ga PHILOSOPHICAL TRANSACTIONS. [aNNO 17 14. 



Observations made at Rome, Nov. 21 in the Morning, N. S. 1713, on the 

 Occultation of the Star t at the Root of the BulPs Northern Horn, by the 

 Moons Disk ; also an Eclipse of the Moon presently after ; with some Emer- 

 sions of Jupiter s First Satellite out of his Shadow. By Sig. Bianchini, F.R.S, 

 N° 340, p. 88. Translated from the Latin. 



At 12h. 54m. 34s,, the star marked t by Bayer was just occultated by that 

 part of the moon nearly in the middle between the maculae of Aristarchus and 

 Galilaeus. 



At 14h. Om. 14s. Si ri us is in the meridian ; whence the times are verified. 



At 14h. 32 m. 57 s., the star t, which had emerged some minutes from be- 

 hind the moon, in its diurnal revolution, precedes the moon's western limb by 

 33s. of time, and the moon's centre by 103s. or 1 m. 43s. of time. 



At 15h. the penumbra on the moon's limb, which before was more dilute, 

 gradually becomes more dense. 



At I5h. 4 m. 20s. the moon, in that part of her limb next the macula 

 Schiccardi, begins to enter into the true shadow. 



At 17h. 27 m. 45s. the moon quite emerged from the true shadow. 



Sept. -14, at 8h. 38m. 20s. anno 1713, at Rome, Jupiter's first satellite 

 emerged. — At 8h. 44m. the 3d satellite exactly covered the 4th. — Sept. -Lf, at 

 lOh. 36m. 23 s. the first satellite emerged out of Jupiter's shadow. — Nov. 4-f, 

 at 7 h. 32 m. 22s. the first satellite emerged. — Nov. 28 O. S. or Dec. 9 N. S. at 

 5h. 45s. the first satellite emerged. — Dec. 21 O. S. at 5h. 50m. 22s. the first 

 satellite again emerged from Jupiter's shadow. 



From these observations, accurately calculated, it is plain, that the second 

 equation, which we suppose to arise from the progressive motion of light, does 

 necessarily take place : for, after 57 revolutions of the first satellite, in which 

 Jupiter receded from the earth more than the radius of the orbis magnus, the 

 last eclipse was seen almost 9 minutes later than it should have been, according 

 to the tenor of the first observation ; which agrees with Cassini's Hypotheses. 

 From the same observations it is also plain, that the motion of Jupiter's first 

 satellite is somewhat swifter than by Cassini's very accurate tables ; yet that 

 inconsiderable error seems scarcely to exceed 2 minutes of time, in each 

 revolution of Jupiter, or in 12 years, by which the heavens anticipate 

 Cassini's calculation : but with this correction, the agreement will be pretty 

 accurate. 



