602 Foreign and Miscellaneous Intelligence. 



finding a north-west passage, observed on the 7th May, 1822, the 

 following occultation of Antares by the moon : 



Immersion of the star at the bright limb of the moon 8 h 52' 34".93 

 mean time ; emersion at the dark limb at 10 h 5' 27". 8 mean time. 

 Both phenomena were well observed, and the time determined on 

 the preceding and the following days by equal altitudes. The lati- 

 tude of the place of observation (the isle of Serpents at the North- 

 East Cape) was found by a Dollond reflecting circle = 22. 53' 54".15. 

 Not having met with corresponding observations in other places, he 

 has calculated the observations by Burckhardt's tables, and finds by 



these tables, and a compression = , the longitude of Rio 



308.65 



Janeiro by the immersion = 3* V 20-.97 1 f p is * 



emersion t= 3 h 2' 18 ".51 J 



The mean of the two will therefore give the longitude of Rio Janeiro 

 = 2 h 52' 58."0 west of Greenwich. 



8. PENDULUM OBSERVATIONS. 



Captain Luetke has communicated to M. Fuss, the Secretary of the 

 Imperial Academy of St. Petersburgh, the following pendulum ob- 

 servations, made during the circumnavigation of the Russian vessel 

 Seniavine. The invariable pendulum employed in this expedition 

 was the same which had before been used by Captain Basil Hall 

 in South America. A series of pendulum experiments had been 

 made with it at the Royal Observatory at Greenwich before leav- 

 ing England, and the same were repeated at the same place after 

 the return from the expedition. The latter gave -f^ of an oscillation 

 more, which Captain Luetke attributes to the knife-edge having been 

 a little blunted. Instead of distributing this difference in arithmetical 

 proportion over the whole interval elapsed, it has been preferred to 

 adopt the mean of the two results. The two sets of observations 

 made at St. Petersburgh for ascertaining the effect of the temperature 

 upon the pendulum, one during a mean temperature of 31J Fahr., 

 the other in a temperature of 82 J- Fahr., proved that each degree of 

 the thermometer causes, in 24 hours, a difference of 0.458 oscilla- 

 tion. This exceeds the quantity resulting from Captain Sabine's ex- 

 periments by 0.033, although the instruments were made of the same 

 bell-metal, and are of the same dimensions. Captain Luetke cannot 

 ascribe this difference to any other cause but a less density of the 

 metal used for his pendulum. In consideration of the various circum- 

 stances attending the observations, Captain Luetke is inclined to think 

 that the observations at Greenwich, St. Petersburgh, Petropawlofsk 

 (St. Peter's and St. Paul's), Valparaiso and the Bonin islands, are 

 the best, and will not deviate more than -fa oscillation from the 

 truth ; while at Sitka and the island of Ualan the uncertainty may 

 amount to oscillation. The observations least to be depended on 

 are those at the Guahan islands, and at St. Helena, where he cannot 



* Petersburgh Trans. 1830. 



