of length, the wave-length of some determined kind 
of light in vacuo, 

As a unit of time, the period of vibration of this light, 

As a unit of mass, the mass of a single molecule of a specified 
substance. 

By determining a unit of length in terms of wave-lengths of 
light, a standard would be obtained independent of any gradual 
contraction of the terrestrial globe, which naturally would produce 
a change in the length of the meridian, or other terrestrial 
disturbance. Likewise, it would be independent of molecular 
changes occurring in a metallic bar, and naturally affecting its 
dimensions. The length of a wave of light would under all 
conditions be most invariable, as it depends solely on the 
elasticity of the ether. Such a unit, then, gives us a means of 
establishing the permanent values of the meter, as by determining 
its length in these minute distances represented by the vibration 
of particles producing one kind of light, we have a much better 

1 Maxwell, Electricity and Magnetism (third edition, Oxford, 1891), vol. i. pp. 3, 4. 



STANDARDS AND COMPARISON 261 

means of fixing its invariability than by comparing it with the 
length of a meridian or with the seconds' pendulum. 

In order to define the standard of length in terms of the 
wave-length of light, a study of different sources of light was 
essential, and was carried on by Professor Michelson with great 
thoroughness. For this purpose, he used the luminous vapors of 
metals produced by the passage of an electric current from the 
induction coil through a vacuum tube. By a process of elimina- 
tion, he found that the most suitable source of light was the 
spectrum furnished by the metal cadmium, which gave a series of 
lines valuable for his purpose. The visible spectrum of this 
metal consisted of four groups of lines, — one red, which was single 
and also fine ; the second, a series of fine green lines ; the third, 
a blue line ; the fourth, a violet line. In his early experiments, 
Professor Michelson used the green rays, but in later work, 
especially by M. Hamy and M. Chappuis, the others were 
employed and greater precision was attained. 1 

Professor Michelson's method is based on the fact that inter- 
ference is produced in a beam of light after two of its component 
parts are compelled by means of reflection to travel distances 
slightly unequal. The earliest application of this principle of 
interference in metrology was when Fizeau endeavored to 
determine accurately the coefficients of expansion of samples of 
various substances. By placing a plano-convex lens over and 
very close to the terminal surface of the body to be studied, and 
causing a beam of sodium (yellow) light to fall from above on the 
lens, he was able to obtain the optical phenomenon known as 
interference by observing the reflected beam. This was similar 
in nature to the well-known experiment called Newton's rings, 
where the difference in path of the rays of light reflected from 
the surface of a body and those reflected from the surface of the 
lens produces interference. The reason for this is found in the 
fact that waves of monochromatic light, when so impeded that a 
part of them lose a half-wave length or some odd number of 
half-wave lengths, will neutralize each other, and consequently 
produce darkness when they reach a certain point. This is due 
to the particles at this point being under the influence of waves 
in opposite phases. If, on the other hand, where they meet, the 

1 Guillaume, La Convention du Metre, p. 147. 



262 EVOLUTION OF WEIGHTS AND MEASURES 

number of half-wave lengths is even, there is increased effect, 
which is manifested by greater brightness. In the case of a lens, 
arranged as above, there would be a series of alternate light and 
dark concentric rings. If white light is used, these rings will 
show spectral colors, which become complex with an increase in 
distance from the center. With such an arrangement, Fizeau was 
able only to measure short distances, which did not exceed 12 or 
15 mm. in length. His method was useful, however, in measuring 
accurately the screw of the micrometer of the comparators. 1 

Using the same idea, but developing it practically, Professor 
Michelson was able to measure the length of the meter in terms 
of waves of light. Part of the difficulty was solved by the 
American physicist when he found a suitable source of light, as 
has been described above, but it was largely due to his ingenious 
methods and apparatus, as well as to his manipulative skill, that 
he was able to carry his plan to so successful a conclusion. 2 His 
arrangement was, in substance, as follows : Light from the given 
source, S, was allowed to fall on a glass plate at A, ground so 
that the surfaces were perfectly plane and parallel. This plate 
was placed obliquely to the axis of the beam and on the side A 
was silvered, so that it formed a semi-transparent reflector. The 
beam falling on this silvered surface was divided into two parts, 
one of which passed through the silver film and glass, and after 
reflection at E in the mirror B to a mirror, N t from which it 
was reflected back through the glass plate to the interior 
surface of the film, where it underwent reflection again, 
back through the glass and to a telescope, T, so arranged as to 
enable the fringes produced in its field to be observed. The other 
part of the beam was reflected at the silvered surface and trans- 
mitted through a second glass plate, Q, whose thickness was equal 
to the first, to a mirror, M, where it was reflected back through 
the first plate in the same direction as the first beam. Both 

1 J. Rene Benoit, "Etudes sur l'appareil de M. Fizeau pour la mesure des 
dilatations appartenant au Bureau International des Poids et Mesures," vol. ii. 
Travaux et M6moires, Bureau International des Poids et Mesures, Paris. 

2 Guillaume, La Convention du Metre (Paris, 1902), pp. 146-169. A. A. Michelson, 
"Determination expe>imentale de la valeur du metre en longueurs d'ondes 
lumineuses," vol. xi. Travaux et Mdmoires, Bureau International des Poids et 
Mesures, Paris. 



STANDARDS AND COMPARISON 263 



H 





A 



V 



264 EVOLUTION OF WEIGHTS AND MEASURES 

beams meeting at the telescope, interference phenomena would 
appear if there were any difference in the length of their respective 
paths, ADFEFDAC and ABAC. By displacing one of the mirrors 
by a small amount through the agency of a screw, this difference 
of position could be measured in terms of wave-length. The first 
task of the investigator was to determine the length of a very short 
standard by displacing the fringes for a counted number of wave- 
lengths. Then with this as a standard, he would be able to construct 
a standard twice as long and derive its length in wave-lengths. In 
this way Professor Michelson prepared a number of standards of 
lengths, each double the length of another, so that he was able to 
step from one to the other and at the same time preserve the 
original accuracy, Finally he standardized a piece one decimeter 
in length, and with this he made a comparison with the inter- 
national meter, displacing it ten times and measuring the displace- 
ment by interference methods so as to start from the first line of 
the meter and then reach the second, and so on ; using three 
different kinds of light, viz. the red, green, and blue of the 
cadmium spectrum, he determined the wave-length of each or 
the number of times this wave-length was contained in the 
standard meter. The wave-lengths for each color were as 
follows : 

Red radiations 1 meter =15531 63 '6 \ R , of which k R = -64384722 /x. 

Green radiations 1 meter = 1966249*7 Xv, of which A F = "50858240 /x. 

Blue radiations 1 meter = 2083372-1 X B , of which A B = -47999107 /x. 

The accuracy of this work is almost incredible, as the 
variation in the measurements was only about one part in ten 
million. In fact, where a precision of from one-fourth to 
one-fifth of a micron is possible in the case of determining 
the relative length of two standards, here is an absolute 
measurement which gives the length of a standard in terms 
of a natural unit, under conditions reproducible at any time. This, 
of course, gives a permanent check on the integrity of the meter, 
as in the event of the international prototype being damaged 
or destroyed, sufficient data is at hand to enable such physicists 
as may be found at any international laboratory or bureau of 
standards to redetermine this fundamental unit. The apparatus of 
Professor Michelson represented the highest skill of the instrument 



STANDARDS AND COMPARISON 265 

maker, as mirrors and optical planes were finished to a high 
degree of exactitude, reaching in some cases an accuracy as 
great as 40 ^ 00 of a millimeter, or the -^ of the mean wave- 
length of light. 

Just what this work of determining standards of length in 
terms of the wave-length of light means to science can be readily 
understood if a moment's consideration be given to the enormous 
mass of scientific and technical literature and knowledge, to the 
numberless instruments of measurement and tools and appliances 
of trade. At first thought it would seem that if some cataclysm 
should suddenly destroy all these evidences of advancement, then 
the poor individual who might have survived would be compelled 
to begin all over again, and his standards and units would 
have to be new, and he would have no means of connect- 
ing his system with the past. All the observations on 
matters astronomical or terrestrial, all that mass of information 
which it has taken centuries and centuries to accumulate, would 
be hopelessly lost because of the break in the standards of 
measurement. The meter would be gone, the quadrant of the 
earth no longer the same, and apparently our last tie broken. 
ISTot all the ties, for one, a little one, remains, like hope in the 
bottom of Pandora's box. A wave of light so small that a 
thousand would scarcely reach across the eye of a needle, this 
is the key to the restoration of our system of most complicated 
and complete units. So long as the earth has a material exist- 
ence, so long as there is light and heat, so long is man in 
the position to rebuild his system of units and standards. 

The work of Michelson in comparing the international meter 
with the wave-lengths of light has put our system upon a 
foundation that is as permanent as the universe. If man were 
transported to the uttermost confines of the universe, he would 
still have the little waves of light, and they would be just the 
same as here. 

If some day we are able to communicate with the dwellers 
upon some other planet, it will be a simple thing to communicate 
to them our standard of length and time and mass, and with the 
little waves of light to convey our message we may ultimately 
impart our exact knowledge to them, and receive theirs in 
return. The laws of light motion, of gravitation, of electricity 



266 EVOLUTION OF WEIGHTS AND MEASURES 



are undoubtedly identical for the whole universe, and given 
the first communication of another world we would be 
able to establish a truly universal system of units and stan- 
dards. By this means inter-planetary communication would 
be placed upon a quantitative basis, and the omnipresent, ever- 
lasting, but ultra-microscopic wave of light would be the 
universal, unchanging standard. 



APPENDIX. 

TABLES OF CONVERSION FEOM COMMON TO METRIC 

MEASURES, USEFUL CONSTANTS AND 

EQUIVALENTS. 



NOTE. 

Unless otherwise specified, the following tables are based 
on the U.S. Legal Equivalents. They are derived for the 
most part from the Tables of Equivalents published by the 
National Bureau of Standards of the U.S. Department 
of Commerce and Labor. 



LEGAL EQUIVALENTS OF THE UNITED STATES. 
Act of July 28, 1866. Revised Statutes 3570. 

MEASURES OF LENGTH. 



Metric Denominations and Values. 


Equivalents in Denominations in Use. 


Myriameter, 


. 


10,000 meters. 


6-2137 miles. 


Kilometer, 


- 


1,000 meters. 


0-62137 miles or 3,280 feet and 10 inches. 


Hectometer, 


- 


100 meters. 


328 feet and 1 inch. 


Dekameter, 


- 


10 meters. 


393-7 inches. 


Meter, 


- 


1 meter. 


39-37 inches. 


Decimeter, 


- 


y (7 of a meter. 


3-937 inches. 


Centimeter, 


- 


y^jTj- of a meter. 


0-3937 inch. 


Millimeter, 


- 


ToVo" °f a meter. 


0-0394 inch. 



MEASURES OF CAPACITY. 



Metric Denominations and Values. 


Equivalents in Denominations in Use. 


Names. 


Number 
of Liters. 


Cubic Measure. 


Dry Measure. 


Liquor or 
Wine Measure. 


Kiloliter \ 
or Stere J 

Hectoliter 

Dekaliter 

Liter 

Deciliter 

Centiliter 

Milliliter 


1000 
100 
10 

1 

1 

TO" 

1 

TTT0" 

TO-TRF 


1 cubic meter 
YX7 of cubic meter 

10 cubic decimeters 
1 cubic decimeter 
To- cubic decimeter 
10 cubic centimeters 
1 cubic centimeter 


1 -308 cub. yards 

/ 2 bushels and \ 
\ 3 35 pecks J 
9-08 quarts 
0-908 quart 
6 -1022 cub. inches 
0-6102 cub. inch 
0-061 cub. inch 


264-17 gallons. 
26-417 gallons. 

2-6417 gallons. 
1 -0567 quarts. 
0-845 gill. 
0-338 fluid ounce. 
0-27 fluid dram. 



MEASURES OF SURFACE. 



Metric Denominations and Values. 



Equivalents in Denominations in Use. 



Hectare, 

Are, 

Centare, 



10,000 square meters. 
100 square meters. 
1 square meter. 



2-471 acres. 

119 "6 square yards. 

1,550 square inches. 



270 EVOLUTION OF WEIGHTS AND MEASURES 



WEIGHTS. 



Metric Denominations and Values. 


Equivalents in De- 
nominations in Use. 


Names. 


Number of 
Grams. 


Weight of what 
Quantity of Water at 
Maximum Density. 


Avoirdupois Weight. 


Millier or Tonneau 

Quintal 

Myriagram 

Kilogram or Kilo 

Hectogram 

Dekagram 

Gram 

Decigram 

Centigram 

Milligram 


1,000,000 

100,000 

10,000 

1,000 

100 

10 

1 

1 
To" 

TTTO 

1 


1 cubic meter 

1 hectoliter 

10 liters 

1 liter 

1 deciliter 

10 cubic centimeters 

1 cubic centimeter 

jjy cubic centimeter 

10 cubic milliliters 

1 cubic milliliter 


2204-6 pounds. 
220-46 pounds. 
22-046 pounds. 
2-2046 pounds. 
3-5274 ounces. 
•3527 ounce. 
15*432 grains. 
1 -5432 grains. 
0-1543 grain. 
0-0154 grain. 


1000 



BRITISH LEGAL (BOARD OF TRADE) EQUIVALENTS. 

May, 1898. 



LINEAR MEASURE. 



Metric. 

1 Millimeter (mm. ) (t o~Vo" m - ) 
1 Centimeter (y^xj m -) 
1 Decimeter \y$ m.) 

1 Meter (m. ) 

1 Dekameter (10 m.) 
1 Hectometer (100 m.) 
1 Kilometer 



003937 Ins. 
0-3937 Ins. 
3-937 Ins. 
' 39-370113 Ins. 
3-280843 Ft. 
. 10936143 Yds. 
10-936 Yds. 
109-36 Yds. 
•62137 Mile. 



1 Inch 

1 Foot (12 ins.) 
1 Yard (3 ft.) 
1 Fathom (6 ft.) 
1 Pole (54 yds.) 



Imperial. 

= 25-400 Millimeters. 
0-30480 Meter. 
0-914399 Meter. 
1-8288 Meters. 
5-0272 Meters. 



1 Chain (22 yds.) = 20-1168 Meters. 



1 Furlong 



: 201 168 Meters. 



1 Mile (8 furlongs) = 1-6093 Kilometers. 



BRITISH LEGAL EQUIVALENTS 271 

SQUARE MEASURE. 
Metric. 
1 Square Centimeter = 0*15500 Sq. In. 

1 Sq. Decimeter (100 sq. centimeters) = 15*500 Sq. In. 

1 Sq. Meter (100 sq. decimeter,) = { ™™ g; ^ 

1 Are (100 sq. meters) = 119*60 Sq. Yds. 

1 Hectare (100 ares or 10,000 sq. meters) = 2*4711 Acres. 

Imperial. 
1 Square Inch = 6*4516 Sq. Centimeters. 

1 Sq. Ft. (144 sq. ins.)= 9*2903 Sq. Decimeters. 
1 Sq. Yard (9 sq. ft.) = "836126 Sq. Meter. 
1 Perch (30£ sq. yds.) = 25*293 Sq. Meters. 
1 Rood (40 perches) = 10*117 Ares. 
1 Acre (4840 sq. yds.) = 0*40468 Hectare. 
1 Sq. Mile (640 acres) =259 Hectares. 

CUBIC MEASURE. 
Metric. 
1 Cubic Centimeter = '0610 Cubic In. 

1 Cubic Decimeter (c.d.) (1000 cubic centimeters) = 61*624 Cubic Ins. 

. « . . ., t /1AAA .. , . . > f 35*3148 Cubic Ft. 

1 Cubic Meter (1000 cubic decimeters) =■{ nrvf , neA ~ , . «.. 

I 1*307954 Cubic Yds. 

Imperial. 
1 Cubic Inch = 16*387 Cubic Centimeter. 

1 Cubic Foot (1728 cub. ins.) = 0*028317 Cubic Meter. 
1 Cubic Yard (27 cub. ft.) = 0*764553 Cubic Meter. 

CAPACITY. 

Metric. 

1 Centiliter ( T J<j liter) = *670 Gill. 
1 Deciliter ( T V liter) = *176 Pint. 
1 Litre = 1 *75980 Pints. 

1 Dekaliter (10 liters) =2*200 Gallons. 
1 Hectoliter (100 liters) = 2*75 Bushels. 

Imperial. 
1 Gill = 1 *42 Deciliter. 

1 Pint (4 gills) = *568 Liters. 

1 Quart (2 pints) = 1 *136 Liters. 
1 Gallon (4 quarts) =4*5459631 Liters. 
1 Peck (2 gallons) =9*092 Liters. 
1 Bushel (8 gallons) =3*637 Dekaliters. 
1 Quarter (8 bushels) = 2*909 Hectoliters. 



272 EVOLUTION OF WEIGHTS AND MEASURES 



WEIGHT. 
Metric. 



1 Milligram (iijjyjj grm.) = 
1 Centigram ( T J^ grm. ) = 
1 Decigram (y o g rm - ) = 
1 Gramme (1 grm.) = 

1 Dekagram (10 grm.) — 
1 Hectogram (100 grm.) = 

1 Kilogram (1000 grm.) = 

1 Myriagram (10 kilog.) = 
1 Quintal (100 kilog.) 
1 Tonne (1000 kilog.) 

1 Gramme (1 grm.) = 



1 Gramme (1 grm.) ==■ 

Imperial. 

Avoirdupois. 
1 Grain : 

1 Dram 

1 Oz. (16 drams) 

1 Pound (16 oz. or 7000 grains) = 
1 Stone (14 lb.) 
1 Quarter (28 lb.) 

1 Hundredweight (cwt.) (112 lb.) = { 

lTon(20cwt.) 

Troy. 
1 Grain 

1 Pennyweight (24 grains) 
1 Troy ounce (120 pennyweights): 

Apothecaries' Weight. 
1 Grain : 

1 Scruple (20 grains) : 

1 Drachm (3 scruples) -. 

1 Oz. (8 drachms) : 



Avoirdupois. 
0-015 Grain. 
0-154 Grain. 
1 -543 Grains. 
15-432 Grains. 
5-664 Drams. 
3-527 Oz. 
f 2-2046223 Lb. oz. 
115432-3564 Grains. 
22-046 Lb. 
1-968 Cwt. 
0-984 Ton. 
Troy. 
/ 0-03215 Oz. Troy, 
t 15-432 Grains. 

Apothecaries' Weight. 
( 0-2572 Drachm. 
| 0-7716 Scruple. 
I 15-432 Grains. 



0-0648 Gramme. 

1 -772 Grammes. 
28-350 Grammes. 

0-45359243 Kilogram. 

6 "350 Kilograms. 
12-70 Kilograms. 
50-80 Kilograms. 

0-5080 Quintal. 
/ 1-0160 Tonnes or 
U016 Kilograms. 

0648 Gramme. 

1 "5552 Grammes. 
31-1035 Grammes. 

0-0648 Gramme. 

1 -296 Grammes. 

3-888 Grammes. 

31-1035 Grammes. 



APOTHECARIES' MEASURE. 



1 Minim 

1 Fluid Scruple 

1 Fluid Drachm (60 minims) 

1 Fluid Ounce (8 drachms) 

1 Pint 



= 0-059 Milliliter. 
= 1-184 Milliliters. 
= 3-552 Milliliters. 
= 2-84123 Centiliters. 
= 0-568 Liter. 



1 Gallon (8 pints or 160 fluid oz.) = 4-5459631 Liters. 



EQUIVALENTS OF UNITS OF LENGTH 



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274 EVOLUTION OF WEIGHTS AND MEASURES 



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r- co 00 cp os t»< © >p © cp 
ph tJ< CO OS h 4* t~ © CM ■* 

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ee 


1-524 
4 064 
6-604 
9-144 
11-684 

14-224 
16-764 
19-304 
21-844 
24-384 


ta 


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CM GO CO GO T* OS lO © ip r-H 

rH CO CO 00 rH CO ©OS rH 4* 
PH pH rH rH CM CM 


tH 


cococococo cococococo 

hioo5coi> Hioa«t> 

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rH CO CO 00 rH CO CO 00 -H CO 
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00 


CM CM CM CM CM CM CM CM CM CM 

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00X00 00 00 0000000000 
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coiooo© cb «b oo © cb 

pH pH rH rH CM CM 


rH 


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ip © cp p-i r- CM r- cp op 

CM K5 t<- © CM >b t^ © CM 

rH rH rH rH CM CM 


3rd 
IS 


rHCMCO'cH lOCOfr-OOOi 





OS 


•35433 

•74803 
114173 
1 -53543 
1-92913 

2-32283 
2-71653 
3-11023 
3 50393 
3-89763 




00 


©©co©co co © © © © 

05©CC©t^ HH rH O0 O CM 

-* GO CM CO © C0t^©^00 

rH O ©© 00 00t^t>»CO»O 
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H ^H ^ CM CM CO CO CO 




fr- 


©ososos© OS' os © © © 

lO CM OS CO CO ©t^T*r-,CO 
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CM © © tH 00 CM © © rt< op 
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CM CM CM CM CM CMCMCMCMCM 

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lO lO »C «3 lO UO lfj lO lO »0 

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COO-*I>h 10 © CM © © 
cs©oor-t- © 10 10 t)h ■<* 

rH lO P C0 I>» r-< lO © C0 fr» 

rH rH CMCM CMC0C0 


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t- rH -^ CO CM UO © CO t- © 
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rH ip p CC t- rHippCOt^. 

^•^ CM Ol CM CO cb 


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00 


rH00»OCMOS ©co©t^co 

GO i-H lO © CM ©©T^t^rH 

<—t^<OGiGi OOQOlr^©© 

rH ip p CM © © T*< 00 CM © 

,1, ^ CMCMCM cbcb 


a 

rJ 

1— 1 

9 


CM 


t^-^HOOiO CM OS © CO © 
00 CM ©© CO t^©-*O0CM 
!>• t- © >C 10 tJi hh CO CM (M 

©•^OOpi© ©TfOOCM© 

^^ CM CM CM cb cb 




1— 1 


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CO CO CM CM fh ©©©0000 

©■*Op6l© ©THl^rHip 

^-,^ cm c>i cm cb cb 




O 



•39370 

•78740 
1-18110 
1-57480 

1-96850 
2-36220 
2-75590 
3-14960 
3 54330 




5 

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a 

3 

9 


THCMCOrH lOCOfr-OOOS 



276 EVOLUTION OF WEIGHTS AND MEASURES 



o 

o 
o 

1 

H 9 

rt cc^ o 

H^ 

'■ ^_ 

H 
« 

i— i 



11 

<U c3 


515625 
53125 
546875 
5625 

578125 
59375 
609375 
625 

640625 
65625 
671875 
6875 


703125 
71875 
734375 
75 

765625 
78125 
796875 
8125 


828125 
84375 
859375 
875 


890625 
90625 
921875 
9375 


953125 
96875 
984375 
000 


i-i 


a a 


t- •*» rH CO TtdHOOlO CM OS CO CO 
OSOSOSCO CO 00 t~ t- NO»tO 
© rH 00 CM CO O •* 00 CM © © i* 

co co co 4t< 4t< io io >o cb © t- t- 


OS CO CO O N-^HOO 
>0<OOtfS •** i*t rH CO 
CO CM © © Tf 00 CM CO 
t- CO CO OS 0)00 


>* rH 00 lO 
CO CO CM CM 
© Tf 00 CM 

CM CM <M CM 


CM OS © CO 
CM rH rH rH 
CO © ^f CO 
CM CO CO CO 
CM CM CM CM 

II II II II 


OS © CO © 

©©o © 

CM CO© 7* 

4ti 4ji o >b 

CM CM CM CM 
II II II II 


II II II II II II II II II II II II 


II II II II II II II II 


DO 
r*l 

to 


CO-JmcO NOOSSO rH CM CO rj< 

cococoeo eococo^ ■>*<"*•«*(•*« 


lO CC t~ 00 OS O rH CM 
■<*•*•<*<■<*< Tfl 2 lO MS 


co «* >o © 

"OiSflifl 


t-00 OS© 
lO IO »0 © 


1-h CM CO Ttl 

© © © © 


GO 

§ 

CM 

CO 


i~ CO OS O i-l (N 
rH rH rH CM CM CM 


CO •»* lO CO 
CM CM CM CM 


t» oo 

CM CM 


OS © 
CM CO 


r-i CM 
CO CO 


CO 

,3 
§ 

.-i 


os o H 


M co 


->* 


lO 


© 


oo 

a 

00 


>o 


© 


t~ 




00 






CO 






- 


Hn 










CM 


o 


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Z c« 

5«a 


lO >0 >0 lO lO iO 
CM >0 i- WON CM IO t— 

© CM CO >0 HSMO CO CM CO it} 
Or 1 CO CM CO CO OS O OOH1- 

i-icotjico r- os © cm -h< >o t~ co 

OOOO OOi-lT-l r-tr-ir+r* 


lO lO >o »o 

NK3N CHON 
HNWO © CM 00 O 
CO CO -h © lO i— 1 CD CM 

o — co 95 co oo os -h 

CM <M CM CM CMCMCMCO 


»o IO 

l-HJt- CO © 

cc co os >o 

CM -* lO t— 

CO CO CO CO 


io *o 

CM IO t- 

CO CM cc »o 

OS © CM CO 
CO rfl rH ^ 


>o >o 

CM iO t- 

CO CO -H< 
iO ©00 
Ttl ^ji tH IO 




• 00 

§1 

s a 


t~ * — ' 00 MIHOOiO CM OS CO CO 

OSOSOSCO CO CO t- t- NO<Dffl 

CO t- rH >p OS CO t- rH ipOSCOb- 

^ ^-t rH CM CM CO CO CO 4* 4tl 

II II II II II II II II II II II II 


OS CO CO O N<*H0O 
OiO"0 •* -Hi -H< CO 
I-H IO OS CO t^rHVOOS 

>o io io cb ©.t-t-t- 


-* rH CO lO 
CO CO CM <M 
CO t- rH ip 

CO 00 OS OS 

II II II II 


CM OS CO CO 
CM rH l-H rH 
OS CO t-rH 

OS © © rH 

n1i"ii"ii 


OS © CO © 

©©©© 

>p OS CO t- 
rH rH Cd CM 

H » u i 


© 


pH CM CO rjt iO©t-00 OS O i-l CM 


CO •>*< lO © *- CO OS © 


rH CM CO 'tl 
CM <M CM CM 


iO © i- 00 
CM CM CM CM 


OS © rH CXI 
CM CO CO CO 






Pi 
<M 

co 


rH CM CO ■* lO CO 


1^ CO OS o 


r^ CM 


CO r* 


iO © 


00 

,2 

to 


rH CM CO 


-* io 


CO 


1~ 


CO 


00 

M 

CO 


h 


CM 


CO 




rH 


00 




- 






CM 


oo 

HCQ 


1 








rH 



COMPARISON OF PRICES 



277 



COMPARISON OF PRICES. 

FRENCH AND GERMAN PRICES FOR METRIC UNITS, BRITISH PRICES 
FOR IMPERIAL UNITS, AND UNITED STATES PRICES FOR UNITED 
STATES STANDARD WEIGHTS AND MEASURES. 

[Based upon the circular of the Secretary of the Treasury dated October 1, 1902, 
fixing the legal equivalent of the (German) mark at 23 '8 cents, of the (French) 
franc at 19*3 cents, and the British pound sterling at $4 '8665. ] 



Francs D ° llara 


Francs Dollars 


Francs D ^ rs 


Francs Dollars 


Shillings Dollars 


per 


per per 
meter. yard. 


Per $ g 
llter - liquid gal. 


per per 
hectoliter, bushel. 


per per 
British U.S. 
imp. gal. liquid gal. 


1 = -088 


1 = -176 


1 = -731 


1 = -068 


1 = -203 


2 = '175 


2 = -353 


2 =1-461 


2 = -136 


2 = -405 


3 = -263 


3 = -529 


3 =2-192 


3 = -204 


3 = -608 


4 = -350 


4 = -705 


4 =2-922 


4 = -272 


4 = -810 


5 - '438 


5 = '882 


5 =3-653 


5 = -340 


5 =1-013 


6 = -525 


6 =1-058 


6 =4-384 


6 = -408 


6 =1-216 


7 = '613 


7 =1-234 


7 =5-114 


7 = -476 


7 =1-418 


8 = '700 


8 =1-411 


8 =5-844 


8 = '544 


8 =1-621 


9 = -788 


9 =1-587 


9 =6*575 


9 = -612 


9 =1-824 


11-423=1 


5-667 = 1 


1-369=1 


14-703=1 


4-935 = 1 


22*846=2 


11-334 = 2 


2-738=2 


29-407=2 


9-871=2 


34-269 = 3 


17-000 = 3 


4-106 = 3 


44-110 = 3 


14-806=3 


45-691=4 


22-667=4 


5-475=4 


58-813=4 


19-742 = 4 


57-115=5 


28-334=5 


6-844 = 5 


73-517=5 


24-677=5 


68-537=6 


34-001 = 6 


8-213=6 


88-220=6 


29-612=6 


79-960 = 7 


39-668=7 


9-581=7 


102-923 = 7 


34-548=7 


91-383=8 


45-334=8 


10-950=8 


117-627=8 


39-483=8 


102-806=9 


51-001 = 9 


12-319=9 


132-330=9 


44-419=9 


Marks Walters 


Marks Dollars 


Marks Do "f 8 


Marks Dollars 


Shillings Dollars 


, „ P er avoir 
kilogram. pound 


per per 
meter. yard. 


ner per 
• U.S 

liter - liquid gal. 


per per 

hectoliter, bushel. 


per per 

British U.S. 

bus. bus. 


1 = -108 


1 = '218 


1 = -901 


1 = -084 


1 = -236 


2 = -216 


2 = -435 


2 =1-802 


2 = -168 


2 = -472 


3 = -324 


3 = -653 


3 =2-730 


3 = -252 


3 = '707 


4 = -432 


4 = -871 


4 =3-604 


4 = -335 


4 = -943 


5 = -540 


5 =1-088 


5 =4-505 


5 = -419 


5 =1-179 


6 = -648 


6 =1-306 


6 =5-406 


6 = -503 


6 =1-415 


7 = -756 


7 =1-523 


7 =6-307 


7 = -587 


7 =1-650 


8 = -864 


8 =1-741 


8 =7-207 


8 = -671 


8 =1-886 


9 = -972 


9 =1-959 


9 =8-108 


9 = -755 


9 =2-122 


9-263=1 


4-595 = 1 


1-110=1 


11-923=1 


4-241=1 


18-526 = 2 


9-190=2 


2-220 = 2 


23-847=2 


8-483 = 2 


.27-789 = 3 


13-785=3 


3-330 = 3 


35-770 = 3 


12-724=3 


37-052=4 


18-380=4 


4*440=4 


47-693 = 4 


16-965 = 4 


46-316 = 5 


22-975 = 5 


5 550=5 


59-616 = 5 


21-207 = 5 


55-579=6 


27-570 = 6 


6-660=6 


71-540=6 


25-448=6 


64-842=7 


32-165=7 


7-770=7 


83-463=7 


29-689 = 7 


74-105=8 


36-760=8 


8-880=8 


95-386=8 


33-931 = 8 


83-368=9 


41-355=9 


9-990=9 


107-310 = 9 


38-172=9 



278 EVOLUTION OF WEIGHTS AND MEASURES 



LENGTH. 
INCHES AND CENTIMETERS.— EQUIVALENTS FROM 1 to 100. 



Inches to Centimeters. 


Inches to Centimeters. 


Centimeters to Inches. 


Centimeters to Inches. 







50 


127 000 







50 


19-6850 


1 


2 540 


51 


129 540 


1 


•3937 


51 


20-0787 


2 


5-080 


52 


132 080 


2 


•7874 


52 


20-4724 


3 


7-620 


53 


134-620 


3 


1-1811 


53 


20-8661 


4 


10-160 


54 


137-160 


4 


1-5748 


54 


21-2598 


5 


12-700 


55 


139-700 


5 


1*9685 


55 


21-6535 


6 


15-240 


56 


142-240 


6 


2-3622 


56 


22 0472 


7 


17-780 


57 


144 780 


7 


2-7559 


57 


22-4409 


8 


20 320 


58 


147 320 


8 


3-1496 


58 


22-8346 


9 


22-860 


59 


149-860 


9 


3 5433 


59 


23 2283 


10 


25 400 


60 


152-400 


10 


3-9370 


60 


23 6220 


11 


27 940 


61 


154-940 


11 


4-3307 


61 


24-0157 


12 


30-480 


62 


157-480 


12 


4-7244 


62 


24-4094 


13 


33 020 


63 


160020 


13 


5-1181 


63 


24-8031 


14 


35-560 


64 


162-560 


14 


5-5118 


64 


25-1968 


15 


38-100 


65 


165-100 


15 


5-9055 


65 


25-5905 


16 


40-640 


66 


167-640 


16 


6-2992 


66 


25-9842 


17 


43-180 


67 


170-180 


17 


6-6929 


67 


26-3779 


18 


45-720 


68 


172-720 


18 


7-0866 


68 


26-7716 


19 


48-260 


69 


175-260 


19 


7-4803 


69 


27-1653 


20 


50-800 


70 


177-800 


20 


7-8740 


70 


27-5590 


21 


53 340 


71 


180-340 


21 


8-2677 


71 


27-9527 


22 


55-880 


72 


182-880 


22 


8-6614 


72 


28-3464 


23 


58-420 


73 


185-420 


23 


9-0551 


73 


28-7401 


24 


60-960 


74 


187-960 


24 


9-4488 


74 


29-1338 


25 


63-500 


75 


190-500 


25 


9-8425 


75 


29-5275 


26 


66-040 


76 


193-040 


26 


10-2362 


76 


29-9212 


27 


68-580 


77 


195-580 


27 


10-6299 


77 


30-3149 


28 


71-120 


78 


198-120 


28 


11-0236 


78 


30-7086 


29 


73-660 


79 


200-660 


29 


11-4173 


79 


31-1023 


30 


76-200 


80 


203-200 


30 


11-8110 


80 


31-4960 


31 


78-740 


81 


205-740 


31 


12-2047 


81 


31-8897 


32 


81-280 


82 


208-280 


32 


12-5984 


82 


32-2834 


33 


83-820 


83 


210-820 


33 


12-9921 


83 


32-6771 


34 


86 360 


84 


213-360 


34 


13-3858 


84 


33-0708 


35 


88-900 


85 


215-900 


35 


13-7795 


85 


33-4645 


36 


91 '440 


86 


218-440 


36 


14-1732 


86 


33-8582 


37 


93-980 


87 


220-980 


37 


14-5669 


87 


34-2519 


38 


96-520 


88 


223-520 


38 


14-9606 


88 


34-6456 


39 


99-060 


89 


226-060 


39 


15-3543 


89 


35 0393 


40 


101-600 


90 


228-600 


40 


15-7480 


90 


35-4330 


41 


104-140 


91 


231-140 


41 


16-1417 


91 


35-8267 


42 


106-680 


92 


233-680 


42 


16-5354 


92 


36-2204 


43 


109-220 


93 


236-220 


43 


16-9291 


93 


36-6141 


44 


111-760 


94 


238-760 


44 


17-3228 


94 


37-0078 


45 


114-300 


95 


241-300 


45 


17-7165 


95 


37-4015 


46 


116-840 


96 


243-840 


46 


18-1102 


96 


37-7952 


47 


119-380 


97 


246-380 


47 


18-5039 


97 


38-1889 


48 


121 -920 


98 


248-920 


48 


18-8976 


98 


38-5826 


49 


124-460 


99 


251-460 


49 


19-2913 


99 


38-9763 



LENGTH: FEET AND METERS 



279 



LENGTH. 
FEET AND METERS.— EQUIVALENTS FROM 1 to 100. 



Feet 


Meters. 


Feet 


Meters. 


Meten 


s. Feet. 


Meters. Feet. 







50 


15 24003 







50 164 04167 


1 


•30480 


l 


15-54483 


1 


3-28083 


1 167 32250 


2 


•60960 


2 


15-84963 


2 


6-56167 


2 170-60333 


3 


•91440 


3 


16-15443 


3 


9 84250 


3 173-88417 


4 


1-21920 


4 


16-45923 


4 


13-12333 


4 177-16500 


5 


1-52400 


5 


16-76403 


5 


16-40417 


5 ISO -44583 


6 


1 -82880 


6 


17-06883 


6 


19-68500 


6 183-72667 


7 


2-13360 


7 


17 37363 


7 


22-96583 


7 187-00750 


8 


2-43840 


8 


17-67844 


8 


26-24667 


8 190-28833 


9 


274321 


9 


17-98324 


9 


29-52750 


9 193 56917 


10 


3-04801 


60 


18-28804 


10 


32-80833 


60 196-85000 


1 


3-35281 


1 


18-59284 


1 


36-08917 


1 200-13083 


2 


3 65761 


2 


18-89764 


2 


39-37000 


2 203-41167 


3 


3-96241 


3 


19-20244 


3 


42-65083 


3 206-69250 


4 


4-26721 


4 


19-50724 


4 


45-93167 


4 209-97333 


5 


4-57201 


5 


19-81204 


5 


49-21250 


5 21325417 


6 


4-87681 


6 


20-11684 


6 


52-49333 


6 216-53500 


7 


5-18161 


7 


20-42164 


7 


5577417 


7 219-81583 


8 


5-48641 


8 


20-72644 


8 


59-05500 


8 223 09667 


9 


5-79121 


9 


21-03124 


9 


62-33583 


9 226-37750 


20 


6-09601 


70 


21-33604 


20 


65-61667 


70 229-65833 


1 


6-40081 


1 


21-61084 


1 


6S -89750 


1 232-93917 


2 


6-70561 


2 


21-94564 


2 


72-17833 


2 236-22000 


3 


7-01041 


3 


22-25044 


3 


75-45917 


3 239-50083 


4 


7-31521 


4 


22-55525 


4 


78-74000 


4 242-78167 


5 


7-62002 


5 


22-86005 


5 


82-02083 


5 246 06250 


6 


7-92482 


6 


23-16485 


6 


85-30167 


6 249 34333 


7 


8-22962 


7 


23-46965 


7 


88-58250 


7 252-62417 


8 


8-53442 


8 


23-77445 


8 


91-86333 


8 255-90500 


9 


8-83922 


9 


24-07925 


9 


95-14417 


9 259-18583 


30 


9-14402 


80 


24-38405 


30 


98-42500 


80 262-46667 


1 


9-44882 


1 


24-68885 


1 


101-70583 


1 265 74750 


2 


9-75362 


2 


24-99365 


2 


104-98667 


2 269 02833 


3 


10-05842 


3 


25-29845 


3 


108-26750 


3 272-30917 


4 


10-36322 


4 


25-60325 


4 


111-54833 


4 275-59000 


5 


10-66803 


5 


25-90805 


5 


114-82917 


5 278-87083 


€ 


10-97282 


6 


26-21285 


6 


118-11000 


6 282-15167 


7 


11-27762 


7 


26-51765 


7 


121-39083 


7 285-43250 


8 


11-58242 


8 


26 82245 


8 


124-67167 


8 288-71333 


9 


11-88722 


9 


27 12725 


9 


127 95250 


9 291-99417 


40 


12-19202 


90 


27-43205 


40 


131-23333 


90 295-27500 


1 


12-49682 


1 


27-73686 


1 


134-51417 


1 298-55583 


2 


12-80163 


2 


28-04166 


2 


137-79500 


2 301-83667 


3 


13-10643 


3 


28-34646 


3 


141-07583 


3 305-11750 


4 


13-41123 


4 


28-65126 


4 


144-35667 


4 308-39833 


5 


13-71603 


5 


28-95606 


5 


147-63750 


5 311-67917 


6 


14-02083 


6 


29-26086 


6 


150-91833 


6 314-96000 


7 


14-32563 


7 


29-56566 


7 


154-19917 


7 318-24083 


8 


14-63043 


8 


29-87046 


8 


157-48000 


8 321-52167 


9 


14-93523 


9 


30-17526 


9 


160-76083 


9 324-80250 



280 EVOLUTION OF WEIGHTS AND MEASURES 



LENGTH. 

YARDS AND METERS.— EQUIVALENTS FROM 1 to 100. 



Yards 


Meters. 


Yards 


Meters. 


Meter? 


Yards. 


Meters 


Yards. 







50 


45-72009 







50 


54-68056 


1 


•91440 


51 


46-63449 


1 


1-09361 


51 


55-77417 


2 


1-82880 


52 


47-54889 


2 


2-18722 


52 


56-86778 


3 


2 74321 


53 


48-46330 


3 


3-28083 


53 


57-96139 


4 


3-65761 


54 


49-37770 


4 


4-37444 


54 


59-05500 


5 


4-57201 


55 


50-29210 


5 


5-46806 


55 


60-14861 


6 


5-48641 


56 


51-20650 


6 


6-56167 


56 


61-24222 


7 


6-40081 


57 


52-12090 


7 


7-65528 


57 


62 33583 


8 


7 31521 


58 


53-03530 


8 


8-74889 


58 


63 42944 


9 


8-22962 


59 


53-94971 


9 


9-84250 


59 


64-52306 


10 


9-14402 


60 


54-86411 


10 


10-93611 


60 


65-61667 


11 


10-05842 


61 


55-77851 


11 


12 02972 


61 


66-71028 


12 


10-97282 


62 


56-69291 


12 


13-12333 


62 


67-80389 


13 


11-88722 


63 


57 60731 


13 


14-21694 


63 


68-89750 


14 


12-80163 


64 


58-52172 


14 


15-31056 


64 


69-99111 


15 


1371603 


65 


59-43612 


15 


16-40417 


65 


71 08472 


16 


14-63043 


66 


60-35052 


16 


17-49778 


66 


72-17833 


17 


15-54483 


67 


61-26492 


17 


18-92139 


67 


73-27194 


18 


16-45923 


68 


62-17932 


18 


19-68500 


68 


74-36556 


19 


17-37363 


69 


63-09372 


19 


20-77861 


69 


75-45917 


20 


18-28804 


70 


64-00813 


20 


21-87222 


70 


76-55278 


21 


19-20244 


71 


64-92253 


21 


22-96583 


71 


77-64639 


22 


20-11684 


72 


65-83693 


22 


24-05944 


72 


78-74000 


23 


21 03124 


73 


66-75133 


23 


25-15306 


73 


79-83361 


24 


21-94564 


74 


67-66573 


24 


26-24667 


74 


80-92722 


25 


22-86005 


75 


68-58014 


25 


27-34028 


75 


82-02083 


26 


23-77445 


76 


69-49454 


26 


28-43389 


76 


83-11444 


27 


24-68885 


77 


70-40894 


27 


29-52750 


77 


84-20806 


28 


25-60325 


78 


71-32334 


28 


30-62111 


78 


85-30167 


29 


26-51765 


79 


72-23774 


29 


31-71472 


79 


86-39528 


30 


27 43205 


80 


7315214 


30 


32-80833 


80 


87-48889 


31 


28-34646 


81 


74-06655 


31 


33-90194 


81 


88-58250 


32 


29-26086 


82 


74-98095 


32 


34-99556 


82 


89-67611 


33 


30-17526 


83 


75-89535 


33 


36-08917 


83 


90-76972 


34 


31-08966 


84 


76-80975 


34 


37-18278 


84 


91 -86333 


35 


32-00406 


85 


77 72415 


35 


38-27639 


85 


92-95694 


36 


32-91846 


86 


78-63855 


36 


39-37000 


86 


94-05056 


37 


33-83287 


87 


79-55296 


37 


40-46361 


87 


95-14417 


38 


34-74727 


88 


80-46736 


38 


41 -55722 


88 


96-23778 


39 


35-66167 


89 


81-38176 


39 


42-65083 


89 


97-33139 


40 


36-57607 


90 


82-29616 


40 


43 74444 


90 


98-42500 


41 


37-49047 


91 


83-21056 


41 


44-83806 


91 


99-51861 


42 


38-40488 


92 


84-12497 


42 


45-93167 


92 


100-61222 


43 


39-31928 


93 


85-03937 


43 


47-02528 


93 


101-70583 


44 


40-23368 


94 


85-95377 


44 


48-11889 


94 


102-79944 


45 


41-14808 


95 


86-86817 


45 


49-21250 


95 


103-89306 


46 


42-06248 


96 


87-78257 


46 


50-30611 


96 


104-98667 


47 


42-97688 


97 


88-69697 


47 


51-39972 


97 


106-08028 


48 


43 89129 


98 


89-61138 


48 


52-49333 


98 


107-17389 


49 


44-80569 


99 


90-52578 


49 


53-58694 


99 


108-26750 



LENGTH: MILES AND KILOMETERS 



281 



LENGTH. 

MILES AND KILOMETERS.— EQUIVALENTS FROM 1 to 100. 



Miles. 


Kilometers. 


Miles. 


Kilometers. 


Kilometers. Miles. 


Kilometers. Miles. 







50 


80-4674 







50 


3106850 


1 


1-6093 


l 


82-0767 


1 


•62137 


l 


31-68987 


2 


3 2187 


2 


836861 


2 


1-24274 


2 


32-31124 


3 


4-8280 


3 


85-2954 


3 


1-86411 


3 


32-93261 


4 


6-4374 


4 


86 9047 


4 


2-48548 


4 


33-55398 


5 


8-0467 


5 


88-5141 


5 


3-10685 


5 


34-17535 


6 


9-6561 


6 


90 1234 


6 


3-72822 


6 


34-79672 


7 


11-2654 


7 


91 -7328 


7 


4-34959 


7 


35-41809 


8 


12*8748 


8 


93-3421 


8 


4-97096 


8 


36-03946 


9 


14-4841 


9 


94-9515 


9 


5 59233 


9 


36-66083 


10 


16 0935 


60 


96-5608 


10 


6-21370 


60 


37-28220 


1 


17 7028 


1 


981702 


1 


6-83507 


1 


37-90357 


2 


19-3122 


2 


99-7795 


2 


7-45644 


2 


38-52494 


3 


20-9215 


3 


101 -3889 


3 


8-07781 


3 


39-14631 


4 


22-5309 


4 


102-9982 


4 


8-69918 


4 


39-76768 


5 


24-1402 


5 


104-6076 


5 


9-32055 


5 


40-38905 


6 


25-7496 


6 


106-2169 


6 


9-94192 


6 


41 01042 


7 


27 3589 


7 


107-8263 


7 


10-56329 


7 


41-63179 


8 


28-9682 


8 


109-4356 


8 


11-18466 


8 


4225316 


9 


30-5776 


9 


111 0450 


9 


11-80603 


9 


42-87453 


20 


32-1869 


70 


112-6543 


20 


12-42740 


70 


43-49590' 


1 


33-7963 


1 


114 2637 


1 


13-04S77 


1 


44-11727 


2 


35-4056 


2 


115-8730 


2 


13-67014 


2 


44-73864 


3 


37-0150 


3 


117-4823 


3 


14-29151 


3 


45-36001 


4 


38-6243 


4 


119-0917 


4 


14-91288 


4 


45-98138 


5 


40-2337 


5 


120-7010 


5 


15-53425 


5 


46-60275 


6 


41-8430 


6 


122-3104 


6 


1615562 


6 


47 22412 


7 


43 4524 


7 


123 9197 


7 


16-77699 


7 


47-84549 


8 


45-0617 


8 


125-5291 


8 


17-39836 


8 


48-46686 


9 


46-6711 


9 


127 1384 


9 


18-01973 


9 


49-08823 


30 


48-2804 


80 


128-7478 


30 


18-64110 


80 


49-70960 


1 


49-8898 


1 


130-3571 


1 


19-26247 


1 


50-33097 


2 


51-4991 


2 


131-9665 


2 


19-88384 


2 


50-95234 


3 


53-1085 


3 


133-5758 


3 


20-50521 


3 


51-57371 


4 


54-7178 


4 


135-1852 


4 


21-12658 


4 


52-19508 


5 


56-3272 


5 


136-7945 


5 


21 -74795 


5 


52 -81 645 


6 


57-9365 


6 


138-4039 


6 


22-36932 


6 


53-43782 


7 


59-5458 


7 


1400132 


7 


22-99069 


7 


54-05919 


8 


61-1552 


8 


141 -6226 


8 


23-61206 


8 


54-68056 


9 


62-7645 


9 


143-2319 


9 


24-23343 


9 


55-30193 


40 


64-3739 


90 


144-8412 


40 


24-85480 


90 


55-92330 


1 


65-9832 


1 


146-4506 


1 


25-47617 


1 


56-54467 


2 


67-5926 


2 


148-0599 


2 


26-09754 


2 


57-16604 


3 


69-2019 


3 


149-6693 


3 


26-71891 


3 


57-78741 


4 


70-8113 


4 


151-2786 


4 


27-34028 


4 


58-40878 


5 


72-4206 


5 


152-8880 


5 


27-96165 


5 


59 03015 


6 


74-0300 


6 


154-4973 


6 


28-58302 


6 


59-65152 


7 


75 6393 


7 


156-1067 


7 


29-20439 


7 


60-27289 


8 


77-24S7 


8 


157-7160 


8 


29-82576 


8 


60-89426 


9 


78-8580 


9 


159-3254 


9 


3044713 


9 


61-51562 



282 EVOLUTION OF WEIGHTS AND MEASURES 



AREAS. 
ACRES AND HECTARES.— EQUIVALENTS FROM 1 to 100. 



Acres 


Hectares. 


Acres 


Hectares. 


Hectares. Acres. 


Hectares. Acres. 







50 


20-23436 







50 


123-55220 


1 


0-40469 


l 


20-63905 


1 


2-47104 


l 


126 02324 


2 


0-80937 


2 


21 -04374 


2 


4-94209 


2 


128-49428 


3 


1-21406 


3 


21 -44842 


3 


7-41313 


3 


130-96533 


4 


1-61875 


4 


21-85311 


4 


9-88418 


4 


133-43637 


5 


2-02344 


5 


22-25780 


5 


12-35522 


5 


135-90742 


6 


2-42812 


6 


22-66249 


6 


14-82626 


6 


138-37846 


7 


2-83281 


7 


23-06717 


7 


17-29731 


7 


140-84950 


8 


3-23750 


8 


23-47186 


8 


19-76835 


8 


143-32055 


9 


3-64219 


9 


23-87655 


9 


22-23940 


9 


145-79159 


10 


4-04687 


60 


24-28124 


10 


24-71044 


60 


148-26264 


1 


4-45156 


1 


24-68592 


1 


27-18148 


1 


150 73368 


2 


4-85625 


2 


25-09061 


2 


29-65253 


2 


153-20472 


3 


5 26093 


3 


25-49530 


3 


32-12357 


3 


155-67577 


4 


5-66562 


4 


25-89998 


4 


34-59462 


4 


158-14681 


5 


6-07031 


5 


26-30467 


5 


37-06566 


5 


160-61786 


6 


6-47500 


6 


26-70936 


6 


39-53670 


6 


163-08890 


7 


6-87968 


7 


27-11405 


7 


42 00775 


7 


165-55994 


8 


7-28437 


8 


27*51873 


8 


44-47879 


8 


168 03099 


9 


7-68906 


9 


27-92342 


9 


46 94983 


9 


170-50203 


20 


8-09375 


70 


28 32811 


20 


49-42088 


70 


172-97308 


1 


8-49843 


1 


28-73280 


1 


51-89192 


1 


175-44412 


2 


8-90312 


2 


29-13748 


2 


54 36297 


2 


177-91516 


3 


9-30781 


3 


29-54217 


3 


56-83401 


3 


180-38621 


4 


9-71249 


4 


29-94686 


4 


59-30505 


4 


182-85725 


5 


1011718 


5 


30-35154 


5 


61-77610 


5 


185-32829 


6 


10-52187 


6 


30-75623 


6 


64-24714 


6 


187-79934 


7 


10-92656 


7 


31-16092 


7 


66-71819 


7 


190-27038 


8 


11-33124 


8 


31-56561 


8 


69 18923 


8 


192-74143 


9 


11-73593 


9 


31-97029 


9 


71-66027 


9 


195-21247 


30 


12 14062 


80 


32 37498 


30 


74-13132 


80 


197-6S351 


1 


1254531 


1 


32-77967 


1 


76-60236 


1 


200 15456 


2 


12-94999 


2 


33-18436 


2 


79-07341 


2 


202-62560 


3 


13-35468 


3 


33-58904 


3 


81-54445 


3 


205-09665 


4 


13-75937 


4 


33-99373 


4 


84-01549 


4 


207-56769 


5 


14-16405 


5 


34-39842 


5 


86-48654 


5 


210-03873 


6 


14-56874 


6 


34-80310 


6 


88-95758 


6 


212-50978 


7 


14-97343 


7 


35 20779 


7 


91-42863 


7 


214-98082 


8 


15-37812 


8 


35-61248 


8 


93-89967 


8 


217-45187 


9 


15-78280 


9 


36-01717 


9 


96-37071 


9 


219-92291 


40 


1618749 


90 


36-42185 


40 


98-84176 


90 


222-39395 


1 


16-59218 


1 


36-82654 


1 


10131280 


1 


224-86500 


2 


16-99686 


2 


37 23123 


2 


103 78385 


2 


227 33604 


3 


17-40155 


3 


37-63592 


3 


106-25489 


3 


229-80709 


4 


17-80624 


4 


38-04060 


4 


108-72593 


4 


232-27813 


5 


18 21093 


5 


38-44529 


5 


111-19698 


5 


234-74917 


6 


18-61561 


6 


38-8499S 


6 


113-66802 


6 


237 22022 


7 


19-02030 


7 


39-25466 


7 


116-13906 


7 


239-69126 


8 


19-42499 


8 


39-65935 


8 


118-61011 


8 


242-16231 


9 


19-82968 


9 


40 06404 


9 


121 08115 


9 


244-63335 



CAPACITY : LIQUID QUARTS TO LITERS 283 

CAPACITY. 
LIQUID QUARTS TO LITERS.— EQUIVALENTS FROM 1 to 100. 



Quarts. Liters. 


Quarts. Liters. 


Liters 


Quarts. 


Liters. 


Quarts. 







50 


47*31793 







50 


52-83409 


1 


•94636 


l 


48-26429 


1 


1-05668 


l 


53-89077 


2 


1-89272 


2 


49-21065 


2 


2-11336 


2 


54-94746 


3 


2-83908 


3 


50-15701 


3 


3-17005 


3 


56 00414 


4 


3-78543 


4 


51-10337 


4 


4-22673 


4 


57 06082 


5 


4-73179 


5 


52-04972 


5 


5-28341 


5 


58-11750 


6 


5-67815 


6 


52-99608 


6 


6 34009 


6 


59-17418 


7 


6-62451 


7 


53-94244 


7 


7-39677 


7 


60 23086 


8 


7-57087 


8 


54-88880 


8 


8-45345 


8 


61 -28755 


9 


8-51723 


9 


55-83516 


9 


9-51014 


9 


62-34423 


10 


9-46359 


60 


56-78152 


10 


10-56682 


60 


63-40091 


1 


10-40994 


1 


57-72788 


1 


11-62350 


1 


64-45759 


2 


11-35630 


2 


58-67423 


2 


12-68018 


2 


65-51428 


3 


12-30266 


3 


59-62059 


3 


13-73686 


3 


66-57096 


4 


13-24902 


4 


60-56695 


4 


14-79355 


4 


67 62764 


5 


14-19538 


5 


6151331 


5 


15-85023 


5 


68-68432 


6 


15-14174 


6 


62-45967 


6 


16-90691 


6 


69-74100 


7 


16-08810 


7 


63-40603 


7 


17-96359 


7 


70-79768 


8 


17-03446 


8 


64-35239 


8 


19-02027 


8 


71-85437 


9 


17-98081 


9 


65 29875 


9 


20-07696 


9 


72-91105 


20 


18-92717 


70 


66-24510 


20 


21-13364 


70 


73-96773 


1 


19-87353 


1 


67-19146 


1 


22-19032 


1 


75-02441 


2 


20-81989 


2 


68-13782 


2 


23-24700 


2 


76-08109 


3 


21-76625 


3 


69-08418 


3 


24-30368 


3 


77-13778 


4 


22-71261 


4 


70-03054 


4 


25-36036 


4 


78-19446 


5 


23-65897 


5 


70-97690 


5 


26-41705 


5 


79-25114 


6 


24-60532 


6 


71-92326 


6 


27-47373 


6 


80-30782 


7 


25-55168 


7 


72-86961 


7 


28-53041 


7 


81-36450 


8 


26-49804 


8 


73-81597 


8 


29-58709 


8 


82-42119 


9 


27-44440 


9 


74-76233 


9 


3061377 


9 


83-47787 


30 


28-39076 


80 


75-70869 


30 


31-70046 


80 


84-53455 


1 


29-33712 


1 


76-65505 


1 


32 75714 


1 


85-59123 


2 


30-28348 


2 


77-60141 


2 


3381382 


2 


86-64791 


3 


31 -22983 


3 


78-54777 


3 


34-87050 


3 


87 '70459 


4 


32-17619 


4 


79-49412 


4 


35-92718 


4 


88-76128 


5 


33-12255 


5 


80-44048 


5 


36-98387 


5 


89-81796 


6 


34-06891 


6 


81-38684 


6 


38-04055 


6 


90-87464 


7 


35-01527 


7 


82-33320 


7 


39-09723 


7 


91-93132 


8 


35-96163 


8 


83 27956 


8 


40-15391 


8 


92-98800 


9 


36-90799 


9 


84-22592 


9 


41-21059 


9 


94-04469 


40 


37-85436 


90 


85 17228 


40 


42-26727 


90 


95-10137 


1 


38-80070 


1 


86-11863 


1 


43-32396 


1 


96-15805 


2 


39-74706 


2 


87-06499 


2 


44-38064 


2 


97-21473 


3 


40-69342 


3 


88-01135 


3 


45-43732 


3 


98-27141 


4 


41-63978 


4 


88*95771 


4 


46-49400 


4 


99-32809 


5 


42-58614 


5 


89-90407 


5 


47-55068 


5 


100-38478 


6 


43-53250 


6 


90-85043 


6 


48-60737 


6 


101-44146 


7 


44-47886 


7 


91-79679 


7 


49-66405 


7 


102-49814 


8 


45-42521 


8 


92-74315 


8 


50-72073 


8 


103-55482 


9 


46-37157 


9 


93-68950 


9 


51-77741 


9 


104-61150 



284 EVOLUTION OF WEIGHTS AND MEASURES 



CAPACITY. 
GALLONS AND LITERS.— EQUIVALENTS FROM 1 to 100. 



Gallons 


Liters. 


Gallons. Liters. 


Liters 


Gallons. 


Liters 


Gallons. 







50 


189 2717 







50 


13-20852 


1 


3 7854 


l 


193-0572 


1 


•26417 


l 


13-47269 


2 


7-5709 


2 


196-8426 


2 


•52834 


2 


13-73686 


3 


11-3563 


3 


200-6280 


3 


•79251 


3 


14-00103 


4 


15-1417 


4 


204-4135 


4 


1 -05668 


4 


14-26521 


5 


18-9272 


5 


208-1989 


5 


1-32085 


5 


14-52938 


6 


22-7126 


6 


211-9843 


6 


1 -58502 


6 


14-79355 


7 


26 4980 


7 


215-7698 


7 


1 -84919 


7 


15-05772 


8 


30-2835 


8 


219-5552 


8 


2-11336 


8 


15-32189 


9 


34-0689 


9 


223-3406 


9 


2 37753 


9 


15-58606 


10 


37-8543 


60 


227-1261 


10 


2-64170 


60 


15-85023 


1 


41-6398 


1 


230-9115 


1 


2-90588 


1 


16-11440 


2 


45-4252 


2 


234-6969 


2 


3-17005 


2 


16-37857 


3 


49-2106 


3 


238-4824 


3 


3-43422 


3 


16-64274 


4 


52-9961 


4 


242-2678 


4 


3-69839 


4 


16-90691 


5 


56-7815 


5 


246-0532 


5 


3-96256 


5 


17-17108 


6 


60-5670 


6 


249-8387 


6 


4-22673 


6 


17-43525 


7 


64-3524 


7 


253-6241 


7 


4-49090 


7 


17-69942 


8 


68-1378 


8 


257-4095 


8 


4-75507 


8 


17-96359 


9 


71-9233 


9 


261-1950 


9 


5 01924 


9 


18-22776 


20 


75-7087 


70 


264-9804 


20 


5-28341 


70 


18-49193 


1 


79 4941 


1 


268-7658 


1 


5-54758 


1 


18-75610 


2 


83 2796 


2 


272-5513 


2 


5-81175 


2 


19-02027 


3 


87-0650 


3 


276-3367 


3 


6-07592 


3 


19-28444 


4 


90-8504 


4 


280-1222 


4 


6-34009 


4 


19-54861 


5 


94 6359 


5 


283-9076 


5 


6-60426 


5 


19-81279 


6 


98-4213 


6 


287-6930 


6 


6-86843 


6 


20 07696 


7 


102-2067 


7 


291-4785 


7 


7-13260 


7 


20-34113 


8 


105-9922 


8 


295-2639 


8 


7-39677 


8 


20-60530 


9 


109-7776 


9 


299 0493 


9 


7-66094 


9 


20-86947 


30 


113-5630 


80 


302-8348 


30 


7-92511 


80 


21-13364 


1 


117-3485 


1 


306-6202 


1 


8-18928 


1 


21 -39781 


2 


121-1339 


2 


310-4056 


2 


8-45345 


2 


21-66198 


3 


124-9193 


3 


314-1911 


3 


8-71763 


3 


21-92615 


4 


128-7048 


4 


317-9765 


4 


8-98180 


4 


22-19032 


5 


132-4902 


5 


321-7619 


5 


9 24597 


5 


22-45449 


6 


136-2756 


6 


325-5474 


6 


9-51014 


6 


2271866 


7 


140 0611 


7 


329-3328 


7 


9-77431 


7 


22-98283 


8 


143 8465 


8 


333-1182 


8 


10-03848 


8 


23-24700 


9 


147 6319 


9 


336-9037 


9 


10-30265 


9 


23-51117 


40 


151-4174 


90 


340-6891 


40 


10-56682 


90 


23-77534 


1 


155-2028 


1 


344-4745 


1 


1083099 


1 


24 03951 


2 


158-9882 


2 


348-2600 


2 


11-09516 


2 


24-30368 


3 


162-7737 


3 


352-0454 


3 


11-35933 


3 


24-56785 


4 


166-5591 


4 


355-8308 


4 


11-62350 


4 


24-83202 


5 


170-3446 


5 


359-6163 


5 


11-88767 


5 


25-09619 


6 


174-1300 


6 


363-4017 


6 


12-15184 


6 


25 36036 


7 


177-9154 


7 


367-1871 


7 


12-41601 


7 


25-62454 


8 


181 -7009 


8 


370-9726 


8 


12-68018 


8 


25-88871 


9 


185-4863 


9 


374-7580 


9 


12-94435 


9 


26-15288 



MASSES : AVOIRDUPOIS POUND AND KILOGRAM 285 



MASSES. 
AVOIRDUPOIS POUND & KILOGRAM.— EQUIVALENTS FROM 1 to 100. 



Pounds 


Kilos. 


Pounds 


Kilos. 


Kilos. 


Pounds. 


Kilos. 


Pounds. 







50 


22-67962 







50 


110-2311 


1 


•45359 


l 


23 13321 


1 


2-2046 


l 


112-4357 


2 


•90718 


2 


23-58681 


2 


4-4092 


2 


114-6404 


3 


1-36078 


3 


24-04040 


3 


6 6139 


3 


116-8450 


4 


1-81437 


4 


24-49399 


4 


8-8185 


4 


119-0496 


5 


2-26796 


5 


24-94758 


5 


11-0231 


5 


121-2542 


6 


2-72155 


6 


25-40118 


6 


13-2277 


6 


123-4589 


7 


317515 


7 


25-85477 


7 


15 4324 


7 


125 6635 


8 


3-62874 


8 


26-30836 


8 


17 6370 


8 


127-8681 


9 


4 08233 


9 


26-76195 


9 


19-8416 


9 


1300727 


10 


4-53592 


60 


27 21555 


10 


22 0462 


60 


132-2773 


1 


4-98952 


1 


27 66914 


1 


24-2508 


1 


134-4820 


2 


5-44311 


2 


28 12273 


2 


26 4555 


2 


136-6866 


3 


5-89670 


3 


28-57632 


3 


28-6601 


3 


138-8912 


4 


6-35029 


4 


29 02992 


4 


30-8647 


4 


141-0958 


5 


6-80389 


5 


29-48351 


5 


33 0693 


5 


143-3005 


6 


7-25748 


6 


29-93710 


6 


35-2740 


6 


145 5051 


7 


7-71107 


7 


30-39069 


7 


37 4786 


7 


147-7097 


8 


8-16466 


8 


30-84429 


8 


39-6832 


8 


149-9143 


9 


8-61826 


9 


31-29788 


9 


41-8878 


9 


152-1189 


20 


9-07185 


70 


31-75147 


20 


44 0924 


70 


154-3236 


1 


9-52544 


1 


32-20506 


l 


46 2971 


1 


156-5282 


2 


9 97903 


2 


32-65865 


2 


48-5017 


2 


158-7328 


3 


10-43263 


3 


33 11225 


3 


50 7063 


3 


160-9374 


4 


10-88622 


4 


33-56584 


4 


52-9109 


4 


163 1421 


5 


11-33981 


5 


34-01943 


5 


55-1156 


5 


165-3467 


6 


11-79340 


6 


34-47302 


6 


57 3202 


6 


167-5513 


7 


12-24700 


7 


34-92662 


7 


59-5248 


7 


169-7559 


8 


12-70059 


8 


35-38021 


8 


61-7294 


8 


171-9605 


9 


13-15418 


9 


35-83380 


9 


63 9340 


9 


1741652 


30 


13-60777 


80 


36-28739 


30 


66-1387 


80 


176-3698 


1 


14-06137 


1 


36-74099 


l 


68 3433 


1 


178-5744 


2 


14-51496 


2 


37-19458 


2 


70-5479 


2 


180-7790 


3 


14-96855 


3 


37-64817 


3 


72-7525 


3 


182-9837 


4 


15-42214 


4 


3810176 


4 


74-9572 


4 


185-1883 


5 


15-87573 


5 


38-55536 


5 


77*1618 


5 


187 3929 


6 


16-32933 


6 


39-00895 


6 


79-3664 


6 


189-5975 


7 


16-78292 


7 


39 46254 


7 


81-5710 


7 


191-8021 


8 


17 23651 


8 


39-91613 


8 


83 7756 


8 


194-0068 


9 


17-69010 


9 


40-36973 


9 


85-9803 


9 


196-2011 


40 


18-14370 


90 


40 82332 


40 


88'1849 


90 


198 4160 


1 


18-59729 


1 


41-27691 


1 


90-3895 


1 


200-6206 


2 


19-05088 


2 


41-73050 


2 


92-5941 


2 


202-8253 


3 


19-50447 


3 


42 18410 


3 


94-7988 


3 


205 0299 


4 


19-95807 


4 


42-63769 


4 


97 0034 


4 


207 2345 


5 


20 41166 


5 


43 09128 


5 


99-2080 


5 


209-4391 


6 


20-86525 


6 


43 54487 


6 


1014126 


6 


211-6437 


7 


21-31884 


7 


43-99847 


7 


103-6172 


7 


213-8484 


8 


21 -77244 


8 


44-45206 


8 


105-8219 


8 


216 0530 


9 


22-22603 


9 


44-90565 


9 


108-0265 


9 


218 2576 



286 EVOLUTION OF WEIGHTS AND MEASURES 



COMPARISON OF THE VARIOUS TONS AND POUNDS 
IN USE IN THE UNITED STATES. 

FROM 1 to 10 UNITS. 



Long Tons. 


Short Tons. 


Metric Tons. 


Kilograms. 


Avoirdupois 
Pounds. 


Troy Pounds. 


•00036735 
•00044643 
•00073469 
•00089286 
•00098421 


•00041143 
•00050000 
•00082286 
•00100000 
•00110231 


•00037324 
•00045359 
•00074648 
•00090718 
•00100000 


•37324 
•45359 
•74648 
•90718 

1 


■822857 
1 

1-64571 
2 
2-20462 


1 

1-21528 

2 

2-43056 

2-67923 


•00110204 
•00133929 
•00146939 
•00178571 
•00183673 


•00123429 
•00150000 
•00164571 
•00200000 
•00205714 


•00111973 
•00136078 
•00149297 
•00181437 
•00186621 


1-11973 
1-36078 
1 -49297 
1-81437 
1-86621 


2-46857 

3 

3-29143 

4 

4-11429 


3 

3-645S3 
4 

4-86111 
5 


•00196841 
•00220408 
•00223214 
•00257143 
•00267857 


•00220462 
•00246857 
•00250000 
•00288000 
•00300000 


•00200000 
•00223945 
•00226796 
•00261269 
•00272155 


2 

2-23945 
2-26796 
2-61269 
2-72155 


4-40924 

4-93714 

5 

5-76000 

6 


5-35846- 

6 

6-07639 

7 

7-29167 


•00293S78 
•00295262 
•00312500 
•00330612 
•00357143 


•00329143 
•00330693 
•00350000 
•00370286 
•00400000 


•00298593 
•00300000 
•00317515 
•00335918 
•00362874 


2-98593 

3 

3-17515 

3-35918 

3-62874 


6-582S6 

6-61387 

7 

7-40571 

8 


8 

8-03769 
8-50694 
9 
9-72222 


•00393683 
•00401786 
•00492103 
•00590524 
•006S8944 


•00440924 
•00450000 
•00551156 
•00661387 
•00771618 


•00400000 
•00408233 
•00500000 
•00600000 
•00780000 


4 

4-08233 

5 

6 

7 


8-81849 

9 

11-0231 
13-2277 
15-4324 


10-71691 
10-93750 
13-39614 
16-07537 
18-75460 


•00787365 
•00885786 
•89287 
•98421 

1 


•00881849 
•009920S0 

1 

1-10231 

1-12000 


•00800000 

•0090000 

•90718 

1 

1-01605 


8 
9 

907-18 
1,000-00 
1,016-05 


17-6370 
19-8416 
2,000-00 
2,204-62 
2,240-00 


21-43383 
24-11306 

2,430-56 

2,679-23 

2,722-22 


1-78571 

1-96841 

2 

2-67857 

2-95262 


2 

2-20462 
2-24000 
3 
3-30693 


1-81437 

2 

2-03209 

2-72155 

3 


1,814-37 
2,000-00 
2,032-09 
2,721-55 
3,000-00 


4,000-00 
4,409-24 
4,480-00 
6,000-00 
6,613-87 


4,861-11 
5,358-46 
5,444-44 
7,291-67 
8,037-69 


3 

3-57143 
3-93683 
4 

4-46429 


3-36000 

4 

4-40924 

4-48000 

5 


3-04814 
3-62874 
4 

4-06419 
4 53592 


3,048-14 
3,628-74 
4,000-00 
4,064-19 
4,535-92 


6,720-00 
8,000-00 
8,818-49 
8,960-00 
10,000-00 


8,166-67 
9,722-22 
10,716-91 
10,888-89 
12,152-78 


4-92103 

5 

5-35714 

6-90524 

6 


5-51156 

5-60000 

6 

6-61387 

6-72000 


5 

5-08024 
6-44311 
6 
6-09628 


5,000-00 
5,080-24 
5,443-11 
6,000-00 
6,096-28 


11,023-11 
11,200-00 
12,000-00 
13,227-73 
13,440-00 


13,396-14 
13,611'H 
14.5S3-33 
16,075-37 
16,333-33 


6-25000 

6-88944 

7 

7-14286 

7-87365 


7 

7-71618 
7-84000 
8 
8-81849 


6-35029 

7 

7-11232 

7-25748 

8 


6,350-29 
7,000-00 
7,112-32 
7,257-48 
8.000-00 


14,000-00 
15,432-36 
15,680-00 
16,000-00 
17,636-98 


17,013-89 
18,754 60 
19,055-56 
19,444-44 
21,433-83 


8 

8-03571 
8-85786 
9 


8-96000 
9 

9-92080 
10-08000 


8-12838 
8-16466 
9 
9-14442 


8,128-38 
8,164-66 
9,000-00 
9,144-42 


17,920-00 
18,000-00 
19,841-60 
20,160-00 


21,777-78 
21,875-00 
24,113-06 
24,500-00 



MEASURES OF CAPACITY 



287 



MEASURES OF CAPACITY. 
EQUIVALENTS FROM 1 to 10. 



Milli- U.S. 
liters. Liquid 
(c.c.) Ounces. 


(c - c,) Drams. 


U.S. 
Apothe- 
caries' 
Scruples. 


Milli- 
liters, 
(c.c.) 


U.S. 
Liquid Liters. 
Quarts. 


U.S. 
Liquid Liters. 
Gallons. 


1 =0-03381 


1 =0-2705 


0-8115 = 


1 


1 =0-94636 


0-26417= 1 


2 =0-06763 


2 =0-5410 


1 


1-2322 


1-05668=1 


0-52834= 2 


3 =0-10144 


3 =0-8115 


1-6231 = 


2 


2 =1-89272 


0-79251= 3 


4 =0-13526 


3-6967=1 


2 


2-4645 


2-11336=2 


1 = 3-7S543 


5 =0-16907 

6 =0-20288 

7 =0-23670 

8 =0-27051 

9 =0-30432 


4 =1-0820 

5 =1-3525 

6 =1-6231 

7 =1-8936 
7-3934=2 


2-4346 = 
3 

3-2461 = 
4 

4-0577 = 
4-8692 = 


3 

3-6967 

4 

4-9290 

5 

6 


3 =2-83908 
3-17005 = 3 

4 =3-78543 
4-22673=4 

5 =4-73179 


1-05668= 4 
1-32085= 5 
1-58502= 6 
1-84919= 7 
2 = 7-57087 


29-574=1 


8 =2-1641 


5 

5-6S07 = 


6-1612 
7 


5-28341=5 


2-11336= 8 


59-147=2 


9 =2-4346 


6 


7-3934 


6 =5 67815 


2-37753= 9 


8S-721 = 3 


11-0901 = 3 


6-4923 = 


8 


6-34009=6 


3 =11 -3563a 


118-295=4 


14-7869=4 


7 


8-6257 


7 =6-62451 


4 =15-14174 


147-869=5 


18-4836=5 


7-3038 = 


9 


7-39677=7 


5 =18-92717 


177-442=6 


22-1803=6 


8 


9-8579 


8 =7-5708S 


6 =22-71261 


207-016=7 


.25-8770=7 


9 


11-0901 


8-45345=8 


7 =26-49804 


236-590=8 


29-5737=8 






9 =8-51723 


8 =30-28348 


266-163 = 9 


33-2704 = 9 






9-51014=9 


9 =34-06891 


U.S. 

Dry Liters. 
Quarts. 


Pack's. Liters - 


Deka- 
liters. 


U.S. 
Pecks. 


U.S. Hecto- 
Bushels. liters. 


U.S. Hectolitres 
Bushels per 
per Acre. Hectare. 


0-9081=1 


0-11351= 1 


0-8S10 = 


1 


1 =0-35239 


1 =0-S707S 


1 =1-1012 


0-22702= 2 


1 


1-1351 


2 =0-70479 


1-14840 = 1 


1-8162=2 


0-34053= 3 


1-7620 = 


2 


2-83774 = 1 


2 =1-74156 


2 =2-2025 


0-45404= 4 


2 


2-2702 


3 =1-05718 


2-29680 = 2 


2-7242=3 

3 =3-3037 
3-6323=4 

4 =4-4049 
4-5404=5 

5 =5-5061 


0-56755= 5 
0-68106= 6 
0-79457= 7 
0-90808= 8 
1 = 8-80982 


2-6429 = 
3 

3-5239 = 
4 

4-4049 = 
5 


3 

3-4053 

4 

4-5404 

5 

5-6755 


4 =1-40957 

5 =1-76196 
5-67548=2 

6 =2-11436 

7 =2-46675 


3 =2-61233 
3-44519=3 

4 =3-48311 
4-59359=4 

5 =4-353S9- 


5-4485 = 6 

6 =6-6074 
6-3565=7 

7 =7-7086 
7-2646 = 8 


1-02157= 9 

2 =17-61964 

3 =26-42946 

4 =35-23928 


5-2859 = 
6 

6-1669 = 
7 
7-0479 = 


6 

6-8106 
7 

7-9457 
8 


8 =2-81914 
8-51323=3 

9 =3-17154 
11-35097=4 


5-74199=5 

6 =5-22467 
6-S9039=6 

7 =6-09545 


8 =8-8098 


5 =44-04910 


7-9288 = 


9 


14-18871 = 5 


8 =6-96622 


8-1727 = 9 


6 =52-85892 


8 


9-0808 


17-02645=6 


8-03879=7 


9 =9-9110 


7 =61-66874 


9 


10-2159 


19-S6420=7 


9 =7-83700 




8 =70-47856 






22-70194=8 


9-18719=8 




9 =79-28838 






25-53968=9 


10-33558=9 



288 EVOLUTION OF WEIGHTS AND MEASURES 



MEASURES OF MASS. 
EQUIVALENTS FROM 1 to 10. 



Grains. 


Grams. 


Avoir- 
dupois 
Ounces. 


Grams. 


Ounces. Grams - 


Avoi r- Kilo- 
dupois _ZZfI 
Pounds. ^ ams - 


Troy Kilo- 
Pounds, grams. 


1 


= 0-06480 


0-03527 = 


1 


0-03215= 1 


1 =0-45359 


1 =0-37324 


2 


= 0-12960 


0-07055 = 


2 


0-06430= 2 


2 =0-90718 


2 =0-74648 


3 


= 0-19440 


0-10582 = 


3 


0-09645= 3 


2-20462=1 


2-67923 = 1 


4 


= 0-25920 


0-14110 = 


4 


0-12860= 4 


3 =1-36078 


3 =1-11973 


5 


= 0-32399 


0-17637 = 


5 


016075= 5 


4 =1-81437 


4 =1-49297 


6 


= 0-38879 


0-21164 = 


6 


0-19290= 6 


4-40924=2 


5 =1-86621 


7 


= 0-45359 


0-24692 = 


7 


0-22506= 7 


5 =2-26796 


5-35846 = 2 


8 


= 0-51839 


0-28219 = 


8 


0-25721= 8 


6 =2-72155 


6 =2-23945 


9 


= 0-58319 


0-31747 = 


9 


0-28936= 9 


6-61387=3 


7 =2-61269 


15-4324 


= 1 


1 


28-3495 


1 = 31-10348 


7 =3-17515 


8 =2-98593 


30-8647 


= 2 


2 


56-6991 


2 = 62-20696 


8 =3-62874 


8-03769 = 3 


46-2971 


= 3 


3 


85-0486 


3 = 93-31044 


8-81849=4 


9 =3-35918 


31-7294 


=4 


4 


113-3981 


4 =124-41392 


9 =4-08233 


10-71691=4 


77-1618 


=5 


5 


141-7476 


5 =155-51740 


11-02311=5 


13-39614=5 


92-5941 


=6 


6 


170-0972 


6 =186-62088 


13-22773=6 


16-07537=6 


108-0265 


= 7 


7 


198-4467 


7 =217-72437 


15-43236=7 


18-75460=7 


123-4589 


=8 


8 


226-7962 


8 =248-82785 


17-63698=8 


21-43383=8 


138-8912 


= 9 


9 


255-1457 


9 =279-93133 


19-S4160=9 


24-11306=9 



APOTHECARIES' AND METRIC WEIGHT 



289 







£ 


s 










5 


< 


s 




M 




« 


S 






O 


5 




3 





2 


s 


«s< 


to 


J 


5s 


o 


3 


M 


fc> 




H 


n 


P5 


Q 


O 


3 


O 


ft 


o 



6 s 

►J <! 



CO S 



OS 00 

t? iH 

00 fr- 

re g 

~' CO 



co o> 



£ o 



• leo 



C5 00 



o le * 



GO eo 

£: oo 

iC IO 

OS <N 

Ol rH 



co oo 



O 

Id 



5 2 

ft s 



'•? 00 



J? en 



co S3 



co c* 



o 
l« 



z < 



C5 CO 

§3 



Sg 



00 

CO 00 

Ci rH 



^ S3 

« CO 



o 

r § 



i§ 






^ 52 

»o 2 

oi . 

r-l eo 



co 2 



CO t~ 

s s 

^-i CJ> 

CO ^ 



o 

2 § 



c- o 



CO 

CO to 
9 o 
Ol oo 

9 r-i 

© « 

ICO 



II 



2 s 

CM 2 

co £ 

i § 

• l*« 



oi p 

8.p 



8.1 



oi S 

3 5 



o 



O o 

rH 

01 00 

SS8 

§ 3 

Pico 



CO O 
O rH 
O 00 

SI 

9|« 



co 3 

•O 53 
P § 

5 51 

oi « 



© ^ 



t> rH 

3 ># 



rj< OS 



CO 
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IO 

3 2 



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IO 00 

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3d 






290 EVOLUTION OF WEIGHTS AND MEASURES 



TABLE GIVING 

DENSITY (SPECIFIC GRAVITY), MELTING POINT 

AND BOILING POINT 

MISCELLANEOUS ELEMENTS AND SOLIDS. 



Density. 



Melting Point. 
Centigrade. 



Boiling Point. 
Centigrade. 



Aluminium 

Amber 

Antimony - 

Asbestos - 

Asphaltum 

Bismuth ■ 

Bone 

Brass 

Bronze 

Butter 

Cadmium - 

Calcite 

Chalk 

Cobalt 

Constantan 

Copper 

Cork- 

Feldspar - 

German silver - 

Glass, common - 
,, plate, crown - 
,, flint, light 
,, ,, heavy - 

Gold --- - 

Granite 

Graphite - 

Gutta percha - 

Gypsum - 

Ice .... 

Iron, cast - 
,, wrought - 
,, wire 
,, cast steel 

Ivory 

Lard - 

Lead - 

Lime, burned - 

Magnesium 

Manganese 

Manganin - 

Marble 

Mica - - - . 

Nickel 

Paraffin 

Platinum - 

Porcelain - 

Potassium - 

Quartz 

Rubber, unvulcanised 
,, hard - 



2-60— (270) 

1-078 

6-71 

2-0—2-8 

1-07—1-2 

9-8 

1-7—2-0 

8-1—8-6 

8-7 

0-86 

8-6 

2-7 

2-25—2-69 

8-6 

8-8 

8-5—8-9 

0-2 

2-55 

8-5 

2-50—2-70 

2-45—2-72 

3-15—3-4 

3-6-3-9 

19-2—19-3 

2-5—2-9 

1-8—2-24 

0-96—0-98 

2-32 

0-9167 

7-1—7-7 

7-8 

7-7 

7-8 

1-9 

0-93 

11*3 

2-3—3-2 

1-7 

7 4 

8-4 • 

2-65-2-8 

2-65—2-93 

8-8—8-9 

0-87 

21-4—21-5 

2-2—2-5 

0-87 

2-65 

0-92-0-95 

1*2 



600-850 
425—450 

267—268 

900—920 

31—315 
315—320 

1500—1800 
1000—1150 



1000 

800 

to 

1400 

1065 




1200—1400 



1300—1400 

41—42 
325—327 

630 
1900? 



1450—1600 

38—56 

1800 

62 
2000 



1400— 1700 
1400—1700 

760-770 



100 



1450—1600 
About 1100 



350— 430 
687—731 



MISCELLANEOUS ELEMENTS AND SOLIDS 291 

MISCELLANEOUS ELEMENTS AND SOLIDS— Continued. 



Density. 



Melting Point. 
Centigrade. 



Boiling Point. 
Centigrade. 



Sandstone - 

Serpentine 

Silver 

Slate - 

Sodium 

Spermaceti 

Sulphur 

Tallow, beef - 

,, mutton 
Tin - 

Wax, Japanese 
,, white 
,, yellow 
Wood, beech 

, , box 

,, elm 

, , oak 

,, poplar - 

yellow pine 



Zinc 



2 2— 2 5 
2-4—2-7 

10-5 
2-6-2-7 

0-98 
0-8S— 0-94 

2 07 

0-97 

0-92 
7 3 

0-99 
0-96—0-97 
0-96-0-97 

0-85 

1-33 

0-80 
0-7—0-8 

0-40 

0-66 

715 



960 

95-6—97-6 

44 

114 

43 

47—50 

227—232 

54 

63 

62 



412—420 



740 

448 

1450—1600 



930—950 



LIQUIDS. 



Acid, hydrochloric - 


1-24 






,, nitric - 


1-42 






,, sulphuric 


1-84 






Alcohol, ethyl - 


0-7911 


-130 


78-3 


,, methyl, wood 


0-80 




66 


Amyl acetate - 


0-90 




140 


Aniline, oil 


1-02 




185 


Benzol, 


0-881 


5 


80-3 


Carbon di sulphide - 


1-265 


-113 


46 


Chloroform .... 


1-53 


-70 


61-2 


Ether, sulphuric 


0-717 


-118 


34-9 


Glycerine ----- 


1-24—1-26 


-20 


290 


Mercury ----- 


13 596 


-38-8 


357 


Oil, linseed - 


93 






,, olive 


0-91 






Petroleum, crude 


1-75—1-84 






,, refined - 


0-84 






,. rhigolene 


0-65—0-66 




40—70 


,, gasolene - 


0-66—0-69 




70—90 


,, benzene - 


0-69 -0-70 




90—110 


Phenol, carbolic acid 


1-08 


40 


180 


Turpentine, oil - 


0-87 







GASES. 



Air 


0-001293 




-200 


Carbonic acid - 


1865 


-57? 


- 78 to - 80 


Hydrogen ----- 


0901 


-250 


-256 


Nitrogen ----- 


1251 


-203 to -214 


-194 


Oxygen 


1429 




- 181 to - 184 


Water vapor - 


0804 





100 



292 EVOLUTION OF WEIGHTS AND MEASURES 



THERMOMETER SCALES. 
CENTIGRADE AND FAHRENHEIT EQUIVALENTS. 

For Absolute Temperatures add 273° to Centigrade Scale. 



Centigrade. 


Fahrenheit. 


Remarks. 


Centigrade. 


Fahrenheit. 


Remarks. 


-273 


-549-4 


' ' Absolute zero. " 


-6-1 


21 




-250 


-418 


Hydrogen boils. 


-6 


212 




-200 


-328 


Temp, liquid air. 


-56 


22 




-190 


-310 


Nitrogen boils. 


-5 


23 




-180 


-292 


Oxygen boils. 


-4-4 


24 




-170 


-274 




-4 


24-8 




-160 


-256 




-39 


25 




-150 


-238 




- 3 3 


26 




-140 


-220 




-3 


26 6 




-130 


-202 


Alcohol freezes. 


-2-8 


27 




-120 


-184 




-22 


28 




-110 


-166 




-2 


28-4 




-100 


-148 




-1-7 


29 




-80 


-112 


Carbonic acid gas 


-1-1 


30 




-60 


-76 


boils. 


-1 


30-2 




-40 


-40 


Mercury melts. 


-06 


31 




-30 


-22 


Ammonia boils. 





32 


Water freezes. 


-25 


-13 




06 


33 




-20 


-4 




1 


33-8 




-19 


-22 




1-1 


34 




-18 


-0-4 




1-7 


35 




-17'8 







2 


35-6 




-17 2 


1 




2 2 


36 




-17 


1-4 




2-8 


37 




-16-7 


2 




3 


37 4 




-161 


3 




3 3 


38 




-16 


3 2 




3 9 


39 




-15-6 


4 




4 


39-2 


Maximum density 


-15 


5 




4-4 


40 


of water. 


-14-4 


6 




5 


41 




-14 


6-8 




5 6 


42 




-13-9 


7 




6 


42-8 




- 13\3 


8 




61 


43 




-13 


8-6 




6 7 


44 




-12-8 


9 




7 


44 6 




-122 


10 




7-2 


45 




-12 


10-4 




7-8 


46 




-11*7 


11 




8 


464 




-li-i 


12 




8-4 


47 




-11 


122 




8-9 


48 




-10-6 


13 




9 


48-2 




-10 


14 




9 5 


49 




-94 


15 




10 


50 




-9 


15-8 




106 


51 




-8-9 


16 




11 


51-8 




-8-3 


17 




11-2 


52 




-8 


17'6 




11-7 


53 




-7'8 


18 




12 


53-6 




-7'2 


19 




12-3 


54 




-7 


19-4 




12-8 


55 




-6-7 


20 




13 


55-4 





THERMOMETER SCALES 



293 



THERMOMETER SCALES. 
CENTIGRADE AND FAHRENHEIT EQUIVALENTS. 

For Absolute Temperatures add 273° to Centigrade Scale. 



Centigrade. 


Fahrenheit. 


Remarks. 


Centigrade. 


Fahrenheit. 


Remarks. 


133 


56 




33 


91-4 




13-9 


57 




33 3 


92 




14 


57 2 




33-9 


93 




14-4 


58 




34 


93 2 




15 


59 




34-4 


94 


Ether boils. 


15'6 


60 




35 


95 




16 


60-8 




35 6 


96 




16-1 


61 




36 


96-8 




167 


62 




36-1 


97 




17 


62 6 




36-7 


98 




172 


63 




37 


98-6 


Human blood tem- 


17-8 


64 




37 2 


99 


perature. 


18 


64 4 




37-8 


100 




18-3 


65 




38 


100-6 




18-9 


66 




38-3 


101 




19 


66-2 




38-9 


102 




19-4 


67 




39 


102-4 




20 


68 


Proper room tem- 


39-4 


103 




20-6 


69 


perature. 


40 


104 




21 


69-8 




43 3 


110 




211 


70 




45 


113 




21-7 


71 




48 9 


120 




22 


71'6 




50 


122 




22 2 


72 




54 4 


130 




22-8 


73 




55 


131 




23 


73-4 




60 


140 


Chloroform boils, 62*. 


23-3 


74 




65 


149 


Potassium melts, 62°. 


23 9 


75 




65-6 


150 


Methyl alcohol bis., 66*. 


24 


75 2 




70 


158 


Woods alloy melts, 65°. 


24 4 


76 




71-1 


160 




25 


77 




75 


167 




25-6 


78 




76-7 


170 




26 


78-8 




80 


176 


Ethyl alcohol boils, 79°. 


26-1 


79 




82-2 


180 




26-7 


80 




85 


185 




27 


80-6 




87-8 


190 




27 2 


81 




90 


194 




27-8 


82 




93-3 


200 




28 


82-4 




95 


203 


Sodium melts, 96°. 


28-3 


83 




98-9 


210 




28-9 


84 




99 


210-2 




29 


84-2 




99-4 


211 




29-4 


85 




100 


212 


Water boils, under 


30 


86 




125 


257 


76 cm. pressure. 


30 6 


87 




150 


302 




31 


87'8 


Critical tempera- 


175 


347 




311 


88 


ture of carbonic 


200 


392 


Solder melts, 183°. 


317 


89 


acid. 


250 


482 


Tin melts, 227°. 


32 


89-6 




300 


725 


Lead melts, 335°. 


32-2 


90 




350 


662 


Mercury boils, 


32-8 


91 




400 


752 


357° 3. 



294 EVOLUTION OF WEIGHTS AND MEASURES 



MISCELLANEOUS CONSTANTS AND EQUIVALENTS. 

tt = 3*1416. tt 2 = 9*8696. 1/tt = 0"31831. 4tt= 12*566. 

1/4*- = 0*07958. Jog7r= -49715. log tt 2 = -99430. log l/7r=f*50285. 

log 4tt= 1-09921. log 1/4tt = 2*90079. 

Base of the natural system of logarithms, e = 2*7183, log e= -43429 (Briggs). 

Modulus „ „ „ M= l/loge = 2-3026, log M= -36222 (Briggs). 

Radian = angle where the arc equals the radius = 57° '2958 = 3437' '75 = 206265". 
log radian (in degrees) = 1 "75812, (in minutes) = 3 "53628, 
(in seconds) = 5 "31443. 

Steradian = the solid angle at the center of a sphere of unit radius which is sub- 
tended by the unit area. Total angle at a point equals Air steradians. 

Earth's radius in kilometers — 

equatorial = 6378 "2, polar = 6356 "5, mean = 6367 "4, 

log equatorial = 3 "80469, log polar = 3 "80321 , log mean = 3 "80396. 

Mean solar year = 365 "2422 days = 8765 "8 13 hours = 525948 "8 min. =31556928 sec. 

Stellar day is 3 min. 55 "9 sec. shorter than the mean solar day, =0*99727 day. 

Velocity of sound in dry air at 0°C. is 331 meters per second. 

Coefficient of expansion of gases = 1/273 = *003665. 

Acceleration of gravity at poles = 983 *2 ; at equator = 978 *0 ; at 45° = 980 *6 ; at New 
York = 980*2 ; at Greenwich = 981*2 ; at <f>° latitude = 978(1 +0*0052 sin 2 0). 

1 gram of water 1°C. = minor calorie = 4*2 x 10 7 ergs = 4 "2 joules. 

Latent heat of water = 80; of steam = 539. 

Specific, heat of air at constant pressure = "237. Ratio of specific heats =1*40. 

Capillary constant of water = 7 "7, of alcohol = 2 "3, of mercury = 50 rng./mm. 

Velocity of light in vacuo = 3 x 10 10 cm. /sec. 

Wave length of sodium light = "0005893 mm. 

Length of the meter in wave lengths of red cadmium light = 1553163 "5. 

1 ampere of current deposits 1 "118 mgr. of silver per second = 0"1740c.c. (H. and 0. ). 

A plate of quartz 1 mm. thick at 18° C. rotates the plane of polarization 21° '71. 

Ohm = resistance of a column of mercury 1 sq. mm. cross-section, 106 "3 cm. long. 

E.M.F. of Latimer Clark cell at 18° is 1-434, of cadmium (Weston) cell at 4° is 
1-0190. 

The solar constant = 3 gram-calories per sq. cm. per minute. 

The mass of the hydrogen atom is = 10 -24 gram ; of the electron is = 10 -27 gram. 

Value of e/m = 4*5 x 10 17 electrostatic = 1 *5 x 10 7 electromagnetic. 

Velocity of the electrons — beta particles = 2-7 x 10 10 , alpha particles = 3 x 10 9 . 

Probable speed of a molecule of oxygen at 0° C. =376*6 m./sec. , of hydrogen = 1500*9. 

Mean free path of a molecule of air at a pressure of 76 cm. and at 0° C. =9*6 x 10~ 6 . 

Number of molecules of air in a c.c. at 0° C. and 76 cm. =6 x 10 19 . 

One atmosphere pressure = 76 cm. of mercury =1*0132 megadynes per sq. cm. 

A knot is a speed of one nautical mile per hour =1*1515 statute miles or 1S53'25 
meters per hour. 

A miner's inch of water is from 1*20 to 1*76 cu. ft. per min. =0*708 liter per sec. 

Ratio of the probable error to the mean error is 0*6745 (2/3). 

Light year is the distance travelled by light in one year = 9*467 x 10 12 kilometers 
= 5*8825 x 10» miles. 



INDEX. 



PACE 

Abbot. Gen. Henry L. - - 21 1 

Abraham 4, 19 

Absolute measurements - - 204 
Absolute system - 200 

Academy of Sciences, Paris, 47, 48, 65 
Academy of Sciences, Paris, Sup- 
pression of - - - - 52 
Academy of Sciences, National, 

U.S. - - - 127, 129, 210 
Academy of Sciences, St. Peters- 
burg 71 

Acts of Congress 

119, 121, 127, 128, 129, 131, 132, 210 
Actus - - - - - - 26 

Adams, John Quincy 

109, 115, 116, 117, 118 
Aeginetan talent and mina - 27, 28 
Airy, Sir G. B. - - - 100, 247 

Ale gallon 35 

Alexandrian talent - - 25, 32, 33 
Alloys, Nickel steel - - - 221 
Amenoemopht ... - 22 
American Geographical and Statis- 
tical Society - - - - 125 
American Metrological Society - 129 
Ampere - 206, 207, 208, 209, 211 

Amphora 28 

Angle, Measurement of - - 2< 12 
Anglo-Saxon measures of length - 36 
Angular acceleration - - - 202 
Angular velocity - - - - 202 
Anti-Metric argument of American 
Society Mechanical Engineers 

145-162 
Apothecaries' pound 32 

Ar 142 

Arabs, Measures of - - 29, 38 

Arago 100 

Arbitrary units - - - - 5 

Arbuthnot 10 

Arc of Meridian, Measurement of 55 
Archinne 94 



Are 54 

Argentine confederation - - 76 

Ark, Dimensions of - - - 11 
Aroura - - - - 20, 23 

Arpent 45 

Articles of confederation, Weights 

and measures in - - - 109 

As, Roman unit of weight - - 26 

Assize of bread and ale 32, 35, 242 

Association geodesique - - 71 
Assyrian documents, Measures 

in 16 

Astronomy, Babylonian - - 12 

Ater 23 

Athena, Temple of 25 

Athenian talent 27 

Attic foot 25 

Aulne, Derivation of - - - 26 

Aune des marchands - - - 38 

Aune of Paris - - - - 38 

Aune, Swiss 97 

Australia and the metric system - 102 

Austria adopts metric system - 90 
Austria- Hungary signs metric 

treaty 75 

Autun, Talleyrand, Bishop of - 46 
Avoirdupois pound 

33, 34, 35, 122, 123, 248 

Babylonia, Measures of 8, 9, 11, 12, 13, 
14, 15, 16, 17, 18, 19, 22 
Bache, Professor A. D. 122, 123, 124 
Baden adopts decimal measures - 82 
Baily, F. - - - - 231, 243 
Balance - 24, 236, 237, 238, 239 
Baldwin locomotive works - - 188 
Bancroft, George - - - - 125 
Barcelona - - - - 49, 56 
Barker, Geo. F. - - - - 211 
Barley corn as a unit - - - 8, 29 
Barnard, Prof. F. A. P. - - 129 
Barus, Carl 211 



296 



INDEX 



Base measurement 


PAGE 

- 55 


Bassot 


- 41 


Bath 


- 20 


Beal 


6 


Belgic foot - 


- 31 


Belgium adopts metric system 


- 91 



Belhaven and Stenton, Lord 101 

Benoit, J. Rene - - 69, 219, 251 
Berthollet - - - - 54, 99 

Bessel 40, 223 

Bigourdan, M. - - - 41 

Binary subdivision - - - 179 
Bird standard .... 244 
Bismer-pund 96 

Black cubit 29 

Blaine, James G. - - - - 159 
Board of Trade British specifica- 
tions 215 

Board of Trade electrical stan- 
dards 242 

Body measures 6 

Boeckh - - - - 11, 29, 30 

Boisseau 66 

Borda - - - 47, 48, 54, 250, 251 

Brandis, J. 11 

Brazil and metric treaty - - 75 
Briggs, Ernest B. - - - 187 

Brighton railway, England - - 168 

Brisson 54 

British Association committee on 

units - - - 205, 207 
British Association unit of resist- 
ance 207 

British engineers in Egypt - - 92 
British imperial gallon - - 36 

British imperial standards 

245, 246, 247, 248, 249 
British imperial standard yard - 246 
British pharmacopoeia - 192, 197 

British standards of length and 

weight - 245, 246, 247, 248, 249 
British Weights and Measures 

Association - 163 

Brix 69 

Bronze standard No. 11 - - 247 

Brumaire 53 

Brumer comparator - - - 234 
Bunge balance ... - 238 
Bureau International des Poids et 

Mesures established - - 76 
Bureau of Standards, U.S. - 131, 132 

Cadmium spectrum, Lines of - 261 
Calendar, French reforms in 52, 53 

Caliph-Al-Mamum 29 

Calipers for standards of length 

224, 229 
Canaan, Civilization of - - 19 

Capacity, Electrical - - 203, 209 



Capacity, Measures of 

5, 27, 28, 35, 144, 240 

Carat 3, 25 

Cassini - - - - 44, 49, 54 

Cattle standard - - - - 3 

Centesima 43 

Centigram - - - 146, 147, 148 
Centiliter ----- 144 
Centime - - - - - 45 

Centimeter 139 

Centner 86 

Centuria 43 

C.G.S. or centimeter-gram-second- 
system - - 102, 199, 205, 206 
C.G.S. electro-magnetic units - 207 
Chambers of Agriculture favour 

metric svstem - - - 102 
Chaney, H. J. - - 30, 37, 247 

Chappuis, M. - - - - 261 
Charlemagne 37 

Charlemagne, " Pile de " - - 39 
Chase, Salmon P. 126 

Chicago congress - 208 

Chisholm, H. W. - - 25, 32, 33, 244 

Clark cell 207 

Clark, Capt. A. R. - - - 69 
Clarke's spheroid- 62 

Coast and Geodetic Survey stand- 
ards - - - 114, 121, 122 
Colles, Geo. W. - - - - 133 
Collet, M. A. - - - - 258 
Cologne, Mark of - - 32, 40 

Colonial Governors, British, favour 

metric system - - - 159 
Commemorative medal for metric 

system - - - - 63, 64 
Commercial pound (libra mercatoria) 33 
Committee on coinage, weights 

and measures reports 73, 75, 87, 
90, 91, 120, 121, 128, 130, 133 
Committee of weights and measures 
and of moneys of Paris Ex- 
position of 1867 - - - 85 
Comparison of standards of length 229 
Comparator of Borda - - - 230 
Comparator of Lenoir - - - 230 
Compensated bars - - - 251 
Conder, C. R. - - - - 22 
Condorcet - - - - 47, 48 
Conference of British Colonial 

Premiers - - - - 159 

Congius 28 

Congress, U.S., considers weights 

and measures - - 113, 127 

Congress, Acts of 

119, 127, 128, 131, 132 
Conservatoire des Arts et Metiers 

69, 250, 251, 252 
Conservatory, Meter of - - 73 



INDEX 



297 



Continental Congress, legislation 

on weights and measures, - 109 
Corinth, Units of weight in - - 27 

Corn bushel 35 

Corn gallon 35 

Corps Legislatif receives standard 

meter and kilogram - - 63 
Cotton values quoted decimally - 167 

Coulomb 54 

Coulomb, unit of quantity 203, 206, 207 
Cross- wires - - - - 231, 234 
Crypt chapel 30 

Crystal standards - - - 236 

Cubit - - 6, 13, 14, 15, 20, 22, 26 
Cunin-Gridaine 83 

Currency, Decimal - - 85, 110 
Curvature, Unit of 202 

Dagobert 37 

Daniell cell 205 

Deben or uten 24 

De Bonnay, Marquis 46 

Decagrams - 146, 148 

Decaliter - 144, 145 

Decameter - 138, 139 

Decigrams - - - - 146, 148 

Deciliter 144 

Deciina 43 

Decimal Association - - - 101 
Decimal clocks ... - 168 
Decimal hour .... 168 
Decimal multiplication - - 167 

Decimal system of coinage - 85,110 
Decimal system of Jefferson - 111 

Decimal system of money pro- 
posed in France 45 

Decimes 45 

Decimeter - - - - 138, 139 
Decistere - - - - - 144 

Decuria 43 

Didrachms 25 

Delambre .... 54, 60 
Delambre and Mechain, Base du 

Systeme MUrique - - - 41 

De Luc 99 

Denier 38 

Denmark signs metric treaty - 76 
De Puvy, Charles A. - - - 168 
De Sarzec, E. - - - 14 

De Schubert, Gen. T. F. - - 69 
Dessert-spoonful ... - 198 

Digit 6 

Directive force .... 202 
Dividing engine - 225 

Domesday book - - - 31 

Double weighing - 237 

Drachmas 27 

Draughting room, Metric system 

in 181 



)rusus, Foot of - 


PAGE 

- 26 


)unkirk 


49, 56 


)u Vernois, Prieur 


- 44 


Sarth inductor 


- 204 


3dgar, Laws of - 


- 30 


3d ward L, Laws of 


- 34 


fid ward II. . Laws of - 


- 36, 242 


Mward III., Laws of - 


- 243 


Sgypt, metric measures 


- 92 



Egyptian measures, Ancient 

11, 20, 22, 23, 24 

Ehalkus 27 

Electrical congress, Chicago 208, 216 
Electrical congress, Paris - - 215 
Electrical congress (St. Louis) 216, 241 
Electrical measure, U.S. units of 131 
Electromotive force - - - 204 
Elephantis, Cubit of - 22 

Elizabeth, Standards of 34, 36, 243 

Ell 26, 36, 89 

Elle 83 

End standard (metre a bouts) - 74 
End standards (e talon a bouts) - 223 
Energy, Unit of - - - - 202 
Engineering, Metric system in - 172 
England, Progress of metric 

system in - - - - 98 
English Bible, Weights and meas- 
ures in 20 

English parliamentary accounts 

and papers 91 

English yard 

3, 31, 36, 243, 244, 245, 246 

Ephah 20 

Eratosthenes 29 

Erg 202, 206 

Euboic talent 27 

Everest, Col. George 69 

Exchequer, Standards of - 34, 109 
Exodus, Weights and measures at 

time of 20 

Export business and uniform 

measures .... 133 
Ezekiel .... 20, 23 

Fabbroni 256 

Farad 203, 206 

Farmers' Associations favour 

metric system - - - 102 

Fathom 6 

Federal constitution, Weights and 

measures in - - - - 109 

Finland, metric system adopted - 95 

Fizeau 261 

Fleetwood, Bishop - - - 30 

Floreal 53 

Foerster, W. .... 87 

Foot 6, 25, 26, 31, 37, 38, 44, 89, 112 



298 



INDEX 



PAGE 

Force, Units of - 200, 202 

Forney, M. N. - - - - 185 
Foster, Secretary of State - - 159 
France, Measures of - - 37, 43 

French Academy 99 

French foot 38 

French standards of length - 37, 249 
French standards presented to 

various nations - - - 83 
French standards of weight 38, 250 

Fructidor 53 

Fundamental units - - S, 200 
Fuss 83 



42, 55 

- 164 

- 43 

- 200 

8, 89, 90 

9, 22, 24 

- 15 



Galileo 15 

Gallatin, Albert, Minister - 119,121 
Gambey, Comparator of - 69, 232 

Gan 15 

Gar 15 

Garden 15 

Gas thermometer - - - 228 

Gauges - - - 176, 177, 178 

Gauss, Carl Friedrich - - 200, 201 
Gauss (unit) .... 215 

Genesis .... 11-19 

Geodetic or trigonometrical survey 

" Geometrical " inch - 
Geometric foot 
German Magnetic Union 
Germany, Metric system in 

86, 87, 
Ghizeh, Pyramid of 

Gin 

Gird 30 

Godin and Bouguer 44 

Goldsmith's Hall, Standard of - 248 

Gore, J. H. 43 

Gouon and Penin 64 

Gradus 26 

Graham, George 36 

Gram 54, 146 

Gratings, Diffraction - - - 226 
Gravimetric method - - - 193 
Great circle 42, 48 

Great rnina 16 

Great pyramid - - 7, 9, 22, 24 
Greaves, John - - - 29, 30 
Greece, Measures of ancient - 25 

Greece, Metric system in - - 92 
Greek cubit - - - - 22, 25 
Greek foot ----- 25 
Gregorian calendar resumed in 

France 53 

Griffiths, F. L. - - - - 23 

Gros 39, 66 

Gudea scale - - - - 13, 14 
Gunter, Edmund- 9S 

Gur 16 



Guillaume, Ch. Ed. 

vii., 35, 39, 221, 223, 228 
Guizot 83 

Halsey and Dale, The Metric 

Fallacy 134 

Hamy, M. 261 

Hand-breadth - - - - 6, 13 

Harpham, F. E. - - - 41 

Harris ------ 34 

Harrison, President Benjamin - 131 
Hassler - - 114, 121, 122, 123 
Hastings, Charles S. - - - 211 
Haute-Guyenne 45 

Haiiy 54, 62 

Hebrew weights and measures 

19, 20, 21 
Hectar(e) - - - - 51, 142 
Hectogram - 51, 148 

Hectoliter - - - - 51, 145 
Hectometer - - - - 51, 139 
Hekatompedos 25 

Hekt 23 

Henry (unit) - - - - 210 
Henry L, Yard of - - - 3, 31 
Henry III., Statutes. of - 32, 

Henry IV. 

Henry VII. 34, 

Henry VIII., Statutes of - 
Henry, Prof. Joseph - 

Henu 

Herschel, Sir John - - 7, 
Hilgard, J. E. - 

Hin 

Hindus, Weights and measures of 
Hiuen-Tsiang - 
Holland, Metric system in - 82, 93, 
Hoi ton, Michigan, Base at - - 141 

Homer 21 

Hommel - - - - 11, 12, 13 
House of Commons Committee 

report - - - - 
House of Deputies, France, bill 
Hultsch .... 
Hundredweight - 
Hungary, Metric system in - 
Hunt, Wm. H. - - - 
Huygens - 
Hydrogen scale - 
Hydrogen thermometer 



33 

33 

35 

34 

129 

23 

164 

129 

21 

18 

6 

94 



100 
67 
25 

156 
91 

195 
43 

228 

228 



Ibanez, General 77 

Iced bar base apparatus - - 141 

Ideler, L. 12 

Imperial bushel - - - 35, 249 
Imperial standards 

245, 246, 247, 248, 249 

Inch 26, 36 

India, Ancient measures of - - 6 



INDEX 



299 



PAGE 

- 208 

120, 121 

186 



181 



200 



216 

208 



216 

75 
209 



Inductance, Unit of 

Ingham, S. D. - 

Institution of Electrical Engineers 

Instruments of precision, Use of 

metric system in - 
Intensity of magnetism, Measure- 
ment of 

International American Conference 

of 1890 - 103, 159 

International ampere - - - 209 
International Bureau of Weights 

and Measures - 75, 76, 77, 129, 
221, 226, 260 
International Commission 

61, 72, 9 
International Congress of Elec- 
tricians (Chicago) - 
International Congress of Elec- 
tricians (Paris) - - 207, 208 
International Congress of Elec- 
tricians (St. Louis) 
International Convention of 

Weights and Measures 
International Coulomb 
International electrical units 

131, 199, 209 
International farad - - - 209 
International Geodetic Association 71 
International kilogram, Definition 

of - - - - ." . " 78 
International metric commission 

72, 73, 74, 75, 76, 77, 78 
International metric prototype 

standards - 76, 77, 252, 254, 255, 
256, 257, 258, 259 
International ohm - - 207-209 
International Postal Convention 127 
International Postal Union - - 151 
International prototype meter 

130, 136, 221, 252, 255 
International standard kilogram 

78, 258, 259 
International Statistical Congress 126 
International volt - - - 209 

Invariability of standards - 219, 260 
Israelites, measures - - 19, 20, 21 
Italy, Metric system in - - 93 

Jacobi 205 

Japanese weights and measures - 93 
Jefferson, Thomas 

110, 111, 112, 113, 114, 115 

Jeremiah 23 

Jews, Weights and measures of - 19 
Johns, Rev. C. H. U. - - 16, 17, 18 

Josephus 10 

Jomard - - - - 10, 30 
Joule ---- 206, 208, 209 
Jugerum 26 



Ka 

Kab - 

Karsten 

Kasbu - 

Kat or Kiti - 

Kater, Captain Henry 

99, 100, 119, 120, 
Keith, Rev. George Skene 
Kelly - 
Kelvin - 

Kennedy, A. R. S. 
Khar - - - 
Khet --- - 
Kilogauss 

Kilogram 50, 62, 63, 73, 
147, 256, 
Kilogram of the Archives 
73, 74, 75, 147, 
Kilometer - 
Kilowatt 
King Edgar - 
Kirwan 
Kiti or Kat - 
Koenigsberg standard - 
Kohlrausch, Rudolf 
Kor .... 
Korn-Tonde- 
Kupffer 



PAGE 

- 16 
16, 21 

- 40 

- 15 

- 24 

122, 222, 245 

- 99 
31, 37 

- 101 

- 20 

- 23 

- 23 

- 215 
74-146, 
257, 258, 259 

256, 257, 258 

- 50, 138 

- 206 

- 30 

- 98 

- 24 

- 223 

- 201, 205 

- 21 

- 96 

- 234 



47 : 



Lacaille 

La Condamine 

Lagrange 

Lalande 

Laplace - -47, 48, 

Larsam or Larsa - 

Lathes - 

Latin prefixes 

Latin Union 

Latitude, Determination of 

56, 57, 58, 59 
Lavoisier .... 62, 98, 99 
Leading screw of lathes - - 187 



■ 49 

- 44 

48, 54 

- 229 
54, 65, 98, 99 

- 13 

- 182 

- 137 

- 85 



Lefevre-Gineau 

Lehmann 

Lenoir - 

Lepsius 

Leroux, Alfred 

Lever comparator 

Le Verrier - 

Libbrae metrica - 

Libra - 

Libra mercatoria 

Library catalogue cards 

Lieue - 

Lignes - 

Line and reel 

Line standards (etalon a 

Linnard, J. H. 

Liter .... 



62, 256 

15, 18 

14, 230, 251, 256 

13, 22 

- 71 

- 230 

- 69 

- 82 

- 28 

- 33 

- 140 

- 97 
44, 45 

- 23 
- 223 

- 134 
54, 145 



traits) 



300 



INDEX 



PAGE 

Liverpool Cotton Association - 167 

Livre 39, 45, 97 

Livre de Troyes - 33 

Livre Esterlin ... 32, 38 
Livre poid de marc 39 

London Exposition of 1851 - 83, 84 

Longitude 59 

Long ton 168 

Louis XVI. 45 

Lumber, Measurement of - - 178 

Maass concordats - - 83, 97 

Machine shop, Metric system in - 182 
Madison, President James - - 115 
Magna Charta, Weights and 

measures in - - - - 32 
Magnetic field, Unit of - - 203 

Magnetic pole, Unit of - - 202 

Maine approves metric system - 122 
Mairan, Toise of - - - 61 

Marc 39 

Marc de Troyes - - - - 33 
Marine Hospital Service - 192-195 
Mark of Cologne 32, 40 

Mass, Measures of 146 

Master Car Builders' Association 

173, 185 

Mauss, C. 250 

Maxwell, (unit) - - - 203, 215 
Maxwell, J. Clark - - - 260 
Measures of capacity - - 144, 240 
Mechain - - - 41, 54, 60, 61 
Mechanical engineering and manu- 
facturing, Metric system in - 172 
Mechanical engineers, American 

Society of - 145-162 

Medical department of the army 

192, 195, 196 
Medical department of the navy 

192, 195 
Medical papyri 24 

Medicine and pharmacy, Metric 

system in 191 

Medimnus 23 

Megameter 138 

Memphis, Necropolis at - - 22 
Memphis-Faium road - - - 23 
Mendenhall, J. C. - - - 164 

Mesures usuelles - - 65, 66, 67 

Meter - - 49-54, 62-63, 139 

Meter of the Archives 62, 71, 73, 75, 
221, 225, 249, 251 
Meter of the conservatory - 63, 251 
Meter of the observatory - - 251 
Method of interference for measur- 
ing differences of length - 225 
Metre a bouts 74 

Metre a traits - - - 72, 73, 74 
Metric measures of capacity 144, 240 



PAGE 

Metric measures of length - - 138 
Metric measures of mass - - 146 
Metric measures of surface - - 142 
Metric measures of volume - - 143 
Metric prescriptions - - - 192 
Metric standard of U.S. Coast 

Survey 114 

Metric standard of United States 130 
Metric system - - 39, 41, 61, 63 
Metric system in U.S. Congress 

133, 134 
Metric thread .... 183 

Metric ton 147 

Metric wire gauges - - - 178 
Metrological Society, American - 129 
Mexico, Metric system in - - 103 
Michelson, Prof. A. 

211, 260, 261, 262, 263, 264, 265 

Micro-farad 206 

Micrometer-microscope 

230, 231, 233, 234 
Micrometer screws - - - 229 

Micron 140 

Milan, Metric system introduced 

in 82 

Mile 26, 31 

Milia pasuum - - - 26, 31 
Miller, W. H. - - - 35, 248 
Miller, Sir John Riggs - 99, 163 

Milligram - - . 146, 148 

Milligram weights - - - 148 

Milliliter 144 

Millimeter - 138 ; 140 

Millimicron - 138^ 140 

Mina - - -16,21,25,27,28,32 
Mina, Babylonian 16 

Mina, heavy - - - - 16 

Mina, light 16 

Mina, Phoenician 16 

Mint, U.S., standard troy pound 119 

M'Leod 99 

Modius 28 

Moment of rotation, Unit of - 202 
Momentum, Unit of - 202 

Monge 48, 54, 99 

Moore, Dr. 123 

Morin, General A. - - 41, 69 

Morris, Robert - - - - 110 
Mouton, Gabriel - - - - 43 
Miinzpfund - - - • - - 86 

Myriameter 138 

Myriagram - • - - 146, 147 

Napoleon I. - - - 65, 77, 82, 92 
Napoleon III. - - - - 71 
National Academy of France - 49 
National Academy of Sciences, 

U.S. - - - 127,129,211 
National Assembly (French) - 46 



INDEX 



301 



PAOE 

National Bureau of Standards - 132 
National Institute of Sciences and 

Arts (French) - - 53, 63 
National Physical Laboratory 

(England) - - - 152, 241 
National prototype meter of the 

United States - - - 130 
Natural standards 5 

Natural units - - - - 5 
Neutral plane .... 222 
New Hampshire approves metric 

system 125 

Newton's rings - 261 

New Zealand adopts metric system 102 
Nickel five cent, piece- - - 128 
Noak, Ark of - - - - 11 
Normal-Aichungs-Kommission 87, 90 
North German Confederation - 87 
Norway - - - - 95, 96 



Oboles - 


. 


38, 39 


Ohm - - ,- 


. 


- 206 


Ohm's law - 


. 


- 204, 206 


Oke - 


. 


- - 92 


Oldberg, Oscar 


- 


- 195 



Old Testament, Weights and 

measures of - - - 19, 20, 21 
Olympian foot 25 

Oner 21 

Opticians' use of metric system - 181 
Orguia, or fathom - - - 25 
Origin of weights and measures - 1 i 
Ounce - - - - 25, 26, 32, 33 

Pace 2, 6 

Palestine Exploration Fund, 

Quarterly statement, 1902 - 22 

Palm - 6 

Palm, Babylonian - - - 14 

Palmipes or foot 26 

Parasang - - - - - 15 
Paris Academy of Sciences 46, 47, 71 
Paris Exposition - - 70, 84, 85, 129 
Paris International Electrical 

Congress - - 207, 208, 215 
Parliamentary reports 91 

Parliament, Burning of Houses of, 

1834 35 

Parliamentary standard - - 249 

Parthenon 25 

Par value 167 

Passus ------ 26 

Paucton - - - - 7, 10, 37 

Pavilion Breteuil - - - 77 

Pence 32 

Pendulum as a unit of length 

15, 37, 42, 44, 46, 48, 49, 111, 245 
Penny, or sterling - - - 32 
Pennyweight - - - - 32 



Perch ... - 


PAGE 

- 45 


Perche - 


- 97 


Perpignan, Base at 


- 55 


Pertica or Decempeda - 


- 26 


Peru, Toise de 


44, 249 


Petrie, Flinders - 


- 18, 23, 24 


Pfund - 


- 82, 83, 86 



Philippine Tariff Act, 1901 - - 132 
Philosophical drachm, ounce, and 

pound 98 

Phoenician weights and measures 18, 21 
Physicalisch Technische Reich san- 

stalt 152 

Picard 43 

Pied de roi 37 

Pied geometrique 44 

Pied (Swiss) .... 97 

Pile of Charlemagne - - 39, 250 
Pinte (French) - 145 

Platinum for standards - 236, 257 
Platinum Iridium standards 

74, 77, 148, 221, 252 
Platinum metres • - - 62, 251 

Pliny 26 

Plumb-line 15 

Plutarch 25 

Pluviose 53 

Polar axis ----- 164 
Polar flattening - - - 48, 59, 62 

Polaris 39 

Polar radius - - - - 164 

Polybius 26 

Polychrome Bible - - - 14 

Porto Rico, Metric measures in - 132 
Portugal, Metric system in - - 94 
Postal Congress of 1863 - - 126 

Pot (Swiss) 97 

Potential difference, Unit of - 203 
Pound - 27, 32, 33, 34, 38. 119, 248 
Power, Unit of - - - - 202 
Pratt & Whitney Co. - - - 185 

Prairial 53 

Prescriptions, Metric - - - 197 
Priestley, Dr. - - - - 98 

Prony 54 

Ptolemy Lagos 24 

Pyx chapel 30 

Quadrant (unit of inductance) - 208 
Quantity of electricity, Unit 203, 209 
Quarteron ----- 39 
Quarteron (Swiss unit of capacity) 97 
Queen Anne, Gallon of - - 35 

Queen Elizabeth, Standards of 

35, 36, 243, 247 
Quintal ... - 146, 147 
Quito, arc 44 



Railway shares 



167 



302 



INDEX 



Rawlinson - 

Rayleigh, Lord • 

Rayon astronomique 

Reed - 

Regnault 

Reichsanstalt 

Resistance - 

Retail Trades Associations favour 

metric system 
Rhine countries, Measures in 
Rhine foot - 

Richard L, Laws of - - 

Riders 

Ridge way 3 



PAGE 

- 13 

- 207 

- 43 

- 15 

- 69 
152, 241 

203, 204, 205 



102 
26 
40 
31 

148 
4, 18 



Rock crystal standards 148, 236 

Rogers, Wm. A. - - - 185, 235 
Rome, Weights and measures of - 26 
Rosenberger - - - 204, 205 

Rosebery, Lord - 101 

Rowland, Henry A. - 207, 211, 226 
Royal foot (French) ... 37 
Royal Society (British) 

46, 47, 84, 99, 101 
Ruggles, Samuel B. - - - 126 
Ruprecht balance - - - 237 
Russia, Weights and measures of 94 
Ruthe 82 



Salces, Base at - - - 

Sagene 

Sar 

Sauvage, Ed. 

Saxon weights and measures 30, 

Schoenus .... 



31 



55 
94 
15 
183 
,32 
23 



Schools, Metric system in 125, 129, 165 

Schiraz, Anania de 

Schumacher, Professor 

Screws, Cutting of 

Screw-cutting lathe 

Screw threads 182, 183, 184, 185 

Seah - 

Second's pendulum 



15, 36, 37 

48, 49, 



44 



25 

248 
182 
186 
186 
21 
46, 



Sellers, Dr. Coleman 
Sellers, Wm. 
Seller's standard - 
Seller's thread 
Senkereh tablet - 
Sensibility of balance - 
Sexagesimal system 
Sextarii 
Shaku - 

Shaw-Caldecott, W. - 
She - - - - 
Sheet and plate iron and 

U.S. standard scale 
Shekel, Babylonian 
Shekels of the Hebrews 
Shilling - - 



111, 245 

- 161 

- 183 

- 183 

- 185 
13, 17 

- 239 

- 12 

- 28 

- 93 
13, 17 

- 15 



steel, 



131 
16 
21 
32 



PAGE 

Shoppen 83 

Short ton 168 

Shuckburgh, Sir George 

120, 230, 231, 245 

Shuckburgh scale - - - 100 

Shuckburgh's comparator - 230, 231 

Siemens, Alex. - - 186, 216, 217 

Siemens, Werner - 205 

Silver coinage by metric weight - 128 

Silver voltameter - 210,211,212 

Sizes of screw threads - 

Skaal-Pund 

Smith, Prof. R. H. 

Smyth, Piazzi - 

Societe d'Eneouragement pour 
l'lndustrie Nationale 

Solid angle unit - 

Solive 

Solon - - - - 

Sols 

Solvay Process Company 

South America, Metric system 
used in 

South and Central America, Metric 
system employed in 103, 107 

Spain, Adoption of metric system 
in 

Span 

Spanish Geographical and Statis- 
tical Institute 

Spartan States use Babylonian 
talent - 

Specific gravity of standard 






184 
96 

135 
10 

183 

- 202 

- 65 

- 27 
38, 39 

- 168 



Specific gravity tables 



160 

108 

95 
6 

158 

27 
- 238 
290, 291 
Specifications for ampere and volt 211 
Spencer - - - - - 102 
Square measures - 142 

Stadion 25 

Standard avoirdupois pound - 248 

Standard bars for base measure- 
ments - 
Standard kilogram and meter 
Standard cell 212, 213, 214 
Standard gauges - 
Standardization - 
Standards of capacity - 
Standard sizes 
Standard troy pound of 1758 
Standard troy pound, U.S. Mint 
Standard yard (Elizabeth) - 
Standard yard (Henry VII.) 
Standard yard, British 

244, 245, 246, 247 
Standard yards of United States 114, 247 
Standards and comparison - - 218 
Standards Commission, British 35, 100 
Standards office - 
Standards of mass 
Standards of the Netherlands 



215 



141 
254 
216 
176 
154 
240 
175 
34 
119 
36, 243 
36, 243 



246 
236 

93 



INDEX 



303 



PAGE 

Standards of the United States - 122 
Standards of resistance - - 241 
Standards of resistance, current 

and electrical pressure - - 242 
Standards, Permanence of - - 228 
State standards - - - 121, 122 

Steel tape 140 

Stere 54, 144 

Sternberg, Gen. Geo. M. - - 196 

Strabo 23, 26 

St. Louis Exposition - - - 216 
St. Petersburg Academy of 

Sciences 71 

Sweden, Metric system adopted - 95 
Switzerland, Metric system in 82, 97 
Syrian standard 21 

Systeme International, S.I. or 

S.J. 183 

Table-spoonful - - - - 198 
Talent, Alexandrian - - - 25 

Talleyrand 46 

Taps and dies .... 183 
Teachers' Associations endorse 

metric system - - - 102 

Teaspoonful 198 

Tel-el-Amarna correspondence - 19 
Temperature measurements - - 227 

Thermidor 53 

Thermometers, thermometric meas- 
urements ... . 227 
Thermometer scales, Table of - 290 

Tillet 47 

Tittman, 0. H. - - - - 120 

Toise 38, 44, 97 

Toise de macons 38 

Toise de Perou - - 38, 54, 249 

Toise du Grand Chatelet - 38, 249 
Torque, Unit of - - - - 202 
Tortuosity, Unit of - - - 202 
Totten, C. A. S. - - - - 10 
Tours, Standards of - - 39 

Tower Pound - - - 32, 33, 34 
Tralles- - - - 62, 81, 82, 114 

Transits 58 

Treasury Department, U.S., Stan- 
dards of - 123 
Treaty, Metric 75 
Tresca - - 74, 252, 253, 254, 255 
Trigonometrical survey - - 55 

Troughton 230 

Troughton scale - 114, 121, 122, 247 
Troy pound - - 25, 33, 34, 119, 248 
Troyes, Standards of - - 33, 39 

Trowbridge, John - - - 211 

Tumblerful 198 

Tungri, Belgic foot of - - - 31 
Turkey, Measures of - - - 97 
Tweedmouth - - - - 102 I 



PAGE 

Ulna - - - - - - 26 

Ulna or Aulne - - - - 31 

Unit acceleration - - - 200' 
United States, Weights and meas- 
ures of - - - - 103, 109 

United States Army, Med. Dept. 195 

United States Bureau of Standards 131 

United States Navy, Med. Dept. 195 

United States Pharmacopoeia - 192 

Unit of Intensity of Magnetism - 200 

Units 1 

Unit velocity - - - - 200 

Units, Absolute - - - - 200 

Units, Arbitrary 5 

Units, Fundamental 8 

Units, Natural ... - 5 

Upton, J. K. - - - - 91 

Ush 15 

Usuelle - - - - 65, 66, 67 



Vauclain, S. M. - 
Vandermonde 
Van Swinden 
Vendemiaire 
Vernet, Base near 
Vienna coin treaty 
Virga or Verge - 
Virga - - - - 
Virgula geometrica 
Volt - - - 
Volume, Measures of - 
Von Humboldt, Alex. - 



- 188 

- 54 
- 61, 80, 82, 

- 53 

- 55 

- 85 

- 31 

- 43 

- 43 
206, 209, 212 

- 143 

- 200 



Wales, Philip S. - - - - 195 
Warren, Gen. Charles 10 

Washburne, E. B. - - - 130 
Washington, President - 111, 113 
Watchmakers use of metric threads 181 

Water clock 12 

Watt (unit) - - 202, 206, 208, 209 
Watt, James 98 

Wave length of light - 229,260,261, 
262, 263, 264, 265, 266 
Weber, Wilhelm - - 201,204,205 
Weighing, Earliest - - - 4 
Weights and Measures Act 

(British, 1878) - - - 101 
Westminster Abbey - - - 30 

Weston cell 216 

Wheat bushels - - - - 156 
Whitworth standard - - 183, 186 
Willans & Robinson, Messrs. - 187 
William the Conqueror, Decree of 30 
Williams, R. P. - - - - 125 
Winchester standards - - - 30 
Winchester bushel - - 35, 122 
Winchester corn gallon - - 35 
Wine gallon - - - - 35 



304 



INDEX 



PAGE 

Wine glass - - - - - 198 
Windom, Secretary of the Treasury 159 



Wire and sheet metals 
Wolf, C. - 
Wolf, M. - 
Wolff, F. A. 
Wollaston, Wm. H. 
Wood worth, John M. 
Work, Unit of - 



176 
62, 230, 251 

- 230 
- 206, 215 

- 99 

- 195 
202, 206 



World's Columbian Exposition - 208 



Wrottesley, Sir John 



PAGE 

99 



Yard or gird 30, 31 

Yard standards - 36, 1 14, 243, 247 
Yates, James 84 

Young, Dr. Thomas 99 

Yusdrumin pound of Charlemagne 29 



Zollpfund 
Zollverein 



86, 89 
- 86 



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