If the problem of fire protection is the most important task confronting a Forest officer on the National Forests, then certainly fire prevention is next in importance. Obviously it is easier to prevent fires than to fight them. All large conflagrations have their origin in small fires which if they could be reached in time could probably be put out by one man. But in regions remote from water and supplies fires may start and reach vast proportions before a party of fire fighters can get to the scene, no matter how promptly the start is made. By far the best plan, therefore, is to prevent fires rather than to depend upon fighting them after they get started. To this end the Forest Service has given the most earnest consideration. During the dangerous season the main attention of Forest Supervisors and Forest Rangers is devoted to preventing fire. Extra men are employed, the Forests are systematically patrolled, and a careful lookout is maintained from high points. Roads and trails are so built that every part of the Forests may be quickly reached with pack animals. Tools and food for fire fighters are stored at convenient places. The Ranger stations and lookout houses are connected with the office of the Forest Supervisor by telephone, so that men may be quickly assembled to fight a dangerous fire which the patrolman cannot subdue alone. Each Forest Supervisor endeavors to secure the coöperation of all forest users in the work of preventing fires and in reporting and helping to fight them in case they get started. Probably the beginning point of any discussion of forest fires is a consideration of their causes. The Forest Service has kept careful records year after year (by calendar and not fiscal years) concerning the cause, the damage, the area burned over, the cost of fighting and many other matters. During the calendar year 1917 there were 7,814 forest fires on the National Forests. Of these the National Forests of California had to contend with 1,862. Of the total number of forest fires 40 per cent. were confined to less than 1/4 of an acre, 28 per cent. to less than 10 acres, while 32 per cent. spread over areas greater than 10 acres. The large percentage of small fires shows how efficiently the National Forest fire protection organization works in keeping the area burned over to the lowest possible acreage.