Experiments on Vibrating Surfaces. 389 



mountain of Infelberg, with chronometers, fextants, and arti- 

 ficial horizons of different forms, in order to compare them; 

 and I am fully convinced that the geography of Germany 

 will foon be improved by the ufe of thefe inftruments, which 

 M. von Zach has recommended and made better known. 



This ufeful congrefs would perhaps have been more nu- 

 merous ; but M. Vega wrote to me from Auftria, that he was 

 not able to obtain permifiion to meet us at Gotha ; and, 

 what is ftill worfe, he was obliged to fend my letter, and 

 his own anfwer, to the minifter for his infpe&ion. The 

 king of Prufiia, on the other hand, made an addition of 

 j 200 livres to the allowance of his aftronomer on account of 

 this journey. The aftronomer of Gottingen, though a fub- 

 je& of the king of England, experienced no difficulty. 



An Engliffi Journal had hinted to the duke of Gotha, 

 that a French aftronomer might perhaps be employed with 

 other revolutions than thofe of the heavenly bodies ; but I 

 did not find that this fuggeftion diminiflied in the leaft the 

 favourable reception I had been taught to expecl. We at 

 laft feparated, after being fully convinced of the utility of 

 fuch conferences, and with a refolution of renewing them as 

 often as we could *. 



[To be concluded in next Number.] 



IX. Obferuations and Experiments in regard to the Figures 

 formed by Sand, Gfcr. on Vibrating Surfaces, by J. G, 

 Voigt. From Neues Journal der Phyfik, by Profejfor 

 Gren, Vol. Ill 



Dr. CHLADNI of Wittemberg, by his experiments on 

 vibrating furfaces, in the year 1787, opened a new field in 

 mechanics, viz. the confideration of the curves formed by 

 furfaces put in a ftate of movement, His difcoveries, there*- 



* For Profeflbr Rodc's account of this meeting of aftioiiomers, lee 

 p. 314 of the prcfent volume. 



C c 3 fo«j 



