While considering the subject of personal safety, churches must not escape notice. The occurrence of fire in a church is by no means an uncommon event. The heating apparatus in close proximity to the organ is a common cause of fire. Although the outbreak may be small, the consequent panic may result in many fatalities. Provision for rapidly emptying a church is, however, rarely made, although many disastrous church fires have proved its necessity. Thus the width of aisles and door openings should be ample, while doors should open outwards, and should never be locked while a service is being held. Gallery staircases should be planned on the same principles as those discussed in reference to theatres: they should lead directly to the open air, and must never lead to an exit to be used in common with people from the floor of the church.