46 Mr. J. S. Stuart Glennie on the 
12. The theory of electricity here proposed is the develop- 
ment of the idea of the tension of atoms as above defined. Hence 
it is an immediate, not a mediate, mechanical conception of the 
phenomena ; for the conceptions of atoms or of centres of lines 
of pressure are not hypotheses, but convenient forms of the 
general conception of the parts of matter as mutually repelling. 
And the ground of the theory is this, that if matter is so con- 
ceived, experimental facts may themselves at once, and with- 
out the aid of hypothetical virtues or ethers, be mechanically 
conceived. For the theory has arisen from finding that the 
more simply facts were worded the clearer expressions they 
became of the general laws of motion; and that hypotheses 
only obscured the meaning and necessity of the relations of 
phenomena. It should therefore seem to be here sufficient 
briefly but clearly to express the conception of tension in its 
general relations, without entering into any detailed explanation 
of how it applies to different phenomena; for if there is any 
truth in the theory, such application ought at once to appear to 
those who can look at phenomena, and not at their hypothetical 
representations only, at least admissible. The clear proof that 
phenomena can be thus immediately (from a general conception of 
matter, and without aid of hypotheses) mechanically conceived, 
rests, of course with analysis, on the data of recorded and fur- 
ther experiments. 
13. Little more, therefore, will here be offered than prima 
facie evidence of the truth of the theory. The above considera- 
tions suggest that this may perhaps best be given by a state- 
ment of those general mechanical conceptions of (I.) the nature, 
(II.) the states, and (III.) the effects of electricity, which appear 
to be rather inductive generalizations of phenomena than hy- 
potheses by which they are to be explained. A few experi- 
mental facts will be recalled under each head, but rather as 
suggestive of others than as by any means exhaustive of those 
which might be cited in support of these generalizations. 
14, As to (I.) the nature of electricity: it is conceived as a 
permanent (not alternating) displacement of molecular centres of 
lines of pressure. Hence duality and polarity. For by such 
displacement there is evidently a tendency to produce motion 
of opposite characters in opposite directions ; the pressure of the 
lines being increased in the direction of displacement, and cor- 
respondingly diminished in the opposite direction. Hence also 
the identity of the various forms in which electricity may be de- 
veloped; the various conditions of such displacement differing only 
in intensity and quantity; and these being inversely as each other. 
For if intensity is conceived as amplitude of displacement, it is 
clear that, as the condition of a great displacement of a centre of 
