86 View of the Progress of 



VII. Littrow on the Motion of the Earth round its Centre of 



Gravity. 

 This interesting paper is intended as a specimen of a simplifi- 

 cation of some of the calculations in the Mecanique celeste, 

 which Professor Littrow has already extended to the second and 

 fifth books of that elaborate work ; and which all true lovers of 

 mathematical science will be anxious for his continuing and 

 making public with as little delay as possible. 



VIII. Buzengeiger on the Methods emploxjed by the Greek 



Geometers in the Extraction of Roots. 

 Principally from Archimedes and Theon after Commanding 



IX. Littrow's Contributions to the Geography of Hungary. 

 From observations of Bogdanich, in his last illness, not 

 agreeing well with each other. 



X. David on Negative Refraction in the Neighbourhood of the 

 Earth. 

 The obgervations were made at Prague, but they merely show 

 some irregularities in the refractions of the sun's rays, at con- 

 siderable altitudes. 



XI. Extracts from Zach's Letters. 

 The first relates to records of eclipses, and the errors of ephe- 

 merides ; the second to the family of Bonaparte. 



XII. Extract of a Letter from Professor Littrow. 

 On the accuracy of the circle used by Bessel. 



XIII. Zach on two Comets observed by Pons. 

 Their places somewhat loosely determined with moderate 

 instruments. 



XIV. Extract of a Letter from Dr. Olbers. 



Containing observations, and the elements of one of Pons'i» 



comets. 



