oi tas OF 
PHILOSOPHICAL MAGAZINE 
AND JOURNAL. 
I. On the Nature and Laws of Friction. By Mr. Tuomas 
TREDGOLD. 
Tue great perfection to which the art of constructing machines 
has arrived in this country would lead a person, unacquainted 
withthe real nature of its progress, to imagine that the laws which 
regulate the motion of bodies had been deeply studied ; and that 
every aid which reason or scientific experiment could give, had 
been successfully employed to surmount the natural difficulties of 
the subject. 
- This, however, is not the case; as it has been through repeated 
trials, and tentative methods only—attended with an immense 
loss of capital—that this perfection has been attained : and it is 
a lamentable fact, that even now the knowledge of machinery is 
so much confined to particulars, and exists in so detached and 
unconnected a state, that were any sudden revolution to happen 
in the affairs of this country, the greater part of it would be 
buried in oblivion. 
One great defect in the theory of machines is the want of pro- 
per formule to calculate the effect that can be produced by a 
given power; and one of the most common causes of failure is 
our imperfect knowledge of the nature, laws, and quantity of 
friction. 
How often has an ingenious machine been contrived with the 
fairest prospect of success, but, when tried on a large scale, it 
has either been racked to pieces in a few months by requiring a 
greater moving power than it was calculated to sustain—or it 
has been totally inefficient for its intended purpose ? 
Long practice may give the power of erecting machines of the 
same kind with tolerable success, under a considerable differenee 
of moving power; but this very practice must have arisen out of 
repeated trials, and is generally dear-bought wisdom, though 
seldom at the mechanician’s own expense. 
In whatever manner an effect is produced by the intervention 
Vol, 53, No. 249. Jan, 1819. A2 of 
