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Length measures in great variety—gauges, bars, rules, tapes, level rods—are standardized under known conditions of temperature and manner of support. Researches are made as to the design and use of such instruments, as well as their change with heat. All length standards used in manufacturing, in engineering—whether measuring lands, laying out buildings or other structures, or making maps and charts—or in scientific work must come directly or indirectly from the Bureau. Likewise the Bureau is the legal custodian of the standards of mass, and all makers of weights and balances and weighing instruments, from the most delicate used by chemists and physicists to the heaviest used in commerce, depend upon the Bureau for their standards.

Each year many thousand glass measures—flasks, pipettes, burettes, cylinders, and other forms used by chemists and others—are tested. Such tests are made by determining accurately the volume of distilled water contained or delivered by the vessel at a certain temperature. Cubic-foot standards are also verified for use in testing gas and water meter provers. Likewise each year hydrometers in large numbers are tested, mainly for use by the Internal-Revenue Service to measure the densities of liquids in order to assess the proper tax. The Bureau is called upon also to determine densities of solids, liquids, and gases in special cases. These tests of length, mass, and capacity are fundamental, and with time form the basis of more complex measure of energy and the properties of materials. Many of the tests requested require the development of special apparatus and methods.

The importance to science and industry of correct standards and uniformity of measures of length, mass, and capacity is apparent, but it is equally important that standards be provided for the measure of electricity, heat, light, pressure, power, and other quantities. Moreover, the standards here involved are far more complex. Their preparation and comparison involve measurements and research of a high order in practically all branches of physics and chemistry. This work includes standard measuring instruments for temperatures ranging from the lowest to the highest attainable; the establishing of the standard temperature scale, and the determination of standard heating values of combustibles; and testing of pyrometers for measuring the high temperatures used in the steel, glass, pottery, and other industries. The standards and instruments of the electrical industries are no less important or varied in their nature. They involve as fundamental units those of electrical resistance and electromotive force, as well as those of capacity, inductance, and magnetic quantities. The Bureau maintains also a laboratory for preparing and testing standards of illumination used in the manufacture of electric lamps or the testing of gas, oil, and other illuminants. The optical work of the Bureau also requires its special units and standards, for the special optical problems involved, the tests of optical materials and instruments, and the determination of optical constants of industrial and scientific importance.

Standards for manufacturers are not constructed at the Bureau of Standards except in rare cases, although the Bureau has designed standard weights and prepared specifications for the several grades. In general, standards are purchased from the makers of standard measures and sent to the Bureau from time to time for comparison with the Government standards and certification of errors. The degree of precision with which they are compared is planned to meet the exact needs—to avoid at once needless overprecision for the usual cases and also to insure the adequate high precision where that is required for more fundamental or exacting work. The nice adjustment of the degree of precision to the specific case in hand requires the experience and judgment of the specialist.

The testing of water, gas, and electric meters practically concerns all who utilize such services. These services should, of course, be as accurately measured as are the ordinary articles of trade, and yet proper provision is often wanting for impartial tests of the accuracy of such meters. While the public may suffer loss through faulty meters for which proper testing facilities are inaccessible, yet suspicion may exist without cause, and in such cases it is equally important that the accuracy should be authoritatively attested. Most of this work is for manufacturing or central-station plants or for municipalities.

The work of testing materials is another important branch of the Bureau's functions. Public safety rests upon the certainty that the materials used for buildings, bridges, railroads, and other structures are of sufficient strength and stability. The time has passed when the strength of materials can be taken for granted. With the rapid increase in the height of buildings, length of spans of bridges, and speed of transportation new problems in safety and efficiency arise, which should not be left to guesswork or even personal judgment. Positive tests by assured methods alone can guarantee that, to begin with, the materials are properly selected for the work. By means of strain gauges and other means, the finished structure may be studied under service conditions. Experience is the ultimate test, but until the knowledge of materials is sufficiently complete the best substitute when judgment must be formed in advance is based on the laboratory test. The Bureau cooperates with other agencies in placing the testing of materials upon a scientific basis as fully as possible.

The growing appreciation of the vast waste due to defective materials and their misuse has raised the whole question of efficiency. Adequate testing or measurement is the keynote to the solution of the central problem. The testing of Government supplies is an illustration. In this work the various branches of the Government are cooperating with the Bureau and the purchasing officers in amending the faulty definitions, varying practices, and imperfect specifications, and providing suitable working standards of quality and methods of testing. The development of specifications has been made the subject of special conferences at the Bureau, attended by Government experts, manufacturers, and users, and the results obtained in the case of electric lamps, Portland cement, paper, and other materials show the value of such work. Among the more important groups of materials tested are metals and metal products, ceramics, cement and concrete, lime, stone, wood, bituminous materials, paint materials, inks, paper, textiles, rubber, leather, adhesives, and a large range of miscellaneous manufactured products.

The Bureau of Standards is located in the northwest section of Washington, D. C, at an elevation of 350 feet above the Potomac River, on a natural hill site of about 16 acres—a location admirably suited to its work, being practically free from mechanical and electrical disturbances. It occupies a group of five buildings, each of which was designed especially for the purpose for which it is used. In addition, it maintains laboratories in Pittsburgh and Northampton, Pa., and Charleston, S.- C.

Besides an extensive modern equipment of scientific instruments and apparatus for experimental and testing work, the Bureau's facilities are in many respects unique, since the range of work is so varied. In the heat division temperature ranges are available from that of liquid air to the heat of a vacuum electric furnace; in electrical work wide ranges of current are available; in chemical work the usual facilities are supplemented by many special services. For the experimental work electrical power, refrigeration, steam, gas, compressed air, vacuum, liquid air, freezing brine, time service for precision purposes, and many other facilities are available.

The Bureau is provided with a technical library of more than 10,000 volumes, chiefly on physics, chemistry, and technology, and regularly receives about 300 journals relating to subjects in its field of work. The Bureau has issued more than 250 publications giving the results of its scientific work and describing the various lines of testing now going on. These are available for public distribution.

Prof. S. W. Stratton has been at the head of the Bureau since its organization in 1901.

LAW PERTAINING TO THE BUREAU OF STANDARDS.

[As modified by acts of February 14, 1903, and March 4, 1913 ]

The Congress shall have Power To * * * fix the ^|£°/"^'J"tfcm' Standard of Weights and Measures.

The Office of Standard Weights and Measures shall here- 1J?me; ,.,

r 1 _ _ ii< Mar. 3,1901 (SI

after be known as the Bureau of Standards.1 stat., i*m sec. 1.

The functions of the bureau shall consist in the custody BifreaS!10Ds of of the standards; the comparison of the standards used in 'm 'secscientific investigations, engineering, manufacturing, commerce, and educational institutions with the standards adopted or recognized by the Government; the construction, when necessary, of standards, their multiples and subdivisions; the testing and calibration of standard measuring apparatus; the solution of problems which arise in connection with standards; the determination of physical constants and the properties of materials, when such data are of great importance to scientific or manufacturing interests and are not to be obtained of sufficient accuracy elsewhere.

The bureau shall exercise its functions for the Gov- whom the Buernment of the United States; for any State or munici- refmh^eT"a' pal government within the United States; or for any scientific society, educational institution, firm, corporation, or individual within the United States engaged in manufacturing or other pursuits requiring the use of standards or standard measuring instruments. All requests for the services of the bureau shall be made in accordance with the rules and regulations herein established. The officers and employees of the bureau shall consist Personnel of of a director, at an annual salary of five thousand dollars; ariesf" and salone physicist, at an annual salary of three thousand five hundred dollars; one chemist, at an annual salary of three thousand five hundred dollars; two assistant pnysicists or chemists, each at an annual salary of two thousand two hundred dollars; one laboratory assistant, at an annual salary of one thousand four hundred dollars; one laboratory assistant, at an annual salary of one thousand two hundred dollars; one secretary, at an annual salary of two thousand dollars; one clerk, at an annual salary of one thousand two hundred dollars; one messenger, at an annual salary of seven hundred and twenty dollars; one engineer, at an annual salary of one thousand five hundred dollars; one mechanician, at an annual salary of one thousand four hundred dollars; one watchman, at an annual salary of seven hundred and twenty dollars, and one laborer, at an annual salary of six hundred dollars.2

1 Name adopted July 1,1903.

s Appropriations for the Bureau of Standards are contained annually in the legislative, executive, and judicial appropriation act. For present personnel and salaries, see current act.

howhe appointed ^h® director shall he appointed by the President, by duties. 'and with the advice and consent of the Senate. He shall im., sec. s. have tne general supervision of the bureau, its equipment, and the exercise of its functions. He shall make an annual report to the Secretary of Commerce, including an abstract of the work done during the year and a financial statement. He may issue, when necessary, bulletins for public distribution, containing such information as may be of value to the public or facilitate the bureau in the exercise of its functions. offlcCTlo^rform Hereafter in the case of the absence of the Director of duties of Director, the Bureau of Standards the Secretary of Commerce may stat"mi)9U (Se designate some officer of said bureau to perform the duties of the director during his absence. A^fstmtTs'i '^aa omcers and employees provided for by this Act, stat.,iuo),sec.e. except the director, shall be appointed by the Secretary of Commerce, at such time as their respective services may become necessary. itenS'ropriat,on ^he following sums of money are hereby appropriated: mi.,««. 7. * * * toward the erection of a suitable laboratory, of fireproof construction, for the use and occupation of said bureau, including all permanent fixtures, such as plumbing, piping, wiring, heating, lighting, and ventilation, the entire cost of which shall not exceed the sum of three hunsmnsi5)lm ^ dred and twenty-five thousand dollars, one hundred thousand dollars; for equipment of said laboratory, the sum of ten thousand dollars; for a site for said laboratory, to be approved by the visiting committee hereinafter provided for and purchased by the Secretary of Commerce, the sum of twenty-five thousand dollars, or so much thereof as may be necessary ;1 * * * expenses of the visiting committee, and contingencies of all kinds, the sum of five thousand dollars, or so much thereof as may be necessary, to be expended under the supervision of the Secretary of Commerce, cnlrged'. *" * For au comparisons, calibrations, tests, or investigator, s, mi (si tions, except those performed for the Government of the stat.,iu9),sec.8. Tjjnte(j States or State governments within the United States, a reasonable fee shall be charged, according to a schedule submitted by the director and approved by the Secretary of Commerce, comm^ce t0o' The Secretary of Commerce shall, from time to time, make regulations, make regulations regarding the payment of fees, the ibid., sec. 9. limits of tolerance to be attained in standards submitted for verification, the sealing of standards, the disbursement and receipt of moneys, and such other matters as he may deem necessary for carrying this Act into effect.

1 The sundry civil appropriation act of August 24,1912 (37 Stat., 477), appropriated the sum of $85,000 for the purchase Oi additional land for the enlargement of the present site of the Bureau of Standards. Of this sum {68,034 was expended and 706,526 square feet of ground were acquired.

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