24 CARNOT. 
day, beyond the limits of science), the movement effected 
would be hardly the breadth of a hair. 
If the ideal machine, the machine endowed with all 
imaginable perfections, adds nothing to the force which 
puts it in action, at any rate it takes nothing away from 
it; it transforms the effects by rigorous equivalents. It 
is not thus with a real machine; in this case the power 
and the resistance communicate with one another by 
means of pieces which we had supposed inflexible, and 
which are not so; by means of chains and cords whose 
roughness cannot but be injurious; the movable parts, 
moreover, turn in collars or sockets where great friction 
takes place; all these causes united absorb in pure loss 
a very noticeable part of the motive force; so that the 
effect of a machine must always be inferior to that which 
would have been engendered by the power acting directly 
on the resistance. 
These results of theory, which are, moreover, com- 
pletely confirmed by experience, yet allow that, under 
certain points of view, some particular machine may be 
recommended without paradox; that it may be useful 
and often even indispensable. For instance, considerations 
of solidity or ornament necessitate the carrying to the sum- 
mit of certain edifices blocks of stone or marble whose 
weight is beyond the strength of the most vigorous work- 
man; suppress the windlass and analogous machines, 
and one man will no longer be able to execute the work 
which the architect has conceived ; it will be necessary 
to unite the strength of thousands of arms at the same 
point; the narrowness of space will prevent that; the 
character of grandeur will disappear from all the monu- 
ments of architecture; the triumphal arch, the * palace, 
will only be constructed, like the humble cottage, of 
little rough stones. 
