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184 ESSAYS ann OBSERVATIONS 
5 eB 
Concerning the fudden and furprifing Changes 
obferved in the Surface of Jupiter’s Body ; 
by the fame. 
HERE have been more fudden and 
| furprifing changes obferved on the 
furface of Fupiter’s body, than on any other 
planet in the fyftem. Cafini has obferved 
'feveral belts rife on his body in one hours’s 
time; and fpots, in very different forms, are 
often feen upon him. I could with that the 
pofition of his fatellites were well confidered 
when thofe changes happen: for, fince Fu- 
piter has four moons, fome of which are 
much nearer to him than our moon is to the 
earth; when they are all in conjunction or 
oppofition to one another, very great tides 
muft be produced in the ocean there, if there 
be any; and there is ground to fufpec that 
thefe fudden and great changes on his fur- 
face are owing to tides analagous to thofe we 
call 
