Astronomical and Nautical Collections* 101 



House of Commons by Mr. Davies Gilbert, praying that his Ma- 

 jesty would be graciously pleased to give directions for ascertain- 

 ing the length of the pendulum vibrating seconds of time in the 

 latitude of London, as compared with the standard measure in the 

 possession of the House of Commons ; and for determining the 

 variations in length of the said 'pendulum at the principal stations of 

 the trigonometrical survey extended throughout Great Britain. His 

 Majesty's Ministers having requested the assistance of the Royal 

 Society in carrying into effect the objects of the address, their ac- 

 complishment was undertaken by one of the most distinguished 

 members of that society, and completed in 1819; and the account 

 was published by Captain Kater, in the Philosophical Transactions 

 for that year." P. xi. xii. 



" The discrepancies, however, of the results obtained, by 

 combining the lengths of the pendulums observed at the dif- 

 ferent stations in Great Britain and in France, were so great and 

 so irregular, as to prevent any independent conclusion whatsoever, 

 relative to the general figure of the earth, being drawn from the 

 experiments, either of the French philosophers or Captain Kater." 

 P. xiii. 



" Such was the state of the inquiry when the present experi- 

 ments were undertaken ; their design was, to give the method of 

 experiment the advantage of being tried under the circumstances 

 most favourable for the production of a conclusive result ; to ex- 

 tend the suite of stations previously confined to Great Britain and 

 France, to the equator on the one side, and to the highest 

 accessible latitudes of the northern hemisphere on the other; to 

 multiply the stations at both extremities of the meridian, so that by 

 their general combinations the irregular influences of local density 

 might mutually destroy each other, and the variations of gravity 

 due to the ellipticity alone be eliminated ; and to ensure the uni- 

 formity of procedure and strict comparability of the results at all 

 the stations, by the unity of the observer, and the identity of the 

 instruments." 



The experiments were made with a detached pendulum supported 

 by a knife edge, of which the oscillations were compared with those 



