531 



standard, and Bessel's and Sabine's investigation of the atmospheric 

 correction to the vibrations of the pendulum, are noticed. The 

 result of the Astronomer Royal's inquiry into the points of support 

 of a bar proper for preventing extension of its upper surface by its 

 flexure is given. The state of the science of Standards in the year 

 1834 is then described as follows. It had been shown that it was 

 imprudent to trust to points or lines traced on the surface of a bar, 

 and therefore, supposing the Standard to be a line-measure, only two 

 lines or points ought to be used, sunk to the middle of the bar's 

 thickness. It had been shown that it was imprudent to lay the bar 

 upon a table or upon fixed supports of any kind, and therefore the 

 bar must be stiff enough to bear to be supported upon a few points 

 at which rollers could be conveniently applied. It had been shown 

 that the physical reference provided in the Act of Parliament of 1824 

 was erroneous in one particular and doubtful in another ; and, as it 

 seemed likely that similar uncertainties might be found in any other 

 physical reference, the conviction was gradually rising that it would 

 be better to trust, for restoration, to attested copies of the Standard. 

 The question of the propriety of adopting line-measure or end-measure 

 for the National Standard, which in this country had been practically 

 decided (without a single opposing instance as regarded accurate 

 standards) in favour of line-measure, had again been raised by Bessel's 

 adoption of end-measure. 



On 1834, October 1 6, occurred the fire at the Houses of Parliament, 

 in which the Standards were destroyed. 



Section III. records the appointment of the Treasury Commission 

 of 1838, its proceedings and Report ; the appointment of the Treasury 

 Commission of 1843, and its proceedings to the death of Mr. Baily 

 in 1&44. The Report of the first Commission recommended the 

 adoption of a material Standard, without any reference to physical 

 experiment ; and recommended that four copies should be made, of 

 which one should be immured in a wall of a public building, that the 

 new Standard should, by means of bars which had been compared 

 with the old Standard, be made as nearly as possible equal in length 

 to the old Standard, and that the superintendence of the construction 

 should be entrusted to a Committee. These recommendations 

 were adopted by the Lords Commissioners of the Treasury, and led 

 to the appointment of the second or Superintending Committee, and 



