GEOLOGY AND EVOLUTION. 289 
tion to the plane of its orbit. The various moons are in their places, and Saturn 
has his rings. 
Thus far, however, all these miniature celestial bodies have been in a state 
of quiescence. Presently Signor Perini, by simply turning a key, sets the solar 
system in motion, slowly or swiftly, as he pleases. The sun turns on his axis, 
and the planets revolve around the sun in proper elliptical orbits, which are 
traced around the inside of the dome, which is 14 feet in diameter at its base 
and 14 feet high. By an ingenious watch-work arrangement inside the earth, 
which is the size of a walnut, our world is made to revolve on its axis, which 
latter always points to the same quarter of the heaven. In like manner the moon 
goes round the earth. 
The machinery is arranged in the chamber above the dome, clock-work 
being the motive power, the originality in the arrangement being the method by 
which the inventor effects the elliptical motion of the planets. Not a sound is 
heard ; the machinery works, like its great prototype, in solemn silence. 
Signor Perini, who has been prompted to this work solely from the enthusi- 
asm of a mechanician, has devoted his nights and mornings to this structure for 
seven years, and has spent on it about £700. The earth alone cost £40. The 
planetarium can be made of any size, from the dome of St. Paul’s to a little 
thing that might be used for school instruction. It is now standing at 77 New- 
man Street, Oxford Street.—London Graphic. 
ChE ONL 
GEOLOGY AND EVOLUTION. 
BY THE LATE PROF. B. F. MUDGE. 
CHAPTER VI.—ARTICULATES. 
‘CRUSTACEANS. —TRILOBITES. —DEFECTIVE RECORDS. 
: The fourth sub-kingdom of animated nature, the Articulates, appears with 
the first fossils of the lower sub-kingdoms, at the opening of the Silurian Age. 
By the symmetrical laws of evolution, these should have made their appearance 
only after time had allowed them to become developed from the lower sub-king- 
-doms. It is also not a little remarkable that with the first evidence of any of 
_ this division we find distinct traces of a class of animals whose bodies had no 
solid substance. The trails of worms (Annelids) with casts of their burrows re- 
main to show their existence, and 185 different species have been described from 
the Silurians. ‘Their existence affords us another significant fact, that animal life 
however soft or frail, may show its character, even from the oldest geological 
Iv—19 
