I90O-I TRANSACTIONS. 39 



The series of standard avoirdupois weight (7,000 grains to 

 the pound) constructed m 1588 in the reign of Queen 

 Elizabeth, by which all the commercial weights of England 

 were regulated up to 1824, were derived from a 56-lb. 

 (4 stones) avoirdupois standard of Edward. Ill (1327-1377). 

 The Elizabethan standard yard i?, too, the unit upon which 

 the present Imperial yard is directly based, through the 

 respective copies by Graham (1742), Bird (1760), Sheep- 

 shan.ks and Baily (1855). 



By the Imperial Act of 1824, the standard yard of 1760 

 and the brass Troy pound of 1758, of 5,760 grains were 

 made the units of measure, and declared to be the only " ori- 

 ginal and genuine standards," from which all other Imperial 

 weights and measures were to be derived. The former were 

 destroyed by the burning of the Houses of Parliament in 

 1834. ' 



In the Act of 1824, referred to, a provision, based on 

 scientific principles, but in this case impractical, was made 

 for the contingency of loss of the original standards. From 

 experiments made, it \^ as found that a cubic inch of distilled 

 water, at 62° K., barometer at 30 inches, weighed 252*458 

 grains ; and also that a pendulum vibrating seconds of mean 

 time in the latitude of London, in a vacuum at the level of 

 the sea, measured 39'i393 standard inches. Theoretically it 

 was therefore comparatively simple, to find the length of a 

 standard inch (hence yard) by means of a pendulum. Hav- 

 ing a standard inch, the cubic inch would follow by its 

 equivalent in water of 252*459 standard grains, and hence 

 means obtained for the restoration of the standard Troy 

 pound. However, when it became necessary after 1834 to 

 obtain some material standards for again legalizing, the scien- 

 tific men of the day decided upon furnishing the same by 

 comparison with copies of the original (1824) standards, — and 

 then, by Act of Parliament making such prepared measures 

 the standards. By the Act of 1855, the Imperial pound 

 (avoirdupois) of 7,000 grains was substituted for the former 



