ON THE SYSTEMS OF COSMOGONY. 
nntron, and the more difficult the arrange- 
ment, in the lifter so much greater will be 
the diminution of power in tlieele* tro-magnet. 
Again, if tlie electricity in the electro-magnet 
be easily arranged by the induction of the 
voltaic helix, it will be easily forced back to 
its natural state by the reaction of that belong- 
ing to the lilter. Hence it follows that when 
the inducins' power of the electro-magnet is 
very great (which it is when the lifter is in 
contact with its ends), it will possess sufficient 
\ ower to vanquish the coercitive force of the 
lilter, arrange by induction a large portion of 
the electricity of the lifter, and thus exhibit 
powei ful attraction. When the lifter is re- 
moved to a certain distance, one-tenth of an 
inch for example, the power of the electro- 
magnet being much diminished in conse- 
quence of the distance, whilst the difficulty of 
overcoming the coercitive force of the lifter is 
incieased, the effect will be very small com- 
pared with the former. For, if the inducing 
power be only equal to the coercitive foice 
of the litter, no attraction whatever will take 
place ; and hence the impossibility of mag 
netizing a large bar of steel tempered as hard 
as possible, by means of a small permanent 
magnet with a soft temper. 
Now, if the coercitive force of the electro- 
magnet be incieased, which is done either by 
employing a long magnet, or using hard iron 
or untempered steel, such a magnet will sui- 
4n 
fer a less diminution by the reaction of the 
lifter in the case of increased difficulty of 
arrangement in the lifter, than in the case of 
the short electro-magnet of perfectly soft 
iron. 
In the case of the permanent magnet of tem- 
pered steel, the electricity belonging to it was 
arranged with difficulty, and after repeated 
touches oi another magnet, and consequently 
it will easily vanquish the coercitive power of 
a piece of soft iron, and induce a magnetic 
state upon it, whilst the peculiar arrangement 
of its own electricity will remain nearly un- 
changed. Hence its attractive powers will 
diminish nearly as the squares of lire distances 
of the soft iron from its \)o\eSj or imaginary 
centres of accumulation, a law which cannot 
exist in the case of the electro-magnet the 
electricity of which is so easily put in motion 
i-oundthe elementary molecules of the iron by 
the reaction of the lifter. 
In the explanation given by Mr, Rainey 
the lifter is supposed to react powerfully on the 
electro;-magnet so as to increase its power, a 
supposition which cannot possibly be admitted- 
For the electro-magnet must, in the first place, 
give the lifter all its magnetic power, conse- 
quently the power of the lifter never can exceed 
tliat of the electro magnet, and consequently 
never can induce a higher magnetic state in it 
than what has already been done Iry the volatic 
helix. — Phil. Mag. for Aug» 1836, 
THE 
STUDY OF SCIENCE, 
A FAMILIAR INTRODUCTION 
TO THE 
PRINCIPLES OF NATURAL PHILOSOPHY. 
As, among our readers, there may he some who have not had opportunities of becoming' 
acquainted with the recent elaborate researches and ingenious speculations of learned men 
in the several departments of Natural Philosophy, we have determined to devote a certain 
number of pages monthly, to form a series of lectures in the several branches of science, by 
way of a familiar introduction to the study of Natural Philosophy with modern discoveries. 
GEOLOGY. 
{Continued from pa^e 349.) 
The proper object and design of geology, 
therefore, must be the study of the general 
structure of what may be termed the shell 
of the terrestrial globe ; for though specula- 
tions relative to the nature of the internal 
strata, or even the nucleus of the mass, are 
not wholly inadmissible, yet they must ever 
be regarded as of secondary importance, and 
should be no further pursued than they are 
•warranted by those facts and appearances 
■which come immediately under our observa- 
tion. This consideration, however, was 
entirely lost sight of by those earlier writers, 
who; either incidentally or professedly treat- 
ed of the earth. It would be profitless 
labour to pursue at length the reveries of a 
host of bold theorists, who sprung up be- 
tween the period of the rivival of learning in 
Europe and the middle of the last century ; 
and whose systems of cosmogony, as they 
vainly styled them, have by more sober in- 
quirers been justly stigmatized as romances, 
indebted for their existence to the prolific 
powers of imagination. 
But while so many philosophers were busily 
employed in endeavouring to erect systems 
of cosmogony on the basis of their own most 
imperfect knowledge of the nature of mineral 
bodies, or drew their ephemeral theories solely 
from imagination, there were some who more 
wisely applied themselves to the observation 
of nature, and to the collection of correct 
information relative to the productions of the 
mineral kingdom in general, and especially 
concerning those fossils which exhibit traces 
of having originated from organization. 
