Lightning might set the grass afire; a match carelessly dropped by the cigarette-smoker; a camp fire not properly put out; or any mischievously-inclined individual might set the whole country ablaze.
Indeed, the greatest prairie fire I have record of was maliciously started to windward of my ranch by an ill-disposed neighbour (one of the men whose cattle the Scotch Company had closed out and who ever after had a grudge against me) purposely to burn me out.

He did not quite succeed, as by hard fighting all night we managed to save half the grass; but the fire extended 130 miles into Texas, burning out a strip from thirty to sixty miles wide.

On account of a very high wind blowing that fire jumped my "guard," a term which needs explanation.

All round my pasture, on the outside of the fence, for a distance of over forty miles was ploughed a fire-guard thus: two or three ploughed furrows and, 100 feet apart, other two or three ploughed furrows, there being thus a strip of land forty miles long and 100 feet wide.

Between these furrows we burnt the grass, an operation that required great care and yet must be done as expeditiously as possible to save time, labour and expense.