Levers; Wheel and Cogs

Eighteen months ago we first saw Maria and Mike Gordon's 'Simple Science' series and welcomed Maria's simply expressed ideas and Mike's expressly simple - but effective - pictures. That series has grown since, and has now spawned 'Simple Technology' in which illustrator Mike is joined by Caroline Rush on words. The result is as agreeable and assimilable as its predecessor. We observe the force-amplifying principle of the lever and its many involvements in daily life - from gardener's barrow to burglar's jemmy. Being, in effect, a rosette of radially arranged levers, a cogwheel is a force-amplifier too, and the basics of the wheel having been discovered the cog is a logical step, with the vicar's bicycle handily available to illustrate it.

This series promises Slopes and Pulleys next and should make a useful addition to infant technology shelves.