384 Hijlorjy of AJlronomy for 179S. 



Our labour is more important, finceit gives the exact pofitiori 

 of all the ftars which aftronomers may have occalion to ufe. 

 Herfchel obferves only things invifible, and aftronomcrs have 

 need of fenfible objects that are always prefent to their view. 



We may therefore fay of C. Lefrancais, what Virgil faid 

 of Palinurus : Sydera cuncla notal tac'ilo labcnt'ia carlo ; for he 

 has really clone what Palinurus never did. C. Lefrancais has 

 already reduced 6000, and he promifes 40CO for the prefent 

 year, though each requires thirty-fix operations. In the 

 month of September T caufed to be erected in the Military 

 School a new meridian telefcope by Lenoir, with a 

 large object-glafs by Caroche : it is better placed than the 

 former; the fupports have no connection with the roof, and 

 the inftrument is lefs fubject to vary by the changes of tem- 

 perament. With this inftrument we ihall continue to deter- 

 mine the right afcenfion of the principal ftars of nil our zones 

 of fifty thoufand. 



The theory of phvfical aftronomyhas alio had a remarkable 

 epoch this year. C. Laplace, to whom we are indebted for 

 an explanation of the acceleration of the moon, has found 

 that the apogeum and node have likewife fecular equations; 

 and this noble difcovery has been confirmed by a great num- 

 ber of obfervations. It would be ufeful to confirm it ftill far- 

 ther, by the obfervations of the middle ages, of which there 

 are a few. The manufcript of Ibn-Iunis, an Arabian of the 

 tenth century, contains valuable obfervations : the original is 

 at Leyden, and we have made fruitlefs efforts to obtain a 

 copy of it. C. Cauffin, one of our profeffors of Arabic, of- 

 fered to go to Leyden and copy the obfervations ; but I have 

 found a copy among the manufcripts of J. Delifle, my pre- 

 deceffbr in the College de France, and I hope we ihall loon 

 have the refults of thefe valuable obfervations. 



On the 19th of March, the Inftitute propofed, as the fub- 

 ject of a prize, a comparifon of 500 obfervations of the moon, 

 with the tables to determine better the 22 equations which 

 we employ at prefent for the moon's motion; and I already 



know 



