ADDRESS. ΧΧΧΥ 
What its size was would seem to be a problem beyond the grasp of reason. 
But human genius has been permitted to triumph over greater difficulties. 
The planet Neptune was discovered by Adams and Le Verrier, before a ray 
of its light had entered the haman eye; and, by a law of the solar system 
recently announced tothe world, we can determine the original magnitude 
of the broken planet long after it has been shivered into fragments; and we 
might have determined it even after a single fragment had proved its exist- 
ence. This law we owe to Mr. Daniel Kirkwood of Pottsville, a- humble 
American, who, like the illustrious Kepler, struggled to find something new 
among the arithmetical relations of the planetary elements. Between every 
two adjacent planets there is a point where their attractions are equal. If 
we call the distance of this point from the sun the radius of a planet’s sphere 
of attraction, then Mr. Kirkwood’s law is, that in every planet the square 
of the length of its year, reckoned in days, varies as the cube of the radius 
of its sphere of attraction. This law has been verified by more than one 
American astronomer ; and there can be no doubt, as one of them expresses 
it, that it is at least a physical fact in the mechanism of our system. This 
law requires, like that of Bode, the existence of a planet between Mars and 
Jupiter; and it follows from the law that the broken planet must have been 
a little larger than Mars, or about 5000 miles in diameter, and that the length 
of its day must have been about 575 hours. ‘The American astronomers 
regard this law as amounting to a demonstration of the nebular hypothesis 
of Laplace ; but we venture to say that this opinion will not be adopted by 
the astronomers of England. 
Among the more recent discoveries within the bounds of our own system, 
I cannot omit to mention those of our distinguished countryinan, Mr. Lassell 
of Liverpool. By means of a fine twenty feet reflector, constructed by 
himself, he detected the only satellite of Neptune which has yet been dis- 
covered, and more recently an eighth satellite circulating round Saturn—a 
discovery which was made on the very same day, by Mr. Bond, Director of 
the Observatory of Cambridge in the United States. Mr. Lassell has still 
more recently, and under a singularly favourable state of the atmosphere, 
examined the very minute, but extremely black shadow of the ring of Saturn, 
upon the body of the planet. He observed the line of shadow to be notched, 
as it were, and almost broken up into a line of dots, thus indicating mountains 
upon the plane of the ring—mountains, doubtless, raised by the same in- 
ternal forces, and answering the same ends, as those of our own globe. 
In passing from our solar system to the frontier of the sidereal universe 
around us, we traverse a gulf of inconceivable extent. If we represent the 
radius of the solar system, or of Neptune’s orbit (which is 2900 miilions of 
miles), by a line two miles long, the interval between our system, or the orbit 
of Neptune, and the nearest fixed star, will be greater than the whoie cir- 
cumference of our globe—or equal to a length of 27,600 miles. The pa- 
rallax of the nearest fixed star being supposed to be one second, its distance 
from the sun will be nearly 412,370 times the radius of the earth’s orbit, or 
13,746 times that of Neptune, which is 30 times as far from the sun as the 
earth. And yet to that distant zone has the genius of man traced the 
Creator’s arm,—working the wonders of his power, and djffusing the gifts of 
his love—the heat and the light of suns—the necessary elements of physical 
and intellectual life. 
It is by means of the gigantic telescope of Lord Rosse that we have be- 
come acquainted with the form and character of those great assemblages of 
stars which compose the sidereal universe. Drawings and descriptions of 
