AUG 13 1971 -^4 UNITED STATES DEPARTMENT OF COMMERCE 161670 C. R. SMITH, Secretary NATIONAL BUREAU OF STANDARDS / a. v. astin, Director Special Publication 304A. Issued 1968. lUj h Brief History and Use of THE ENGLISH AND METRIC SYSTEMS OF MEASUREMENT with a CHART OF THE MODERNIZED METRIC SYSTEM "Weights and measures may be ranked among the necessaries of life to every individual of human society. They enter into the eco- nomical arrangements and daily concerns of every family. They are necessary to every occupation of human industry; to the distribution and security of every species of property; to every transaction of trade and commerce ; to the labors of the husbandman ; to the in- genuity of the artificer; to the studies of the philosopher ; to the researches of the antiquarian, to the navigation of the mariner, and the marches of the soldier; to all the exchanges of peace, and all the operations of war." —JOHN QUINCY ADAMS When the American Colonies sepa- sembly of France on May 8, 1790, of the length of a great circle of the rated from the mother country to to enact a decree, sanctioned by Louis earth. This idea found favor with the assume among the nations of the XVI, which called upon the French French philosophers at the time of the earth a separate and individual sta- Academy of Sciences in concert with French Revolution, men who were tion, they retained, among other the Royal Society of London to "de- generally opposed to any vestige of things, the weights and measures duce an invariable standard for all of monarchical authority and preferred that had been used when they were the measures and all weights." Hav- a standard based on a constant of colonies, namely, the weights and ing already an adequate system of nature. measures of England. It is probable weights and measures, the English The French Academy assigned the that these were at that time the most were not interested in the French name metre (meter), from the Greek firmly established and widely used undertaking, so the French proceeded metron, a measure, to the unit of weights and measures in the world. with their endeavor alone. The result length which was supposed to be one England a highly coherent nation, is what is known as the metric system. ten millionth of the distance from separated by sea from many of the The metric system was conceived the north pole to the equator, along turmoils of the European continent, as a measurement system to the base the meridian running near Dunkirk, had long before established stand- ten: that is, the units of the system, Paris, and Barcelona. An attempt was ards for weights and measures that their multiples, and submultiples made to measure this meridian from have remained essentially unchanged should be related to each other by northern France to southern France, up to the present time. The yard, simple factors of ten. This is a great from which the true distance from established by Henry II, differs only convenience because it conforms to the pole to the equator could be by about 1 part in a thousand from our common system for numerical no- calculated. The best techniques then the yard of today. The pound of tation, which is also a base ten system. available were used. Although the op- Queen Elizabeth I shows similar Thus to convert between units, their erations were carried out during a agreement with the present avoir- multiples, and submultiples. it is not politically disturbed time, the results dupois pound. necessary to perform a difficult mul- were in error only by about 2000 No such uniformity of weights and tiplication or division process, but meters, a remarkable achievement in measures existed on the European simply to shift the decimal point. those days. continent. Weights and measures dif- The system seems to have been first Meanwhile the National Assembly fered not only from country to coun- proposed by Gabriel Mouton, a vicar had preempted the geodetic survey, try, but even from town to town and of Lyons, France, in the late 17th cen- upon which the meter was to be based, from one trade to another. This lack tury. He proposed to define the unit and established a provisional meter. of uniformity led the National As- of length for the system as a fraction The unit of mass called the gram was For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 — Price 20 cents 1 0; The Modernized Metric Syt M E 1 8 i 7 9 1 0 Centimeter-! j 1 2 | 4 LLuJ,j,,ii,l!d,.,i,,I ! ii,,Li,..,L,,LL,L.iJ 11, iiiiiiLiiiii ' 1 ' W ' ill ' m Inchu 1>3 lU ' 1*6 ' VS VI 1'8 119 1 INCH 1 FOOT Y A 1,1,1,1,1,1,1, 1, J, I 1, 1, 1, nl,l,l,l,ln, I, ill, 1, 1,1,1,1,1, 1,1, 1,1, lJ.1.1, 1, 1,1,1,1, 1,1,1, 1, 1,1,1, 1,1,1,1,1^^ 1.1, 1,1, 1, 1,1,1, 1,1,1, 1,1,1,1,1,1,1,1, ill, 1,1,1, hi,!,!, I 1, 1,1.1,1,1,1,1, 1, 1,1, 1,1, 1,1,1,1,1 THE International System of Units— viated SI —is a modernized version 1 :ub c c ECI METER 1 LIQUID QUART system. It was established by inter also called (approximately) I liter 0.946 liter ment to provide a logical and interconnec ] 00c cm for all measurements in science, industry, SI is built upon a foundation of base units nitions, which appear on this chart. All oil The Six Base Units of Measured! METER-m SECOND s KILOGRAM -kg The meter is defined as 1 650 763.73 wavelengths in The second is defined as the duration of 9 192 631 The standard for the unit of mass, the kilogram, is a vacuum of the orange-red line of the spectrum of 770 cycles of the radiation associated with a specified cylinder of platinum-iridium alloy kept by the Inter- krypton-86. transition of the cesium atom. It is realized by tun- national Bureau of Weights and Measures at Paris. ing an oscillator to the resonance frequency of the A duplicate in the custody of the National Bureau of cesium atoms as they pass through a system of mag- Standards serves as the mass standard for the United nets and a resonant cavity into a detector. States. This is the only base unit still defined by an artifact. DIRECTION OF MAGNETIC FIELD U.S. PROTOTYPE An interferometer is used to measure length by means of light waves. Closely allied to the concept of mass is that of FROM OSCILLATOR force. The SI unit of force is the newton (N). A force of 1 newton, when applied for 1 second, will give to of atomic beam spectrometer. The trajectories A schematic an a 1 kilogram mass a speed of 1 meter per second are drawn for those atoms whose magnetic moments are The SI unit of area is the square meter (m ). Land (an acceleration of 1 meter per second per second). "flipped" in the transition region. is often measured by the hectare (10 000 square meters, or approximately 2.5 acres). The SI unit of volume is the cubic meter (m ). Fluid volume is often measured by the liter (0.001 cubic The number of periods or cycles per second is meter). called frequency. The SI unit for frequency is the —- ACCELERATION OF lm/j' 1968 hertz (Hz). One hertz equals one cycle per second. Standard frequencies and correct time are broad- Is 2 cast from NBS stations WWV, WWVB, WWVH, and One newton equals approximately two tenths of a WVWL, and stations of the U.S. Navy. pound of force. Many shortwave receivers pick up WWV on fre- The weight of an object is the force exerted on it quencies of 2.5, 5, 10, 15, 20, and 25 megahertz. by gravity. Gravity gives i mass l downward accelera- National Bureau of Standards Special Publication 304 A The standard radio broadcast band extends from tion of about 9.8m s (Supersedes Miscellaneous Publication 232) 535 to 1605 kilohertz. The SI unit for work and energy of any kind is For sale by the Superintendent of Documents, U.S. Government Dividing distance by time gives speed. The SI unit the joule (J). Printing Office, Washington, D.C. 20402 - Price 20 cents for speed is the meter per second (m/s), approxi- 1J — 1 N • lm mately 3 feet per second. References: The SI unit for power of any kird is the watt (W). Rate of change in speed is called acceleration. NBS Handbook 102, ASTM Metric Practice Guide, 40 cents The SI unit for acceleration is the meter per second NBS Misc. Publ. 247, Weights and Measures Standards of the iw= 4^ United States, A Brief History, 35 cents per second (m/s=). Is NBS Misc. Publ. 286. Units of Weight and Measure, Definitions and Tables of Equivalents, $1.50 Special Publication This chart is one-third the actual size of the full-scale wall chart, NBS 304, which is availabl m A ' U.S. DEPARTMENT OF COMMERCE ^mrmr^ The International System of Units (SI) National Bureau of Standards '<t 61 1 and its relationship to U.S. customary units 6,0 S „i„j ,, m l„i,,,l,i,Ii,!!i,,Jm„i ,,,,i j LL,LJi.a.i.iJ L±, lj lj l.l i ,.i SLlu i ,LuLa,, - l| l |l l| l |l l| ll|l|l l | | | | W^^ | « 1 1 1 1 1 1 1 1 1 1 1 1 3l4 1 3l5 1 zl« 2I3 214 m« 2l5 zk 2l7 2>S 219 3l0 3ll 3l2 3l3 D 2 FEET '''''''''''' llhlllllllllLlliJllllllllllllllllllllllllllllllll^ ially abbre- derived from these base units.