G 21860 ) | April, 
Vv. SIR JOHN HERSCHEL AND MODERN 
ASTRONOMY. 
Astronomy is remarkable, as the solitary example of a science, for 
which exactness has been secured by the elucidation of the laws 
reculating a power which is associated with every form of matter. 
The laws ruling the influences of that power or principle, as exerted 
through space, have been developed with a clearness which removes 
every shadow of doubt. 
When Newton determined by the most careful examination of 
facts, and by the penetrating power of his mental analysis, that 
every body circulating in space, was compelled to move in obedience 
to the force of Gravitation, acting according to the law of the 
inverse square, he furnished the key by which all astronomical 
problems connected with “the stars in their courses” could be 
solved.—The stone flung into the air by the playing child—the 
ball projected at high velocity from a piece of artillery—the planet 
rolling with majestic regularity across the celestial vault—the twin 
and triple stars circulating mysteriously about each other in the 
remoteness of the heayens—the yet inscrutable nebule—and the 
space-exploring comets,—are, each and all, equally bound to move 
in obedience to a force, of which we know only the daw of action. 
But the knowledge of this law has placed a wand in the grasp of 
the astronomer, by which he feels out worlds, ere yet they are 
visible to human sense. 
Every reflecting mind will naturally inquire, What is this all- 
pervading power which we call Graviratton, binding the Moon to 
the Earth, the Planets to the Sun, and the Solar System itselt, to 
some immeasurably-distant star; which, though it be the centre of 
motion to our small group of planets, may be itself but’the satellite 
of some yet grander luminary—distributing its energies from depths 
of space to which no telescope has ever penetrated? And such a 
mind—while impressed with the immensity of power displayed— 
will ever feel its littleness when compelled to own, that of the cause 
of that power it is deeply ignorant. 
“The law of Gravitation,” says Sir John Herschel, “ the 
most universal truth at which human reason has yet arrived— 
expresses not merely the general fact of the mutual attraction of 
all matter; not merely the vague statement that its influence 
decreases as the distance increases, but the exact. numerical rate 
at which that decrease takes place; so that when its amount is 
known at any one distance, it may be calculated exactly for any 
other.”* 
* «A Preliminary Discourse on the Study of Natural Philosophy.’ 
