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at present. The second meaning connotes objective heat, 
the force heat, that phenomenon of matter whose effects we 
can measure in certain definite ways. It is with this 
second meaning that we are concerned to-night. Having 
limited our subject somewhat, I wish to limit it further. 
The science of heat concerns itself with two main subjects, 
first, the transcendental problems which deal with the 
nature of heat, which endeavour to explain it as a form of 
motion, &c., 8zc. These conclusions may or may not be 
eventually confirmed by experience. At present they are 
powerful and ingenious theories which enables us to map 
out our knowledge to arrange and classify it, but I humbly 
crave permission to doubt whether any of them may be 
considered a final solution and pro tanto, I must have my 
hands free. This is not really of consequence in our dis- 
cussion to-night, for I have no intention of entering into 
such a difficult and crooked controversy. The nature of 
heat is, in fact, outside our present subject. Eschewing the 
transcendental problems we shall very briefly consider only 
the direct effects of heat upon matter. So far then as our 
experience can take us heat is a peculiar condition or 
phenomenon of matter, which we can modify, increase, or 
lessen, which is universally present in greater or lesser 
intensity, and which we measure relatively by a com- 
parison with a certain fixed standard. However 
duced, whether by chemical action, by percussion, by 
friction, &c., &c., there is one result which seems uni- 
versal and which may be considered to be the corre- 
lative of heat. This result is universally present and 
modified in various ways it is probably the only result. So 
that if we- exclude the feeling of heat we may define heat 
by using this result as an alternative term. The addition and 
abstraction of heat are correlative respectively with an in- 
crease and decrease in the bulk of the matter operated upon. 
If we add heat we increase the bulk of the substance ope- 
