Length of the Pendulum at Paramatta. -167 



remarkable example of the great good that may be effected 

 by an active and intelligent observer, with even very ordinary 

 instruments. Amongst the other papers we notice a very 

 valuable one by M. Mathieu on some experiments made by 

 the French, on the invariable pendulum, in the southern 

 hemisphere; and in which will be found some new and in- 

 teresting matter. These experiments are compared with those 

 made by Sir Thomas Brisbane in New South Wales (which 

 appear to have been communicated to the Board of Longitude 

 at Paris, as well as to the Royal Society of London): and the 

 result produces nearly the same compression of the earth as 

 that previously deduced by Capt. Kater. Prior to the sailing 

 of the expedition, M. Arago assembled Cap. Duperrey and his 

 principal officers at the Royal Observatory at Paris, and in- 

 structed them in the mode of conducting the delicate observa- 

 tions which they were about to make, and of handling the va- 

 rious instruments that would be necessary for that purpose. 

 In mentioning this gentleman's name, we observe with much 

 pleasure that he has been raised, in the Board of Longitude, 

 to the class of Astronomes, in the place of M. Delambre de- 

 ceased : whilst MM. Nicollet and Damoiseau are the two new 

 members added to the class of Astronomes Adjoints. The 

 latter (it may be remembered) has lately made himself cele- 

 brated by his new formulce for the lunar tables, inserted in the 

 ConfiaissaJice des Terns for 1824; and for which he appears to 

 have been rewarded with the cross of the order of St. Louis, 

 and of the Legion of Honour. These facts show that our neigh- 

 bours are alive to the advancement of astronomy, and to the 

 promotion of the best interests of the country. 



We regret that M. Schumacher's Astronomische Hiilfstafeln 

 for 1 824 are not yet arrived. 



LENGTH OF THE PENDULUM AT PARAMATTA. 



In Capt. Kater's account of Sir T. Brisbane's experiments 

 made with an invariable pendulum in New South Wales, 

 Philosophical Transactions 1823, p. 323, he thus states the 

 general results of them : 



" If the number of vibrations resulting from Sir Thomas 

 Brisbane's experiments at Paramatta be compared with the 

 mean number of vibrations made by the pendulum at London, 

 we shall have 39-07696 inches for the length of the pendulum 

 vibrating seconds at Paramatta ; -0052704 for the diminution 

 of gravity from the pole to the equator; and j^j.^^; for the 

 resulting compression ; the length of the j)enduluni vibrating 

 seconds at London being taken at 39-13929 inches. 



" The experiments at Paramatta being compared with those 

 3 N 2 made 



