Quotation from: General Science

Written by: Bertha M. Clark

166. Compound Machines. Out of the few simple machines mentioned in
the preceding Sections has developed the complex machinery of to-day.
By a combination of screw and lever, for example, we obtain the
advantage due to each device, and some compound machines have been
made which combine all the various kinds of simple machines, and in
this way multiply their mechanical advantage many fold.