Page:The American Cyclopædia (1879) Volume XVI.djvu/559

 WEIGHTS AND MEASURES 539 fusion has existed and has been well nigh un- avoidable, growing out of gradual or repeated changes in the standards in current use. As would be expected, the modern legal or con- ventional standards, as reproduced and in ac- tual use, were found after a time to be subject to considerable variation. For example, from 1650 to 1688 there were in England three dif- ferent measures of the wine gallon : 1, the more general opinion and usage gave 281 cubic inches to the gallon ; which, it should be noted, is the capacity of a cylinder of 6 in. height and 7 in. diameter, taking the circumference at 22 in. ; 2, the customary standard at Guildhall, supposed to be of such capacity, was later found on measurement to contain only 224 cubic inches ; 3, the real and legal standard, pre- served at the treasury, contained 282 cubic inches. The corn gallon differed from any of these, being 268 - 6 cubic inches. Some suppose the gallons of 231 and 282 inches to have origi- nated under separate enactments, the latter from one of Henry VII., directing that the gallon contain 8 Ibs. of wheat ; but Oughtred holds that the larger or beer gallon was allowed for liquids which yield froth, while the less gallon was that appropriated to the liquids, such as wine and oil, which, as not frothing, show at once their true volume. Variations of this sort in measures must have existed without intention, and increased ; and hence the sec- ond step toward exactitude of measurements became necessary, namely, that of making ac- curate comparisons of the various standards of each given sort in a country. Attempts of this kind appear in England to have been com- menced under the auspices of the royal society in 1736 and 1742 ; in the former year, by a comparison of the English, French, and old Roman standards ; and in the latter, by the de- termination, by George Graham, of the length of a pendulum beating seconds at London (at 39-13 in.), and the construction of a standard yard. Of this, under direction of the house of commons, Mr. Bird prepared two accurate cop- ies, respectively marked " Standard yard, 1758 " and " 1760," and intended for adoption as the legal standards. He determined and prepared also the pound troy, the original of that now in use. Of these two standards no intentional alteration has since been made ; so that these and the>r derivatives are now in use in England and the United States. The third proposed step in the Way of rendering measures exact, has reference rather to the means of making the standards recoverable in case they should be lost. In the definite pursuit of this pur- pose, the French philosophers of the time of the revolution took the lead, and devised the metric system, in which the unit of length is de- rived from the dimensions of the earth, and the units of capacity and weight are made depen- dent upon the former, while the whole has deci- mal multiples and subdivisions. As this system has since gone into very extended use, a full ac- count of it will be given after completing the history of the English and American standards. The efforts of the French philosophers called attention in England to the desirableness of having the standards commensurable with a natural unit ; and for this purpose the length of the seconds pendulum at London was selected. Reports made in 1816, 1818, and 1820, to the house of commons, based on experiments and comparisons, in which Wollaston, Dr. Young, Capt. Kater, and Prof. Playfair took a prom- inent part, led to the adoption of the imperial measures and standards, under the act 5 George IV., which took effect Jan. 1, 1826, and which the law of 5 and 6 William IV., taking effect Jan. 1, 1836, did not modify in respect to the standards adopted. The weights and measures which had been in vogue in England previous to these acts, based on Bird's stan- dards, 1758 and 1760, had meanwhile become established in the United States, so that here the standards of the old English system are still in force. In the imperial measures, the yard copied from the standard of 1760 was to be of brass, and measured at the temperature of 62 F., while its length was further defined by declaring that of the pendulum beating sec- onds of mean time in the latitude of London, at the above temperature, in a vacuum, and at the level of the sea, to be 89*1393 inches of the above standard. The pound troy, from the standard of 1758, is also defined by deter- mining that the cubic inch of distilled water weighed in air by brass weights, at 62, the barometer being at 80 inches, is equal to 252-458 grains (the pound being 5,760 grains). The standard for measures of capacity, wheth- er dry or liquid, was declared to be the gal- lon, to contain 10 Ibs. avoirdupois weight (this pound being 7,000 grains troy) of distilled wa- ter, weighed in air, at 62 F., the barometer showing 30 inches this to be thenceforward the measure for all liquids; and the bushel was determined by the requirement that it should contain 8 ' such gallons. These stan- dards only became compulsory as the sole legal measures after Jan. 1, 1836. The gallon in this system contains 277-274 cubic inches. The former wine gallon is hence 0-83311 of the im- perial, or very nearly 6 of the former to 5 of the latter ; while the old or Winchester bushel (so called because its standard was long pre- served at Winchester) was 0-969447 of the imperial bushel, or about 83 of the former to 32 of the latter. Soon after the standards were prepared they were destroyed by the burning of the houses of parliament (1834); but fortunately the astronomical society had procured a most carefully prepared copy of the imperial standard yard, and the mint was in possession of an exact copy of the pound, so that it was possible to reproduce the lost stan- dards with great precision. The commission appointed in 1838 to restore them, of which Airy, Baily, Herschel, Lubbock, and Sheep- shanks were members, after much investiga- tion, reported in 1841 that, since the passage