_Forest Fire History._ Very important also in fire protection are the studies which the Forest Service is carrying on, dealing with forest fire history. For many years back, records have been kept on all fires: their causes, area burned over, date of the fire, damage caused, the exact location of each fire, the cost of fighting it, the total number each month and each calendar year, and many other data. More recently records have been kept upon still further details connected with each fire, such as: the time elapsed between the start and the discovery of a fire, between the discovery and the report to the proper official, between the report and the beginning of the actual work of fighting, and the time required to put the fire out. Intensive studies have been made also upon the length and character of the fire season on each Forest, for it is important to know the maximum length, the minimum length and the average length of the fire season. These data show how much extra help must be hired for fire patrol and fire fighting, and during what periods the greatest damage is done, based both on acreage burned over and by the number of fires. Studies of this kind yield positive information on what areas of each Forest are particularly liable to lightning fires, to camp fires, and to incendiary fires. With this knowledge the Forest Supervisor can plan and distribute his men and funds more intelligently; they tell him during what period he can expect the most trouble, and therefore must have the greatest number of fire fighters at his command. It is scientific study like this that is doing more than anything else to solve the fire protection problem in the Western States. _Relation of Forest Fires to the Weather._ In coöperation with the United States Weather Bureau, the Forest Service studies weather conditions in relation to forest fires. Weather forecasts have been sent to each Forest Supervisor throughout the fire season, informing him of the probable weather conditions. The velocity and duration of the wind, the temperature, the precipitation, and the relative humidity are all factors which greatly affect the inflammability of the forest. Forest Supervisors have been informed in these forecasts of what are known as emergency conditions, that is, an unusual and abnormal combination of weather conditions which make fire danger very great. These conditions may be a high wind, low relative humidity, high temperatures, or a combination of the three. When a Forest Supervisor is informed by the District Forester that emergency conditions are likely to exist during the next ten days or so, he immediately sends an alarm to all his Rangers to be especially watchful.