SPREAD AND SEVERITY OF FOREST FIRES 259 



companiment of every severe surface or crown fire. Figures 

 taken from the report of the State Forester of Connecticut for 

 1916 illustrate the effect of high winds. Two weeks of dry 

 windy weather culminating in two days of high winds on 

 May nth and 12th proved to be the worst fire season of the 

 year. "Of the sixteen fires reported during the year as ex- 

 ceeding one hundred acres in extent, ten occurred on these 

 two days. The total acreage of these ten fires was reported 

 as approximately twelve thousand, — nearly 60 per cent of 

 the entire acreage burned in the state during the year." ^^ 



Precipitation. — Moisture is the controlling factor govern- 

 ing the inflanmiability of fuel. During rainy periods or 

 seasons when the ground is covered with snow fires rarely if 

 ever are able to run. 



In seasons of low precipitation the danger from fire is great 

 and rises rapidly with a lengthening of the drouth. Very 

 slight precipitation is soon evaporated and is of small and 

 temporary value in reducing inflammability. 



Relative Humidity. — The relative humidity of the atmos- 

 phere has an important effect on the inflammability of fuel,' 

 since the latter either absorbs moisture from the air as the 

 relative humidity rises or evaporates moisture as it falls. The 

 chief significance from the forest fire standpoint of cloudy 

 versus suimy days, of hot versus cold days and of day versus 

 night is found in the changes in relative humidity which ensue. 



Methods of Forest Fire Protection. — The methods of ob- 

 taining protection from forest fires may be summarized under 

 four heads. 



I. The elimination of the causes from which forest fires 

 originate. 



As the gathering of statistics on forest fires has progressed, 

 the numerous causes from which forest fires originate have 

 been classified under eight major sources. The last published 



