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permanent magnets were four times as strong, and the 
electro-magnets passed § of an inch from them, doubtless W 
would be greater, but so also would (a — b), and it does not 
W 
follow that , -r with which we are concerned would be at 
(a-b) 
all changed. What becomes then of the dogmatic assertion 
that the duty of a grain of zinc could he increased tenfold ? 
Now let us turn to the paper in the “ Quarterly Journal.” 
Here we may find enough in one article for our present 
purpose, taking chap. II. Art. 2. — “ Why are we forced to 
suppose that the same amount of fuel produces the 
same amount of energy, whether it is consumed in the steam 
engine, the horse the gnat ? At any rate, we may 
observe that the very phrase is certainly a misnomer, and a 
misnomer of such a kind as to have a fatal effect in pro- 
ducing a false conception of things. For mechanical energy 
just as often produces cold as heat ; it may produce either 
heat or cold, or neither. In fact, as a general rule, though 
with notable exceptions, every pushing or compressing force 
produces heat, and every pulling or expanding force cold. 
Place a weight on a pillar, and the weight produces heat in 
the pillar ; hang it on a wire and it cools the wire.” “ In ex- 
actly the same way, in a fire-syringe use force to press down 
the piston, it produces heat — heat enough to kindle tinder ; 
but use the same force to pull up the piston, and it produces 
cold.” Surely this is enough to show that the author’s notions 
of what he is attacking are, to say the least of it, shallow; 
for what he quotes as paradoxes are simple deductions from 
the two laws of Thermodynamics. That a wire is cooled by 
stretching follows from the fact that heat expands it. In 
the case of the fire-syringe the case is simpler. The work- 
ing body is the air in the syringe ; on pulling up the piston 
this air does work, and therefore uses up heat and is cooled. 
Mr. Highton seems to imagine that because the arm of the 
experimenter does work, it is done on the air in the syringe, 
whereas this column of air and the observer are really 
co-workers in raising the air external to the cylinder. 
To point out all the fallacies of these papers in detail 
