VOL. LVIII.] 



PHILOSOPHICAL TRANSACTIONS. 



-497 



II. Extract of a Letter, dated Fienna, April 4, IJQt, from Father Joseph 

 Liesganig, Jesuit, to Dr. Bevis, F. R. S., contaijiing a short Account of the 

 Measurement of Three Degrees of Latitude under the Meridian of Vienna, 

 From the Latin, p. 15. 



These 3 degrees measured by father Liesganig, constitute the arc between 

 Sobieski, near Brunn, in Moravia, and Waradin, in Croatia. The terrestrial 

 arc is constituted by 22 large triangles, connected by measured bases, of more 

 than 6000 Paris toises each. The celestial arc was determined by many obser- 

 vations of fixed stars, made with a 10 foot sector, at several stations; by which 

 he deduced the length both of the whole arc, and of several of the intermediate 

 parts. Hence he found the length of the degree between Vienna and Gratz, 

 186 toises less than that between Vienna and Brunn, towards the north, but that 

 between Waradin and Brunn almost 300 toises greater. A difference, so great, 

 he ascribes to the attraction of certain mountains near some of the stations. 

 A synopsis of the celestial and the terrestrial arcs here follow. 



Arc of the Celestial Meridian. 



VOL. XII. 



3S 



