WEIGHTS AND MEASURES. Weights and measures are fundamental necessities of commerce, industry and science. Measurement is required in the estd-r.ition of lands and waterways, in their lovati,ii and transfer. in the work of construction of buildings, bridges, railroads and other engineering works, in the manufacture of foods, in the preparation of compounds and in the purchase, and sale of materials. Weights and measures arc essential to all barter of goods. Here, the ac curacy may range from the 'heap' or 'pile' of ancient times to the one one-hundredth of a cent used in cotton and speller quotations 'on change,' estimates of value which we call prices being based on a specified weight of gold. Weights and measures are essential in all construction whether the precision be the 'rule of thumb,' or the millionth of an inch in optical work, or the one-ten-thousandth of an inch in the manufacture of fine machinery. The pharmacist with his weights compounds the prescriptions which mean health and life to the sick. In the extractive and compounding in dustries, weights and measures are used to de termine the essential proportions in analyses and compounds, and precision is the main con dition of reproducibility of results. Likewise the manufacturer must accurately weigh, meas ure and test his materials to secure perfect construction. Surveying and navigation would be very primitive were it not for the rigorous measurements of base lines, accurate triangu lation, precise leveling, including even such delicate measurements as the variation of lati tude. Weights and measurements will in fact be found necessary in the discovery and in the statement of industrial and scientific facts of all kinds. The birth of the exact sciences was coincident with the development and application of quantitative measurements to the phenomena of nature, and the rapid growth of modern science has since been parallel with that of pre cision. James Watt was one of the earliest to suggest international standards which would enable scientific results when published in terms of such standards to be intelligible and repro ducible the world over. Precise and uniform standards made possible the interchangeability of parts in machinery, first practically applied by Eli Whitney and to-day one of the most im portant principles in manufacturing.
Classification.— Weights and measures or dinarily include those defining length, area. vol ume, capacity and weight. These are relatively the most important measures used by man. However, within the last half century when such products as power, electric current, heat. light, refrigeration and services or other kinds have entered the world's markets as commodi ties for manufacture, purchase and sale — the scope of weights and measures has widened to include units used in the measurement of vr locity, pressure, enera, electricity, tempera ture and illumination. Technical requirements also resulted in a series of compound units such as the knot, a unit of speed for vessels of one minute of the earth's circumference per hour; the ton-mile used in transportation rates and statistics; the foot-pound, a unit of energy: the dyne, the international unit of force and other units of the centimetre-gram-seccmd syltem of scientific units in use throughout the world Such compound units are multiplying apace with the technical needs. and have proven of in estimable value and ecom my by the facility and precisism which they afford in conveying exact quantitative results of experiment and ohsersa tinn. With advancing needs the units of weight and measure have extended to microscopic and to telescopic dimensions. The millimicron of the physicist and the still smaller Angstroem unit which it requires 254,000,500 to make one inch, are used in spectrum analysis for measur ,rang the dimensions of light waves, while on the i.iher hand the •earth's orbit' (meaning the
mean radius of the orbit) is used by astron omers in measuring stellar distances. In addi tion, the •light-year' is used for the greatest al.tances, this unit being the distance which befit traverses in one year, or about 6,000,000. 0.0.000 miles. With the extension and divi sion in size of units, the kinds of instruments utilised and methods of application of the units themselves have multiplied. Almost every oc cupation has its particular units, its methods of making measurements and its special measuring instruments. A few of the of the latter may be cited, such as the common desk rulers, carpenter's folding rules, draughtsman's ales, surveyor's chains, engineer's tapes and ;eve] rods, lumberman's log rules and board measures, the merchant's yard stick, the tailor's upe. the shoe, glove and hat-measures, machin lo•s scales, measuring bars, micrometers, mi crometer calipers, limit gauges of ring and p:ug types, end and line standards of precision. la measuring volume we have the standard ca pacity measures, milk measures, beer measures, w uoden dry measures, a vast variety of stand ard flasks, glass graduates such as burettes, aipettes and other volumetric apparatus of the druggist, physicist and chemist. the gauging rods for casks and cargoes, gasometers reading la cubic feet. tanks and reservoirs with gradu ated scales reading volumes directly. For unghing. we have even-balance scales, steel i-ards. platform scales, spring balances, all ranging from the most delicate analytical bal ances to the master scales for weighing canal boats and railway trains. Scales are especially designed for every particular need, and the countless varieties attest the high state of the an of weighing and its great importance in in dustrial and scientific work. Such instruments have multiplied in form and number and the demand for them has grown so rapidly that the mains facture of weights, measures and meas uring instruments forms in itself a whole ith the development of units of measure of the order of inter-molecular distances on the cane hand and of almost interstellar distances on 'be other, and the multiplication of kinds of in strumeats used in measurement has come the miention of a large variety of measuring ap pliances which automatically indicate the result upon a scale. Of this class are thermometers, spring balances, aneroid barometers, pressure c speedometers and indicating meters of at uM an ds. Computing scales not only indicate the weight but show the computed total price of the article at several prices per pound. Many of this class of instruments also make continuous record of the measurements show ing by a curve the values at successive moments of time. Of this type are the automatic record ing instruments used to record temperature. air pressure, sunshine, rainfall. electrical quanti ties as well as tide recorders, anemometers and many others. Equally interesting are those measuring instruments like dividing engines, trip scales or trip measures which besides nicas uring definite lengths, weights or quantities au tomatically perform certain operations, such as graduating a scale, delivering or tipping a cer tain weight of grain, or delivering certain vol umes of liquids. Closely related are those de vices which integrate quantities delivered or magnitudes measured, such as the small map wheels which measure distances on maps, or the planimeters which measure areas within irregu lar contours, and all forms of gas and water meters, integrating rain gauges, integrating watt meters for measuring electric power con sumed. These instruments usually indicate on a dial the total number of units measured since the last zero setting.