The Forest Fire Danger Index (FFDI) was originally invented by the grandfather of Australian bushfire science, Alan Grant McArthur, during the 1950s and ‘60s. Alan published his landmark paper, “Controlled burning in eucalypt forests” in 1962. Leaflet No. 80, as it was known, proved a turning point for forest and fire managers across Australia. More importantly, Alan was very practical forester and wanted his work to be useful to people in the field, so after several iterations he came up with the now familiar circular slide rule called the Forest Fire Danger Meter (FFDM). The Mk 4 version first appeared in operational use in 1967. This is the Mark 5 from 1992Alan McAthur's scientific legacy with the FFDI meter is unquestionably huge and has served forest firefighters very well over the decades.Control burning meter Series of circular slide rules to calculate Forest Fire Danger Index (FFDI)bushfire, forests commission victoria (fcv)