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VI I r. Ajlronomical Obfervations, In iwO Letters from M. 

 Francis de Zach, Profeffbr of Mathematics, and Member of 

 the Royal Academies of Sciences at Marfeilles, Dijon, and 

 Lyons, to Mr. Tiberius Cavallo, F. R, S. 



Read December 23, 1784. . 



SIR, Lyons, ApfH 4, lySj.' 



1SEND you the account of the obfervations on the eclipfc 

 of the moon, which I have made together with the rev. 

 Father le Fevre, Aftronomer at Lyons, in the Obfervatory 

 called au grand College i to which I fliall add the obfervations of 

 the vernal equinox ; fome obfervations on Jupiter's fatellites, 

 made at Marfeilles by M. Saint JacoLJEs de Sylvabelle ; 

 and, laftly, a new fblution of a problem that occurs in com- 

 puting the orbits of comets. If you think that thefe obferva- 

 tions do in any way deferve the notice of the Royal Society, I 

 fhall be v^ery glad you would communicate them. In order to 

 afcertain the going of the pendulum clock, I took feveral cor- 

 refponding altitudes of the fun, which you will find in the fol- 

 lowing table. On the day of the ecliple the Iky was very 

 ferene, nothing could be finer, and it continued fo during the 

 obfervation. I determined to ufe an achromatic telefcope of 

 3! feet length, that fhews obje<Sls in their natural pofition, be- 

 caufe the dikited and uncertain te<"mination of the true fhadow 

 of the earth appears more perfectly defined by fmall than by 

 Vol. LXXV. T ' large 



