â€¢ FROM THE DESK OF THE CHIEF HYDROLOGIST: THE METRIC SYSTEM WHAT IS IT AND HOW WILL IT AFFECT US WHEN ADOPI'ED. One of the most basic needs of our modern society is to be able to make measurements quickly, accurately and in readily understandable terms. Yet the world society still uses three widespread systems, only one of which meets these criteria. They are: (1) U. S. Customary; (2) British Imperial; and (3) Systeme International d'Unites (metric). Of these only the Systeme International is consistent, that is, its various units are all interrelated and based upon a decimally established unit, the meter. The U. S. Customary (USCS) and the British Imperial (BIS) are similar and both are based on the "English" System1which is a hodge-podge of largely arbitrary, inconsistent and unrelated units. All these systems have grown up or were devised to measure length, mass (weight) and capacity (volume), and connnonly were arbitrarily derived. Thus the USCS and BIS units of length, the yard and the foot, are reputed to have been determined by King Henry I of England in 1100 A.D. The "yard" was said to be the distance from the tip of his nose to the tip of his middle finger, and the "foot" was the distance from his heel to the tip of his big toe. Other units, such as the inch, ounce, gill and ton were derived from other sources such as ancient Egypt, Greece, Rome, Normandy and Scandinavia, some so old as to be lost in antiquity. Compounding the hodge-podge of non-related measurements that became the USCS and BIS were other problems such as that resulting from failure to discriminate between "mass" and ''weight." fuss and weight were generally taken to be the same whereas they are only related properties. For example, a man has the same mass here on earth as on the moon but his weight is only about 1/6 as great on the moon as on earth. , It had long been recognized that standard units of measurement are desirable, particularly in industry, connnerce and monetary exchange. By a "standard of measurement" is meant an object which, under specified conditions, serves to define, represent or record the magnitude of a given unit. Basic standards of measurement in the uses are the yard (length) and avoirdupois pound (weight). The yard is defined in terms of the SI by the U. s. Congress (1954) as equal to 0.9144 of the SI meter. The fundamental units of the BIS are also the yard and the pound, unrelated to the SI but defined by standards created for that purpose. In 1959 the BIS defined and accepted the "international yard" and the "international pound" according to metric standards. The "international gallon" had previously been established as 10 pounds of water at 62F (Fahrenheit) equals 277.42 cubic inches by calculation, and a bushel equals eight gallons. The Troy pound was abolished in the BIS in 1879 but the Troy ounce was retained. There are important differences between the two "English" systems. For example in the BIS units of dry measurement are the same as for liquid measurement but in the USCS they are not. The French, in the mid-17th Century began working on a consistent and interrelated-units system. Their thought congealed in 1670 and was proposed as the
â€¢ Page Two metric system by the Vicount of Lyons at that time, However, the French political climate then prevented its adoption and it was not until the reforms brought about by the Revolution that, in 1795, it was adopted by French legislative action and a metal bar was manufactured to serve as the standard meter of reference. The standard meter, based on the decimal system (as is our monetary system), is the fundamental unit of the metric system (SI). It is a unit of length equal to 39.37 inches and is supposed to be (though it is not actually) one-tenmillionth of the distance from the equator to the north pole as measured along a meridian running north through Paris. The meter was subsequently redefined (1960) to be of a length equal to 1,650,736.73 wave lengths in a vacuum of the orange-red light of the gas Krypton 86. This is a precise value, readily measured in laboratories the world over, and never varies measurably. Back in 1790 President George Washington invited the Congress to study the metric system with a view to its replacing the hodge-podge English system. Secretary of State Thomas Jefferson strongly supported adoption of the metric system with its decimal-based measurements. But Congress could not be persuaded to adopt the "new" system and, except mainly for U. S. scientists, medical doctors, and pharmacists, it was cast aside. It wasn't until R.R. 596, passed by Congress on July 28, 1866, that acceptance was gained in this language: " â€¢â€¢â€¢â€¢ it shall be lawful throughout the United States of America to employ the weights and measures of the metric system â€¢.â€¢â€¢ " Sporadically attempts were made to make the metric system mandatory in the United States but all have failed, But other countries in the meantime had adopted the SI and by 1965 about 90 per cent of the world's population was using it. In 1965 Great Britain established a gradual, stepwise adoption of the system with a target date for complete conversion by 1975. The British Metrication Board reported in 1970 that a few firms having completed metrification found that the changeover cost much less than had been anticipated and that the financial benefits were quick and substantial. In January, 1970, the Canadian Ministry of Industr Trade and Commerce recommended to the Parliament conversion to the metric system saying that it is not only desirable but inevitable. In January, 1968, the Irish Republic adopted the SI also establishing 1975 as its goal for completion of metrification, Australia and New Zealand have recently set 1976 as their goal for conversion to the SI. With this final swing of the other major English-speaking nations to SI this leaves the United States as the only government still clinging to the old USCS, a position that now is untenable. The U. s. Senate, earlier this year, approved adoption of the SI but the House did not act upon it. I would guess that within the year the changeover will be approved and then at long last the United States will join the rest of the civilized world in the long-overdue use of the metric system of consistent units of measurement. But even without compulsion of the law there has been a move toward metrification of the United States, Our Olympic athletes compete in international meets in races and other events measured in meters and kilometers and lift weights and put a shot or throw a discus weighed in kilograms. Our medical doctors write prescriptions not in grams or gills of the USCS but in grams of the SI, and even our cigarette hucksters are getting on the bandwagon with
Page Three 100-millimeter length cigarettes; additionally, tar and nicotine is stated in milligrams. Some automobile and motorcycle engines are now listed in terms of liters or cubic centimeter displacement, and some foods are using metric measurements --vitamins and minerals are always listed in milligrams. Scientists of the United States long have made measurements of scientific phenomena in the SI which in recent years has been extended and refined to six basic units: meter, kilogram, second, ampere, kelvin and candela. Units derived from these basics include the newton (force); the hertz (frequency in cycles per second); and the joule (all forms of energy including calories). Thus many of us already are somewhat familiar with, at least, the names of some of the SI units. And those of us who are scientists have a great deal of familiarity with them. If the system is adopted here on a step-increase basis as in Great Britain, it will be no great chore to learn the terminology and concepts of the magnitudes each unit involves. The terms that will be mostly used in water and land resources studies and management are given in the following table.
I. Units of Length: SI uses 1 m. 39.37 in. 1 dm. 3.97 in. 1 cm. 0.397 in. 1 km. 0. 6214 mi. II, Units of Area: 1 sq. cm.. = 0.001 sq. ft. = 0.155 sq. in. 1 sq. m. = 1.076 sq. ft. = 1550 sq. in. 1 sq. km. = 247.1 A = 0.3861 sq. mi. 1 hec. = 2.4 71 A. = 107,600 sq. ft. .. Units of Volume (Capacity): 1 cu. m. = 35.31 cu. ft.= 61,023 cu. in. 1 cu. m. = 264. 2 gal. = 1,057 qt. = 2,113 pts. 1 cu. m. = 1,000 L = 1.308 cu. yds. 1 L. = 1,000 cu. cm. = 0,03531 cu. ft. 1 L. = 61.02 cu. in. = o. 264 gal. 1 L. = 1.057 qt. = 2.113 pt. IV. Units of Flow: 1 cu. cm. per sec. = 0,0002642 gal. per sec. 1 cu. m. per sec. = 35.31 cu. ft. per sec. = 264. 2 gal. -1 cu. m. per min. = 2,118.6 cu. ft. per min. per sec. = 15,852 gal. per hr. 1 cu. m. per hr. = 127,116 cu. ft. per hr. = 951,120 gal. per hr. 1 cu. m. per day = 3,050, 784 cu. ft. per day = 22 . â€¢ aas ; 8so gal.per day v. Units of Weight: 1 gram= 0.003 kg. = 0.035 oz. (avdp) 1 gram= 1,000 mg. = 0.032 oz. (tr) 1 mg. = 0,001 grams 1 kg. = 1,000 grams= 2.205 lbs. = 0.0011 tons (short) 1 kg. = 35.274 oz. (avdp) uses 1 in. 1 ft. 1 yd. 1 mi. 1 A = 0.0016 sq. mi. = 1 sq. in. = 1 sq. ft. = 1 sq. yd. = 1 A. = 1 sq.mi. = 1 cu. in. = 1 cu. ft. = 1 cu. yd. = 1 fl. oz. = 1 qt. = 1 gal. = 1 A. /ft. = 325,829 gals. = 1 cu. ft. per sec. = 1 cu. ft. per min. = 1 cu. ft. per hr. = 1 oz, (fl) = 1.805 cu.in.= 1 oz.(tr) = 1 lb. = SI 2.54 cm. = 0.0254 m. 0.3048 m. 0.9144 m. 1. 609 km. 0. 404 6 hectares 6.416 sq. cm. 929.030 sq. cm. = 0.0929 sq. m. 0.836 sq. m. = 8361 sq.cm. 0.4047 sq. hectometers (hectares) 2.59 sq.km.=259 hectares= 2,590,000 sq. m â€¢ 16.39 cu. cm. 0.0283 cu. m. = 28.32 L. 7.65 cu. m. 29. 573 ml. o. 946 L. 3.785 L. 1,233.49 0.028 cu. 1.68 cu. 100.8 cu. cu. m. m. per sec. = 28.32 L. per sec. m. per min. = 1,699.2 L. per sec. m. per hr. = 10,195.2 L.per sec. = 29.57 grams = 31.103 grams
A -acre avdp -avoirdupois cm -centimeter cu -cubic dm -decimeter fl -fluid ft -feet gal -gallon hec -hectares hr hour in -inches kg -kilogram km -kilometer L -liter lb -m mi -min -ml -oz -pt -pound qt meter sec miles sq minute tr milliliters yd ounce pint ---quart second square troy yard GARALD G. PARKER, C.P.G. CHIEF HYDROLOGIST AND SENIOR SCIENTIST 09-08-72