1S4 Scientific Notices — Miscellaneovit. (Feb. 



9. Abstract of Capt. Rater's Account of the Construction and 

 Adjustment of the new Standard of Weights and Measures of 

 the United Kingdom of Great Britain and Ireland, lately read 

 before the Hoyal Society. 



The author, after stating that the weights and measures of 

 the United Kingdom are founded on a standard, whose length 

 is determined by its proportion to that of a pendulum vibra- 

 ting mean time in London, which has been ascertained by 

 him to be 39' 13929 inches of Sir George Shuckburgh's scale, 

 deems it necessary, on account of the importance of the result, 

 to consider what degree of confidence it is entitled to. For this 

 purpose it is necessary to compare this final result with those 

 obtained in other experiments and by difierent methods. Now 

 it appears that previously to the experiments detailed in the 

 author's paper on the subject in the Phil. Trans, for 1818, on 

 which this result rests, another series is there mentioned, made 

 with the same instruments, but under circumstances which 

 occasioned their rejection, and which owing to some repairs 

 in the instruments between the two series, which occasioned a 

 material alteration in the distance between the knife edges, 

 have all the weight of experiments made with a different pen- 

 dulum. The result of these rejected experiments, however, 

 differed only two ten-thousandths of an inch from that ulti- 

 mately adopted. 



The author next compares the lengths of the seconds pen- 

 dulum at Unst and at Leith Fort, as ascertained by him with an 

 invariable pendulum, whose vibrations had previously been 

 tletermined in London, and whose length was thus known in 

 terms of the London seconds pendulum, and as ascertained by 

 M. Biot at the same stations by means of a variety of pen- 

 dulums, and by a totally different method of observation — that 

 of Borda. The results of this comparison are, a difference be- 

 tween the determinations of Mons. B. and of the author, of 0*00029 

 inch in excess at the former station, and 0'00015 in defect at 

 the latter. 



From this near agreement of all the results, he considers that 

 the length of the seconds pendulum in London maybe regarded 

 as certainly known to within one ten-thousandth of an inch ; 

 while from the near agreement of the results of the French 

 and English experiments on the length of the pendulurn, he 

 concludes that the length of the metre in parts of Sir G. 

 Schuckburgh's scale may also be regarded as known within 

 one ten-thousandth of an inch. 



From an account recently published by Captain Sabine of his 

 valuable experiments for the determination of the variations in 

 length ofthe seconds pendulum, Capt. K. observes, doubts may be 

 inferred ofthe accuracy ofthe method employed by him for the 



