220 Mr. Scoresby’s experiments and observations on the 
magnets ; and that percussion has a tendency to develope 
polarity in iron and steel not previously magnetic. Both 
these propositions are undoubtedly true ; but they are under 
different conditions. Percussion, whilst it diminishes the 
energy of a magnet when held alone, or even upon an iron 
bar, would probably augment its energy if it were placed 
with consistent poles in contact with a more powerful magnet, 
which is the condition of wires magnetised by percussion ; 
because, if they be hammered upon a substance not mag- 
netic, little or no energy is developed. [See Experiment 
No. X.] These different effects would appear to be the 
necessary result of a tendency to equality of condition — a 
tendency which is precisely similar in respect to bodies of 
unequal temperatures when placed in contact, or even in 
juxta-position. For as a hot body placed near, or among, 
cold substances of greater mass and capacity than itself, has 
its temperature brought down nearly to the state of the colder 
substances, whilst a cold body has its temperature raised by 
contact with hot substances ; in like manner, a strong magnet 
hammered upon an iron rod, has its energy brought down 
towards the condition of the iron ; and a bar not magnetic, 
or slightly so, hammered upon the same rod, has polarity 
developed in it, and raised progressively up to the condition 
of the iron. 
As I apprehend it would be in vain to attempt to produce 
such strong magnetic effects, as we derive from percussion, 
by the simple use of the same bars and apparatus in any of 
the known modes of touching , it becomes probable that this 
process might be applied, in connection with other modes of 
magnetising, for giving increased power to magnets. The 
