THE YARD, PENDULUM, AND METRE. 43! 



pendulum vibrating seconds, not at but in the latitude of 

 London : a very different thing, as General Sabine has 

 pointed out in his " Account of Experiments to determine 

 the figure of the Earth by means of a Pendulum vibrating 

 Seconds in different latitudes." For the object would have 

 been then, as it really was on the occasion of the actual 

 destruction of the parliamentary standard in 1834, not 

 to produce a theoretically better, but as far as possible to 

 reproduce the same identical length by the most summary 

 process ; without undertaking circumnavigatory voyages, 

 or entering on any theoretical discussion. The new act 

 necessary for legalizing the standard so arising would 

 probably have sanctioned this procedure, and we should 

 have thenceforward had a standard of a purely local 

 character, assuming for the fundamental basis the indi- 

 vidual seconds pendulum in London. 



(12.) This, however, is not now the case. On the de- 

 struction of the standard of 1760 by the burning of the 

 Houses of Parliament, the new standard was constructed, 

 not by any measurement of the length of the pendulum 

 (for in the ten years elapsed since 1826 very grave 

 doubts had been raised, or rather very serious sources 

 of error pointed out in the processes used for the pur- 

 pose on the former occasion) but, by an assemblage 

 and most careful comparison of all the scales and stand- 

 ards of any authority which could be got together re- 

 sulting in the production of one primary and a great 

 many secondary standards, in all human probability ab- 

 solutely identical with that destroyed. The act, more- 

 over, (of 1855) which constituted that one our legal yard, 



