42 JOURNAL AND PROCEEDINGS. | 
In the meanwhile the language of the Kinetic Theory is almost 
indispensable in teaching Science, and probably for a long time yet 
the song of the molecules will continue to be sung ; but more stress 
than at present customary should be laid on the fact that this theory 
is merely a theory, an hypothesis, a metaphorical representation of 
nature—bearing the same relation to the truth that a power diagram 
does to a steam engine,—and that it is not in any sense to.be regarded 
as a ‘‘ discovery of the inner life of matter.” 
