As mankind moved from primitive to more civilised ways of living, it began to use machines more and more. The history of civilisation almost parallels the ever-widening use of  machines. The reader can learn in this How and Why Wonder Book all about machines no matter how complex they appear. These machines seem to be a combination of two or more of six simple ones – the lever, the inclined plane, the wedge, the screw, the wheel and axle and the pulley.  This book describes clearly how each type of machine is useful in applying force in order to make work easier. This publication like several others in the How and Why Wonder Book series includes several interesting experiments. By carrying out these experiments children will discover some laws of machines for themselves and see why it is that we  depend on machines to do much of the world’s work.

paperback  – showing some wear and tear and discolouration of pages – in a reasonable condition in view of age ( 1960)