148 FISCHER: LENGTH STANDARDS AND MEASUREMENTS 



together with a set of Troy weights, were then sent over to the 

 Paris Academy, which body, in a hke manner, had the measures 

 of a French half toise laid off upon the rods, and keeping one as 

 previously agreed upon, returned the other, with a standard 

 weight of two marcs to the Royal Society. This, I believe, is 

 the first recorded instance where the standards of tw^o inde- 

 pendent nations were compared with one another. 



In the year 1758 the House of Commons appointed a com- 

 mittee to inquire into the original standards of weights and 

 measures of England; under instructions from that committee, 

 two brass rods were prepared by the celebrated instrument 

 maker, John Bird, respecting which the committee reports as 

 follows : 



And having these rods, together with that of the Royal Societj' laid 

 in the same place, at the Exchequer, all night with the standards of 

 length kept there, to prevent the variation which the difference in tem- 

 perature might make upon them, they were all the next morning com- 

 pared by means of beam compasses and found to agree as near as it 

 was possible. 



The committee recommended that one of these standards 

 should be made the legal standard of England, but this was not 

 done. Instead; on December 1 of the same year. Parliament 

 created another committee on weights and measures, which, in 

 April, 1759, repeated the recommendation that the standard 

 made by Bird in 1758 should be legalized, and further recom- 

 mended that a copy of it should be made and deposited in some 

 public office, to be used only on special occasions. The copy 

 was made in 1760, but no legislation followed for sixty-four years. 

 When in 1824, Parliament at length took final action. Bird's 

 standard of 1760 was adopted instead of that of 1758. This 

 bar had been generally accepted as the standard for many years 

 by English metrologists and copies of it had been widely cir- 

 culated. One of these, an 82-inch scale made by the celebrated 

 instrument maker, Troughton, of London, was obtained by 

 Ferdinand Hassler of whom I shall have more to say later, and 

 the distance between the 27th and 63d inches of that bar, which 



