Transcription: As the name implies, the cutting edge of a chainsaw is quite literally a chain, much like that found on a motorcycle, except that the chain is provided with a series of serrations or teeth. A sprocket wheel on the small but powerful petrol engine drives the chain around a groove in the cutting arm, and the chain and arm act effectively as the blade of a conventional handsaw. Chainsaws have been widely used in forestry for around 40 years. But apart from the many injuries caused by the blade itself, the fumes from a petrol engine in such close proximity to the user have also been a considerable ...