194 ESSAY ON CLASSIFICATION. 



Neptune . . 60,129 . . 62,000 . 



Uranus . 30,687 . . 31,000 . i 



Saturn . 10,759 . . 10,333 . 



Jupiter 4,333 . . 4,133 . 



Asteroids.. 1,200 to 2,000 1,550 . . 



Mars . 687 . . 596 .. -fr 



Earth 365 . 366 . T 8 T ) _ 8 _ 



Venus . 225 . 227 . |f I T 



Mercury . 88 .. 87 . . f 



In this series the Earth forms a break ; but this appa- 

 rent irregularity admits of an easy explanation. The 

 fractions, | i, f , f, ?, 8 r , if > etc., as expressing the posi- 

 tion of successive leaves upon an axis, by the short way 

 of ascent along the spiral, are identical, as far as their 

 meaning is concerned, with the fractions expressing these 

 same positions, by the long way, namely, i, f, f, |, ^, 



-L-3_ 2.1 



21) 34) 



Let us therefore repeat our diagram in another form, 

 the third column giving the theoretical time of revolution. 



Neptune . . }- . . 62,000 . . 60,129 



. . . . . 62,000 . . 



Uranus -. . . 31,000 . . 30,687 



- i . . - . 15,500 . . 



Saturn . f . . . 10,333 . . 10,759 



. f . . . 6,889 . . 



Jupiter . . f . . . 4,133 . . 4,333 



. f . . 2,480 . . 



Asteroids . f . J,550 . . 1,200 



. . | . . . 968 .. 



Mars . J T . . . 596 .. 687 



Earth f 8 T 366 . . 365 



Venus . -Lf- . 227 .. 225 



i-f ... 140 .. 

 Mercury . f-i . 87 88 



It appears, from this table, that two intervals usually 



